Total and methyl mercury in small marine biota caught off the Coast of Chennai,India

Abstract

This study reports the concentrations of total mercury and methyl mercury in sixteen families of marine biota caught off the coast of Kasimedu in Chennai, India, an important but understudied fish landing region. These included the commonly caught croakers, carangids, rays, goat fish, anchovies, crabs, and prawns. There was no correlation between total mercury or methyl mercury with fish length or mass. All concentrations were lower than the Food Safety and Standards Authority of India limits (total mercury = 500?μg/kg; methyl mercury = 250?μg/kg). Some values were above screening levels (total mercury >40?μg/kg wet weight) when considering possible adverse effects in predatory fish that consume the analyzed biota.

Abbreviations: dw: dry weight; MeHg: methyl mercury; THg: total mercury; ww: wet weight     

Effects of combinations of malathion and cypermethrin on survivability and time of metamorphosis of tadpoles of Indian cricket frog (Fejervarya limnocharis)

This study was undertaken to determine the effect of environmentally realistic concentrations of two commonly used pesticides viz., malathion and cypermethrin, using a fully 3 × 3 factorial experiments on the survivability and time of metamorphosis in a common rice paddy field frog (cricket frog) Fejervarya limnocharis under laboratory conditions. The results suggest that cypermethrin is more toxic than malathion and combinations of higher concentrations of cypermethrin (50 μg/L) with malathion (250 and 500 μg/L) are more deleterious to the survivability of tadpoles. With increasing cypermethrin concentration, the survivability of tadpole decreased (r = ?0.986, P = 0.108). But cypermethrin alone induced early metamorphosis among the surviving tadpoles. However, there was a delay in the time required for metamorphosis induced by malathion and its combination with cypermethrin. The delay in metamorphosis may indicate the altered physiological fitness of the individual. The emergent froglets will be subjected to environmental stressors like high temperature and less humidity of post-monsoon tropical climate that could enhance negative influence triggered by pesticides.     

Soil washing treatability tests for pesticide-contaminated soil

The 1987 Sand Creek Operable Unit 5 record of decision (ROD) identified soil washing as the selected technology to remediate soils contaminated with high levels of organochlorine pesticides, herbicides, and metals. Initial treatability tests conducted to assess the applicability of soil washing technology did not effectively evaluate the removal of the elevated contaminant concentrations that were found. To further evaluate the applicability of soil washing at this industrial site, a second more comprehensive pilot-scale treatability test was conducted. Twenty-three test runs were conducted over a two-week period in late September 1992, using a pilot-scale soil washing device called the volume reduction unit (VRU). The experimental design evaluated the effects of two wash temperatures, two pH levels, three surfactants, four surfactant concentrations, and two liquid-to-soil ratios on the contaminant removal efficiency of the soil washing process. Site soils from layers at three different depths were used in the study. Results from the pilot-scale treatability test indicated that the VRU could achieve contaminant reduction efficiencies of 97 percent for heptachlor and greater than 91 percent for dieldrin in the uppermost contaminated soils (surface to 1-ft. depth). Residual concentrations of heptachlor and dieldrin in the treated soil ranged from 50 ppm to less than 1.6 ppm, and 6.8 ppm to less than 1.6 ppm, respectively. However, the analytical method detection limit of 1.6 ppm was not low enough to provide residual concentration data at the risk-based action levels of 0.55 ppm for heptachlor and 0.15 ppm for dieldrin.     

Decontamination of water polluted by heavy metals with Taro (Colocasia esculenta) cultured in a hydroponic NFT system

The toxicity and bioaccumulation of two heavy metals—lead (Pb) and cadmium (Cd)—in a semi-aquatic plant, Colocasia esculenta (L. Schott), from a synthetic heavy metal solution were studied. Young plants of equal size were grown hydroponically in shallow raceways containing Hoagland medium amended with 20, 40, and 60 mg l^?1 of Pb and 2, 4, and 6 mg l^?1 of Cd. The medium containing heavy metals was allowed to flow through the raceways with a change in influent heavy metal solution on every 5th day. The experiment was continued for 20 days. A set of control raceways—one comprised of nutrient medium with heavy metal supplements, devoid of plants, and another with the plants and nutrient medium having no metal supplement—was also simultaneously run. Chlorosis in the leaves was the prominent toxicity symptom observed due to Pb and Cd on the test plants. A significant decrease in the relative growth, biomass productivity, and total chlorophyll content were noticed in the plants with an increase in concentration of metal supplement in the solution and exposure time. Both metals accumulated to higher concentrations in the roots than in shoots, suggesting that the metals were bound to the root cells and their translocation to the leaves was limited. The results of the 20-day-long experiments indicate that from a phytoremediation perspective, C. esculenta is a promising plant species for remediation of wastewater polluted with lower concentrations of Pb and Cd.     

