辽宁大伙房水库沉积物中有机氯农药和多氯联苯的分布、来源及风险评价

利用GC-MS测定24个大伙房水库表层沉积物中有机氯农药和多氯联苯含量,主要揭示水库沉积物中有机氯农药和多氯联苯的残留特征.结果表明,HCHs的含量为0.70～3.48 ng.g-1,均值为（1.58±0.71）ng.g-1;DDTs的含量为0.85～4.94ng.g-1,均值为（1.94±0.82）ng.g-1;PCBs的含量为1.46～3.52 ng.g-1,均值为（2.42±0.64）ng.g-1.γ-HCH、β-HCH、DDE、DDT和PCB28百分含量较高.高百分含量γ-HCH和DDT表明目前仍在使用的林丹和工业滴滴涕产品;β-HCH、DDE和PCB28可能来自土壤中农药和多氯联苯残留.水库上游污染物含量明显高于水库下游,同时污染物高值点主要集中在浑河河口,表明水库上游浑河河流搬运是水库沉积物中污染物的主要输入来源,并影响污染物在沉积物中的分布.生态风险评价结果表明,沉积物中DDTs和γ-HCH存在较高的生态风险;沉积物中PCBs残留尚未对周围环境造成不利影响.     

污染源管理信息化建设的思考

污染源管理是环境监管的重点,信息化是提高污染源管理水平的重要手段。阐述污染源管理信息化现状,分析污染源管理信息来源及信息化发展中的不足,提出加强基层环保部门污染源监管信息化建设的建议,为污染源管理信息化建设提供借鉴。     

基于BP神经网络的煤层自燃预测

在全面分析影响煤层自燃因素的基础上,建立了煤层自燃预测的人工神经网络模型.应用该模型对某煤田的多个煤层样本进行了训练和预测,网络经过10次训练后,误差达到设定的最小值,6次预测测试中最大误差仅为0.027 8,最小的为0.000 1.研究表明,该模型精度较高,可用于预测煤层自燃的实际应用.     

含硫油品储罐腐蚀产物自燃性的研究

通过模拟储油罐中硫铁化物的生成方式, 分析和研究了H2S气体在无氧条件下,与不同相对湿度的Fe2O3、Fe3O4和Fe(OH)3反应所生成的硫铁化物的自燃性.不同相对湿度的试样经6 h硫化后,其自燃性明显不同.以Fe2O3试样为例,相对湿度为0的硫化产物氧化升温最高为256 ℃,平均升温速率为10.8 ℃/min; 相对湿度为5%、10%和15%的硫化产物,氧化升温最高温度分别为474 ℃、408 ℃和388 ℃,平均升温速率分别为20.5 ℃/min、18.3 ℃/min和13.5 ℃/min.实验结果表明, 不同相对湿度、不同物质的硫化产物,其自燃性有显著差异,样品的相对湿度对硫化产物的自燃性有重要影响.对各种干燥样品的硫化产物进行电镜分析发现,由不同物质硫化所生成的硫化产物结构不同,致使其自燃性有较大差异.硫铁化物氧化反应放热是引发油罐着火的主要因素.     

Denitrification potential enhancement by addition of external carbon sources in a pre-denitrification process

The aim of this study is to investigate the denitrification potential enhancement by addition of external carbon sources and to estimate the denitrification potential for the predenitrification system using nitrate utilization rate （NUR） batch tests. It is shown that the denitrification potential can be substantially increased with the addition of three external carbon sources, i.e. methanol, ethanol, and acetate, and the denitrification rates of ethanol, acetate, and methanol reached up to 9.6, 12, and 3.2 mgN/（g VSS.h）, respectively, while that of starch wastewater was only 0.74 mgN/（g VSS,h）. By comparison, ethanol was found to be the best external carbon source. NUR batch tests with starch wastewater and waste ethanol were carried out. The denitfification potential increased from 5.6 to 16.5 mg NO3-N/L owing to waste ethanol addition. By means of NUR tests, the wastewater characteristics and kinetic parameters can be estimated, which are used to determine the denitrification potential of wastewater, to calculate the denitrification potential of the plant and to predict the nitrate effluent quality, as well as provide information for developing carbon dosage control strategy.     

