Irrigation of Three Wetland Species and a Hyperaccumlating Fern with Arsenic-Laden Solutions: Observations of Growth,Arsenic Uptake,Nutrient Status,and Chlorophyll Content

Engineered wetlands can be an integral part of a treatment strategy for remediating arsenic-contaminated wastewater, wherein, As is removed by adsorption to soil particles, chemical transformation, precipitation, or accumulation by plants. The remediation process could be optimized by choosing plant species that take up As throughout the seasonal growing period. This report details experiments that utilize wetland plant species native to Ohio (Carex stricta, Pycnanthemum virginianum, and Spartina pectinata) that exhibit seasonally related maximal growth rates, plus one hyperaccumulating fern (Pteris vittata) that was used to compare arsenic tolerance. All plants were irrigated with control or As-laden nutrient solutions (either 0, 1.5, or 25 mg As L^?1) for 52 d. Biomass, nutrient content, and chlorophyll content were compared between plants treated and control plants (n = 5). At the higher concentration of arsenic (25 mg L^?1), plant biomass, leaf area, and total chlorophyll were all lower than values in control plants. A tolerance index, based on total plant biomass at the end of the experiment, indicated C. stricta (0.99) and S. pectinata (0.84) were more tolerant than the other plant species when irrigated with 1.5 mg As L^?1. These plant species can be considered as candidates for engineered wetlands.     

An integrated process for the production of 1,3-propanediol,lactate and 3-hydroxypropionic acid by an engineered Lactobacillus reuteri

The process economy of food grade 1,3-propanediol (1,3-PD) production by GRAS organisms like Lactobacillus reuteri (L. reuteri), is negatively impacted by the low yield and use of expensive feedstocks. In order to improve the process economy, we have developed a multiproduct process involving the production of three commercially important chemicals, namely, 1,3-PD, lactate and 3-Hydroxypropionic acid (3-HP), by engineered L. reuteri. The maximum 1,3-PD and lactate titer of 41 g/L and 31 g/L, with a volumetric productivity of 1.69 g/L/h and 0.67 g/L/h were achieved, respectively. The maximum 3-HP titer of 5.2 g/L with a volumetric productivity of 1.3 g/L/h, was obtained by biotransformation using cells recovered from the repeated fed-batch process. The volumetric productivity of 1,3-PD obtained in this study is the highest ever reported for this organism. Further cost reduction can be achieved by using waste feedstocks like milk whey, biomass hydrolysate, and crude glycerol.     

Arsenic Uptake by Lemna minor in Hydroponic System

Arsenic is hazardous and causes several ill effects on human beings. Phytoremediation is the use of aquatic plants for the removal of toxic pollutants from external media. In the present research work, the removal efficiency as well as the arsenic uptake capacity of duckweed Lemna minor has been studied. Arsenic concentration in water samples and plant biomass were determined by AAS. The relative growth factor of Lemna minor was determined. The duckweed had potential to remove as well as uptake arsenic from the aqueous medium. Maximum removal of more than 70% arsenic was achieved at initial concentration of 0.5 mg/l arsenic on 15th day of experimental period of 22 days. Removal percentage was found to decrease with the increase in initial concentration. From BCF value, Lemna minor was found to be a hyperaccumulator of arsenic at initial concentration of 0.5 mg/L, such that accumulation decreased with increase in initial arsenic concentration.     

