涟江上游表层岩溶泉水污染源解析

为明确涟江上游表层岩溶泉水化学污染特征及其污染来源,选取区域内7个地表饮用泉作为研究对象.测定泉水水温(T)、电导率(EC)、溶解氧(DO)、pH、总氮(TN)、总磷(TP)、氨氮(NH4-N)、硝氮(NO3-N)、高锰酸盐指数(COD)并研究其与泉眼半径200、500、1000m范围内耕地、住宅用地及交通用地面积的相...     

北京官厅水库周边农药类POPs暴露的土壤生态效应研究

在前期研究的基础上,围绕北京官厅水库周边2-10 km范围内按不同农药类POPs残留量划分4个区域,监测了土壤中主要农药类POPs(HCHs和DDTs)的含量,分析了土壤酶活性和土壤呼吸强度特征.结果表明,4个区域中有机氯农药残留最高为北辛堡区,其次是怀来县区和官厅镇区,最低为延庆县区,平均含量分别为27.59 ng·...     

Electroreduction of hexavalent chromium using a porous titanium flow-through electrode and intelligent prediction based on a back propagation neural network

● Titanium-based flow-through electrode achieved high Cr(VI) reduction efficiency. ● Flow-through pattern enhanced the mass transfer and reduced cathodic polarization. ● BPNN predicted the optimal electroreduction conditions of flow-through cell. Flow-through electrodes have been demonstrated to be effective for electroreduction of Cr(VI), but shortcomings are tedious preparation and short lifetimes. Herein, porous titanium available in the market was studied as a flow-through electrode for Cr(VI) electroreduction. In addition, the intelligent prediction of electrolytic performance based on a back propagation neural network (BPNN) was developed. Voltametric studies revealed that Cr(VI) electroreduction was a diffusion-controlled process. Use of the flow-through mode achieved a high limiting diffusion current as a result of enhanced mass transfer and favorable kinetics. Electroreduction of Cr(VI) in the flow-through system was 1.95 times higher than in a parallel-plate electrode system. When the influent (initial pH 2.0 and 106 mg/L Cr(VI)) was treated at 5.0 V and a flux of 51 L/(h·m²), a reduction efficiency of ~99.9% was obtained without cyclic electrolysis process. Sulfate served as the supporting electrolyte and pH regulator, as reactive CrSO₇²⁻ species were formed as a result of feeding HSO₄⁻. Cr(III) was confirmed as the final product due to the sequential three-electron transport or disproportionation of the intermediate. The developed BPNN model achieved good prediction accuracy with respect to Cr(VI) electroreduction with a high correlation coefficient (R² = 0.943). Additionally, the electroreduction efficiencies for various operating inputs were predicted based on the BPNN model, which demonstrates the evolutionary role of intelligent systems in future electrochemical technologies.     

新疆五彩湾露天煤炭开采环境成本内部化驱动因素分析

通过分析五彩湾露天煤炭开采中环境成本内部化驱动因素分析,为类似地区实现矿产资源开发与生态环境保护双赢提供理论参考。本文运用德尔菲法和熵权法相结合,对该矿区露天煤矿企业资源开采环境成本内部化因素进行深入分析。对各影响因素的分析结果表明:矿区企业煤炭开采技术水平,对环境成本内部化的驱动因素最强,其余依次是煤炭市场行情、矿区环境管理能力、矿区煤炭资源开发强度等。研究结论:首先要严格审查进入准东开采矿业企业的技术能力,严格矿产开发技术标准,建立并不断完善相关企业环境成本核算制度等措施,并严格监督执行。其次要扩大煤炭市场范围,延长煤炭产业链,提高煤炭产品附加值;第三,着力加强环境管理部门的能力建设,解决各驱动因素之间失衡问题,提高各因素的整体性驱动强度,最终实现矿区煤炭开采与环境保护双赢的生态文明建设目标。     

Identification and assessment of environmental burdens of Chinese copper production from a life cycle perspective

The environmental burdens of Chinese copper production have been identified and quantified in the context of typical technologies, materials supplies and environmental emissions by a life cycle approach. Primary and secondary copper production using copper ores and scraps, respectively, were analyzed in detail. The flash and bath smelting approaches and the recycling of copper scraps were selected as representative copper production processes. A quantitative analysis was also conducted to assess the influence of material transport distance in copper production. Life cycle assessment （LCA） results showed that resources depletion and human health contribute significantly to environmental burdens in Chinese copper production. In addition, the secondary copper production has dramatically lower environmental burdens than the primary production. There is no obvious distinction in overall environmental burdens in primary copper production by flash or bath smelting approach. However, resources depletion is lower and the damage to human health is higher for flash smelting approach. Ecosystem quality damage is slight for both approaches. Environ- mental burdens from the mining stage contribute most in all life cycle stages in primary copper production. In secondary copper production, the electrolytic refining stage dominates. Based on the life cycle assessment results, some suggestions for improving environmental performance were proposed to meet the sustainable development of Chinese copper industry.