Cobalt in alluvial Egyptian soils as affected by industrial activities

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渭干—库车河三角洲绿洲土壤盐渍化空间分布特征遥感监测研究

渭干-库车河三角洲绿洲是位于塔里木盆地北缘的具有典型干旱特征的绿洲。干旱地区生态环境脆弱,土壤盐渍化严重破坏了国民经济的生产和生态环境的平衡,所以对干旱区盐渍化问题进行系统的研究是非常必要的。本文采用研究区的2001年8月6日遥感图像进行K-L和K-T变换,经过一系列波段结合．我们得到TM3、KL3、KT2波段结合是盐碱地信息提取的最佳波段结合;然后把研究区的等高线矢量图转换成DEM立体图,以及分类结果和DEM之间进行对比,结果表明,立体图的凹区和分类图的盐碱地基本重合在一起,从而我们得到导致该地区的盐渍化问题的自然和人文因素中,地形因素是占在主导地位的。     

Microbial detoxification of metalaxyl in aquatic system

Four microorganisms, Pseudomonas sp. （ER2）, Aspergillus niger （ER6）, Cladosporium herbarum （ER4） and Penicilluim sp. （ER3）, were isolated from cucumber leaves previously treated with metalaxyl using enrichment technique. These isolates were evaluated for detoxification of metalaxyl at the recommended dose level in aquatic system. The effect of pH and temperature on the growth ability of the tested isolates was also investigated by measuring the intracellular protein and mycelia dry weight for bacterial and fungal isolates, respectively. Moreover, the toxicity of metalaxyl after 28 d of treatment with the tested isolates was evaluated to confirm the complete removal of any toxic materials （metalaxyl and its metabolites）. The results showed that the optimum degree pH for the growth of metalaxyl degrading isolates （bacterial and fungal isolates） was 7. The temperature 30℃ appeared to be the optimum degree for the growth of either fungal or bacterial isolates. The results showed that Pseudomonas sp. （ER2） was the most effective isolate in metalaxyl degradation followed by Aspergillus niger （ER6）, Cladosporium herbarum （ER4） and Penicilluim sp. （ER3）, respectively. There is no toxicity of metalaxyl detected in the supematant after 28 d of treatment with Pseudomonas sp. （ER2）. The results suggest that bioremediation by Pseudomonas sp. （ER2） isolate was considered to be effective method for detoxification of metalaxyl in aqueous media.     

三峡库区水华优势藻类生长动力学的普适性研究

从蓝绿藻中选取绿藻门的普通小球藻(Chlorella vulgaris,CV藻)为研究对象,应用Monod方程考察氮、磷营养盐对CV藻生长的影响,分别计算出CV藻对TP、TN的半饱和常数KSP和KSN结果表明KSN>>KSP,说明TP对CV藻生长的影响明显大于TN.CV藻生长速率对磷质量浓度反应很灵敏:与空白值相比,在0.002 mg·L-1的低浓度下u就有提高,而浓度到0.2 mg.L-1时,u明显增大;但在0.000-0.050 mg·L-1氮浓度范围内u几乎没有变化.通过系统比较CV藻与优势蓝绿藻,甚至海水藻的生长动力学特征,探讨了CV藻与其它蓝绿藻的动力学普适性和共同性,证实这些藻类都具有非常类似的生长动力学和生态学特征.因此,推测CV藻生长动力学模型可以从整体上反映和代表库区优势蓝绿藻的生长行为.同时分析和归纳了蓝绿藻生长模型的相似性和规律性,得出三峡库区优势藻类生长行为存在普遍一致性的初步结论.     

Numerical study on the ozone formation inside street canyons using a chemistry box model

Tropospheric ozone is a secondary air pollutant produced in the presence of nitrogen oxides (NO_x),volatile organic compounds (VOCs),and solar radiation.In an urban environment,ground-level vehicular exhaust is the major anthropogenic source of ozone precursors.In the cases of street canyons,pollutant dilution is weakened by the surrounding buildings that creates localized high concentration of NO_x and VOCs,and thus leads to high potential of ozone formation.By considering the major physical and chemica...     

