Blog List

Wednesday, 8 June 2016

Power Foods for the Workplace

Power Foods for the Workplace
Photo Credit LDProd/iStock/Getty Images

Overview

It's that time of day and you're zoning out. Lethargy kicks in, your eyes glaze over and your head is dangerously close to the keyboard. You've hit the midday slump.
But you're not alone in this crash. People often begin craving coffee or snacks from the vending machine at around 2 or 3 p.m.
"They want a pick-me-up," said Sheah Rarback, registered dietitian and director of nutrition for the Mailman Center for Child Development at the University of Miami, "due to the plunge of energy level caused by our natural circadian rhythm, not getting a good night's sleep, skipping breakfast or eating a lunch of processed carbohydrates without added protein."
The secret is to power up ahead of time, lessening, or even preventing, the collapse. Still, all is not lost if you failed to fuel up; there also are immediate options. Just avoid grabbing sugary snacks that give you an initial rush but leave you more tired and hungry an hour later.
The best fare for preventing or defeating the afternoon skids combine fiber and protein, are low in fat and sugar, and provide less than 200 calories.

The plunge of energy [is] caused by our natural circadian rhythm, not getting a good night's sleep, skipping breakfast or eating a lunch of processed carbohydrates without added protein.

- Sheah Rarback, registered dietitian and director of nutrition for the Mailman Center for Child Development at the University of Miami

Beat the Slump

Quick tips to help avoid the midday crash:
• Don't skip breakfast.
• Eat a well-portioned lunch. Not eating enough will leave you with few nutrients and little energy. Eating too much will make you bloated and sluggish.
• Get at least eight hours of sleep at night.
• Avoids sweets, which will cause your blood sugar to spike and then crash.
• Get up and move every hour to help the blood flow and reduce fatigue.
• Avoid foods that are high in sodium and fat. They can make you feel bloated.
• Exercise regularly to rev up your energy levels.

Walnuts and Almonds

Stave off the blood sugar roller coaster ride by grabbing a healthy handful of almonds -- about 23 -- in the morning. Almonds help stabilize blood sugar levels for the rest of the day, according to a study by Purdue University researchers published in the January 2011 issue of "Nutrition and Metabolism."
And the next time you're under a deadline, try snacking on a handful of walnuts, or 12 to 14 walnut halves, to help improve your mood and brainpower. According to a 2007 University of Pittsburgh study, omega-3 fatty acids found in walnuts may boost brain areas that help bring mood into balance.
For a treat with a kick, toast 2 cups of walnuts in 2 tablespoons of olive oil, 1 teaspoon of cinnamon and 1 teaspoon of cayenne pepper in an oven set at 375 degrees F. The cayenne pepper adds heat and anti-cancer fighting properties.

Low-Fat Dairy

The milk sugar, or lactose, in low-fat dairy foods give you instant energy, while the high amount of protein helps fend off hunger afterward, says Susie Garcia, a registered dietitian based in Oakland, California.
For a healthy morning boost, add a dollop of yogurt to a bowl of oatmeal. The pairing of a prebiotic and probiotic food contributes to healthy digestion and immunity, and prevents bloating.
Make a habit of adding milk to your coffee. Or better yet, make low-fat yogurt or string cheese a part of your morning routine, because while those cups of Joe offer the caffeine boost to kick-start your day, regular consumption may affect bone health over time. According to the National Institutes of Health Office of Dietary Supplements, caffeine increases the amount of calcium lost in the urine.

Avocado and Olive Oil

An avocado a day keeps hunger pangs away, especially helpful when your midday funk includes the munchies. Heart-healthy monounsaturated fats in avocado and olive oil slow down the emptying of the stomach so you feel satisfied longer. And according to a study published in the October 2008 issue of "Cell Metabolism," the oleic acid from olive oil helps suppress hunger between meals. 
"Oleic acid triggers a reaction in the body that keeps hunger at bay and activates an area in the brain that tells the body it is feeling full," said Rarback.
Avocados are also rich in potassium, which regulates kidney function and blood pressure, and folate, a B vitamin that helps the body produce and maintain new cells.
For a mid-morning or afternoon snack, halve a small avocado and remove the pit. Drizzle with olive oil and sprinkle with salt and pepper to taste.

Hard-Boiled Egg

With just 80 calories, one protein-packed hard-boiled egg can curb your appetite for hours. In a study published in the June 2010 issue of "Appetite," participants reported higher levels of satiety and satisfaction three to four hours after eating a high-protein, low-carbohydrate breakfast than after a low-protein, high-carb meal.
"Protein takes longer to digest than carbohydrates, so it provides longer satiety and sustained energy levels," said Garcia.
Convenient to eat, one hard-boiled egg takes about 10 minutes to make -- three minutes to achieve a hard boil, then seven minutes to sit covered. Boil a batch on Sunday and store them in the fridge for up to a week. When it's time to enjoy one, sprinkle it with paprika, pepper and salt, then squeeze a bit of lemon juice on it to taste.

Blueberries

After lunch, treat yourself to a cup of blueberries topped with low-fat whipped cream. At just 80 calories per cup and no fat, blueberries will sharpen your focus for the rest of the afternoon.
In a Tufts University study published in the January 2010 issue of "Journal of Agricultural and Food Chemistry," rats fed blueberries over a period of four months performed better on tests for memory and mental alertness. Blueberries are one of the most antioxidant-rich foods, explains Rarback. Their compounds fight free radical damage and trigger the growth of new brain cells.
Or you might consider switching your afternoon coffee to a glass of blueberry juice. In a study published in the April 2010 issue of the same journal, people with age-related memory problems performed better on learning and memory tests than the control group after drinking blueberry juice every day for two months.

Dark Chocolate

If your afternoon workday collapse is accompanied by stress, reach for a piece of dark chocolate, which triggers the release of endorphins that will pick up your mood. Serotonin, the calming neurotransmitter, is also affected by chocolate, Rarback says.
Rich in flavonoids, these pieces of decadence have antioxidant power that helps resist cell damage caused by free radicals, and according to a study published in the June 2010 issue of "BMC Medicine," dark chocolate may help lower blood pressure.
But snack in a serving-controlled manner. Limit yourself to only one or two dark chocolate drops or squares, advised Garcia.

