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151.
Triclosan (TCS) is an antimicrobial agent widely used in many personal care products. This study investigated the occurrence of TCS in effluents, biosolids and surface waters, and its fate in wastewater treatment plants (WWTPs). The aqueous concentrations of TCS in nineteen effluents from Australian WWTPs ranged from 23 ng/L to 434 ng/L with a median concentration of 108 ng/L, while its concentrations in nineteen biosolids ranged from 0.09 mg/kg to 16.79 mg/kg on dry weight basis with a median concentration of 2.32 mg/kg. The removal rates for TCS in five selected WWTPs were found to range between 72% and 93%. Biological degradation was believed to be the predominant removal mechanism for TCS in the WWTPs. However, adsorption onto sludge also played a significant role in the removal of TCS in the WWTPs. TCS at concentrations up to 75 ng/L was detected in surface waters (outfall, upstream, and downstream) from five rivers receiving effluent discharge from WWTPs. Preliminary risk assessment based on the worst-case scenario showed that the TCS concentrations in surface waters might lead to risks to aquatic organisms such as algae. Based on the TCS levels in the biosolids, application of biosolids on agricultural land may also cause adverse effects in the soil environment.  相似文献   
152.
The potential of five nonionic surfactants, Triton X-100, Brij35, Ethylan GE08, Ethylan CD127, and Ethylan CPG660 for enhancing release of carbaryl and ethion from two long-term contaminated soils was evaluated using the batch method. Incorporation of the surfactants into soils enhanced the release of both pesticides to various extents, which could be related to the type of pesticides and type and the amount of surfactants added. Release of ethion was dramatically enhanced by aqueous concentrations of surfactants above their critical micelle concentration values. This was attributed to solubility enhancement through incorporation of the highly hydrophobic compound within surfactant micelles. A concentration of 10 g L(-1) of various surfactants released >70% of the total ethion from the soil irrespective of the surfactant. For carbaryl, the surfactants were effective at low concentrations and dependence on concentration was lower than in the case of ethion. The ethylan surfactants (GE08, CD127, and CPG660) had a higher potential than Triton X-100 and Brij35 for releasing the pesticides. However, there was still a significant portion of carbaryl (11% of the total) and ethion (17% of the total) left in the soil. Our study also showed that there must be an optimal concentration of each surfactant to maximize the mass transfer of pesticides. At some threshold concentration level, additional surfactant started to inhibit the mass transfer of solute from the soil into the water. The results suggested that surfactants could help remediation of soils polluted by pesticides. The choice of surfactant should be made based on the properties of pesticides.  相似文献   
153.
Summary The impacts of human activities on the bio-geophysical and socio-economic environment of the Himalayas are analysed. The main man-induced activities which have accelerated ecological degradation and threatened the equilibrium of Himalayan mountain ecosystems are stated as: unplanned land use, cultivation on steep slopes, overgrazing, major engineering activities, over-exploitation of village or community forests, lopping of broad leaved plant species, shifting cultivation (short cycle) in north-east India, tourism and recreation. Monoculture in forests, erosion and landslides have resulted in one–third of the total Himalayan land area becoming environmentally derelict. Cold desert conditions prevail in 41,500 km2 of north-west Himalayas and are encouraged by traditional pasturalism. The geo-morphological conditions are major factors responsible for landslides which cause major havoc every year in the area. Other physical problems exist, such as eutrophication, drying up of the natural springs, the recession of the glaciers and changes in surface and ground water hydrology. Wild fauna, like musk deer (Moschus mischiferus) and the snow leopard (Panthera uncia), are now under threat partially due to changes in their habitat and the introduction of exotic plant species. Population pressure and migration are major factors responsible for poverty in the hills. The emigration of the working male population has resulted in the involvement of women as a major work-force. This work includes trekking for hours to collect fodder, timber and drinking water in addition to household duties. Guidelines, with special emphasis on the application of environmental impact assessments for the management of the Himalayas, are proposed.Drs Ahmad and Rawat are scientists, and Dr Rai is a research associate, at the Government of India, Ministry of Environment and Forests, G.B. Pant Institute of Himalayan Environment and Development. Correspondence should be addressed to Dr Afroz Ahmad.  相似文献   
154.
The present study aims to analyze the interaction of prevailing biotic pressure on soil environment with emphasis on its physicochemical and microbiological characteristics determining soil fertility status and thus supporting plant and animal biodiversity in Nanda Devi Biosphere Reserve (NDBR) which is located in northern part of Uttaranchal hills between 79 degrees 40'E to 80 degrees 05'E longitude and 30 degrees 17'N to 30 degrees 41'E latitude. The experimental results revealed that the physico-chemical characteristics (viz., moisture, pH, EC, C, N, P, K, CEC) of soil were maximum in moderately grazed meadow and minimum in intensively grazed meadow. Soil microbial analysis measured in terms of total viable count (TVC) exhibited grazing sensitivity trend being maximum population of bacteria > fungi > actinomycetes. The soil microbial population was positively correlated with soil respiration, dehydrogenase activity, acid phosphatase and microbial biomass, which exhibited uneven trend with grazing pressure. Soil from moderately grazed meadow showed highest microbial count and enzyme activities, whilst intensively grazed meadow showed lowest microbial count and enzyme activities. This depicts the beneficial role of prescribed grazing up to limited extent in management of soil fertility, which might have supported luxuriant growth of a variety of grasses.  相似文献   
155.
Microbial fuel cells (MFC) utilize microbes as catalysts to convert chemical energy to electricity.Inocula used for MFC operation must therefore contain active microbial population.The dye reduction-based electron-transfer activity monitoring (DREAM) assay was employed to evaluate different inocula used in MFCs for their microbial bioelectrical activity.The assay utilizes the redox property of Methylene Blue to undergo color change from blue to colorless state upon microbial reduction.The extent...  相似文献   
156.
The performance of Vicia faba L. in soil amended by different concentrations of fly ash has been studied. The parameters considered are seed germination, growth behaviour and nodulation frequency of the plant. Results revealed that while fly-ash amendment to the soil improved the growth performance at initial stages with application of lower concentrations, it was inhibitory at higher exposure concentrations. Although there was no difference in survival rates, but the seedling growth was reduced in comparison to control plants. Fly ash delayed the nodulation as lesser number of nodules was recorded at higher amendments. Results suggested feasibility of growing V. faba in fly ash contaminated area.  相似文献   
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