Rapidly diminishing mangrove forests in Myanmar (Burma): a review

IPCC predictions indicate an increase in temperatures by 1.5–7°C in some Amazonian regions during the twenty-first century. These changes could disrupt the present distribution patterns of organisms, including wetland plant species. In this work, we determined in microcosms the effects of scenarios combining elevated temperature and atmospheric CO₂ concentration on the germination and initial growth of the arborescent Amazonian aquatic macrophyte Montrichardia arborescens. Seeds were germinated, and seedlings produced were monitored over a 5-month period in four microcosms: Control: ambient temperature and CO₂ level; Mild: Control + 1.5°C and + 200 ppm CO₂; intermediate: control + 2.5°C and + 400 ppm CO₂; Extreme: Control + 4.5°C and + 850 ppm of CO₂. Rapid light response curves and Fv/Fm values taken in seedlings showed a decrease in electron transportation rate with CO₂ and temperature elevation. Mild and Intermediate treatments stimulated biomass production; Extreme treatment and Control produced similar results. The severe climatic changes expected in the future may negatively influence carbon accumulation in M. arborescens. Since aquatic macrophytes in Amazonian wetlands and wetlands worldwide are key plant species, further studies are needed to predict their fate in a global change perspective.     

Prospect of phytoaccumulation of arsenic by Brassica juncea (L.) in Bangladesh

The phytoaccummulation of arsenic by Brassica juncea (L.) was investigated for varying concentrations selected within the range that is evident in Bangladeshi soil. B. juncea (Rai and BARI-11) was grown in the hydroponic media under greenhouse condition with different concentrations (0.5, 1.0, 15, 30, 50 and 100 ppm) of sodium arsenite. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) was used to analyze the data. Mapping of potential area of phytoaccumulation of arsenic by B. juncea was done using Geographic information system (GIS). Arsenic was detected at lower concentrations (0.5 and 1.0 ppm) only at root system of the plant. For higher concentrations (15, 30, and 50 ppm) arsenic was detected both in the root and shoot systems. The results suggested that at 15 and 50 ppm uptake was higher compared to 30 ppm. For 100 ppm of arsenic no plant growth was observed. In Bangladesh, where concentration of arsenic is at lower level and present only at rooting zone, B. juncea may be used for phytoaccumulation of arsenic keeping usual agronomic practices. However, for higher concentrations, B. juncea can be regarded as a good accumulator of arsenic where uptake of arsenic was up to 1% of total biomass of the plant.     

Plant biomass and nutrients (C,N and P) in natural,restored and prior converted depressional wetlands in the Mid-Atlantic Coastal Plain,U.S.

Monitoring is an essential component of restoration and measurements of biomass and nutrient concentrations are often used as indicators of ecosystem function. We studied restored depressional wetlands in the U.S. Mid-Atlantic Region. The first study, part of the U.S. Department of Agriculture Conservation Effects Assessment Project (CEAP-Wetlands), compared hydrologically restored wetlands (aged 5–10 years) with natural wetlands and prior converted croplands. We measured aboveground biomass and plant nutrient concentrations at Coastal Plain sites, from Delaware to North Carolina. At the CEAP sites, herbaceous biomass was highest in Restored wetlands, while existing tree biomass was highest in Natural sites. Nutrient concentrations were significantly higher in Prior Converted and Restored sites, relative to Natural sites. In the second study, we compared biomass and nutrient data at a separate set of restored sites, originally sampled by the Smithsonian Environmental Research Center (SERC) in 1994 and resampled in 2011, 15 years later. The primary temporal change was increased tree biomass near the upland-wetland boundary. Both studies indicate that these restored wetlands are in early stages of plant succession, but should develop similarly to natural sites if succession is allowed to progress for decades. This time could be reduced by planting late-successional species characteristic of undisturbed local natural sites. Nutrient data, especially for the SERC wetlands, indicated that these restored wetlands resemble natural sites more in terms of plant nutrient concentrations and that the sites, similar to natural wetlands, will become less nitrogen limited as the impacts of previous agricultural activities decline.     