Citrus Fruits

When you're about ready to doze off at your desk, smell an orange. Sniffing citrus scents can stimulate alertness, according to research published in the November 2003 issue of "Experimental Biology and Medicine."
Then eat the fruit. Its natural sugars are digested within 30 minutes, providing quick and enduring energy.
"Fruits contain fiber and other complex carbohydrates that provide more lasting energy than eating candy with no fiber," said Elizabeth Ward, registered dietitian and author of "MyPlate for Moms, How to Feed Yourself & Your Family Better."
Furthermore, eating half of a grapefruit before a meal can help you lose weight, says a Scripps Clinic study published in the spring 2006 issue of "Journal of Medicinal Food."
Enjoy grapefruit by cutting it in half, scooping out the flesh and topping the grapefruit sections with a half-cup of cottage cheese


www.livestrong.com
at No comments:

Find Your Motivation

Find Your Motivation
A young man climbing up a rock wall at the gym. Photo Credit Ramonespelt/iStock/Getty Images

Overview

Though they may have you subconsciously biting your nails, lighting up after lunch or grabbing one more fistful of fries, your bad habits didn't start out bad. There was motivation behind them.
"All habits -- even bad habits -- start out as true friends. They help, or helped, us deal with something," said Meg Selig, a counselor and author of "Changepower! 37 Secrets to Habit Change Success." 
Many habits help us regulate our moods, she says, so changing could leave us without a way to feel good.
When you "want" chocolate to "feel better," for example, you don't really want chocolate.
"You want a dopamine release," said Marie-Josee Shaar, founder of Smarts and Stamina in Pennsylvania.
Dopamine is a chemical that makes you feel good, and chocolate helps your body release it. That good feeling is the motivation behind your craving. But if you can find another way to get the dopamine -- through sleep, exercise or interaction -- you can satisfy the craving without the calories, Shaar says. (See the sidebar "Get What You Really Want" for more on this.)
Tell yourself that mistakes are just a part of change. Begin talking to yourself like your own best friend rather than your worst enemy.
- Meg Selig, counselor and author of "Changepower! 37 Secrets to Habit Change Success"

Motivation is the driving force behind our bad habits, so tap into yours and use it to form new, good habits. By identifying what you want and how you'll get it, you can shape new behaviors that, with a little practice, will become as routine as your bad habits ever were.

Find Your "Why" to Get Motivated

When performing interviews with weight-loss research subjects, Joanna Buscemi is not only interested in what people want to change, but also in what they don't want to change.
"If they're fine with how many vegetables they're eating, then I'm not going to harp on them about that," said the psychology researcher and Ph.D. candidate at the University of Memphis.
Instead, Buscemi says, she focuses on things that her subjects want to change and helps them find motivators. And these motivators can stem from any number of influences, not only from the positive things we see.
"People can also be motivated by wanting to avoid pain," said Selig. "I quit smoking because I had a beloved aunt who couldn't quit and died from lung cancer."
Selig kicked her habit to avoid the pain of cancer and to prolong her life. The motivators you find should be specific to you, she says, and make you want something positive for yourself. Instead of "I don't want to die," choose a statement like "If I quit smoking, I'll have a good, long life."
Once you've found a motivator, staying amped up can be challenging. People who want to make a change "are very motivated, but that motivation is teetering on the brink of collapse," said Jared Meacham, owner and personal training director at Precision Body Designs in Covington, Louisiana. 
You can strengthen faltering motivations, though, with quickly noticeable results. Set an easy, short-term starter goal to give yourself an early boost, Meacham suggests. Choose a one- or two-week mark, and pick something very attainable: Reduce your fast-food consumption by one meal per week or increase your workouts by one session per week. Use your success with the smaller step to get pumped for the next, bigger step.

Be Specific and Realistic About What You Want

Think back to the chocolate mentioned earlier. When you're craving chocolate, you know specifically what you want. You don't want candy. You don't want sugar or even just a treat. You want chocolate.
But when we resolve to make changes, we're rarely this specific. We want to "lose weight" or "eat less junk food" or "exercise more." And such vague goals are problem No. 1, says Selig.
"You have to know how you'll know when you've succeeded," she said, adding that a good goal is a "S.M.A.R.T." goal. S.M.A.R.T. is an acronym for "specific, measurable, attainable, realistic and timely," and the first two in the list are the most crucial. Creating a measurable outcome -- losing 20 lbs, drinking two fewer sodas a week or going to the gym three times per week -- makes your goal as specific as your craving.
How do you choose an attainable measurement for success? Start by analyzing and recording where you are now, says Buscemi.
If you'd like to drink fewer soft drinks or visit the gym more, she suggests spending some time recording how much or how little you're performing these behaviors now to set more realistic targets. If you're drinking four sodas per day, for example, cutting back to three per week is probably too ambitious at the start.
"If you're not exercising at all, don't go straight to seven days per week," she advised.
Turning your larger goal into smaller, bite-sized steps will help you reach the bigger outcome.
"I work with the client to focus on very short-term outcomes, to inch them forward," Meacham said. The smaller goals build to larger goals and can have a domino effect.

Figure Out How You'll Do It

"Studies show that when people start engaging in healthy behaviors, they're likely to engage in other healthy behaviors," Selig said.
But be aware: You are going to fail and falter along the path to your big goal. Everyone does; it's inevitable. But dealing with these small failures properly is the key to lasting change, Selig says. 
"Change your self-talk from discouraging to encouraging," she said. If you fall off the diet wagon and double up on dessert, don't beat yourself up and consider the day a waste. Instead, Selig suggests telling yourself "that mistakes are just a part of change. I'm not going to make matters worse by overdoing it for the rest of the day. Begin talking to yourself like your own best friend rather than your worst enemy."
Even friends can make us trip up, offering temptations to slip. Be ready with a plan of how you want to react, advises Shaar, and rehearse it.
"Be ready with what you'll say: 'No thanks, I'm good' or 'I don't want to feel bloated,'" she said. Rehearsing the exact words you'll use will help keep you from fumbling or clamming up when faced with an enticing offer.
"The other benefit is that it tells other people that you're someone that doesn't overeat," said Shaar. "They won't be prompting you as much in the future."
Sharing your goal with certain friends can help you stay on track, too, Selig says.
"Telling other people will help hold you accountable. They'll give you support, and it gets your pride into it in a good way -- you don't want to have to tell them you didn't exercise this week," she said. "But be selective. Tell the people who can really help you, rather than those who can undermine you."

Practice Any Way You Can

Turning a behavior into a subconscious habit can take a while -- about 66 days on average, Selig says, but up to 250 days for a more complex habit.
You get there with practice -- and not always in a direct way. If you're trying to avoid junk food, for example, you can make the behavior stick better by finding other ways to practice the habit, says Shaar.
"Speak your resolution, write your goals and visualize yourself doing it," she said.
Find creative ways to reinforce your goal. Make a text version of the goal, for example, and use it as the screensaver on your computer. 
Or change your password. "Instead of the name of your spouse, use 'sexy2011,'" said Shaar, "because you want to be sexier in 2011. You're reinforcing it: 'I'm a healthy person. I'm an active person.'"

www.livestrong.com
at No comments:

Evaluating innovation diffusion readiness among architectural and engineering design firms: Empirical evidence from Australia

Published Date
November 2012, Vol.27:50–59, doi:10.1016/j.autcon.2012.05.009

 Title 
Evaluating innovation diffusion readiness among architectural and engineering design firms: Empirical evidence from Australia
  • Author 
  • Kriengsak Panuwatwanich ,
  • Rodney A. Stewart 
  • Griffith School of Engineering, Griffith University, Gold Coast Campus, Queensland 4222, Australia
Accepted 9 May 2012. Available online 2 June 2012.

Abstract
This paper conceptualises the development of an innovation diffusion readiness (IDR) framework used for monitoring innovation diffusion maturity levels within the architectural and engineering design (AED) firm context. To achieve this, a survey was conducted with a number of Australian AED firms, using a validated survey instrument developed elsewhere. The key findings based on the study sample of 158 professionals representing 44 AED firms showed that the overall level of IDR among the sampled firms was moderate to high. Using cluster analysis, three main clusters of these firms were uncovered: Very High, High and Moderate IDR. Further analysis indicated that clusters with higher IDR appeared to perform significantly better in diffusing innovative design practices. This finding highlighted that firms shifting to a higher IDR cluster could achieve a significant improvement in the diffusion of this type of innovation. The paper also provided a number of recommendations for future research.

