Arsenic tolerances in rice (Oryza sativa) have a predominant role in transcriptional regulation of a set of genes including sulphur assimilation pathway and antioxidant system

World wide arsenic (As) contamination of rice has raised much concern as it is the staple crop for millions. Four most commonly cultivated rice cultivars, Triguna, IR-36, PNR-519 and IET-4786, of the West Bengal region were taken for a hydroponic study to examine the effect of arsenate (As^V) and arsenite (As^III) on growth response, expression of genes and antioxidants vis-à-vis As accumulation. The rice genotypes responded differentially under As^V and As^III stress in terms of gene expression and antioxidant defences. Some of the transporters were up-regulated in all rice cultivars at lower doses of As species, except IET-4786. Phytochelatin synthase, GST and γ-ECS showed considerable variation in their expression pattern in all genotypes, however in IET-4786 they were generally down-regulated in higher As^III stress. Similarly, most of antioxidants such as superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), catalase (CAT), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) increased significantly in Triguna, IR-36 and PNR-519 and decreased in IET-4786. Our study suggests that Triguna, IR-36 and PNR-519 are tolerant rice cultivars accumulating higher arsenic; however IET-4786 is susceptible to As-stress and accumulates less arsenic than other cultivars.     

Cypermethrin induced alterations in nitrogen metabolism in freshwater fishes

In the present study, two fresh water fishes namely, Channa punctatus and Clarias batrachus, were exposed to three sub-acute concentrations of synthetic pyrethroid, cypermethrin, for 96 h to evaluate the role of amino acids in fulfilling the immediate energy needs of fishes under pyrethroid induced stress as well as to find out the mechanism of ammonia detoxification. The experiments were designed to estimate the levels of free amino acid, urea, ammonia and the activities of aspartate aminotransferase (AAT), alanine aminotransferase (AlAT), glutamate dehydrogenase (GDH), glutamine synthetase (GS) and arginase in some of the vital organs like brain, gills, liver, kidney and muscle of both fish species. The significant decrease in the levels of amino acids concomitant with remarkable increase in the activities of AAT, AlAT and GDH in these vital tissues of fish species elucidated the amino acid catabolism as one of the main mechanism of meeting out the immediate energy demand of the fishes in condition of cypermethrin exposure. The levels of ammonia were significantly increased at 10% of 96 h LC(50) of cypermethrin in the different organs such as brain, gills, liver, kidney and muscle of both fish species while 15% and 20% concentrations of 96 h LC(50) of cypermehrin registered remarkable decline in both fish species. The differential increment in the activities of GDH, GS and arginase and in the level of urea established three different alternative mechanisms of ammonia detoxification. The results indicated that in C. punctatus, the prevalent mode of nitrogen excretion is in the form of conversion of ammonia into glutamine and glutamate while in C. batrachus, the excessive nitrogen is excreted in the form of urea synthesized from ammonia.     

Reproduction, larval growth, and reproductive development in African clawed frogs (Xenopus laevis) exposed to atrazine

Reproductive success and development of F2 offspring from F1 adult African clawed frogs (Xenopus laevis) exposed to atrazine throughout larval development and as sexually mature adults was examined. Larval X. laevis were exposed to one of four nominal concentrations of atrazine (0, 1, 10, 25 microg atrazine/l) beginning 96 hr after fertilization and continuing through two years post-metamorphosis. Clutch size and survival of offspring were used as measurement endpoints to gauge reproductive success of the F1 frogs. Larval survivorship and time to metamorphosis were used to gauge developmental success of the F2 offspring from atrazine-exposed frogs. Testes in F1 and F2 frogs were examined for incidence of anomalies, such as testicular ovarian follicles, and sex ratios in F2 offspring were investigated to determine if exposure to atrazine caused trans-generational effects (effects on F2 individuals due to exposure of F1 individuals). There were no effects of any of the studied concentrations of atrazine on clutch size of F1 frogs. There were also no effects on hatching success or time to metamorphosis. Sex ratios did not differ between F2 offspring among treatments. There was no evidence to suggest a transgenerational effect of atrazine on spawning success or reproductive development of X. laevis. This is consistent with the presence of robust populations of X. laevis in areas where they are exposed to atrazine that has been used for several decades for weed control in production of corn. Our observations also are consistent with the results of most other studies of frogs where no effects were found to be associated with exposure to atrazine. Our data do not support the hypothesis that atrazine significantly affects reproductive fitness and development of frogs.     