The Rengen Grassland Experiment: Effect of Soil Chemical Properties on Biomass Production, Plant Species Composition and Species Richness

The Rengen Grassland Experiment (RGE), set up on a Nardus grassland in 1941, consists of a control and five fertilizer treatments (Ca, CaN, CaNP, CaNP-KCl and CaNP-K₂SO₄). In 2005, soil chemical properties were analyzed to investigate the effect of soil variables on biomass production, plant species composition and species richness of vascular plants. Further, the effect of sampling scale (from 0.02 to 5.76 m²) on species richness was investigated. Soil properties (plant-available contents of K, P, C:N ratio, and pH) and biomass production were found to be strictly dependent on the fertilizers applied. Diversification of soil P content between treatments with and without P application is still in progress. Biomass production was most positively affected by P and K soil contents under N application. Furthermore, pH had a small positive effect on biomass production, and C:N ratio a moderately negative one. Two types of nutrient limitation were recognized: (1) limitation of total biomass production and (2) limitation of individual plant species. Long-term addition of a limiting nutrient affected the grassland ecosystem in three ways: (1) causing a change in plant species composition without significant increase in total biomass production, (2) causing no change in species composition but with significant increase in total biomass production, and (3) causing substantial change in plant species composition accompanied by significant increase in total biomass production. The explanatory power of all measured soil properties on plant species composition was almost the same as the power of the treatment effect (61.7% versus 62% of explained variability in RDA). The most powerful predictors of plant species composition were soil P, K and Mg contents, pH, and biomass production. The soil P content and biomass production were the only variables leading to a significant negative effect on species richness. An almost parallel increase in species richness with increasing sampling area was detected in all treatments. Constant differences among treatments were independent of sampling area.     

Responses of morphological and physiological traits to herbivory by snails of three invasive and native submerged plants

3种入侵和本地沉水植物形态和生理性状对螺类牧食的响应 沉水植物水盾草(Cabomba caroliniana)已成为中国太湖流域的优势入侵水生植物。与外来物种的原产地环境相比,引入地新环境中存在的专食性天敌较少。外来物种可能会逃避其原产地环境中的天敌牧食,又因为它们的适口性相对较差,从而导致在引入地外来物种通常比本地物种遭受的牧食者影响更低(天敌逃逸假说)。本研究的目的是比较水盾草与共生的本地沉水植物对本地牧食者的响应。我们进行了一个中宇宙尺度实验,研究了水盾草和两种共生的本地沉水植物黑藻(Hydrilla verticillata)和穗花狐尾藻(Myriophyllum spicatum)对两种本地广食性腹足纲螺类萝卜螺(Radix swinhoei)和环棱螺(Sinotaia quadrata)的牧食响应。记录了它们的形态性状指标(总生物量、冠根比和相对生长率)和生理性状指标(叶片总非结构性碳、木质素和纤维素)。研究结果表明,环棱螺对3种沉水植物性状指标的影响较少。随着本地广食性螺类萝卜螺数量的增加,黑藻和穗花狐尾藻大部分植物性状发生了改变,而水盾草的植物性状表现出相对稳定的趋势。水盾草对萝卜螺的牧食更具抵抗力,这与天敌逃逸假说的假设一致。这一发现说明牧食性螺类促进了水盾草的入侵,这可能会改变沉水植物群落中的物种组成。     

Effects of salinity and clipping on biomass and competition between a halophyte and a glycophyte

Global climate change will likely result in the reduction of water levels in intermountain wetlands and ponds, and the vegetation communities associated with these wetlands are an important forage source for livestock. Lowered water levels will not only constrict wetland plant communities, it will potentially change aquatic and soil salt concentrations. Such an increase in salinity can reduce plant growth and potentially affect competitive interactions between plants. A greenhouse experiment examined the effects of salinity and competition on the growth of two wet meadow grass species, Poa pratensis (a glycophyte) and Puccinellia nuttalliana (a halophyte). The following hypotheses based on published data were tested: (1) Biomass of both species will decrease with increasing concentration of salt; (2) root:shoot (R:S) ratio of P. pratensis will decrease with increasing salt concentration while R:S ratio of P. pratensis and P. nuttalliana will increase with clipping; (3) competitive importance will decrease for P. pratensis and P. nuttalliana with increasing salt concentration because salt induces a stress response and competitive importance is reduced in stressed environments. A factorial design included 3 plant treatments (P. nuttalliana alone, P. pratentsis alone, P. nuttalliana + P. pratensis) × 4 salinity rates (control; 5, 10, 15 g/L NaCl) × 2 clipping intensities (plants clipped or not clipped) for a total of 24 combinations replicated 6 times over a period of 90 days. We found a reduction in dry biomass as salinity increased, and this effect was greatest for P. pratensis. (1.94 g (SE 0.13) at 0 g/L NaCl to 0.22 g (SE 0.11) at 15 g/L NaCl). The R:S ratio of P. pratensis was reduced by salinity, but not for P. nuttalliana. Competitive importance of both species was reduced by clipping and by salinity, but the effect was greater and more consistent for P. pratensis. We conclude that salt concentration reduces plant growth and the effect of competition.     