Highlights

► This research conceptualises an innovation diffusion readiness (IDR) framework. ► IDR levels of Australian architectural and engineering design firms were assessed. ► Three main clusters of sampled firms based on three IDR levels were identified. ► Higher IDR clusters were found to be better in diffusing innovative design practice.

Keywords

  • Australia
  • Architect
  • Cluster analysis
  • Design
  • Innovation diffusion
  • Readiness
  • Engineer
 Table 1
Table 1.
 Table 2
Table 2.
 Table 3
Table 3.
Fig. 1.
Fig. 2.
 Table 4
Table 4.
 Table 5
Table 5.
 Table 6
Table 6.
Fig. 3.
 Table 7
Table 7.

For further details log on website :
http://www.sciencedirect.com/science/article/pii/S0926580512000829
at No comments:

Effect of applying rhizobacteria and fertilizer on the growth of Ludwigia octovalvis for arsenic uptake and accumulation in phytoremediation

Published Date
September 2013, Vol.58:303–313, doi:10.1016/j.ecoleng.2013.07.018
Open Access, Creative Commons license

Title 
Effect of applying rhizobacteria and fertilizer on the growth of Ludwigia octovalvis for arsenic uptake and accumulation in phytoremediation ☆
  • Author 
  • Harmin Sulistiyaning Titah a,b,d,,,,
  • Siti Rozaimah Sheikh Abdullah a,
  • Idris Mushrifah c
  • Nurina Anuar a
  • Hassan Basri b
  • Muhammad Mukhlisin b
  • aDepartment of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia
  • bDepartment of Civil and Structural Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia
  • cTasik Chini Research Centre, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia
  • dDepartment of Environmental Engineering, Faculty of Civil Engineering and Planning, Institut Teknologi Sepuluh Nopember (ITS), 60111 Keputih, Sukolilo, Surabaya, Indonesia
Received 28 January 2013. Revised 10 June 2013. Accepted 5 July 2013. Available online 30 July 2013.

Highlights
  • •
    The addition of six rhizobacteria consortium at 2% (v/v) could alleviate the toxic effect of As in Ludwigia octovalvis.
  • •
    The addition of NPK fertilizer at 0.02% (w/w) also lightens the toxic effect.
  • •
    Those additions could increase the biomass weight of L. octovalvis.
  • •
    The effectiveness of phytoremediation in treatment with NPK fertilizer addition was the highest compared with As only and As with rhizobacteria at 2%.
  • •
    The NPK fertilizer addition showed the best results in As phytoremediation using L. octovalvis.

Abstract

The aim of this study was to investigate the effect of applying a six-rhizobacterial consortium and nitrogen phosphate potassium (NPK) fertilizer in inorganic arsenic (arsenate) phytoremediation using Ludwigia octovalvis (Jacq.) Raven plants. The experiment included control L. octovalvis plants and three phytoremediation treatments with L. octovalvis plants, namely an arsenic (As) concentration of 39 mg kg−1 only, the addition of a six-rhizobacterial consortium at 2% (v/v) with an As concentration of 39 mg kg−1 and the addition NPK fertilizer at 0.02% (w/w) with an As concentration of 39 mg kg−1. In the As phytoremediation treatment with the presence of As only, plants showed signs of phytotoxicity such as wilting and senescent leaves. L. octovalvis grew well until the end of exposure (Day 42) in the phytoremediation treatment with 2% rhizobacteria consortium or with 0.02% NPK fertilizer addition. The As phytoremediation treatment with 2% rhizobacteria showed the highest removal percentages of bioavailable As (89%), total extractable As (78%) and As in the leachate of the reed beds (98%) resulting in lower As uptake by L. octovalvis than in the other two phytoremediation treatments. This indicates that the bioremediation process played a role in the treatment with 2% rhizobacteria. The fresh weight of L. octovalvis biomass in treatment with 0.02% NPK fertilizer increased by almost five-fold compared with the As only treatment. The effectiveness of phytoremediation in terms of As uptake at Day 42 reached 49.8% in the phytoremediation treatment with 0.02% NPK fertilizer addition. It was the highest than in the other two phytoremediation treatments. In conclusion, NPK fertilizer addition gave the best results in As uptake using L. octovalvis plants in terms of the effectiveness of phytoremediation.

Keywords

  • Rhizobacteria
  • Fertilizer
  • Arsenic
  • Phytoremediation
  • Ludwigia octovalvis
  • Uptake

1 Introduction

Arsenic contaminated soils, sediments, and sludge were the major sources of arsenic contamination of the food chain, surface water, groundwater, and drinking water (Gonzaga et al., 2006). Contamination of As due to industrial activity was estimated reached 4.53 million tons at worldwide (Han et al., 2003). Arsenic species are bioactive and toxic (Zhang et al., 2002) and were toxic to most plant species (Quaghebeur and Rengel, 2005). In soils and groundwater, inorganic arsenic presents mainly as arsenate [As(V)] and arsenite [As(III)] (Wang and Zhao, 2009). As species have different physical and chemical characteristics, resulting in various degrees of mobility, bioavailability and toxicity (Quaghebeur and Rengel, 2005). According to Glick (2010), the Agency for Toxic Substances and Disease Registry (ATSDR) has made a list of chemicals that are often found in polluted areas, including hazardous materials. According to the list released by the ATSDR, there are 275 hazardous and toxic materials that have a negative impact on human health. Based on this list, As is ranked as the first chemical in terms of hazardous and toxic materials, followed by lead (Pb) and mercury (Hg) in second and third place, respectively.
Currently, there are many different types of technologies to remediate contaminated areas. One such technology is the remediation of contaminated soil and groundwater, including heavy metal contamination, through phytotechnology. The concept of using plants to restore areas contaminated with heavy metals is an effective approach and is categorized as a green technology. Phytoremediation is a technology that uses green plants to remediate various media (soil, water or sediment) that are contaminated with different types of contaminants (organic and inorganic) and interact with microorganisms (ITRC, 2001, Ghosh and Singh, 2005, Cho-Ruk et al., 2006 and Sao et al., 2007). Phytoremediation can be conducted using ex situ or in situ methods. Soil or contaminated areas can be directly planted using suitable plants and non-dredged soil when the in situ method is used (USEPA, 2002). Phytoremediation is a cost effective, environmentally friendly, engineering economical, safe, alternative technology to remediate As-contaminated soils and is suitable for use in developing countries (Yang et al., 2012, Ghosh and Singh, 2005and Lasat, 2002). Moreover, phytoremediation based on the ecological principles (Mirza et al., 2011). In addition to treating heavy metal contaminated areas, an additional benefit of phytoremediation is the potential for bioenergy production from the plants used in the phytoremediation process (Ginneken et al., 2007).
In addition to plants, rhizosphere bacteria or rhizobacteria, also known as plant growth promoting rhizobacteria (PGPR), also play an important role in phytoremediation. They are capable of aggressively colonizing plant roots and promoting plant growth (Khan et al., 2009). Some research has been conducted to evaluate the interactions of rhizobacteria and plants to remediate As. Yang et al. (2012) reported that the addition of As-reducing bacteria could promote the growth of Petris vittata and increase As accumulation. Other research has been conducted to evaluate the application of fertilizer on phytoremediation. According to Fayiga and Ma (2006), phosphate rock can be applied as an effective amendment for As phytoremediation since it significantly increased As uptake in P. vittata.
Ludwigia octovalvis was chosen for this study since it was one of the plants that could survive at a contaminated site in Malaysia (Rahman et al., 2009). L. octovalvis is a suffruticose shrub or perennial woody herb growing to 2 m in height with a stem diameter of 1 cm. L. octovalvis plants are supported by sinker roots, one of which may be the taproot, and long white, lateral roots that grow just under the soil surface. According to Chauhan and Abugho (2012), longfruited primrose-willow (L. octovalvis) is a major weed of rice in South and South East Asia. Its other common names include false primrose, primrose willow, swamp primrose, water primrose, willow primrose and yellow willow herb, while in Malaysia it is locally known as “buyang samalam”, “lakom ayer” and “pujang malam”.
The aims of this study were to determine the effects of applying rhizobacteria as a PGPR and fertilizer on the growth of L. octovalvis as well as to assess the effects of these treatments on As uptake and accumulation in L. octovalvis during phytoremediation at optimized conditions of some factors (As loading, retention time and aeration). Based on our previous study (data not published), the optimized conditions were obtained at 39 mg kg−1 As, 42 days and 0.22 L min−1 for aeration.