Neurotoxicity and transcriptome changes in embryonic zebrafish induced by halobenzoquinone exposure

Halobenzoquinones(HBQs) are emerging disinfection byproducts(DBPs) with a widespread presence in drinking water that exhibit much higher cytotoxicity than regulated DBPs. However, the developmental neurotoxicity of HBQs has not been studied in vivo. In this work, we studied the neurotoxicity of HBQs on zebrafish embryos, after exposure to varying concentrations(0-8 μmol/L) of three HBQs, 2,5-dichloro-1,4-benzoquinone(2,5-DCBQ), 2,6-dichloro-1,4-benzoquinone(2,6-DCBQ), and 2,5-dibromo-1,4-benzoqu...     

Do DBPs swim in salt water pools? Comparison of 60 DBPs formed by electrochemically generated chlorine vs. conventional chlorine

Disinfectants are added to swimming pools to kill harmful pathogens. Although liquid chlorine(sodium hypochlorite) is the most commonly used disinfectant, alternative disinfection techniques like electrochemically generated mixed oxidants or electrochemically generated chlorine, often referred to as salt water pools, are growing in popularity. However, these disinfectants react with natural organic matter and anthropogenic contaminants introduced to the pool water by swimmers to form disinfectio...     

Short-term inhalation exposure evaluations of airborne antibiotic resistance genes in environments

Antibiotic resistance is a sword of Damocles that hangs over humans. In regards to airborne antibiotic resistance genes (AARGs), critical knowledge gaps still exist in the identification of hotspots and quantification of exposure levels in different environments. Here, we have studied the profiles of AARGs, mobile genetic elements (MGEs) and bacterial communities in various atmospheric environments by high throughput qPCR and 16S rRNA gene sequencing. We propose a new AARGs exposure dose calculation that uses short-term inhalation (STI). Swine farms and hospitals were high-risk areas where AARGs standardised abundance was more abundant than suburbs and urban areas. Additionally, resistance gene abundance in swine farm worker sputum was higher than that in healthy individuals in other environments. The correlation between AARGs with MGEs and bacteria was strong in suburbs but weak in livestock farms and hospitals. STI exposure analysis revealed that occupational intake of AARGs (via PM₁₀) in swine farms and hospitals were 110 and 29 times higher than in suburbs, were 1.5 × 10⁴, 5.6 × 10⁴ and 5.1 × 10² copies, i.e., 61.9%, 75.1% and 10.7% of the overall daily inhalation intake, respectively. Our study comprehensively compares environmental differences in AARGs to identify high-risk areas, and forwardly proposes the STI exposure dose of AARGs to guide risk assessment.     

四氯联苯对鸡外源原始生殖细胞迁移的影响

为了研究环境污染物四氯联苯对移植的原始生殖细胞增殖性迁移的影响,将发育至14期的供体鸡胚原始生殖细胞用PKH26荧光染料标记,然后移植到经过四氯联苯处理的受体鸡胚生殖新月区域,继续孵化,检测其迁移和增殖情况.结果表明,和对照组相比,四氯联苯可明显降低移植原始生殖细胞在血液和性腺中的数量;四氯联苯对外源性原始生殖细胞迁移有明显影响,但雌二醇对外源性原始生殖细胞的增殖性迁移无明显影响,揭示四氯联苯可能影响的是受体性腺的诱引物质,且这种影响是非雌激素样的作用.     

Modeling the e ects of constructed wetland on nonpoint source pollution control and reservoir water quality improvement

This article describes the integrated modeling approach for planning the size and the operation of constructed wetlands for maximizing retention of nonpoint source pollutant loads and reservoir water-quality improvement at a catchment scale. The experimental field-scale wetland systems (four sets, 0.88 ha each) have been in operation since 2002, where water depth was maintained at 30–50 cm and hydraulic loading rate was at 6.3–18.8 cm/day. The wetland system was found to be adequate for treating polluted stream water with stable removal e ciency even during the winter. The integrated modeling system (modified-BASINS) was applied to the Seokmoon estuarine reservoir watershed and calibrated with monitoring data from constructed wetland, stream, and reservoir. The calibrated integrated modeling system estimated that constructing wetlands on 0.5% (about 114 ha) of the watershed area at the mouth of reservoir could reduce 11.61% and 13.49% of total external nitrogen and phosphorus loads, respectively. It also might improve the nitrogen and phosphorus concentration of the reservoir by 9.69% and 16.48%, respectively. The study suggested that about 0.1%–1.0% of the watershed area should be allocated for constructed wetland to meet specified water-quality standards for the estuarine reservoir at the polder area where land use planning is relatively less complicated.