Improvement of element uptake and antioxidative defense in Brassica napus under lead stress by application of hydrogen sulfide

Heavy metal pollution is one of the major constraints in oilseed rape (Brassica napus L.) production. In this study, protective role of hydrogen sulfide (H₂S) on plant growth under lead (Pb) stress was studied in B. napus. Plants were grown hydroponically in greenhouse conditions under three levels (0, 100, and 400 μM) of Pb and three levels (0, 100 and 200 μM) of H₂S donor sodium hydrosulfide. Outcomes demonstrated that Pb stress significantly reduced the plant biomass, leaf chlorophyll contents, nutrients uptake in the leaves and roots of B. napus plants. Exogenous application of H₂S significantly improved the plant biomass, chlorophyll contents and concentration of macro- and micronutrients in the leaves and roots of B. napus plants under Pb-toxicity conditions. The data indicated that application of Pb alone significantly increased the reactive oxygen species (ROS) as well as malondialdehyde (MDA) in the leaves and roots of plants. Meanwhile, application of H₂S decreased the production of MDA and ROS in the leaves and roots by increasing antioxidant activities under Pb stress. Moreover, this study also revealed that plants treated with H₂S at different concentrations enhanced the contents of total glutathione and glutathione reduced/glutathione oxidized ratio in leaves and roots under different levels of Pb. The results depicted that H₂S improved the plant biomass, uptake of nutrients in the leaves and roots of B. napus plants and enhanced the performance of antioxidant defense system due to its ameliorative potential under Pb stress conditions.     

Mycorrhizal symbiosis and phosphorus fertilization effects on Zea mays growth and heavy metals uptake

Arbuscular mycorrhizal fungi (AMF) can promote plant growth and reduce plant uptake of heavy metals. Phosphorus (P) fertilization can affect this relationship. We investigated maize (Zea mays L.) uptake of heavy metals after soil AMF inoculation and P fertilization. Maize biomass, glomaline and chlorophyll contents and uptake of Fe, Mn, Zn, Cu, Cd and Pb have been determined in a soil inoculated with AMF (Glomus aggregatum, or Glomus intraradices) and treated with 30 or 60 µg P-K₂HPO₄ g^?1 soil. Consistent variations were found between the two mycorrhizal species with respect to the colonization and glomalin content. Shoot dry weight and chlorophyll content were higher with G. intraradices than with G. aggregatum inoculation. The biomass was highest with 30 µg P g^?1 soil. Shoot concentrations of Cd, Pb and Zn decreased with G. aggregatum inoculation, but that of Cd and Pb increased with G. intraradices inoculation. Addition of P fertilizers decreased Cd and Zn concentrations in the shoot. AMF with P fertilization greatly reduced maize content of heavy metals. The results provide that native AMF with a moderate application rate of P fertilizers can be exploited in polluted soils to minimize the heavy metals uptake and to increase maize growth.     

