A field test for the assessment of faecal contamination of potable water

A simple, sensitive, rapid, inexpensive paper strip impregnated with Salmonellal E. coli medium (SEM) was formulated, and placed in a test tube. When potable water of 10 ml was added to the test tube it detected the faecal contamination of water samples within 16-48 h when incubated at room temperature from 20 to 35 degrees C. The positive results were indicated when the medium turned black (hydrogen sulfide production) for the presence of Salmonella sp. and/or the formation of a red ring (free indole from tryptophan) when a few drops of Kovac's reagent was added for the presence of coliform bacteria (E. coli). More than 600 water samples were tested with the new test (SEM) and results showed 99% agreement with that of the standard most probable number (MPN) coliform test and also proved highly successful in the field when it was employed to detect both Salmonella and E. coli. Different water testing laboratories involved in a water quality monitoring programme and governmental agencies evaluated the test media and reported that the test was user friendly, reliable and simple to perform in the field and will be especially useful for screening of both urban and rural water supplies for routine monitoring of bacteriological contamination.     

Chronic exposure to pyrethroid-based allethrin and prallethrin mosquito repellents alters plasma biochemical profile

Continuous exposure of humans to pyrethroid-based mosquito repellents for longer durations may lead to adverse health effects. No information is available on long-term use of these mosquito repellents pertaining to the biochemical changes in human subjects. Therefore, the present study is an attempt to evaluate the status of health in human volunteers exposed to two commercially available mosquito repellent pyrethroids, allethrin and prallethrin, in terms of changes in plasma biochemical profile. Results of this study showed less but significant increase in the levels of plasma glucose, phospholipids, nitrite and nitrate, lipidperoxides with a decrease in plasma cholesterol. No significant changes were observed in the contents of total protein, albumin, globulin, HDL-C and LDL-C. However, SGPT activity increased significantly in persons exposed to only allethrin. Though the present investigation involving a limited number of human subjects indicates the onset of both protective changes as well as derangement in metabolism, a detailed and rigorous study is greatly warranted to arrive at a definite conclusion about the effects of pyrethroid mosquito repellents.     

Changes in contaminant mass discharge from DNAPL source mass depletion: evaluation at two field sites

Changes in contaminant fluxes resulting from aggressive remediation of dense nonaqueous phase liquid (DNAPL) source zone were investigated at two sites, one at Hill Air Force Base (AFB), Utah, and the other at Ft. Lewis Military Reservation, Washington. Passive Flux Meters (PFM) and a variation of the Integral Pumping Test (IPT) were used to measure fluxes in ten wells installed along a transect down-gradient of the trichloroethylene (TCE) source zone, and perpendicular to the mean groundwater flow direction. At both sites, groundwater and contaminant fluxes were measured before and after the source-zone treatment. The measured contaminant fluxes (J; ML(-2)T(-1)) were integrated across the well transect to estimate contaminant mass discharge (M(D); MT(-1)) from the source zone. Estimated M(D) before source treatment, based on both PFM and IPT methods, were approximately 76 g/day for TCE at the Hill AFB site; and approximately 640 g/day for TCE, and approximately 206 g/day for cis-dichloroethylene (DCE) at the Ft. Lewis site. TCE flux measurements made 1 year after source treatment at the Hill AFB site decreased to approximately 5 g/day. On the other hand, increased fluxes of DCE, a degradation byproduct of TCE, in tests subsequent to remediation at the Hill AFB site suggest enhanced microbial degradation after surfactant flooding. At the Ft. Lewis site, TCE mass discharge rates subsequent to remediation decreased to approximately 3 g/day for TCE and approximately 3 g/day for DCE approximately 1.8 years after remediation. At both field sites, PFM and IPT approaches provided comparable results for contaminant mass discharge rates, and show significant reductions (>90%) in TCE mass discharge as a result of DNAPL mass depletion from the source zone.     