Simple digestion procedure followed by the azomethine-H method for accurate boron analysis and discrimination between its fractions in wastewater and soils

Excess boron is a growing environmental problem. It often affects agricultural yields, where reuse of wastewater for irrigation is practiced. This problem raises the need for reliable, simple and economical methods to monitor boron concentrations in wastewater and soil extracts. One such method, the commonly used azomethine-H spectrophotometric method, suffers from color interference, originating from high concentrations of dissolved organic matter, when applied to many wastewater and agricultural soil extracts. Moreover, this method only quantifies free dissolved boron and lacks the ability to quantify boron that is adsorbed to either the dissolved organic matter or suspended solids that are present in the sample. This work suggests a modification of the standard azomethine-H method, in which the solution is digested with potassium persulfate prior to the standard procedure. We show that this pretreatment can overcome the color interference and lead to highly accurate and precise boron analyses in wastewater. In soil extracts, the boron concentrations obtained using the suggested procedure were better correlated to inductively coupled plasma (ICP) spectrometry results than those measured by the standard method, because whereas the standard method quantifies the free dissolved boron only, the modified method, like the ICP method, quantifies the total dissolved boron in the sample. Thus, the suggested modification can be used to quantify the respective distributions of free dissolved boron, boron adsorbed to dissolved organic matter and boron adsorbed to suspended solids in soil extracts and water samples.     

Phycoremediation potential of marine microalga <Emphasis Type="Italic">Tetraselmis indica</Emphasis> on secondary treated domestic sewage for nutrient removal and biodiesel production

Marine microalga Tetraselmis indica (T. indica) was cultivated in secondary treated domestic sewage (STDS) in batch mode. Optimization studies showed that after 14 days of cultivation period, highest biomass yield reached was 0.88 ± 0.04 g/L at the optimum temperature of 27 ± 1 °C and light intensity of 135 μmol m^?2 s^?1. T. indica removed about 60.93% phosphate, 78.46% nitrate, 72.94% chemical oxygen demand (COD), 73.17% biological oxygen demand (BOD), 98.90% total dissolved solids (TDS) and heavy metals (83.11% Cd, 55.67% Ca, 45.12% Cu, 13.67% Mn, 50.88% Pb, and 98.92% Al) from STDS. The level of electrical conductivity was reduced to 0.0974 ± 0.045 dS/m. The fatty acid methyl ester (FAME) profile showed the presence of palmitic acid (12.91%), oleic acid (35.94%), linoleic acid (14.89%) and eicosanoic acid (12.34%). This study indicates the potential of T. indica for removal of pollutants from STDS and also its capability of biodiesel production.     

Is rainfall gradient a factor of livelihood diversification? Empirical evidence from around climatic hotspots in Indo-Gangetic Plains

Farmers in the Indo-Gangetic Plains are constantly seeking ways to adapt to changing circumstances and opportunities that include new technologies, institutions, policies, socio-economic and cultural shifts, as well as a changing climate. The relationship between rainfall and local livelihoods is important to devise policies to improve adaptive capacity of farmers to different drivers of changes. The present study investigates whether the spatial variations in rainfall have prompted the location-specific livelihood diversification by using data from 2660 farm families in the climatic risk areas in India, Nepal and Bangladesh. The results show a higher on-farm livelihood diversification in the areas with high rainfall (1500–2100 mm) compared to medium (900–1500 mm) and very high rainfall regimes (>2100 mm). Based on this study, the optimal range of rainfall for better agricultural livelihood in the context of changing environmental circumstances is from 1500 to 2100 mm. In terms of farm practices changed (proxy of adaptability), farmers responded more frequently to the market-related drivers than climatic stressors. Farmers in climate vulnerable areas (Bihar and coastal Bangladesh for instance) responded more to climatic stressors than those living in relatively less vulnerable areas (Terai for instance). The results imply that livelihood strategies should be tailor-made along the climatic resources such as rainfall, considering other biophysical and socio-economic variations at the spatial scale. Identifying household and farm-level coping strategies along the rainfall gradient can also be useful in targeting interventions to build resilience to shocks.     