CO2 Exchange and Growth of the Crassulacean Acid Metabolism Plant Opuntia ficus-indica under Elevated CO2 in Open-Top Chambers

CO2 uptake, water vapor conductance, and biomass production of Opuntia ficus-indica, a Crassulacean acid metabolism species, were studied at CO2 concentrations of 370, 520, and 720 [mu]L L-1 in open-top chambers during a 23-week period. Nine weeks after planting, daily net CO2 uptake for basal cladodes at 520 and 720 [mu]L L-1 of CO2 was 76 and 98% higher, respectively, than at 370 [mu]L L-1. Eight weeks after daughter cladodes emerged, their daily net CO2 uptake was 35 and 49% higher at 520 and 720 [mu]L L-1 of C02, respectively, than at 370 [mu]L L-1. Daily water-use efficiency was 88% higher under elevated CO2 for basal cladodes and 57% higher for daughter cladodes. The daily net CO2 uptake capacity for basal cladodes increased for 4 weeks after planting and then remained fairly constant, whereas for daughter cladodes, it increased with cladode age, became maximal at 8 to 14 weeks, and then declined. The percentage enhancement in daily net CO2 uptake caused by elevated CO2 was greatest initially for basal cladodes and at 8 to 14 weeks for daughter cladodes. The chlorophyll content per unit fresh weight of chlorenchyma for daughter cladodes at 8 weeks was 19 and 62% lower in 520 and 720 [mu]L L-1 of CO2, respectively, compared with 370 [mu]L L-1. Despite the reduced chlorophyll content, plant biomass production during 23 weeks in 520 and 720 [mu]L L-1 of CO2 was 21 and 55% higher, respectively, than at 370 [mu]L L-1. The root dry weight nearly tripled as the C02 concentration was doubled, causing the root/shoot ratio to increase with CO2 concentration. During the 23-week period, elevated CO2 significantly increased CO2 uptake and biomass production of O. ficus-indica.     

A balanced polymorphism in biomass resource allocation controlled by phosphate in grasses screened through arsenate tolerance

The response of arsenate and non-tolerant Holcus lanatus L. phenotypes, where tolerance is achieved through suppression of high affinity phosphate/arsenate root uptake, was investigated under different growth regimes to investigate why there is a polymorphism in tolerance found in populations growing on uncontaminated soil. Tolerant plants screened from an arsenic uncontaminated population differed, when grown on the soil from the populations origin, from non-tolerants, in their biomass allocation under phosphate fertilization: non-tolerants put more resources into tiller production and down regulated investment in root production under phosphate fertilization while tolerants tillered less effectively and did not alter resource allocation to shoot biomass under phosphate fertilization. The two phenotypes also differed in their shoot mineral status having higher concentrations of copper, cadmium, lead and manganese, but phosphorus status differed little, suggesting tight homeostasis. The polymorphism was also widely present (40%) in other wild grass species suggesting an important ecological role for this gene that can be screened through plant root response to arsenate.     

Physiological responses of peanut seedlings to exposure to low or high cadmium concentration and the alleviating effect of exogenous nitric oxide to high cadmium concentration stress

Abstract

The physiological responses of peanut seedlings exposed to low (5 µM) or high (200 µM) cadmium (Cd) concentration and the ability of sodium nitroprusside (SNP, a donor of NO) to reverse the harmful effects of Cd on peanut (Arachis hypogaea L.) were studied. Changes in plant growth parameters, chlorophyll content, antioxidant system, nutrient contents and Cd accumulation were investigated. The results showed that SNP and 5 µM Cd improved plant growth and chlorophyll content. Furthermore, antioxidative system was up-regulated, and as a result, the production rate of superoxide radical (O₂^??) was reduced. Moreover, the absorption of nutrient elements was not impacted, and Cd toxicity was not observed. However, 200 µM Cd had negative effects on the above measured parameters and dramatically increased the accumulation of Cd in all the plant organs. In the 200 µM Cd treatment, addition of 250 µM SNP stimulated plant growth and increased chlorophyll content. It also enhanced the regulation of antioxidative system and reduced the production rate of O₂^?? and malondialdehyde (MDA) content. Besides, SNP supply enhanced the absorption of nutrient elements and restrained the absorption and transport of Cd.     

