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561.
基于全国30个省份1998~2015年面板数据,采用Super-SBM模型测算农业用水效率,并在观察农业用水量、农业用水效率动静态演进特征的基础上,利用门槛面板回归模型探究农业用水效率对农业用水量的影响。结果表明,全国农业用水量和农业用水效率均呈阶段性下降。农业用水效率对降低农业用水量具有显著的门槛效应,提高农业用水效率是降低农业用水量的有效途径;东部农业用水效率促进农业用水量下降,但须警惕"回弹效应";中部农业用水效率抑制农业用水量增长,且作用逐渐增强;西部农业用水效率提高能够快速降低农业用水量,但作用逐渐减弱。另外,提升农民受教育水平、增加绿水足迹、扩大农业劳动人口能够降低农业用水量,而丰富的水资源禀赋促进农业用水量增加。 相似文献
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Fahmi Ben Fredj Ahmed Wali Moncef Khadhraoui Junkyu Han Naoyuki Funamizu Mohamed Ksibi Hiroko Isoda 《Environmental science and pollution research international》2014,21(6):4716-4726
Heavy metal contamination of soil resulting from treated wastewater irrigation can cause serious concerns resulting from consuming contaminated crops. Therefore, it is crucial to assess hazard related to wastewater reuse. In the present investigation, we suggest the use of biomarker approach as a new tool for risk assessment of wastewater reuse in irrigation as an improvement to the conventional detection of physicochemical accumulation in irrigated sites. A field study was conducted at two major sites irrigated with treated wastewater and comparisons were made with a control site. Different soil depths were considered to investigate the extent of heavy metal leaching, the estrogenic activity, and the biomarker response. Results have shown that a longer irrigation period (20 years) caused a slight decrease in soil metal levels when compared to the soil irrigated for 12 years. The highest levels of Cr, Co, Ni, Pb, and Zn were detected at 20 and 40 cm horizons in plots irrigated with wastewater for 12 years. The latter finding could be attributed to chemical leaching to deeper plots for longer irrigation period. Furthermore, the treated wastewater sample showed a high estrogenic activity while none of the soil samples could induce any estrogenic activity. Regarding the stress response, it was observed that the highest stress shown by the HSP47 promoter transfected cells was induced by a longer irrigation period. Finally, the treated wastewater and the irrigated soils exhibited an overexpression of HSP60 in comparison with reference soil following 1 h exposure. In conclusion, in vitro techniques can be efficiently used to assess potential hazard related to wastewater reuse. 相似文献
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柠檬酸对三峡水库消落区土壤中汞活化及甲基化的影响 总被引:3,自引:1,他引:2
利用室内模拟实验,用不同浓度柠檬酸溶液分别浸提和培养土壤,探讨了植被根系分泌物的主要成分柠檬酸对三峡库区消落带土壤中汞活化及甲基化的影响.结果表明,添加柠檬酸后浸提液中汞含量在达到最高值之前均高于对照组(0 mmol·L~(-1)),且随柠檬酸浓度的增加而增大.0、1、2、4、5、6、8 mmol·L~(-1)浓度下最大汞溶出量随柠檬酸浓度的增加先增大而后保持稳定,分别占供试土壤总汞的1.03%、1.67%、1.99%、2.47%、2.68%、2.73%、2.73%.培养实验中,土壤甲基汞(Me Hg)含量在前3 h内基本维持稳定,随后除对照组增加缓慢外,其余组均开始上升,且上升速率随柠檬酸浓度的升高而增大.在同一培养时段内,土壤Me Hg含量及增加量随柠檬酸浓度的升高而增大.表明柠檬酸对土壤中无机汞向甲基汞的转化过程有一定的促进作用,且促进作用随着柠檬酸浓度的增加而愈加显著. 相似文献
567.