The performance of three cultivars of rice grown near to, and distant from, a fertiliser plant

The effects of three cultivars, two water regimes and two rates of applying nitrogen fertilisers were tested when studying the performance of rice (Oryza sativa L.) near to, and distant from, a fertiliser plant emitting atmospherically dispersed pollutants. The atmosphere near the fertiliser plant had average daily peak concentrations of 144 and 210 microg m(-3) of SO(2) and NO(2), respectively. Growth was less near to, than at a distance from, the fertiliser plant. On average it was decreased by water stress while the effects of different amounts of nitrogen fertiliser were variable. Whilst there were a number of interactions involving nitrogen and water treatments, the most consistent were associated with the responses of the three cultivars at the two locations. The three cultivars performed similarly at the unpolluted control site, but there were major differences at the polluted site. These were most clearly exemplified by changes in the proportion of dry matter allocated to yields of grain and straw. At the unpolluted site, grain accounted for about 30% of the combined yields of grain and straw. At the polluted site, grain accounted for 1, 23 and 31% of the combined grain and straw yields of cultivars CO 43 (the most sensitive), TKM 9 and GR 3 (the most tolerant). Grain yields were closely related to numbers of filled grains per plant. At the polluted site, 98% of grains failed to develop in CO 43, whereas in GR 3, the number of panicles, and therefore the potential number of grains, was significantly enhanced.     

Anti-herbivore activity of soluble silicon for crop protection in agriculture: a review

Environmental Science and Pollution Research - Silicon (Si) is considered an important component for plant growth, development, and yield in many crop species. Silicon is also known to reduce plant...     

Ecological aspects of plankton production

The study was carried out in the neritic and estuarine waters of Porto Novo, Coromandel Coast, Bay of Bengal, India during the period January, 1960 to December, 1967. The average displacement volume of plankton usually varied between 2 and 4 c²/m². During summer, with a season of high plankton productivity, the average plankton displacement volume rose to 8 c²/m³. Generally speaking, the average zooplankton density (standing crop) was usually between 80,000 and 100,000 organisms/m³, of which copepods alone comprised usually between 70,000 and 90,000 organisms/m³. The average copepod density per sample varied from 30,000 to 50,000 organisms/m³. However, in the summer months, the copepod density was usually not less than 100,000 organisms/m³; in some years this was even higher (from 125,000 to 170,000 organisms/m³). Copepods comprised between 80 and 95% of the zooplankton population. The maximum non-copepod population in the zooplankton seldom reached 30%, was ofter below 25%, and usually less than 20%. During the period March to October (in some years as early as February, and in some years up to November), either an increasing or a steady trend of plankton production was evident. It would appear that salinity and rainfall determine the occurrence and distribution of plankton in Porto Novo.Contribution No. 189 from the Centre of Advanced Study in Marine Biology, Marine Biological Station of Annamalai University, Porto Novo, Tamilnadu, India.     

The adoption of a Climate Disaster Resilience Index in Chennai,India

Results derived from the Climate Disaster Resilience Index (CDRI)—consisting of five dimensions (economic, institutional, natural, physical, and social), 25 parameters, and 125 variables—reflect the abilities of people and institutions to respond to potential climate‐related disasters in Chennai, India. The findings of this assessment, applied in the 10 administrative zones of the city, reveal that communities living in the northern and older parts of Chennai have lower overall resilience as compared to the flourishing areas (vis‐à‐vis economic growth and population) along the urban fringes. The higher resilience of communities along the urban fringes suggests that urbanisation may not necessarily lead to a deterioration of basic urban services, such as electricity, housing, and water. This indication is confirmed by a strong statistical correlation between physical resilience and population growth in Chennai. The identification of the resilience of different urban areas of Chennai has the potential to support future planning decisions on the city's scheduled expansion.     

Characterization and Biotechnological Functional Activities of Exopolysaccharides Produced by Lysinibacillus fusiformis KMNTT-10

Journal of Polymers and the Environment - In this study, the production and physicochemical characterization of exopolysaccharide (EPS) produced by Lysinibacillus fusiformis KMNTT-10 were...     

Enzyme hydrolysis of polyester knitted fabric: A method to control the microfiber shedding from synthetic textile

Synthetic textile materials are noted as one of the major contributors to microfiber release from household laundry. The higher usage of synthetic textiles was noted as one of the major reasons for the leaching of microfibers into the aquatic system. Though few laundry aids are available to control the release of microfiber from laundry, no successful methods were developed to control it in the fabric itself. Hence, this research aimed to analyze the effectiveness of surface modification of polyester fabric using lipase enzyme and its impact on microfiber shedding. Taguchi’s L9 orthogonal array was adopted to optimize the enzyme treatment process parameters to reduce microfiber shedding. The results showed that enzyme concentration was the major influencing factor with a contribution of 35.56%, followed by treatment pH (35.247%), treatment time (17.46%), and treatment temperature (11.74%). The optimization with S/N ratio showed minimum microfiber shedding at an enzyme concentration of 0.5 gram per liter (gpl), treatment temperature of 55°C, 6.5 pH, and a treatment time of 45 minutes. Knitted polyester fabric treated with the optimized enzyme treatment condition showed a significant reduction (p<0.05) in microfiber shedding (count—79.11% and mass—85.68%). The surface changes and the interaction of the enzyme on the fabric were confirmed by hydrolytic activity and FTIR analysis. The optimized treatment on different knit structures and fabric with different grams per square meter (GSM) indicated the versatility of the treatment irrespective of fabric parameters. The repeated laundry process (20 washing cycles) showed that the enzyme-treated samples had a significant level (p<0.05) of reduction in shedding than the control sample. The difference in shedding after 20 washes supports the efficiency and longevity of the enzyme treatment process in reducing microfiber shedding.