2 Materials and methods

2.1 Propagation of plant species

L. octovalvis plants were propagated from seeds gathered from a parent plant growing at a contaminated site in Malaysia. The seeds were grown in the greenhouse using garden soil with ratio of top soil:organic material:sand of 3:2:1 until the next generation plants produced seeds in large quantities. Only plants from this generation were used to run the phytoremediation study. The seeds were planted in plastic crates (37 cm × 27 cm × 10 cm). After 3 weeks, individual seedlings were selected from the nursery and transferred to polybags, with two plants per polybag. All of the plants used in the experiment were 8 weeks old with an average fresh weight of 5.9 g per plant at the beginning of the study.

2.2 Treatment with As-spiked sand in the pilot reed bed

The pilot reed beds were constructed of fiberglass tanks, the walls of which were 0.5 cm thick and black in color with dimensions of 92 (L) cm × 92 (W) cm × 60 (H) cm. A layer of medium gravel (2 cm in diameter) was placed at the bottom of the reed bed, and another layer of fine gravel (1 cm in diameter) was placed at the top. The depth of both the medium and fine gravel layers was 10 cm. As-spiked sand was placed in the reed bed at a depth of 10 cm. Each reed bed had a freeboard of approximately 10 cm with a pipe at the bottom for sampling the leachate. The pilot reed beds were supplied with aeration of 0.22 L min−1. The aeration system was run using an air compressor model HP2 (Orimas, Malaysia), and the air flow rate was measured using a flow meter (Cole-Parmer, USA). The aeration system was placed on a layer of medium-sized gravel and run continuously throughout the experiment.
The sand was then spiked with As salt as sodium arsenate dibasic heptahydrate (AsHNa2O4·7H2O) (FlukaChemika, Switzerland). The As concentration was selected based on an arsenate range finding test against L. octovalvis (Titah et al., 2012) and the previous study on optimization (data not published). The As concentrations were 0 mg kg−1 as the control and 39 mg kg−1 in the phytoremediation plants. Control L. octovalvis plants were used in addition to three phytoremediation treatments in L. octovalvis plants, namely an As concentration of 39 mg kg−1, the addition of a six-rhizobacterial consortium at 2% (v/v) with an As concentration of 39 mg kg−1 and the addition of NPK fertilizer at 0.02% (w/w) with an As concentration of 39 mg kg−1. Each pilot scale reed bed for phytoremediation treatment was planted with 100 healthy 8-week-old L. octovalvis plants with a total fresh weight of 590 g. Fig. 1 shows the schematic of the pilot reed beds.
Fig. 1. Schematic diagram of pilot reed beds.
Macronutrients (N, P, K, S, Mg, Ca, K) and a micronutrient (Cl) were analyzed by a Compact IC plus 882 ion chromatography (IC) (Metrohm, Switzerland), while other micronutrients (Fe, Zn, Mn) and trace elements (Pb, As) were determined using an Optima 7300DV inductively coupled plasma-optical emission spectrometer (ICP-OES) (Perkin Elmer, USA). Based on this analysis, the sand contents of the macronutrients were 29.2 mg kg−1 N (nitrate), 1.2 mg kg−1 K, 13.0 mg kg−1 SO42−, 86.5 mg kg−1 Ca, 7.4 mg kg−1 Mg whereas the micronutrient contents were 6.4 mg kg−1 Cl−, 5.5 mg kg−1 Fe, 0.04 mg kg−1 Zn and 1.62 mg kg−1 Mn. The trace elements were not detected.
During the test, plants were watered alternate days since the sand had a low moisture-holding capacity. Moisture was monitored using a moisture-meter model ECH2O (Decagon, USA), while pH and temperature of the spiked sand were monitored using a pH-meter model pH 300 (Cyberscan, Singapore).

2.3 Addition of the rhizobacteria consortium

Based on our previous study, ten rhizobacteria isolated from the roots of L. octovalviscan biosorb As (data not published). However, only six selected rhizobacteria were used in the study. The selected rhizobacteria were Sphingomonas paucimobilis, Arthtobacter globiformis, Bacillus cereus, Bacillus pumilus, Rhizobium rhizogenesand Rhizobium radiobacter. All rhizobacteria were identified using the Biolog GEN III System (USA) and Vitek2 System (France). The calculation of the amount of rhizobacteria added to the reed bed pilot scale was as follows: the bulk density of sand was 26 mL per 100 g of sand, so there was 34.1 L in 131 kg of sand in each pilot reed bed. An amount of 2% (v/v) rhizobacteria was added to each pilot scale reed.

2.4 Addition of fertilizer

The fertilizer used in this study was NPK (15%:15%:15%). Fertilizer addition was based on a study by Huang et al. (2012), with basic nutrient availability of nitrogen (N), phosphorus (P) and potassium (K) in the soil of 200 mg kg−1 each. The mass of sand in the pilot scale reed bed was 131 kg, which was spiked 26.2 g of NPK fertilizer or 0.02% of the total weight of the sand.

2.5 Sampling and analysis of sand and plants

Sampling of the sand was carried out on Day 0, Day 14, Day 28 and Day 42. About 10 g of sand taken from around the plant roots were sampled in three replicates using the grab sampling technique. Meanwhile, after the designated exposure time, three plants were sampled by digging up the plant together with the roots using a plastic scoop and pulled up slowly to prevent any plant parts from being left behind in the tank. Harvesting of the plants was conducted on Day 14, Day 28 and Day 42. The sand and plant samples were then placed in labeled plastic bags and brought to the laboratory for further analysis.

