Effect of commercial formulation of four organophosphorus insecticides on the ovaries of a freshwater teleost, Mystus vittatus (bloch)--a histological and histochemical study

The chronic effect of an exposure to a sublethal concentration of commercial formulation of 4 organophosphorus insecticides such as birlane (chlorfenvinphos), gardona (tetrachlorvinphos), phosdrin (mevinphos) and malathion on midvitellogenic ovaries of Mystus vittatus was investigated using several histological and histochemical techniques. The loss of stage II and III oocytes accompanied by a significant decline in gonadosomatic index was recorded. The vitellogenesis in treated fishes was ceased as the oocytes did not advance to further stages as evidenced by the absence of lipid yolks and the lack of a PAS positive follicular layer. The RNA content of remaining stage I oocytes of exposed fishes resembled that of the stage I oocytes of the control fishes. The absence of delta 5-3 beta-hydroxysteroid dehydrogenase suggested the lack of steroidogenesis. Reduced glucose-6-phosphate dehydrogenase activity was also observed. The significance of these observations has been discussed in light of available literature.     

Multiplex approach for screening genetic markers of microbial indicators.

Genetic markers are expected to provide better specificity in epidemiological studies and potentially serve as better indicators of waterborne pathogens. Methods used to assess genetic markers of emerging microbial indicators include pulsed field gel electrophoresis, polymerase chain reaction (PCR), and microarrays. This paper outlines a high-throughput approach to screen for such genetic markers using a set of theoretical and experimental screening tools. The theoretical screening involves evaluating genes related to the ribosomal RNA and specific functions from emerging indicator groups, followed by experimental validation with appropriate sampling schemes and high-throughput and economical screening methods, such as microarrays, real time PCR, and on-chip PCR. Analysis of a wide range of samples covering temporal variability in location, host, and waterborne disease outbreaks is essential. The proposed approach is expected to shorten the time and cost associated with searching for new genetic markers of emerging indicators by at least 10-fold.     

Assessment of Bacillus subtilis spores as a possible bioindicator for evaluation of the microbicidal efficacy of radiation processing of water.

Gamma and electron-beam irradiation of Bacillus subtilis spores suspended in different types of water was studied to evaluate the inactivation of the spores and assess their possible use as a bioindicator for radiation processing. We found that the inactivation proceeded endogenously, being dose-rate-dependent and affected by oxygen. The radiation resistance of the suspended spores was found to be rather high; therefore, B. subtilis spores used as a bioindicator for efficiency of water treatment by radiation under practical conditions might result in the spores being overly conservative surrogates for pathogenic microorganisms. Moreover, the doserate dependency impedes the use of the spores as a bioindicator. Thus, B. subtilis spores cannot be recommended as a bioindicator for evaluation of the microbicidal efficacy of ionizing radiation processing of water.     

Lead Content of Petrol and Diesel and its Assessment in an Urban Environment

Pakistan is one of the few countries in Asia thatcontinues to use only leaded-petrol as vehicular fuel. Theconcentration of Pb in its petrol reported in 1991 was thehighest (1.5 – 2.0 g Pb L^-1) of all produced by the various Asiancountries and far exceeded the WHOs guideline of 0.15 g Pb L^-1. We have undertaken a study to trace and quantify this toxicelement in the environs of Karachi, Pakistans major metropolis,having more than 30% of the nations total number of vehicles.In this article we report the Pb contents of petrol and dieselcurrently manufactured and marketed in the city. Samples of`Regular petrol collected in 1999 was found to contain 0.363 gPb L^-1 (range: 0.335 – 0.390 g Pb L^-1), a factor of 5 lower than thatmarketed prior to 1991. Its concentration in diesel fuel was muchlower (0.017 g Pb L^-1). Based on the available statistical data onthe type and volume of vehicular traffic, we assessed that thecurrent lead emission from vehicular traffic into the atmosphereis 391 metric tons a year, which is a factor of 2.7 lower thanthat estimated for 1989.     

Eh耦合的稻田土壤镉、砷释放机制

镉（Cd）、砷（As）是稻田土壤的主要重（类）金属污染物,稻田土壤Cd、As的释放与其氧化还原电位（E_h）密切相关,但E_h耦合的稻田土壤砷、镉释放机制仍不清楚.本实验利用高精度土壤微反应器模拟E_h梯度变化过程（-250、-50、170 mV）,研究其耦合的土壤Cd、As及相关元素（Fe、Al、Ca、S、P、DOC）的释放特征,并结合同步辐射微区X射线荧光光谱技术（μ-XRF）探讨了不同E_h（-250、-50、170 mV）条件下稻田土壤As释放机制.结果表明：随着供试体系E_h从-250 mV升高至170 mV,土水混合液中DOC和pH值逐步下降,但Cd、As及相关Al、S、P、Fe元素浓度则同时升高.其中,Cd与S、Al增长均呈先缓后快特征,而As与P、Fe增长则呈先快后缓趋势,说明在E_h升高过程中Cd与S,以及As与Fe间密切相关.同步辐射μ-XRF分析发现,在低E_h条件下,土壤颗粒上As、Fe和S的高含量点信号重合,As-S及As-Fe的可决系数分别在E_h为-250 mV和170 mV条件下最高,说明在低E_h条件下As很可能主要受硫化铁控制,但在高E_h条件下则受铁氧化物影响.综上可知,低E_h条件下,As、Cd主要受到硫化铁的控制.随着E_h的升高,土壤Cd的活性逐渐升高,As的活性则受到铁氧化物控制.本研究结果可为理解土壤Cd、As共同释放机制及调控土壤Cd、As活性提供重要理论依据.     

Optimization of alkaline extraction of natural dye from Henna leaves and its dyeing on cotton by exhaust method

The alkaline conditions for extraction of natural dye from Henna leaves were optimized and the resulting extract was used to further optimize its dyeing conditions on cotton by exhaust method. Dyeings without any mordant were compared with those obtained with premordanting and postmordanting with alum and iron. It was found that dyeings produced with alkaline extracts of Henna leaves have better colour strength than the dye extracts obtained in distilled water. Furthermore, dyeings with alkaline extracts have moderate to good fastness properties and that mordanting did not result in any significant improvement in fastness properties. Finally, in comparative studies between synthetic and this natural dye, it was inferred that natural dye has good potential to act as co-partner with synthetic dye.     

Studies of the effects of temperatures and solar radiation on volatilization,mineralization and binding of 14c‐DDT in soil under laboratory conditions

Abstract

The effects of temperatures and solar radiation on the dissipation of ¹⁴C‐p,p'‐DDT from a loam soil was studied by quantifying volatilization, mineralization and binding. The major DDT loss occurred by volatilization, which was 1.8 times more at 45^oC than at ambient temperature (30°C). Mineralization of DDT slowly increased with time but it decreased slightly with increase in temperature. Binding of DDT to soil was found to be less at higher temperatures (35 and 45°C) as compared to ambient temperature. Degradation of DDT to DDE was faster at higher temperatures.

Exposure of non‐sterilized and sterilized soils treated with ¹⁴C‐DDT to sunlight in quartz and dark tubes for 6 weeks resulted in significant losses. Volatilization and mineralization in quartz tubes were more as compared to dark tubes. The volatilized organics from the quartz tubes contained larger amounts of p,p'‐DDE than the dark tubes. Further, higher rates of volatilization were found in non‐sterilized soils than in sterilized soils. The results suggest that faster dissipation of DDT from soil under local conditions relates predominantly to increased volatilization as influenced by high temperature and intense solar radiation.