Water incubation-induced fluctuating release of heavy metals in two smelter-contaminated soils

The soil moisture regime can affect the release of heavy metals in soil. In the previous studies, slightly polluted soils or artificially contaminated soil samples were considered to investigate the effect of soil moisture. We used highly smelter-contaminated and aged soils to study the release of typical heavy metals(Cu, Zn, Cd and Pb) induced by water incubation in batch experiments with characterization via speciation and X-ray diffraction analyses(XRD). The results show that the leachable concentrations of the heavy metals increased slightly in the first 30 days, decreased drastically between 30 and 90 days, and immobilized relatively constant thereafter. The fluctuation was ascribed to the changes of soil Eh and pH, the reductive dissolution of crystalline iron oxides, the formation of new amorphous iron oxides, the absorption of dissolved organic matter and the precipitation of metal sulfide. Speciation analysis indicated that a proportion of the soil heavy metals was transformed from an exchangeable fraction to a less labile fraction after water incubation. And the presence of a lead iron oxide phase and the peak increasing of zinc sulfide were observed via XRD analyses. Finally, water incubation restrained the release of heavy metals after 180 days of incubation, and reduced the leachability of Cu, Zn, Cd and Pb by as much as 1.61%–7.21% for soil A and 0.43%–3.36% for soil B, respectively. The study findings have implications for the formulation of risk control and management strategies for heavy metals in smelter-contaminated soils.     

基于生态安全格局的县域国土空间生态保护修复关键区域识别—以抚州市宜黄县为例

为了有效实现国土空间生态保护与修复,探讨国土空间生态安全格局构建与生态保护修复关键区域识别的方法具有重要意义。以抚州市宜黄县为例,基于“生态源地—景观阻力面—生态廊道”的基本框架,以MSPA（形态空间格局分析）模型识别生态源地,将生态保护重要性评价成果作为指标之一构建景观综合阻力面,集成最小累积阻力模型（MCR）、重力模型和电路理论,识别与提取生态廊道,构建国土空间生态安全格局。在此基础上,基于电路理论识别生态夹点、障碍点,进而判断出宜黄县国土空间生态保护修复的关键区域,对需要修复的关键区域进行修复分区并提出修复建议。结果表明：宜黄县有10个生态源地;生态廊道共19条,包括7条重要生态廊道和12条一般生态廊道;待修复生态夹点20处,障碍点26处;待修复关键区域38处,划定为5个生态修复分区,分别为农业用地生态建设区、城镇绿地建设维护区、河道治理修复区、生态用地维护修复区以及道路生态廊道畅通区。

     

MPT—AES法测定矿泉水中硅、镁、钙、锶、钾元素

应用MPT－AES法测定了四种矿泉水中的Si,Mg,Ca,K五种元素，实验证明该方法具有分析速度快，准确度及精密度高等优点。     

Revealing the changes of bacterial community from water source to consumers tap: A full-scale investigation in eastern city of China

This study profiled the bacterial community variations of water from four water treatment systems,including coagulation,sedimentation,sand filtration,ozonation-biological activated carbon filtration(O₃-BAC),disinfection,and the tap water after the distribution process in eastern China.The results showed that different water treatment processes affected the bacterial community structure in different ways.The traditional treatment processes,including coagulation,sedimentation and sand f...     

Bioassay: A useful tool for evaluating reclaimed water safety

Wastewater reclamation and reuse has been proved to be an effective way to relieve the fresh water crisis.However, toxic contaminants remaining in reclaimed water could lead to potential risk for reuse, and the conventional water quality standards have difficulty guaranteeing the safety of reclaimed water.Bioassays can vividly reflect the integrated biological effects of multiple toxic substances in water as a whole, and could be a powerful tool for evaluating the safety of reclaimed water.There...     

青岛市李村河黑臭水体整治案例分析

李村河流域是青岛市中心城区流域面积最大的河流系统和过城河道。由于基础设施薄弱、城市面源污染突出、长效机制不健全、河道生态稳定性差、沿岸居民环保意识弱等,导致李村河常年黑臭。自2016年以来,从控源截污、内源治理、生态修复、活水保质和长效机制5个层面对李村河进行综合整治,主要措施包括污水处理厂的提标改造、雨污分流、垃圾清运、淤泥清淤、生态修复及补水、建立河道管理机制等。在生态补水及调蓄整治过程中,通过结合管线非开挖定向钻穿越技术,创新性地对李村河进行再生水管道河底非开挖铺设。通过流域综合整治,消除了水体黑臭现象,将李村河打造成了常年有水、水清岸绿,集休闲健身、生态调节等功能为一体的生态景观廊道。     

基于节点流量校核的供水管网爆管定位研究

针对目前基于节点压力变化定位供水管网爆管的方法,当供水管网中泵切换时,导致定位爆管位置存在误报的问题,提出了基于节点流量校核的管网爆管定位方法.利用奇异矩阵法推导出节点流量灵敏度矩阵,采取奇异矩阵中的最优搜索向量计算方法找到节点流量变化位置,确定爆管管道.首先,将该方法应用于一个小管网,阐述基于节点流量校核的管网爆管定...     

Modeling the impacts of calcite precipitation on the epilimnion of an ultraoligotrophic, hard-water lake

A mass-balance model of calcite precipitation was developed to investigate the interactions of the varied processes governing the generation and fate of calcite in lakes. The model was used in conjunction with data to assess the evolution and impact of calcite precipitation for calcareous, ultraoligotrophic Torch Lake, Michigan (USA). This lake is an ideal setting for implementation of a baseline modeling study of calcite precipitation where the physical drivers could be evaluated without being dominated, as in many systems, by biological processes. The model provides a representation of calcite precipitation with particulate surface area changing over time, and demonstrates that it is possible for the change in water clarity to be explained by calcite precipitation employing standard optical models. Using the mass balance model to quantify the roles of the various chemical, biological and physical processes interacting in the lake's epilimnion, it was shown that the seasonal temperature rise and air-water CO₂ exchange drive calcite precipitation much more than primary production for this ultraoligotrophic system.     

Point‐Nonpoint Trading – Can It Work?1

Ribaudo, Marc O. and Jessica Gottlieb, 2011. Point‐Nonpoint Trading – Can It Work? Journal of the American Water Resources Association (JAWRA) 47(1):5‐14. DOI: 10.1111/j.1752‐1688.2010.00454.x Abstract: Water quality trading between point and nonpoint sources is of great interest as an alternative to strict command and control regulations on point sources for achieving water quality goals. The expectation is that trading will reduce the costs of water quality protection, and may speed compliance. The United States Environmental Protection Agency has issued guidance to the States on developing point‐nonpoint trading programs, and United States Department of Agriculture is encouraging farmer participation. However, existing point‐nonpoint trading programs have resulted in very few trades. Supply side and demand side impediments seem to be preventing trades from occurring in most trading programs. These include uncertainty over the number of discharge allowances different management practices can produce, high transactions costs of identifying trading partners, baseline requirements that eliminate low‐cost credits, the reluctance of point sources to trade with unfamiliar agents, and the perception of some farmers that entering contracts with regulated point sources leads to greater scrutiny and potential future regulation. Many of these problems can be addressed through research and program design.