Seasonal variation on size distribution and concentration of PAHs in Guangzhou city, China

Size distribution aerosol samples were collected at an urban location of Guangzhou in four seasons of 2003-2004 by a MOUDI (Micro-orifice Uniform Deposit Impactor). The particle loading (PM10: 80-397 microg m(-3)) was comparable with some other Asia cities; however, much higher than that of Western Europe and North America. Polycyclic aromatic hydrocarbons (PAHs) were measured by gas chromatography with mass selective detector (GC-MS). Seasonal effects on the size distribution of PAHs are presented. Bimode (accumulation and coarse mode) and unimode (accumulation mode) distributions were observed for low-molecule-weight and high-molecule-weight PAHs. A slight shift to larger particles was found for the accumulation mode in autumn and winter, compared with that of spring and summer. One explanation is that the longer aging process of PAHs in autumn and winter would result in volatilization from finer particles followed by condensation onto coarser particles. Another is there was mixing process of local emission with long-range transported aerosol in autumn and winter. The relative higher value of IcdP/(BghiP+IcdP) and lower value of BghiP/BeP in winter also give evidences to the mixing process. The level of PAHs concentration has been much elevated in recent years. This can be attributed to the fast growth of motor vehicle and energy consumption.     

BP神经网络在降水酸度预测中的应用

本文利用南昌市城市大气中SO2、NOX、TSP等浓度数据及降尘数据建立了BP神经网络的降雨酸度预测模型，结果表明：BP神经网络的预测模型不仅能较好地反映致酸因素与降水酸度的相互关系，而且预测精度也高于多元回归等模型。     

水库温室气体排放及其影响因素

水库是温室气体的一个重要排放源.探讨水库温室气体排放及其影响因素有利于精确估算水库温室气体排放量、减少水利工程与水电开发过程中水库温室气体排放.本文阐述r水库中温室气体的产生机制.总结了水库温室气体的3个排放途径:水库自然排放、水轮机和溢洪道、大坝下游河流,从水库特征、气候、水体pH值、水库中植被状况等角度深入探讨了水库温室气体排放的影响因素.最后,重点分析了水库温室气体排放的空间异质性以及研究结果不确定性的产生根源,并对今后的研究重点进行了展望.     

生物接触氧化处理渗滤液有机物的动力学模型研究

以重庆黑石子垃圾填埋场渗滤液生物接触氧化工艺为依托,针对其处理效果的局限性,设计了强化预处理-生物接触氧化反应器,并进行生物接触氧化反应器试验及其有机物降解动力学模型研究,旨在优化运行参数,提高渗滤液处理效果.结果表明,改进后系统比原工艺处理效果好,COD、NH4 -N、TN平均去除率分别达到95.83%、97.60%、85.60%;出水水质得到大幅度提高,出水COD、NH4 -N、TN平均质量浓度分别为235、35、199 mg/L.对生物接触氧化反应器内垃圾渗滤液有机物降解生化反应过程进行量化研究,得到微生物生长动力学模型为1/θc=0.918 7q-0.002 5;根据生物接触氧化反应器内基质消耗过程的物料平衡,得到生物接触氧化反应器处理垃圾渗滤液有机物生物降解的动力学模型为q=1.09S/(10 230 S).试验结果为生物接触氧化反应器的优化控制、设计与放大提供了参考依据.     

RISK OF EXTREME EVENTS IN A MULTIOBJECTIVE FRAMEWORK1

ABSTRACT: This paper summarizes advances made in risk-based decisionmaking in water resources through use of the partitioned multiobjective risk method (PMRM). (Risk is a measure of the probability and severity of adverse effects.) In the PMRM, the risk of extreme events is differentiated from risk involving less extreme damage severity and is evaluated within a multiobjective framework. Study of the extreme-event risk function f₄(*) has addressed the following issues: methods for calculating f₄(*); the sensitivity of f₄(*) to various parameters, particularly to the partitioning point of the extreme-event range and the selection of probability density functions; insight provided by the statistics of extremes; and the impact of f₄(*) on risk management, for example, in the application of the PMRM to water resources problems. In particular, this paper shares with the reader recent research results on the PMRM, the relationship between the statistics of extremes and the conditional expected value, derived formulas for f₄(*), distribution-free estimates of f₄(*), documented case studies in dam safety, and future research directions.     

上海市TSP-Pb空气质量监测点位优化研究

通过对上海市23个站点的TSP-Pb监测数据的分析,发现TSP与Pb之间具有良好的相关性.因此考虑只用TSP数据对站点进行优化.通过对各站点TSP数据的聚类分析,将所有站点分为6类,然后对包含多个站点的类,将类中各站点与本类均值一同进行再聚类,选取代表站点.最终选取6个站点作为上海市TSP-Pb污染水平的代表站点.优化前后的对比分析表明,优化结果合理,信息损失量小.     

湿地生态系统保护与修复探讨——以洪河自然保护区为例

文章通过对黑龙江省洪河湿地自然保护区的现状进行实地调查及温地成因分析,并针对洪河湿地自然保护区缺水严重、湿地退化,水生生态系统受到一定程度的破坏,局部地方沼泽已经向干草甸演替等问题,依据生态学原理通过工程措施、调节措施、管理及监测措施对洪河湿地自然保护区水生生态系统进行保护与修复.     

零价金属还原技术处理氯代有机物的研究进展

氯代有机化合物是一类常见的环境污染物,由于其水溶解度低,生物反应活性低,用常规的物化及生物处理方法难以将其去除.零价金属还原技术是近几年发展起来的环境污染物治理技术,是很有应用前景的一种非生物降解技术,文章阐述了零价金属还原技术在还原降解氯代有机物方面的应用,包括氯代烷烃、氯代烯烃、氯代芳香族化合物以及有机氯农药等,并提出了该技术存在的一些值得思考的问题,探讨了零价金属还原技术的发展方向.     

应用土壤肥力系统研究法诊断芒果国土壤的矿质营养

广东省赤红壤垦种芒果后，土壤的矿质营养状况基本上改善不大，地力产量仍然很低。应用土壤肥力系统研究法诊断土壤营养元素的结果表明，其缺素效应排序为：Ｎ＞Ｐ、Ｃａ＞Ｋ＞Ｍｇ；土壤Ｆｅ和Ｃｕ无缺素反应，而Ｓ、Ｂ、Ｍｎ、Ｍｏ和Ｚｎ有个别土样显示缺素效应，对这些元素丰缺的确切结论，有待进一步研究。     

Uniformity of domestic wastewater effluent application in a subsurface drip distribution system.

An on-site wastewater treatment project with two separate drip fields was operated for 6 years and received no maintenance. The two drip fields (with different design configurations) contained pressure-compensating emitters (PC) and non-pressure-compensating emitters (NPC), respectively, and received wastewater with an average 5-day biochemical oxygen demand concentration of 23 mg/L. Flowrates of the PC emitters reduced from rated average of 3.50 to 1.00 L/h, and the average flowrate of the NPC emitters reduced from 2.00 to 1.53 L/h. The statistical uniformities were 48 and 71%, and the uniformity coefficients were 70 and 86% for PC and NPC emitters, respectively. Significant, but incomplete, recovery was achieved with field-flushing and consecutive shock-chlorination treatments of 500 and 1000 mg/L.