2种人工湿地的水力停留时间及净化效果

以复合垂直流人工湿地(IVCW)和水平潜流人工湿地(HSCW)为研究对象,研究了2种湿地运行的季节性最佳水力停留时间(HRT)参数,并监测了2种湿地在最佳HRT参数下运行时对污水的净化效果。结果显示:(1)在IVCW中,最佳HRT在春、秋季为8～10 h;夏季为6 h;冬季为12 h。在HSCW中,最佳HRT在春、秋季为10～12 h;夏季为6～8h;冬季为24～36 h。(2)2种湿地对COD的去除率均无显著的季节性差异;湿地进水中NH4+-N/TN比值与TN去除率显著负相关;不同季节下IVCW对TN的去除效果均高于HSCW。(3)水温对TN、TP去除率的影响在IVCW中比HSCW中的明显;水温高时,2种湿地中的TN去除率较高,IVCW中的TP去除率也较高,但HSCW中的TP去除率则较低,它们间均未达到显著的相关性。     

Modeling batch leaching behavior of arsenic and selenium from bituminous coal fly ashes

Correctly predicting the leaching potential of arsenic (As) and selenium (Se) is critical for assessing the environmental impact of coal fly ash. This study investigated the impacts of several key environmental factors, including pH, leaching time, and ash washing on the batch leaching behavior of As and Se from bituminous coal fly ashes. The experimental results demonstrated that As and Se leaching from fly ash increased beyond the minimal leaching pH ranges. Increasing leaching time increased As leaching but decreased Se leaching in the alkaline pH condition. A speciation-based adsorption model was used to quantify the batch leaching data, and determine the intrinsic leaching parameters including the total batch leachable mass and the adsorption constant of As or Se. The modeling approach was validated by correctly predicting the independent batch leaching data in a broad pH range and a different L/S condition. Experimental and modeling results also demonstrated that ash washing and ash aging (longer leaching time) did not change the adsorption constants of As and Se on the ash surface. However, ash washing could increase the availability of As and Se for leaching.     

Gridded inventories of historical usage for selected organochlorine pesticides in Gansu Province, China

HCHs and DDTs were banned in 1983 in China; however, they are still remaining in various environmental media. Since endosulfan was introduced in China in 1994, it is widely used in agriculture. In this study, temporal and spatial uses of endosulfan, HCHs, and DDTs in Gansu province of China have been presented. It is estimated that the total usage is 701 tons for endosulfan between 1994 and 2007, 1,712 tons for HCHs between 1952 and 1983, and 462 tons for DDTs between 1951 and 1983, respectively. Endosulfan usage increased dramatically in 1998 due to its application on other crops except on cotton. The HCH and DDT usage displayed a rapid increase after 1972, reaching the peak in 1976 and in 1975, respectively; since then, they declined until being banned in 1983. The gridded usage inventories of these three kinds of organochlorine pesticides in Gansu province, with a 1/4° longitude by 1/6° latitude resolution, have been created by using different crops for endosulfan and the area of dry farmland for HCHs and DDTs as surrogate data. The most intensive use was in northwestern regions for endosulfan and southeastern regions for HCHs and DDTs in Gansu province.     

西洋参中六种农药残留量的HPLC分析

本文报道了甲基对硫磷等六种农药在西洋参中多残留的高铲液相色谱检测方法。采用乙醚超声波提取,经硅胶柱净化,紫外检测波长采用程序控制,在检测的时间内自动进行四次改变,使每一被检测的农药均在其最大紫外吸收波长处被检测。     

曝气对两种人工湿地污水净化效果的影响

采用复合垂直流和水平潜流2种人工湿地处理混合污水,研究了在气水比(曝气体积/湿地进水体积)为2、4、6、8和10时2种人工湿地对污水的净化效果.结果显示:(1)复合垂直流人工湿地以气水比为2进行曝气时,对污水的净化效果最好,上行池出水的COD、TN、NH4+-N、NO3--N平均去除率比不曝气时分别提高了16.47%、...     

重金属铜、锌、镉、铅复合污染对土壤环境微生物群落的影响

以铜锌冶炼厂附近的水稻土为例 ,研究了重金属复合污染对土壤微生物群落的影响 .结果表明 ,有效铜、锌、镉、铅与微生物生物量碳、微生物生物量氮、微生物商、微生物生物量氮 全氮均呈显著负相关 .重金属污染均能降低细菌、真菌和放线菌的数量 .用BIOLOG生态盘研究了重金属污染对微生物群落结构的影响 ,发现重金属污染明显影响了微生物群落结构 ,反映在典型变量 1(CV1)与重金属元素含量呈极显著正相关 ,因此认为典型变量 1是反映重金属污染程度的有效指标 .经逐步回归分析发现 ,有效铜是影响典型变量 1最主要的因素 .     

粘土矿物修复重金属污染土壤

简要介绍了我国土壤重金属污染的现状与危害.通过粘土矿物在重金属污染土壤中净化功能的阐述,提出利用粘土矿物修复土壤重金属污染的观点.继而从天然和改性粘土矿物特性,叙述了粘土矿物修复土壤重金属污染的机制与应用进展及其影响因素.最后讨论了粘土矿物在修复土壤重金属污染过程中值得注意的几个问题,并展望了粘土矿物在该领域应用中的发展方向.     

陇中黄土高原半干旱区人口问题研究

陇中黄土高原半干旱区是一个自然条件较为特殊的区域,由于各种因素的约束,几十年来尽管各级政府进行了大量的投资,但其面貌并未有实质性的改变,社会发展水平不高,经济基础薄弱。究其原因,较为低下的人口素质,迅速增长的人口数量,以及由这二者形成的矛盾对社会经济产生的负面影响,是障碍这一地区发展的首要因素。     

新型棉纤维吸附剂的制备及性能研究

以棉纤维为基体,利用高锰酸钾和硫酸作为引发剂,将丙烯酰胺聚合后接枝到棉纤维中葡萄糖单元的羟基上,采用四因素三水平正交试验法对接枝聚合反应进行了优化,并且利用霍夫曼降级反应对改性棉纤维进行稳定处理.在不同条件下,研究了改性棉纤维对Cr6 的吸附性能及解吸再生后的吸附性能.结果表明,在最佳实验条件下制备的棉纤维吸附剂对Cr6 的吸附率可达86%,且经过5次解吸再生后,其吸附率仍可达到80%以上.该棉纤维吸附剂不仅制备方法简单,而且解吸操作方便,可应用于污水中Cr6 的处理.     

脉冲放电粒子荷电机理的研究

脉冲电晕放电在脉冲期间产生大量的高能电子，形成粒子在电场中的电子荷电．依据粒子附近的电子密度Ｂｏｌｔｚｍａｎ分布和电子在粒子表面传输的速率方程，在电子的动能大于或等于粒子表面势垒能的边界条件基础上得到粒子在脉冲电晕场中粒子荷电的速率方程，并利用龙格库塔法求解荷电速率方程得到粒子在脉冲放电条件下的荷电量．计算结果表明脉冲放电下的粒子荷电量平均是直流电晕放电的离子荷电量的１８倍，最大荷电量是０５—１５μｍ范围内的粒子，荷电量是直流电晕的２６倍．这一结果不仅与Ｄａｖｉｄ的粒子自由电子荷电理论结果相似，而且与微细粒子电子荷电量测试结果基本一致．