Preliminary report on methane emissions from the Three Gorges Reservoir in the summer drainage period

Considerable variations may exist in CH4 emissions from the Three Gorges Reservoir.     

Biosorption mechanisms involved in immobilization of soil Pb by Bacillus subtilis DBM in a multimetal-contaminated soil

Mechanisms of soil Pb immobilization by Bacillus subtilis DBM, a bacterial strain isolated from a heavy-metal-contaminated soil, were investigated. Adsorption and desorption experiments with living bacterial cells as well as dead cells revealed that both extracellular adsorption and intracellular accumulation were involved in the Pb2＋removal from the liquid phase. Of the sequestered Pb（II）, 8.5% was held by physical entrapment within the cell wall, 43.3% was held by ion-exchange, 9.7% was complexed with cell surface functional groups or precipitated on the cell surface, and 38.5% was intracellularly accumulated.Complexation of Pb2＋with carboxyl, hydroxyl, carbonyl, amido, and phosphate groups was demonstrated by Fourier transform infrared spectroscopic analysis. Precipitates of Pb5（PO4）3OH, Pb5（PO4）3Cl and Pb10（PO4）6（OH）2that formed on the cell surface during the biosorption process were identified by X-ray diffraction analysis. Transmission electron microscopy–energy dispersive spectroscopic analysis confirmed the presence of the Pb（II）precipitates and that Pb（II） could be sequestered both extracellularly and intracellularly.Incubation with B. subtilis DBM significantly decreased the amount of the weak-acid-soluble Pb fraction in a heavy-metal-contaminated soil, resulting in a reduction in Pb bioavailability, but increased the amount of its organic-matter-bound fraction by 71%. The ability of B.subtilis DBM to reduce the bioavailability of soil Pb makes it potentially useful for bacteria-assisted phytostabilization of multi-heavy-metal-contaminated soil.     

Efficient dechlorination of chlorinated solvent pollutants under UV irradiation by using the synthesized TiO2 nano-sheets in aqueous phase

Titanium dioxide(TiO2), which is the widely used photo-catalyst, has been synthesized by simple hydrothermal solution containing tetrabutyl titanate and hydrofluoric acid. The synthesized product has been applied to photo-degradation in aqueous phase of chlorinated solvents, namely tetrachloroethene(PCE), trichloroethene(TCE) and 1,1,1-trichloroethane(TCA). The photo-degradation results revealed that the degradation of these harmful chemicals was better in UV/synthesized TiO2 system compared to UV/commercial P25 system and UV only system. The photo-catalytic efficiency of the synthesized TiO2 was 1.4, 1.8 and 3.0 folds higher compared to the commercial P25 for TCA, TCE and PCE degradation, respectively. Moreover, using nitrobenzene(NB) as a probe of hydroxyl radical(.OH), the degradation rate was better over UV/synthesized TiO2, suggesting the high concentration of.OH generated in UV/synthesized TiO2system. In addition,.OH concentration was confirmed by the strong peak displayed in EPR analysis over UV/synthesized TiO2system. The characterization result using XRD and TEM showed that the synthesized TiO2 was in anatase form and consisted of well-defined sheet-shaped structures having a rectangular outline with a thickness of 4 nm, side length of 50 nm and width of 33 nm and a surface 90.3 m2/g. XPS analysis revealed that ≡Ti-F bond was formed on the surface of the synthesized TiO2. The above results on both photocatalytic activity and the surface analysis demonstrated the good applicability of the synthesized TiO2 nano-sheets for the remediation of chlorinated solvent contaminated groundwater.     

家用洗涤剂中特征污染物的检测及潜在风险研究

家用洗涤剂的特征污染物磷与表面活性剂随废水排入环境水体造成水体溶解氧下降、富营养化,破坏水生生态环境。从北京市三个具有代表性的市场购买洗衣液、洗衣粉、洗衣皂和洗洁精四种形态的家用洗涤剂共40个样本,并对其中磷与阴离子表面活性剂(LAS)含量进行检测。结果显示,所有衣用洗涤剂总P2O5含量均小于1.1%,符合无磷洗涤剂国家标准(GB/T 13171.2-2009);而LAS含量差异较大,范围为6.9%~31.4%,基本趋势是洗洁精洗衣液洗衣粉;经估算,洗涤等量衣物,洗衣液的LAS排放量比洗衣粉高49.1%,北京市每年家用洗涤剂LAS产生量至少为1.23万吨;经检测蓟运河北京段水样,61.5%的样点水样中LAS含量达到III类水质标准,但局部地区污染仍较为严重,污染风险不可忽视。     