Integrated hydrochemical and geophysical studies for assessment of groundwater pollution in basaltic settings in Central India

The Pithampur Industrial sectors I, II, and III, located approximately, 45 km from Indore in Central India have emerged as one of the largest industrial clusters in the region. Various types of industries ranging from automobiles to chemicals and pharmaceuticals have been set up in the region since 1990. Most of the industries have effluent treatment plants (ETP) for treating wastewater before its disposal on land and/or in water body. The present study is an attempt to assess the groundwater quality in the watersheds surrounding these industrial sectors to develop the baseline groundwater quality in order to enable the policy makers to facilitate decisions on the development of industries in this region. The industries are located in two sub-watersheds, namely, Gambhir river sub-watershed and Chambal river sub-watershed. Geologically, the study area is located in the Deccan traps of Cretaceous to Paleocene age. The different basaltic flow units underlie clayey soils varying in thickness from 2–3 m. The aquifer is mostly of unconfined nature. Samples have been collected from a network of observation wells set up in the watersheds. The water quality analysis of the groundwater samples has been carried out six times during three hydrological cycles of 2004, 2005, and 2006. The results indicate that a few observation wells in the vicinity of the industrial clusters have very high TDS concentration and exceed the Bureau of Indian Standards (BIS) guideline for TDS concentration. The contamination of groundwater has been more severe in the Gambhir watershed as compared to the Chambal watershed. The presence of the impermeable clay layers has resulted in a slow migration of contaminants from the sources. The findings reveal that there is no significant groundwater contamination in the Pithampur industrial sectors except in the vicinity of the industrial clusters, which indicates that there is good environmental space available for the expansion of industrial units in the Pithampur industrial hub.     

Spatial and temporal estimation of soil loss for the sustainable management of a wet semi-arid watershed cluster

The ungauged wet semi-arid watershed cluster, Seethagondi, lies in the Adilabad district of Telangana in India and is prone to severe erosion and water scarcity. The runoff and soil loss data at watershed, catchment, and field level are necessary for planning soil and water conservation interventions. In this study, an attempt was made to develop a spatial soil loss estimation model for Seethagondi cluster using RUSLE coupled with ARCGIS and was used to estimate the soil loss spatially and temporally. The daily rainfall data of Aphrodite for the period from 1951 to 2007 was used, and the annual rainfall varied from 508 to 1351 mm with a mean annual rainfall of 950 mm and a mean erosivity of 6789 MJ mm ha^?1 h^?1 year^?1. Considerable variation in land use land cover especially in crop land and fallow land was observed during normal and drought years, and corresponding variation in the erosivity, C factor, and soil loss was also noted. The mean value of C factor derived from NDVI for crop land was 0.42 and 0.22 in normal year and drought years, respectively. The topography is undulating and major portion of the cluster has slope less than 10°, and 85.3 % of the cluster has soil loss below 20 t ha^?1 year^?1. The soil loss from crop land varied from 2.9 to 3.6 t ha^?1 year^?1 in low rainfall years to 31.8 to 34.7 t ha^?1 year^?1 in high rainfall years with a mean annual soil loss of 12.2 t ha^?1 year^?1. The soil loss from crop land was higher in the month of August with an annual soil loss of 13.1 and 2.9 t ha^?1 year^?1 in normal and drought year, respectively. Based on the soil loss in a normal year, the interventions recommended for 85.3 % of area of the watershed includes agronomic measures such as contour cultivation, graded bunds, strip cropping, mixed cropping, crop rotations, mulching, summer plowing, vegetative bunds, agri-horticultural system, and management practices such as broad bed furrow, raised sunken beds, and harvesting available water using farm ponds and percolation tanks. This methodology can be adopted for estimating the soil loss from similar ungauged watersheds with deficient data and for planning suitable soil and water conservation interventions for the sustainable management of the watersheds.     