2.6 Laboratory analysis

2.6.1 Sand extraction

Sand extraction was carried out to determine bioavailable As using methods described by Quevauviller (1998). A 5 g sample of sand from each of the sand samples spiked with various concentrations of As was taken using a composite sampling method for extraction. Each sand sample was placed in a plastic tube. After the addition of 50 mL of a solution of ethylene diamine tetraacetic acid disodium (EDTANa2) (Merck, Germany), samples were agitated using an orbital shaker multi RS-60 (Biosan, Lutvia) at 30 rpm for 1 h at room temperature. Then, each sample was centrifuged at about 3000 rpm for 10 min using an 5810R centrifuge (Eppendorf, USA). The samples were filtered through filter paper (Whatman, UK) with a porosity of 0.2–1.1 μm using a vacuum filter model DOA–P504–BN (GAST, USA) The supernatant was collected in polyethylene bottles and stored at 4 °C before analyzing the As content using an ICP-OES Optima 7300DV (Perkin Elmer, USA).
The total extractable As concentration in the spiked sand was determined using the wet digestion method (USEPA, 1996). Approximately 2 g of the wet sand sample was added to 5 mL of 69% HNO3 in 100 mL Erlenmeyer flasks, and the samples were incubated overnight. All samples were placed in hot block tubes, and the hot blocks were placed in a block digester (AIM 600 Digestion System, Australia). Total As was analyzed using an Optima 7300DV ICP-OES apparatus (Perkin Elmer, USA).

2.6.2 Plant extraction

Plant parts (roots, stems and leaves) were dried prior to the extraction procedure. In this experiment, As extraction from the plants was performed using a modified wet digestion method (Plank, 1992, Kalra, 1998 and Temminghoff and Hauba, 2004). Approximately 0.1–0.5 g of the dried plant material was added to 10 mL of 69% HNO3in 100 mL Erlenmeyer flasks, and the samples were incubated overnight. All of the samples were placed in hot block tubes, and the hot blocks were placed in a block digester (AIM 600 Digestion System, Australia). All of the samples were subsequently heated at 95 °C for 1 h and 30 min. After cooling to 80 °C, 8 mL of 30% H2O2 was added. The heating process was then continued at 95 °C for 2 h (the residue should be translucent or white when the digestion is complete). An aliquot of 2.5 mL of dilute aqua regia (HNO3:HCl = 1:3) was then added, and the digested solution was transferred to a 50 mL plastic tube; deionized water was added to bring the volume of the solution to 50 mL. Lastly, the solution was filtered using a 0.45 μm membrane filter paper (Sastec, Malaysia) to further remove any particulates. The As content was then analyzed using the Optima 7300DV ICP-OES instrument (Perkin Elmer, USA).

2.7 Sampling and analysis of leachate

The leachate was sampled on Days 0, 14, 28 and 42 of exposure. About 60 mL of the leachate were collected from the pipe at the bottom of the reed bed. Samples of the leachate were placed in a plastic tube (10 mL) and stored at 4 °C for further As analysis using ICP-OES. All samplings were conducted in three replicates.

2.8 SEM analysis

The scanning electron microscopy (SEM) analysis objective is to find the impact of As on tissues of roots, stems and leaves of L. octovalvis. SEM analysis was conducted using FESEM Model Supra 55VP (Zeiss, Germany). SEM analysis was conducted after 42 days of exposure. Sample preparation was carried out using a method from Pathan et al. (2008).

2.9 Determination of the rhizobacterial populations

The method to determine the rhizobacterial content from the roots of L. octovalvis, sand near plants and the leachate were based on several previously published reports (Harley and Prescott, 2002, Abou-Shanab et al., 2005, Cakmakci et al., 2007and Mittal and Johri, 2007). The determination of the rhizobacterial number using the standard plate count method was performed on Day 1, Day 14, Day 21, Day 28 and the final day of exposure (Day 42).

2.10 Statistical analysis

All statistical tests were performed using SPSS Version 17.0 (IBM, USA). Two-way analysis of variance (ANOVA) at the 95% confidence level (p ≤ 0.05) was used to evaluate significant changes in the fresh-dry weight of L. octovalvis biomass, length of roots and stems, concentration of As in the spiked sand and leachate and the concentration of As in whole L. octovalvis plants.