Dynamics of pesticide residues in nectar and pollen of mustard (Brassica juncea (L.) Czern.) grown in Himachal Pradesh (India)

Residues dynamics of Endosulfan (525.00 g a.i. ha(-1)), Imidacloprid seed treatment (21 g a.i. kg(-1)), Lambdacyhalothrin (75.00 g a.i. ha(-1)) and Spiromesifen (225.00 g a.i. ha(-1)) in nectar and pollen of mustard, Brassica juncea (L.) Czern. grown in Himachal Pradesh (India) were determined through bioassay (using Drosophila melanogaster Meig. as test organism) and GC (Gas chromatographic) and HPLC (High performance liquid chromatographic) methods. In general chromatographic methods were more sensitive for the determination of above given pesticides compared to bioassay method. Average recoveries in nectar samples varied between 82.85 and 88.90% by bioassay and 91.20 and 93.55% by chromatographic techniques. In pollen samples, recoveries varied between 81.44 and 86.44% by bioassay and 88.50 and 91.30% by chromatographic methods. Imidacloprid residues were neither found in nectar nor in pollen samples at the time of sampling i.e. 50% of flowering. The order of average half life of residues was: Lambdacyhalothrin (12.45 h) < Spiromesifen (19.99 h) < Endosulfan (27.49 h) for nectar and Spiromesifen (9.69 h) < Lambdacyhalothrin (12.44 h) < Endosulfan (17.84 h) for pollen samples. It was found that Imidcloprid seed treatment was practically harmless to honey bees, whereas a waiting period of 5 days must be observed on crops sprayed with these chemicals during blooms to avoid any accidental hazards to honey bees.     

Monitoring the condition of natural resources in US national parks

The National Park Service has developed a long-term ecological monitoring program for 32 ecoregional networks containing more than 270 parks with significant natural resources. The monitoring program assists park managers in developing a broad-based understanding of the status and trends of park resources as a basis for making decisions and working with other agencies and the public for the long-term protection of park ecosystems. We found that the basic steps involved in planning and designing a long-term ecological monitoring program were the same for a range of ecological systems including coral reefs, deserts, arctic tundra, prairie grasslands, caves, and tropical rainforests. These steps involve (1) clearly defining goals and objectives, (2) compiling and summarizing existing information, (3) developing conceptual models, (4) prioritizing and selecting indicators, (5) developing an overall sampling design, (6) developing monitoring protocols, and (7) establishing data management, analysis, and reporting procedures. The broad-based, scientifically sound information obtained through this systems-based monitoring program will have multiple applications for management decision-making, research, education, and promoting public understanding of park resources. When combined with an effective education program, monitoring results can contribute not only to park issues, but also to larger quality-of-life issues that affect surrounding communities and can contribute significantly to the environmental health of the nation.     

Energy recovery from sewage sludge by means of fluidised bed gasification

Because of its potential harmful impact on the environment, disposal of sewage sludge is becoming a major problem all over the world. Today the available disposal measures are at the crossroads. One alternative would be to continue its usage as fertiliser or to abandon it. Due to the discussions about soil contamination caused by sewage sludge, some countries have already prohibited its application in agriculture. In these countries, thermal treatment is now presenting the most common alternative. This report describes two suitable methods to directly convert sewage sludge into useful energy on-site at the wastewater treatment plant. Both processes consist mainly of four devices: dewatering and drying of the sewage sludge, gasification by means of fluidised bed technology (followed by a gas cleaning step) and production of useful energy via CHP units as the final step. The process described first (ETVS-Process) is using a high pressure technique for the initial dewatering and a fluidised bed technology utilising waste heat from the overall process for drying. In the second process (NTVS-Process) in addition to the waste heat, solar radiation is utilised. The subsequent measures--gasification, gas cleaning and electric and thermal power generation--are identical in both processes. The ETVS-Process and the NTVS-Process are self-sustaining in terms of energy use; actually a surplus of heat and electricity is generated in both processes.     

Study of air-soil exchange of polycyclic aromatic hydrocarbons (PAHs) in the north-central part of India--a semi arid region

Soil is the major environmental reservoir of organic compounds and soil-air exchange is a key process in governing the environmental fate of these compounds on a regional and global scale. Samples of air and soil were collected to study the levels of PAHs in the air and soil of the Agra region. Concentrations of PAH measured at four locations in the city of Agra, covers industrial, residential, roadside and agricultural areas. Samples were extracted with hexane by ultrasonic agitation. Extracts were then fractioned on a silica-gel column and the aromatic fraction was analysed by GC-MS. The mean concentration of the total PAH (T-PAH) in the air of Agra was 24.95, 17.95 and 14.25 ng m(-3), during winter, monsoon and summer respectively. The average concentration of T-PAH in the soil of Agra was 12.50, 8.25 and 6.44 μg g(-1) in winter, monsoon and summer seasons respectively. The aim of this study was to investigate the rate of approach to equilibrium partitioning of PAHs between air and soil compartments and to determine the direction of net flux of the studied PAH between air and soil. Calculated soil-air fugacity quotients indicate that the soil may now be a source of some lighter weight PAHs to the atmosphere, whereas it appears to be still acting as a long-term sink for the heavier weight PAHs to some extent in this region.