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721.
Zhenhua Zhao Tengfei Mi Liling Xia Wenming Yan Ying Jiang Yanzheng Gao 《Environmental science and pollution research international》2013,20(7):5003-5012
The temporal and spatial distribution characteristics of environmental parameters and the phytoplankton community were investigated in October 2010 and January 2011 in the Qinhuai River, Nanjing, China. Results showed that the water quality in the study area was generally poor, and the main parameters exceeding standards (level V) were nitrogen and phosphorus. The observed average concentrations of the total nitrogen (TN) were 4.90 mg?L?1 in autumn and 9.29 mg?L?1 in winter, and those of the total phosphorus (TP) were 0.24 mg?L?1 in autumn and 0.88 mg?L?1 in winter, respectively. Thirty-seven species, 30 genera, and four phyla of phytoplankton were detected in the river. Cyanophyta and Bacillariophyta were the dominant phyla in autumn, with average abundance and biomass of 221.5?×?104?cells?L?1 and 4.41 mg?L?1, respectively. The dominant population in winter was Bacillariophyta, and the average abundance and biomass were 153.4?×?104?cells?L?1 and 6.58 mg?L?1, respectively. The results of canonical correspondence analysis (CCA) between environmental parameters and phytoplankton communities showed that Chlorophyta could tolerate the higher concentrations of the permanganate index, nitrogen, and phosphorus in eutrophic water; Bacillariophyta could adapt well to changing water environments; and the TN/TP ratio had obvious impacts on the distributions of Cyanophyta, Euglenophyta, and some species of Chlorophyta. CCA analyses for autumn and winter data revealed that the main environmental parameters influencing phytoplankton distribution were water temperature, conductivity, and total nitrogen, and the secondary factors were dissolved oxygen, NH4 +–N, NO3–N, TN, CODMn, TN/TP ratio, and oxidation-reduction potential. 相似文献
722.
目前分子生物技术发展日新月异,已渗透到各相关学科。本文综述了分子生物技术的基本原理与方法,及其在环境工程微生物领域的应用。讨论了分子生物技术在环境工程微生物的检测应用及在污泥、生物膜、底泥和土壤等微生物种群的多样性分析方面,以及环境工程菌的挑选和培养等方面的研究成果及其巨大研究前景,对该技术在环境工程领域的应用与发展提出了一些见解。 相似文献
723.
Li R. Gao Dan. Xia Hai Z. Tian Hai J. Zhang Li D. Liu Yi W. Wang 《Journal of environmental science and health. Part. B》2013,48(5):322-330
Organochlorine pesticides (OCPs) were analyzed in 26 surface sediment samples from the Liaohe River basin, and the distributions of and potential environmental risks posed by OCPs in the basin were evaluated. Eighteen OCPs listed in the Stockholm Convention were determined using isotope-dilution gas chromatography–high resolution mass spectrometry. This is the first study of hexachlorobenzene (HCB) in the Liaohe River basin sediments. The total OCP concentrations were 0.39–68.06 ng g?1 dry weight. The total α-, β-, γ-, and δ-hexachlorocyclohexane (HCH), the total dichlorodiphenyltrichloroethane (DDT – p,p′-dichlorodiphenyldichloroethane (DDD), p,p′-dichlorodiphenyldichloroethylene (DDE), o,p'-DDT, and p,p′-DDT), and the HCB concentrations in the sediment samples were 0.1–28.48 ng g?1 (mean 4.01 ng g?1), 0.08–6.52 ng g?1 (mean 3.07 ng g?1), and 0.18–24.8 ng g?1 (mean 4.38 ng g?1), respectively. The HCB concentrations were higher than the concentrations of the other OCPs, and the HCHs and HCB together were the dominant OCPs. β-HCH was the most abundant HCH isomer. The concentrations of DDTs and other OCPs were relatively low, and the (DDE+DDD)/DDT ratios (>0.5) and DDD/DDE ratios (<1) indicated that no recent DDT inputs had occurred in the Liaohe River system. The main sources of HCHs were probably the historical production and agricultural use of HCH in the study area. The DDT and HCH concentrations were generally below or similar to the concentrations that have been found in other parts of the world. An ecotoxicological evaluation indicated that HCHs in surface sediments pose slight risks to human and ecological health in the Liaohe River basin. 相似文献
724.
725.
研究了pH和温度对2,2’,4,4’-四溴联苯醚(BDE-47)在土壤中的吸附和解吸行为的影响。结果表明,pH和温度都可以影响BDE-47在受试土壤中的吸附和解吸行为。pH升高或降低均会使土壤对BDE-47的吸附能力提高,且在碱性环境中提高的程度更大;酸性或碱性条件下BDE-47在土壤中的解吸滞后性显著增强。温度降低后,土壤对BDE-47的吸附能力提高,5℃时的单点分配系数(Kd,表征土壤对BDE-47的吸附能力)是25℃时的1.03~1.67倍;温度由25℃降低到5℃后,BDE-47在土壤中的解吸滞后性增强。 相似文献
726.
采用微波炉对一定质量的氢氧化钙样品进行活化,利用压汞仪考察了不同微波活化时间及脱氯反应前后的Ca(OH)2总比孔表面积、分段比表面积和孔径分布的变化,并在脱氯实验台上对脱氯效率进行实际测试。结果表明,微波活化存在一个最佳时间,在此时间内样品比孔表面积增大50%左右,而超过这一时间样品比表面积回复性减小;微波活化主要通过增加3~20 nm孔径段的微孔为样品提供更大比表面积;这些新增加的微孔在脱氯反应过程中被完全利用或消耗; 最佳活化时间下的微波活化使Ca(OH)2在较低Ca/Cl摩尔比下获得更大脱氯效率,Ca/Cl摩尔比=4.1时,脱氯效率增加了20%。 相似文献
727.
728.
为研究近场地震作用下库区深水钢筋混凝土高墩的概率损伤特性,以90 m高的矩形空心薄壁钢筋混凝土深水高墩为研究对象,综合考虑桥墩设计参数和近场地震动的随机性,基于OpenSees软件建立深水高墩有限元模型,开展不同水深的7种工况(水深:0、15、30、45、60、75、90 m)下,顺桥向和横桥向近场地震激励的增量动力非线性分析。以截面临界曲率值为损伤指标,研究深水高墩的易损性。结果表明:各工况下,轻微损伤、中等损伤和严重损伤阶段的损伤概率均随地震波峰值加速度的增加而增大,并且当峰值加速度达到1.0g时损伤概率达到最大,而完全损伤阶段的损伤概率则在峰值加速度为0.5g时出现峰值点;近场地震顺桥向激励时,墩身中上部和墩底区域均较容易损伤,而横桥向激励时仅墩底区域较容易损伤;当水深超过45 m后,高墩最大损伤概率变化不大且截面曲率概率需求基本一致,45 m水深为深水高墩显著水深。因此,应重点分析水深达到高墩高度一半时深水高墩的损伤情况。 相似文献
729.
730.