3 Results and discussion

3.1 Observation of the physical growth of L. octovalvis

According to Greenberg et al. (2012), aeration is a one factor in the multi-process phytoremediation system (MPPS) on farmland which aims to accelerate and complete the removal of heavy metals or organic pollutants in the soil. Based on the observation of physical growth in this study, symptoms of As toxicity, such as wilting and senescent leaves, occurred in the phytoremediation treatment with As only. The toxic effects of As on L. octovalvis were alleviated at the As concentration of 39 mg kg−1 with the addition of the selected six-rhizobacterial consortium. All L. octovalvisplants grew well until the end of exposure. The biomass of L. octovalvis increased in the As phytoremediation treatment with the addition of rhizobacteria. The fresh weight biomass of L. octovalvis at the end of the exposure period with the addition of rhizobacteria reached 12.1 ± 1.7 g and was almost double the fresh weight biomass of L. octovalvis with As only (7.3 ± 3.3 g) (Fig. 2). This situation has occurred due to the addition of the six-rhizobacterial consortium that acted as PGPR and enhanced the growth of L. octovalvis. According to Khan et al. (2009), rhizobacteria as PGPR can facilitate plant growth.
Fig. 2. Fresh-dry biomass weight of L. octovalvis (WW, fresh weight; DW, dry weight).
Several studies have been conducted showing similar results. As reported by Nie et al. (2002), there was significant growth of canola plants in As-spiked medium after inoculation with the bacteria Enterobacter cloacae. According Shilev et al. (2006), an increase in biomass of Heliathnus annuss (sunflower) plants on land containing As occurred after adding the bacteria Pseudomonas fluorescens. Wang et al. (2011)reported that the addition of R. radiobacter (Agrobacterium tumefaciens) to increase resistance against Populus deitoides improved As uptake efficiency and increased As translocation.
According to Jetiyanon and Kloepper (2002), the application of microorganisms could reduce or increase the uptake and accumulation of heavy metals by plants. According to Lebeau et al. (2008), PGPR could enhance plant growth and biomass plants in two ways: first indirectly by producing antibiotics that can inhibit pathogenic bacteria in the soil and second in a direct way through improved nutrient and water uptake.
Based on the observation of the physical growth of L. octovalvis, the toxic effects of As in L. octovalvis could be reduced with the addition of NPK fertilizer. Toxic effects were not observed until the end of exposure. All L. octovalvis plants were fresh, healthy and grew well until the average height of the plants reached 102.7 ± 18.2 cm. According to Lihong and Guilan (2009), increased concentrations of phosphate in the medium could reduce the toxic effects of arsenate due to a decrease in As uptake by plants. The addition of phosphate nutrients could reduce the toxic effects of As on plants and could alleviate plant growth inhibition (Gulz, 2002). Cao et al. (2009)reported that the use of additional phosphates may reduce the toxic effects As in Scutellaria baicalensis Georgi plants. Fig. 2 shows that the addition of NPK fertilizer increased the biomass of L. octovalvis. The fresh weight biomass of L. octovalvis at the end of exposure with the addition of NPK fertilizer reached 34.1 ± 6.1 g, which was higher than the fresh weight biomass of L. octovalvis in As phytoremediation with As only (7.3 ± 3.3 g), with nearly a five-fold increase compared to the biomass in phytoremediation with As only.
The ANOVA results of the fresh weight biomass of L. octovalvis showed a significant difference (p < 0.05) in the fresh weight biomass of L. octovalvis in all phytoremediation treatments. Meanwhile, the ANOVA results on the dry weight biomass of L. octovalvis showed a significant difference (p < 0.05) in the phytoremediation treatment with the addition of 0.02% NPK fertilizer against the control and the other two treatments.
L. octovalvis were analyzed for SEM after 42 days of exposure. According to Bercu (2007), the cross section of roots can be subdivided into epidermis, cortex, endodermis and stele, the stele contains the xylem and phloem. Ions were translocated to shoot through the xylem and photosynthate was supplied from shoot to the root through the phloem. Results of SEM analysis for roots at the control (Fig. 3a-1), in treatment with the addition of 2% rhizobacteria (Fig. 3c-1) and in treatment with the addition of 0.02%NPK fertilizer showed the cross sections of the root such as epidermis, cortex, endodermis and stele could be seen clearly (Fig. 3d-1). While the root sections seems less visible and also the toxic effects of As in root tissue of L. octovalvis were detected in the treatment with As only (Fig. 3b-1). SEM analysis results on stems showed the SEM at the control (Fig. 3a-2) and in the treatment with the addition of 0.02% NPK fertilizer looks like the outside part of stems (Fig. 3d-2). SEM of stem in the treatment with the addition of 2% rhizobacteria showed more clear the parts of the stem (Fig. 3c-2), while the sample in the treatment with As only shows the damage of stems tissues and there was a hole inside the stem (Fig. 3b-2).
Fig. 3. SEM micrograph of L. octovavis plant (a-1 to a-4) at control, plant growing at 39 mg kg−1As, (b-1 to b-4) only As, (c-1 to c-4) with addition of 2% rhizobacteria, (d-1 to d-4) with addition of 0.02% NPK fertilizer.
Trichomes were hair cells or leaf hair derived from specialized epidermal cells on leaf or stems surface (Dennis, 2002). Results of SEM analysis on the leaves of L. octovalvis in the treatment with As only showed the damages on tissue leaves were detected and trichomes were not visible (Fig. 3b-3). Meanwhile, trichomes were detected clearly at the control (Fig. 3a-3), treatment with the addition of 2% rhizobacteria (Fig. 3c-3) and treatment with the addition of 0.02% NPK fertilizer (Fig. 3d-3). The size of stomata on the leaves in the treatment with As only (Fig. 3b-4) was even smaller than the stomata on the leaves at the control (Fig. 3a-4), in the treatment with the addition of 2% rhizobacteria (Fig. 3c-4) and in the treatment with addition of 0.02% NPK fertilizer (Fig. 3d-4).
Fig. 4a shows the root length of L. octovalvis. The root length in the phytoremediation treatment with the addition of NPK fertilizer was highest (34.3 ± 10.8 cm) at Day 42. The ANOVA results on the root length of L. octovalvis showed that there was a significant difference (p < 0.05) in the phytoremediation treatment with the addition of 0.02% NPK fertilizer against the control and the other two phytoremediation treatments. The retention time at 14 days was significantly different (p < 0.05) than at 28 and 42 days in phytoremediation with NPK fertilizer addition.
Fig. 4. (a) Root length of L. octovalvis and (b) stem length of L. octovalvis.
Fig. 4b shows the stem length of L. octovalvis. The length of L. octovalvis stems in the phytoremediation treatment with the addition of NPK fertilizer was highest (102.7 ± 18.2 cm) at Day 42. The ANOVA results show that the stem length of L. octovalvisplants was significantly different (p < 0.05) in all phytoremediation treatments. All the retention periods showed a significant difference (p < 0.05).

3.2 Concentrations of bioavailable As, total extractable As in spiked sand and the concentration As in the leachate

The bioavailable concentrations of As in the sand are shown in Fig. 5. The concentration of bioavailable As in the As phytoremediation treatment with the addition of 2% rhizobacteria was less when compared with the other two phytoremediation treatments. According to Khan et al. (2009), rhizobacteria as PGPR could reduce the concentration of bioavailable heavy metals.
Fig. 5. Concentration of bioavailable As and total extractable As in As-spiked sand.
The concentration of bioavailable As in the phytoremediation treatment with the addition of 0.02% NPK fertilizer was lower than the concentration of bioavailable As in phytoremediation treatment with As only. The presence of phosphate could decrease the sorption of As by soil particles and lead to increased concentrations of bioavailable As (Alvares-Benedí et al., 2005). According to Tu and Ma (2003), arsenate and phosphate will compete with each other for soil sorption sites, resulting in a reduction in their sorption by soil and an increase in solution concentrations. Phosphate can replace the sorption of As by soil and lead to increased concentrations of bioavailable As but this depends on the type of soil as the addition of phosphate does not affect the concentration of bioavailable As in volcanic soil. Phosphate addition to arsenic-contaminated soils would enhance arsenic release from soil through competitive exchange (Smith et al., 2002) and thereby increase soil As bioavailability. The content of iron oxide (Fe2O3) and aluminum oxide (Al2O3) in sand used in this study was low. It may be cause phosphate sorption of arsenate low such that the concentration of bioavailable As did not increase. Additionally, bioavailable As was taken up by the roots of L. octovalvis. The ANOVA results show a significant difference (p < 0.05) in the concentrations of bioavailable As in all three phytoremediation treatments compared to the control.
Table 1 shows the removal of bioavailable As in spiked sand. The highest removal percentages (70%) at Day 14 occurred in the phytoremediation treatment with the addition of 2% rhizobacteria. This situation may have occurred due to the addition of As-resistant rhizobacteria assisting in the removal of As. It has been suggested that the bioremediation process plays a greater role in the early phase of the treatment. Aeration in the bioremediation process could support rhizobacteria survival since the six rhizobacteria added in the As phytoremediation treatment were aerobic bacteria. Meanwhile, the percentage of bioavailable As removal in the phytoremediation treatment with As only reached 22%, 53% and 86% at 14, 28 and 42 days of exposure, respectively. This situation occurred because most of the As was taken up and accumulated by L. octovalvis plants, which could be determined from the concentration of As in whole plants of L. octovalvis; this value reached 1103.7 ± 273.3 mg kg−1 at 42 days of exposure. The same of percentage (86%) at Day 42 occurred in As phytoremediation treatment with the addition of NPK fertilizer. Although the concentration of As taken up by L. octovalvis was lower compared with the As only treatment, the dry weight of L. octovalvis was higher than in the As only treatment, resulting in a higher percentage of total As uptake in As phytoremediation with the addition of NPK fertilizer compared with the other two treatments.
Table 1. Percentage of bioavailable As removal in spiked sand.
Phytoremediation treatmentRemoval of As bioavailable in spiked sand (%)
Day 14Day 28Day 42
39 mg kg−1 As only225386
39 mg kg−1 + with addition of 2% rhizobacteria705889
39 mg kg−1 + with addition of 0.02% NPK fertilizer515486
In order to give a true assessment of phytoremediation performance, we tried to convert the uptake concentration by L. octovalvis to total As uptake to indicate the effectiveness of the phytoremediation by using the equation below:
equation1
  • where,
  • C As in plant, concentration of As uptake per plant (mg kg−1)
  • DW plant, dry weight of plant (kg)
  • N plant, number of plants
  • C bioavailable As, concentration of As bioavailable in sand (mg kg−1)
  • W sand, total weight of sand (kg)
These results are depicted in Fig. 6. The effectiveness of the phytoremediation at 42 day of exposure were 17.5, 8.8 and 49.8% in treatment with As only, treatment with the addition of rhizobacteria and treatment with the addition of NPK fertilizer, respectively. Based on the results, it indicated that the best As phytoremediation application was As phytoremediation with NPK fertilizer since total As uptake by L. octovalvis had the highest effectiveness of the phytoremediation at 42 days.
Fig. 6. Percentages of total As uptake.
A comparison of the concentration of bioavailable As and the total concentration of extractable As in the sand treatments shows in Fig. 5. The average ratio of the concentration of bioavailable As to the total concentration of extractable As in the spiked sand for the three phytoremediation treatments was in the range of 0.1–0.5. The total concentration of extractable As at the end of the retention time (42 days) in the three phytoremediation treatments was below the quality standard (16 mg kg−1) of Malaysia (Department of Environment Malaysia, 2009). Phytoremediation using L. octovalvis plants could reduce As concentrations in accordance with the current quality standard.
Fig. 7 shows the concentration of As in the leachates of the reed beds. The concentration of As in the leachate in the phytoremediation treatment with the addition of 2% rhizobacteria showed lower concentrations compared to the other two phytoremediation treatments. According to Yang et al. (2012), the addition of bacteria as PGPR in P. vittata plants decreases the concentration of As in the leachate compared to treatment without the addition of bacteria. The ANOVA results show significant differences in the As concentrations in the leachates (p < 0.05) from the three phytoremediation treatments (As only, As with the addition of 2% rhizobacteria and As with the addition of 0.02% NPK fertilizer).
Fig. 7. Concentration of As in the leachate.
Table 2 shows the percentages of As removal in the leachate. The highest percentage removal of As in the leachate (98%) occurred in the phytoremediation treatment with the addition of 2% rhizobacteria at a retention time of 14 days. At the end of exposure (Day 42), the highest percentage removal of As in the leachate (94%) was still seen in the phytoremediation treatment with the addition of 2% rhizobacteria. The consortia of rhizobacterium may have assisted in removing As in the leachate. While the addition of NPK fertilizer showed an increased percentage removal of As in the leachate from the beginning to the end of exposure, this may have been due to the increasing biomass of L. octovalvis since more As could accumulate in the plants.
Table 2. Percentage of As removal in the leachate.
Phytoremediation treatmentRemoval of As in leachate (%)
Day 14Day 28Day 42
39 mg kg−1 As only889191
39 mg kg−1 + with addition of 2% rhizobacteria989594
39 mg kg−1 + with addition of 0.02% NPK fertilizer909293