基于非本地物种毒性数据推导出的水质基准可为本地物种提供适当保护吗？

基于非本地物种的毒性数据推导出的水质基准一直存在争议,质疑者提出应有针对不同生物区系的水质基准。而这个问题在中国尤为突出。本文作者搜集了38种污染物对本地物种和非本地物种的毒性数据,比较了这些生物的HC₅和物种敏感度分布,结果显示,基于非本地物种推导的水质基准有74%的确定性可以有效保护中国的水生态系统。如果采用评价因子(AF=5)来校正基准,那么可以获得90%的确定性。
精选自Xiaowei Jin, Zijian Wang, Yeyao Wang, Yibing Lv, Kaifeng Rao, Wei Jin, John P. Giesy and Kenneth M. Y. Leung. Do water quality criteria based on nonnative species provide appropriate protection for native species? Environmental Toxicology and Chemistry: Volume 34, Issue 8, pages 1744–1750, August 2015. DOI: 10.1002/etc.2985
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.2985/full     

水环境中重金属铜暴露下青鳉鱼的行为响应

采用生物行为传感器监测青鳉鱼在重金属铜暴露下的行为数据,分析不同暴露浓度(20、10、5、1和0.1 TU)下青鳉鱼的行为响应。20、10、5、1和0.1 TU的暴露浓度下青鳉鱼对重金属污染的行为反应模式符合环境胁迫阈值模型,且不同浓度梯度重金属对青鳉鱼产生不同的行为毒性效应。利用重金属作用下青鳉鱼的行为变化来研究重金属环境胁迫导致的生物行为响应机制,从而得到重金属暴露下生物行为的实时变化过程和趋势,可对水环境生态系统质量进行综合评价。     

Cytotoxicity assessment of monocrotophos in Paramecium caudatum and Oxytricha fallax

Experiments were conducted to evaluate the toxic effects ofmonocrotophos in ciliate models Paramecium caudatum and Oxytricha fallax. In acute toxicity studies higherconcentrations of monocrotophos caused marked increase in mobility of cells exhibiting rocking movements within two mins of exposure but were decreased after 30 mins. LC50 value by mortality curve for 3 hr acute toxicity test of Oxytricha fallax and Paramecium caudatum was found 307.744 +/- 33.27 mg l(-1) and 332.284 +/- 57.52 mg l(-1) respectively. Oxytricha fallax was found sensitive than Paramecium caudatum to monocrotophos. In acute exposure cells showed deformities such as swelling, oval shaped deformity and in higher concentrations shortening of longitudinal axis with blackening of cytoplasm occurred. The length of paramecia was reduced prominently. Similarly enlargement of contractile vacuole and stress egestion of food vacuoles was also observed. The morphological studies showed the changes in shape, size, colour and width of Paramecia and Oxytricha. Frequencies of macronuclear aberrations were significant showing deformities such as rod shaped, elongation, fragmentation, diffusion and total absence of nucleus and were concentration dependent. The data provided in the present study on interaction of pesticides with nuclear structure can be of immense value because most of these pesticides have been reported to have carcinogenic, mutagenic and teratogenic properties.     

华东某铀矿区周边河流表层沉积物的天然放射性评价

利用高纯锗γ能谱分析仪测量中国华东某铀矿区附近河流沉积物的放射性核素比活度,计算γ辐射吸收剂量率(D)、有效镭浓度(Ra_(eq))、外照射指数(H_(ex))、内照射指数(H_(in))、年有效剂量当量(AEDE(室内和室外))和年性腺剂量当量(AGDE)等放射性参数,并开展沉积物的放射性危害评估,最后通过Pearson线性系数确定放射性核素比活度之间的相关性。结果表明,河流沉积物中放射性核素~(238)U、~(226)Ra、~(232)Th和40K的平均比活度分别为51.55、37.32、57.63和756.86 Bq·kg~(-1),除~(226)Ra外,其他放射性核素的比活度均高于中国平均值;距离污染区较远或存在河流稀释作用的区域,沉积物的天然放射性核素处于正常水平,作为建筑材料使用时比活度不存在超标;放射性核素~(238)U、~(226)Ra和~(232)Th之间存在显著相关性。     

大气二氧化硫浓度的光学测定方法

介绍了测定二氧化硫浓度的几种光学方法 ,指出了目前一些化学方法的局限性 ,特别对紫外荧光法的原理、二氧化硫的吸收光谱以及荧光光谱进行分析探讨 ,设计了实验分析系统 ,得出该方法具有操作简单、灵敏度高、可实时在线的智能化优点 ,将会成为今后研究的主导方向。