污水处理厂絮凝剂最佳浓度的小试实践

聚丙烯酰胺作为絮凝剂在污水处理行业使用已很普遍,使用前通过精确小试更准确把握其使用浓度及使用量,可节约生产成本。本文介绍了一种简易的试验装置,用其测定得到污水处理厂絮凝剂的最佳使用浓度。     

Increasing collaboration between China and India in the environmental sciences to foster global sustainability

As the two largest countries by population, China and India have pervasive effects on the ecosphere. Because of their human population size and long international boundary, they share biodiversity and the threats to it, as well as crops, pests and diseases. We ranked the two countries on a variety of environmental challenges and solutions, illustrating quantitatively their environmental footprint and the parallels between them regarding the threats to their human populations and biodiversity. Yet we show that China and India continue to have few co-authorships in environmental publications, even as their major funding for scientific research has expanded. An agenda for collaboration between China and India can start with the shared Himalaya, linking the countries’ scientists and institutions. A broader agenda can then be framed around environmental challenges that have regional patterns. Coordinated and collaborative research has the potential to improve the two countries’ environmental performance, with implications for global sustainability.     

汉江下游鱼类早期资源及梯级联合生态调度对鱼类繁殖影响的初步分析

汉江是长江一级支流,鱼类资源较为丰富。目前汉江中下游建有4座水利枢纽工程,对鱼类洄游和繁殖产生较大影响。在鱼类繁殖季节,为促进汉江中下游鱼类繁殖,2018年6月汉江中下游首次实施梯级联合生态调度。该研究在汉江下游汉川段设置监测断面,采集鱼类早期资源,以分析汉江下游鱼类早期资源多样性,及生态调度对促进汉江下游鱼类繁殖的效果。监测结果表明汉江下游卵苗种类共有36种（属）,其中22种为产漂流性卵鱼类。监测期间卵苗总径流量为118.78亿尾（粒）,其中四大家鱼卵苗为0.87亿尾（粒）,占0.73%,其中鱼卵0.69亿粒,推测汉江下游有4处四大家鱼产卵场。梯级联合生态调度期间,汉川江段出现一次鱼类产卵高峰,鱼卵径流量占总径流量的34.1%,其中四大家鱼鱼卵占家鱼卵总径流量的85.5%,表明梯级联合生态调度对汉江下游鱼类,特别是四大家鱼的繁殖具有积极的作用。建议今后继续开展生态调度,并加强监测和分析工作。     

液体旋流分离器分离效率的研究

液体旋流分离器是水环境污染治理的主要设备之一.分离效率是衡量液体旋流分离器分离过程进行完善程度的最重要的技术指标,它能从质与量两方面反映出设备性能的优劣.当前液体旋流分离器设计过程还缺少具体量化的理论依据,为了给液体旋流分离器的设计提供理论依据,通过液体旋流分离器从水中分离固体粒子的性能实验,得出了液体旋流分离器各部结构尺寸、形状、相对比例对分离效率的不同影响程度,提出了结构参数的最佳取值范围.按照本研究提出的设计原则和方法,可以制造出性能优良的液体旋流分离器.     

洗相废水中银回收技术研究

采用电解法和离子交换法回收洗相废水中的银.结果表明,电解法对高浓度含银洗相废水的银回收处理是一种行之有效的方法.对于中低浓度洗相废水中的银的回收,采用4%硫酸再生IRA-68离子交换树脂,树脂的交换能力可以增加4倍,再生时由于已交换的银被直接固定在树脂上,结果使得再生剂处置和银回收过程更加简单方便.IRA-68离子交换树脂回收中低浓度洗相废水中银的技术具有银回收效率更高、离子交换运行时间更长和操作更为简便等优点,使得传统的离子交换技术得到极大的改进和提高.     

生物质炭对Cd污染土壤团聚体酶活性的影响

为探究生物质炭对Cd污染土壤团聚体酶活性的影响,采用盆栽试验,向模拟Cd污染土壤中添加生物质炭并测定水稻根际土壤团聚体碳循环酶与氧化还原酶活性.结果表明:Cd污染土壤团聚体酶活性对添加量为2.5％的生物质炭响应明显,氧化还原酶活性指数值介于0.522～0.792之间.在2.5mg/kg的外源Cd条件下,2.5％的生物质...