Algal uptake of dissolved organic nitrogen in wastewater treatment plants

The algal uptake of dissolved organic nitrogen(DON) in the anaerobic–anoxic–oxic(A_2O)process was investigated in this study. Anaerobic, aerobic and effluent DON samples from two wastewater treatment plants(WWTPs) were separated into hydrophilic and hydrophobic fractions using a DAX-8 resin coupled with an anion exchange resin and a nanofiltration(NF)pretreatment. Hydrophilic DON accounted for 66.66%–88.74% of the entire DON for the two plants evaluated. After a 15-day incubation, 16.95%–91.75% DON was bioavailable for algal growth, and untreated samples exhibited higher DON bioavailability, with 52.83% DON average uptake rates, compared with the hydrophilic and hydrophobic fractions(45.53% and 44.40%, respectively) because the pretreatment caused the inorganic salt to be resistant to algae. Anaerobic untreated samples, hydrophilic fractions and hydrophobic fractions showed higher DON reduction rates and higher biomass accumulation compared with the other DON fractions due to the decomposition of resistant organics by anaerobic and anoxic bacteria.DON in aerobic and effluent samples of plant A was more bioavailable than that of plant B with usages of 27.49%–55.26% DON. DON bioavailability in the anaerobic–anoxic–oxic process decreased in the following order: anaerobic effluent aerobic. The DON contents were reduced after anaerobic treatment in the two plants. The EEM-PARAFAC model identified three DON components, including two humic acid-like substances and one protein-like substance in plant A and two protein-like substances and one humic acid-like substance in plant B.     

Lipid peroxidation of kidney of the turtle Mauremys reevesii caused by cadmium

Environmental Science and Pollution Research - This research was designed to investigate lipid peroxidation of the kidney of turtle (Mauremys reevesii) caused by cadmium. Turtles were injected...     

Heavy metal exposure has adverse effects on the growth and development of preschool children

Environmental Geochemistry and Health - The purpose of this study was to investigate the associations between levels of lead (Pb), cadmium (Cd), chromium (Cr), and manganese (Mn) in the PM2.5 and...     

城市污泥对不同质地土壤保水效果研究

利用城市污泥滞水性强的特性可开发污泥作为保水剂的新功能。通过土培实验,在砂土、壤土和粘土中加入不同质量的污泥,研究污泥对不同质地土壤的保水效果。结果表明:在充分供水条件下,添加污泥能显著提高3种质地土壤的持水能力,土壤中添加20%的污泥后,砂土、粘土和壤土初始含水率分别增加11.2%、8.7%和8.8%;在3种质地土壤中添加污泥均可增大土壤的保水性,使水分蒸发减慢,且污泥添加量越多,土壤含水率越大;土壤累积失水量主要受到土壤中含水量的影响,也和不同质地土壤自身的蒸发量有关;在150 g土壤中添加10 g污泥,对砂土保水性提高不大,对壤土保水性提高最大,随着添加污泥量的增多,污泥对砂土的保水效果提高最明显。研究表明:开发污泥做为保水剂是可行的,这为污泥的资源化利用提供了新的途径,也为复合保水剂的研制提供了新的廉价材料,对于污泥治理及农业节水都有重要意义。     

Arsenic fractionation and contamination assessment in sediments of thirteen lakes from the East Plain and Yungui Plateau Ecoregions, China

Arsenic（As） fractions in the sediments of seven lakes from East Plain Ecoregion and six lakes from Yungui Plateau Ecoregion, China, were investigated. Results indicated that the total As concentrations in sediment samples of lakes of the East Plain Lake Ecoregion are higher than those of Yungui Plateau Lake Ecoregion. Residual As is the main fraction in sediment samples of lakes from both ecoregions, followed by reducible As and soluble or oxidizable As. The total As is correlated to oxidizable As and residual As in sediment samples from both lake ecoregions. As distribution in sediment samples of lakes of the East Plain Ecoregion appears to be affected by human activity, while the As origin mainly comes from natural sources in sediment samples of lakes in the Yungui Plateau Ecoregion. The potential ecological risk index and geoaccumulation index values suggest ＂low to moderate＂ risk degree and ＂unpolluted to moderately polluted＂ for As in the studied lake sediments.     

混合溶剂的闪点变化规律探析

为考察不同类型溶剂对混合液易燃特性的影响,探索混合溶剂闪点的变化规律,分别将不燃溶剂、阻燃型溶剂、高闪点溶剂及低闪点溶剂与乙醇按不同比例混合,采用闭杯闪点测试仪进行混合液的闪点测试。研究结果表明,添加不燃或阻燃溶剂时,混合液闪点整体呈现逐渐升高趋势,不燃或阻燃溶剂易于提高混合溶剂的安全性能,当不燃或阻燃溶剂体积分数超过0.7以上时,混合液闪点提高幅度较大;添加可燃溶剂时,可燃溶剂的结构不同,对混合液的燃烧特性影响也不同,添加高闪点溶剂可能提高混合液闪点,也可能降低混合液闪点;而添加低闪点溶剂,降低混合液闪点,甚至可能比混合液任一组分闪点值都低;因此选用混合溶剂时,不能盲目,需要严格关注其混合后易燃特性参数的变化。     

如何搞好国有大中型亏损企业的环境保护工作

本文揭示了目前在国有大中型亏损企业中开展环境保护工作的困难与问题，指出这是关系到实现我国中目标的重大课题，并提出了一系列搞好国有大中型亏 企业环境工作的对策和措施，希望能引起社会各界特别是国有大中型企业领导们的重视。     

清代综合治理黄河下游水患的系统科学思想

利用清代在治黄斗争中留下的历史文献, 对清代治理黄河的系统科学思想进行初步的研究与总结, 目的是鉴古知今, 为当代治理好黄河提供借鉴与创意。     

环境影响评价与可持续发展

我国经济发展必须符合可持续发展的战略方针，可持续发展是传统发展方式的一种新变革，它在保证经济增长的同时，要求与生态环境保护相适应，以达到提高人民生活质量和健康水平的目的。我国在过去２０多年来，环境影响评价在协调环境与发展的关系中起了重要作用。本文则着重论述可持续发展的战略观点对环境影响评价在思想、内容和方法上所赋予的新的任务和要求，环境影响评价必须适应这一变革、以迎接人类社会面临的严重挑战。