于2012—2013年6月和12月采集了内蒙古呼和浩特市大气颗粒物样品,用GC-MS分析测定其中16种PAHs的浓度,并用苯并(a)芘(Ba P)致癌、致突变等效浓度、终身致癌超额危险度和预期寿命损失3个指标评价了内蒙古呼和浩特市大气颗粒物TSP和PM_(10)中PAHs的人群健康风险。结果显示:内蒙古呼和浩特市大气颗粒物TSP和PM_(10)中PAHs对成人、儿童的日均暴露剂量范围分别为0.71×10~(-6)~2.01×10~(-6)、0.45×10~(-6)~1.28×10~(-6)和0.31×10~(-6)~2.41×10~(-6)、0.19×10~(-6)~1.15×10~(-6)mg·kg~(-1)·d~(-1);TSP和PM_(10)中PAHs对成人和儿童的终身致癌超额危险度范围分别为2.21×10~(-6)~6.24×10~(-6)、1.41×10~(-6)~3.97×10~(-6)和0.95×10~(-6)~7.47×10~(-6)、0.60×10~(-6)~4.75×10~(-6),终身致癌超额危险度均处于可接受水平范围内(10-4~10~(-6))。TSP和PM_(10)中PAHs对成人和儿童的预期寿命损失范围分别为13.74~38.78、8.752~24.70和5.88~46.39、3.74~29.54 min。 相似文献
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569.
Advanced treatment of biologically pretreated coal gasification wastewater by a novel heterogeneous Fenton oxidation process 总被引:1,自引:0,他引:1
Haifeng Zhuang Hongjun Han Wencheng M Baolin Hou Shengyong Ji Qian Zhao 《环境科学学报(英文版)》2015,27(7):12-20
Sewage sludge from a biological wastewater treatment plant was converted into sewage sludge based activated carbon(SBAC) with Zn Cl2 as activation agent, which was used as a support for ferric oxides to form a catalyst(Fe Ox/SBAC) by a simple impregnation method.The new material was then used to improve the performance of Fenton oxidation of real biologically pretreated coal gasification wastewater(CGW). The results indicated that the prepared Fe Ox/SBAC significantly enhanced the pollutant removal performance in the Fenton process, so that the treated wastewater was more biodegradable and less toxic. The best performance was obtained over a wide p H range from 2 to 7, temperature 30°C, 15 mg/L of H2O2 and 1 g/L of catalyst, and the treated effluent concentrations of COD, total phenols,BOD5 and TOC all met the discharge limits in China. Meanwhile, on the basis of significant inhibition by a radical scavenger in the heterogeneous Fenton process as well as the evolution of FT-IR spectra of pollutant-saturated Fe Ox/BAC with and without H2O2, it was deduced that the catalytic activity was responsible for generating hydroxyl radicals, and a possible reaction pathway and interface mechanism were proposed. Moreover, Fe Ox/SBAC showed superior stability over five successive oxidation runs. Thus, heterogeneous Fenton oxidation of biologically pretreated CGW by Fe Ox/SBAC, with the advantages of being economical, efficient and sustainable, holds promise for engineering application. 相似文献
570.
为研究Fe(Ⅲ)-富马酸盐体系对染料废水的降解效果,在紫外光照射下进行Fe(Ⅲ)-富马酸盐体系中橙黄Ⅱ的光氧化反应试验,考察溶液中初始c〔Fe(Ⅲ)〕、ρ(橙黄Ⅱ)和c(富马酸钠)及溶液p H对橙黄Ⅱ去除率的影响.结果表明,当溶液p H为3~7时,Fe(Ⅲ)-富马酸盐体系对橙黄Ⅱ的去除率随着溶液p H的减小而增大.当溶液中c〔Fe(Ⅲ)〕为25μmol/L、ρ(橙黄Ⅱ)为25mg/L、c(富马酸钠)为250μmol/L、p H为3时、光照反应50 min后橙黄Ⅱ的去除率接近于100%,TOC去除率接近60%.橙黄Ⅱ的去除率随溶液中初始c〔Fe(Ⅲ)〕的增加而逐渐升高,而初始c(富马酸钠)的变化对橙黄Ⅱ的去除率影响不显著.动力学分析表明,橙黄Ⅱ光降解过程符合准一级动力学方程.试验采用荧光法验证了体系反应过程中·OH的产生,有助于对橙黄Ⅱ降解机理的进一步研究. 相似文献