3.3 Uptake and accumulation of As

L. octovalvis plants were harvested at 14, 28 and 42 days. Fig. 8 shows the As concentrations in L. octovalvis plants at every harvesting time point. The highest concentration of As in L. octovalvis plants was 1103.7 ± 273.3 mg kg−1 in the As phytoremediation treatment with As only. The concentration of As in L. octovalvis in As phytoremediation with the addition of 2% rhizobacteria was 198.2 ± 30.7 mg kg−1, while the concentration of As in phytoremediation with the addition of 0.02% NPK fertilizer reached 352.4 ± 77.8 mg kg−1. The ANOVA results on As concentrations in L. octovalvis showed that the As concentration was significantly different (p < 0.05) in the phytoremediation treatment with As only compared to the other two treatments.
Fig. 8. Concentration of As in whole L. octovalvis plants.
The concentration of As in L. octovalvis plants in phytoremediation with the addition of 2% rhizobacteria was lower than the other two treatments, resulting in the highest removal percentages of bioavailable As (89%), total As extractable removal (78%) and As in the leachate (94%). The consortium of six rhizobacteria was resistant to As and were able to biosorb As, so this consortium of six rhizobacteria could assist in the process of As phytoremediation. According to Khan et al. (2009), rhizobacteria as PGPR make the system more effective in minimizing phytobacteria and in mitigating the biotoxicity of bioavailable heavy metals.
In phytoremediation with the addition of 0.02% NPK fertilizer, As concentrations in L. octovalvis plants were lower when compared to phytoremediation with As only. Arsenate [AsO4−3] (the inorganic from of As) and phosphate (PO42−) have analogous forms (Yang et al., 2012). However, plants prefer to take up phosphate over arsenate if the two anions exist at the same time since phosphate has a high affinity uptake system (Tu and Ma, 2003). According to Cao and Ma (2004), phosphate competes with arsenate for plant uptake from the external solution but phosphate more readily enters the plant, so it can prevent arsenate uptake. Low levels of phosphates displace arsenic from soil particles to increase uptake and phytotoxicity, while larger amounts of phosphates compete with arsenic at root surfaces to decrease uptake and phytotoxicity (Patra et al., 2004). The addition of phosphate can reduce the uptake and accumulation of arsenate by plants (Mahimairaja and Bolan, 2011). Pigna et al. (2010) reported the addition of phosphate fertilizer application could prevent the uptake and translocation of As on wheat plants, increasing plant biomass and alleviate the toxic effects of As.
According to Tu and Ma (2003), uptake of arsenate and phosphate by plants is generally competitive. Also, the presence of phosphate in contaminated soils has a role in the phytoextraction process (phytoremediation) (Gonzaga et al., 2006). According to Tu and Ma (2003), the presence of phosphate could affect plant growth, plant biomass weight and biosorption of As by plants. The impact could be an increase in plant growth and biomass weight, a reduction in the toxic effects of As in plants or a reduction or increase in As uptake and biosorption by plants. The effects of the presence of phosphate are predicted to depend on the P/As molar ratio in the soil (Tu and Ma, 2003).
The addition of NPK fertilizer could also directly increase the concentration of nitrogen in the spiked sand, hence reducing As uptake by L. octovalvis plants. According to Chen et al. (2008), the addition of nitrate can alleviate As uptake by rice plants.
The phytoremediation ability of L. octovalvis was assessed by calculating both the bioaccumulation factor (BF) and translocation factor (TF) (Melo et al., 2009) as well as the percentage of translocation from roots to stems after As exposure, as described by Poynton et al. (2004):
equation2
equation3
equation4
Fig. 9 shows the values of BF, TF and the percentage of translocation. The determination of BF showed that the highest BF value was 36.6 in the As phytoremediation treatment with the addition of 0.02% NPK fertilizer on Day 42. This result supports the findings of total As uptake in the previous paragraph.
Fig. 9. Average BF, TF and percentage of translocation of L. octovalvis in As spiked sand.
In terms of TF and the percentage of translocation, phytoremediation with As only provided the highest value at the end of exposure (Day 42). This result also shows that the concentration of As in the plants in this treatment was high (1103.7 ± 273.3 mg kg−1). As a result, the plants showed signs of phytotoxicity, as explained above.
The highest TF (6.3) and percentage of translocation (69.5%) occurred in the As phytoremediation treatment with the addition of 2% rhizobacteria at Day 14. This result shows that the bioremediation process plays a greater role in the early stages of treatment, as explained before.