Evaluation of Atriplex Halimus,Medicago Lupulina and Portulaca Oleracea For Phytoremediation of Ni,Pb, and Zn

Suitable plant species are able to accumulate heavy metals and to produce biomass useful for non-food purposes. In this study, three endemic Mediterranean plant species, Atriplex halimus, Portulaca oleracea and Medicago lupulina were grown hydroponically to assess their potential use in phytoremediation and biomass production. The experiment was carried out in a growth chamber using half strength Hoagland's solutions separately spiked with 5 concentrations of Pb and Zn (5, 10, 25, 50, and 100 mg L^?1), and 3 concentrations of Ni (1, 2 and 5 mg L^?1). Shoot and root biomass were determined and analyzed for their metals contents. A. halimus and M. lupulina gave high shoot biomass with relatively low metal translocation to the above ground parts. Metals uptake was a function of both metals and plant species. It is worth noting that M. lupulina was the only tested plant able to grow in treatment Pb50 and to accumulate significant amount of metal in roots. Plant metal uptake efficiency ranked as follows: A. halimus > M. lupulina > P. oleracea . Due to its high biomass production and the relatively high roots metal contents, A. halimus and M. lupulina could be successfully used in phytoremediation, and in phytostabilization, in particular.     

A natural plant growth promoter,calliterpenone, enhances growth and biomass,carbohydrate, and lipid production in cyanobacterium Synechocystis PCC 6803

Cyanobacteria have evolved photosynthetic mechanisms in which solar energy is used to fix CO₂ into carbohydrates. The lipids from cyanobacteria can be converted to biodiesel by extraction–transesterification methods. The present study demonstrates the usefulness of the natural plant and microbial growth promoter calliterpenone from the plant Callicarpa macrophylla supplemented at three different doses (15, 25, 50 μL of a 0.01 mM solution) per 100 mL BG11⁺ medium for enhancing total biomass, carbohydrate, and lipid yields and reducing the surface-to-volume ratios of cells of Synechocystis PCC 6803. The enhanced total dried biomass, carbohydrate, and lipid production was 316.1, 140.34, and 130.76 %, respectively, higher than the control, and were obtained after 15 days of cultivation at the dose of 15 μL (0.01 mM) of calliterpenone per 100 mL BG11⁺ medium. A decrease in surface-to-volume ratio of cells from 1.19 to 0.84 compared to the control was also observed. Response surface methodology was used to optimize the doses of calliterpenone at different pH of growth media. An increase of 346.95, 187.2, and 134.46 % in biomass, carbohydrate, and lipid yields, respectively, was achieved after 10 days of cultivation in optimized BG11⁺ media at pH 7.5 and with 20 μL (0.01 mM) calliterpenone per 100 mL. Thus, this biomolecule can be exploited for higher yields of Synechocystis PCC 6803 in a relatively shorter culture time making this an attractive strategy for fuel production using this cyanobacterium.     

Reed cut,habitat diversity and productivity in wetlands

There is a conflict between nature conservation and thatching industry regarding the management of reedbeds. On one hand, reedbeds are of an economical importance by providing thatching material, on the other hand, they harbour several endangered species. Reedbeds are typically managed by winter cutting, but its impacts on biodiversity are poorly understood. Our aim was to study the effects of winter cutting on the habitat diversity and structural heterogeneity of wetlands in a lowland alkali landscape (East-Hungary). We tested the following hypotheses: (i) Both diversity of plant species and habitat diversity are lower in winter cut wetlands compared to unmanaged stands. (ii) The distribution of biomass (green biomass, litter and standing dead biomass) is more homogeneous in winter cut wetlands compared to unmanaged ones. We found that winter cutting decreased habitat diversity and structural heterogeneity at multiple scales. Number of plant species and all measures of habitat diversity (number of patches, vegetation types and the length of vegetation margins) had lower scores in cut wetlands than in unmanaged ones. We found that unmanaged wetlands harboured high amount of accumulated biomass and they also maintained high habitat diversity likely due to the heterogeneous distribution of the biomass. In unmanaged wetlands, biomass accumulation did not decrease habitat diversity and also contributed to a higher structural heterogeneity. In cut wetlands, expansion of reed was an important driver of the decrease in habitat diversity and structural heterogeneity. Reed expansion likely overrode fine-scale edaphic conditions (hydrology and salinity) in shaping vegetation patterns; thus we suggest to avoid intensive winter cutting.     

Feeding behaviour of underyearling hybrids of the grass carp, Ctenopharyngodon idella♀ and the bighead, Hypophthalmicthys nobilis♂ on selected species of aquatic plants

Underyearling hybrids of the cross Ctenopharyngodon idella ♀ (grass carp) and Hypophthalmichthys nobilis ♂ (bighead), averaging 104.8 mm total length were stocked for two weeks in cement tanks holding 605 1 of water with various combinations of submersed or floating aquatic plants. The submersed species most preferred were Ceratophyllum demersum, Chara sp. and Najas guadalupensis. Hydrilla verticillata, Hygrophila polysperma, Myriophyllum pinnatum and Utricularia foliosa were fed on from a minor to moderate extent. No feeding damage was observed on Egeria densa and Potamogeton illinoensis. Azolla caroliniana, Lemna sp. and Wolffia columbiana were readily consumed while Salvinia rotundifolia was not preferred when in combination with these floating plant species. Feeding damage to the submersed roots of Eichhornia crassipes and Pistia stratiotes was minor during a 30 day period. Hybrid fingerlings readily fed on mosquito larvae and small leeches when offered to them in an aquarium on one occasion.     

A Review on the Role of Chromium Supplementation in Ruminant Nutrition—Effects on Productive Performance,Blood Metabolites,Antioxidant Status,and Immunocompetence

Interactions of arsenic with essential trace elements may result in disturbances on body homeostasis. In the present study, we aimed to investigate the effects of different arsenic compounds on micromineral content and antioxidant enzyme activities in rat liver. Male Wistar rats were randomly divided into five groups and exposed to sodium arsenite and sodium arsenate at 0.01 and 10 mg/L for 8 weeks in drinking water. The concentration of arsenic increased in the liver of all arsenic-exposed animals. The proportion of zinc and copper increased in animals exposed to 0.01 mg/L sodium arsenite. In addition, these animals presented a reduction in magnesium and sodium content. Superoxide dismutase activity decreased mainly in arsenite-exposed animals, whereas catalase activity decreased in animals exposed to 10 mg/L sodium arsenate. Further, exposure to sodium arsenate at 10 mg/L altered copper and magnesium content in the liver, and reduced total protein levels. Overall, both arsenic compounds altered the liver histology, with reduction in the proportion of cytoplasm and hepatocyte, and increased the percentage of sinusoidal capillaries and macrophages. In conclusion, our findings showed that oral exposure to arsenic compounds disturbs the trace elements balance in the liver, especially at low concentration, altering enzymatic and stereological parameters. We concluded that despite the increase in trace elements content, the antioxidant enzyme activities were downregulated and did not prevent morphological alterations in the liver of animals exposed to both arsenic compounds.     

Phytoremediation potential of Lemna minor L. for heavy metals

Phytoremediation potential of L. minor for cadmium (Cd), copper (Cu), lead (Pb), and nickel (Ni) from two different types of effluent in raw form was evaluated in a glass house experiment using hydroponic studies for a period of 31 days. Heavy metals concentration in water and plant sample was analyzed at 3, 10, 17, 24, and 31 day. Removal efficiency, metal uptake and bio-concentration factor were also calculated. Effluents were initially analyzed for physical, chemical and microbiological parameters and results indicated that municipal effluent (ME) was highly contaminated in terms of nutrient and organic load than sewage mixed industrial effluent (SMIE). Results confirmed the accumulation of heavy metals within plant and subsequent decrease in the effluents. Removal efficiency was greater than 80% for all metals and maximum removal was observed for nickel (99%) from SMIE. Accumulation and uptake of lead in dry biomass was significantly higher than other metals. Bio-concentration factors were less than 1000 and maximum BCFs were found for copper (558) and lead (523.1) indicated that plant is a moderate accumulator of both metals. Overall, L. minor showed better performance from SMIE and was more effective in extracting lead than other metals.