3.4 Bacterial population

The rhizobacteria population on plant roots of L. octovalvis, in the sand and in the leachate is shown in Fig. 10. Total populations of rhizobacteria on the roots of L. octovalvis were higher than in the sand and leachate. The total population on the roots of L. octovalvis was greater in the phytoremediation treatments with the addition of 2% rhizobacteria and 0.02% NPK fertilizer compared to the total population of rhizobacteria in phytoremediation treatment with As only. Rhizosphere soil with high concentrations of nutrients released by the roots attracts more bacteria (Penrose and Glick, 2001). According to Cakmakci et al. (2007), the addition of fertilizer containing nitrogen and phosphorus leads to a significant increase in the number of bacteria. In the present study, the indigenous rhizobacterial population was reduced in control sand. This situation occurred since the experiment was not carried out with the addition of fertilizer in control sand. The ANOVA results on the bacterial population showed significant differences (p < 0.05) in the phytoremediation treatments with the addition of 2% rhizobacteria and 0.02% NPK fertilizer compared to the control and phytoremediation treatment with As only.
Fig. 10. Bacterial population in the roots, As-spiked sand and leachate.

4 Conclusions

We conclude that the effect of applying the six-rhizobacterial consortium at 2% and NPK fertilizer at 0.02% could alleviate the toxic effects of As in L. octovalvis and increase the biomass weight of L. octovalvis. NPK fertilizer addition at 0.02% during As phytoremediation treatment increased the effectiveness of the phytoremediation by L. octovalvis due to increased L. octovalvis biomass. It showed the highest effectiveness of the phytoremediation (49.8%) compared with in other two phytoremediation treatments. Among the three As phytoremediation treatments (As only, As with rhizobacteria at 2% and As with NPK fertilizer at 0.02%), As phytoremediation with NPK fertilizer addition at 0.02% showed the best results.

Acknowledgments

The authors would like to thank Tasik Chini Research, Universiti Kebangsaan Malaysia (UKM) and the Ministry of Higher Education, Malaysia (grant no. UKM-KK-03-FRGS 0119-2010) for funding this research, and the Ministry of National Education of the Republic of Indonesia for providing a doctoral scholarship to the first author.

References

    • Alvares-Benedí et al., 2005
    • J. Alvares-Benedí, S. Bolado, I. Cancillo, C. Calvo, D. García-Sinovas
    • Adsorption–desorption of arsenate in three Spanish soils
    • Vadose Zone J., Volume 4, Issue 2, 2005, pp. 282–290
    • DEM, 2009
    • Department of Environment, Malaysia (Jabatan Alam Sekitar, Malaysia)
    • Contaminated Land Management and Control Guidelines No. 1: Malaysian Recommended Site Screening Levels for Contaminated Land, Malaysia
    • 2009
    • Ginneken et al., 2007
    • L.V. Ginneken, E. Meers, G. Guisson, A. Ruttens, K. Elst, F.M. Tack, J. Vangronsveld, L. Ludo Diels, W. Dejonghe
    • Phytoemediation for heavy metal-contaminated soil combined with bioenergy production
    • J. Environ. Eng. Landsc. Manage., Volume 15, Issue 4, 2007, pp. 227–236
    • Gulz, 2002
    • P.A. Gulz
    • Arsenic uptake of common crop plants from contaminated soils and interaction with phosphate
    • 2002, Dissertation from the Swiss Federal Institute of Technology Zurich for the Degree of Doctor of Natural Science, Switzerland
    • Harley and Prescott, 2002
    • J.P. Harley, L.M. Prescott
    • Laboratory Exercises in Microbiology
    • fifth ed., 2002, McGraw-Hill Companies, Texas
    • Kalra, 1998
    • Y.P. Kalra
    • Handbook of Reference Methods for Plant Analysis
    • 1998, CRC Press, Boca Rotan, FL, USA
    • Khan et al., 2009
    • M.S. Khan, A. Zaidi, P.A. Wani, M. Oves
    • Role of plant growth promoting rhizobacteria in the remediation of metal contaminated soils: a review
    • Organic Farming, Pest Control and Remediation of Soil Pollutants, Sustainable Agriculture Reviews 1, E. Lichtfouse, 2009, Springer Science and Business Media B.V., pp. 319–350
    • Lihong and Guilan, 2009
    • W. Lihong, D. Guilan
    • Effect of external and internal phosphate status on arsenic toxicity and accumulation in rice seedlings
    • J. Environ. Sci., Volume 21, 2009, pp. 346–351
    • Quevauviller, 1998
    • Ph. Quevauviller
    • Methodologies in Soil and Sediment Fractionation Studies, Single and Sequential Extraction Procedures
    • 1998, Royal Society of Chemistry, UK
    • Rahman et al., 2009
    • A. Rahman, A. Amelia, A. Nazri, I. Mushrifah, N.S. Ahmad, J.A. Soffian
    • Screening of Plants Grown in Petrosludge – A Preliminary Study towards Toxicity Testing in Phytoremediation
    • Colloquium on UKM – PRSB Phytoremediation, Malaysia, August, 2009
    • Sao et al., 2007
    • V. Sao, W. Nakbanpote, P. Triravetyan
    • Cadmium accumulation by Axonopus compressus (Sw.) P. Beauv dan Cyperus rotundas Linn growing in cadmium solution and cadmium-zinc contaminated soil
    • J. Sci. Technol., Volume 29, Issue 3, 2007, pp. 881–892
    • Shilev et al., 2006
    • S. Shilev, A. Fernandez, M. Benlloch, E.D. Sancho
    • Sunflower growth and tolerance to arsenic is increased by the rhizopheric bacteria Pseudomonas fluorescens
    • Phytoremediation of Metal-Contaminated Soils, NATO Sciences Series, IV: Earth and Environmental Science 68, J.L. Morel, G. Echevarria, N. Goncharova, 2006, pp. 315–318
    • Temminghoff and Hauba, 2004
    • E.E.J.M. Temminghoff, V.J.G. Hauba
    • Plant Analysis Procedures
    • second ed., 2004, Kluwer, The Netherlands
    • USEPA, 1996
    • USEPA
    • SW 846: Method 3050B – Acid Digestion of Sediments, Sludge and Soils, Rev. 2
    • 1996
    • Yang et al., 2012
    • Q. Yang, S. Tu, G. Wang, X. Liao, X. Yan
    • Effectiveness of applying arsenate-reducing bacteria to enhanced arsenic removal from polluted soils by Petris vittata L
    • Int. J. Phytoremediation, Volume 14, Issue 1, 2012, pp. 88–89
  • ☆
    This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial-No Derivative Works License, which permits non-commercial use, distribution, and reproduction in any medium, provided the original author and source are credited.
  • ⁎ 
    Corresponding author at: Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia. Tel.: +60 149341284.


For further details log on website :
http://www.sciencedirect.com/science/article/pii/S0925857413002693
at No comments:
Subscribe to: Posts (Atom)

Advantages and Disadvantages of Fasting for Runners

Author BY   ANDREA CESPEDES  Food is fuel, especially for serious runners who need a lot of energy. It may seem counterintuiti...