Emissions of SO2, NO and N2O in a circulating fluidized bed combustor during co-firing coal and biomass

This paper presents the experimental investigations of the emissions of SO2, NO and N2O in a bench scale circulating fluidized bed combustor for coal combustion and co-firing coal and biomass. The thermal capacity of the combustor is 30 kW. The setup is electrically heated during startup. The influence of the excess air, the degree of the air staging, the biomass share and the feeding position of the fuels on the emissions of SO2, NO and N2O were studied. The results showed that an increase in the biomass shares resulted in an increase of the CO concentration in the flue gas, probably due to the high volatile content of the biomass. In co-firing, the emission of SO2 increased with increasing biomass share slightly, however, non-linear increase relationship between SO2 emission and fuel sulfur content was observed. Air staging significantly decreased the NO emission without raising the SO2 level. Although the change of the fuel feeding position from riser to downer resulted in a decrease in the NO emission level, no obvious change was observed for the SO2 level. Taking the coal feeding position R as a reference, the relative NO emission could significantly decrease during co-firing coal and biomass when feeding fuel at position D and keeping the first stage stoichiometry greater than 0.95. The possible mechanisms of the sulfur and nitrogen chemistry at these conditions were discussed and the ways of simultaneous reduction of SO2, NO and N2O were proposed.     

珠江三角洲人为氨源排放清单及特征

根据收集的珠江三角洲(珠三角)人为氨源的活动水平数据,采用合理的估算方法和排放因子,建立了该地区2006年人为氨源分类别和分城市的排放清单.结果表明:①2006年珠三角地区人为氨源NH3排放总量约为194.8kt;②农业源是珠江三角洲地区人为氨源的主要排放贡献源,其中畜禽源排放的NH3占总排放量的62.1%,其次是氮肥施用源,其贡献率为21.7%;③畜禽源中肉鸡是NH3排放最大贡献源,占畜禽源NH3排放总量的43.4%,其次是肉猪,其贡献率为32.1%;④广州是珠三角地区2006年人为氨源排放量最大的城市,其次是江门,分别占NH3总排放量的23.4%和19.1%,主要的排放源均为畜禽和氮肥施用源.     

红枫湖钻孔沉积物中滴滴涕的沉积记录

采用GC/MS方法分析了红枫湖钻孔沉积物中滴滴涕的垂直分布状况,并对其来源和生态风险进行了分析和评估.红枫湖钻孔沉积物中滴滴涕的含量介于7.6～23.7ng/g之间,且从底层至表层基本上呈下降的趋势.其中,1981～1983年间有一个急剧下降的过程,随后基本上呈缓慢下降的趋势.沉积物中滴滴涕的组成以p,p′-DDTs(p,p′-DDT、p,p′-DDE和p,p′-DDD的总和)为主,p,p′-DDTs与o,p′-DDTs(o,p′-DDT、o,p′-DDE和o,p′-DDD总和)的比值在5.1～8.4之间,说明沉积物中的滴滴涕主要来源于农药滴滴涕的残留.又因为沉积物中残留的滴滴涕是以它的代谢产物为主,DDT/(DDD+DDE)的比值为0.31～0.84,所以沉积物中的滴滴涕主要源于历史的残留.此外,DDT/(DDD+DDE)和DDE/DDD比值的垂直变化特征显示,尽管我国1983年就禁止了滴滴涕在农业上的使用,但直至1990年前后,红枫湖流域内仍存在滴滴涕使用的可能.风险评价的结果显示,红枫湖表层沉积物中DDE、DDD、DDT和DDTs的含量均介于ERL和ERM值之间,可能造成潜在的生态风险,因此红枫湖沉积物中滴滴涕的污染仍值得密切关注.     

Spatial and temporal variations in groundwater nitrate at an intensive dairy farm in south-east Ireland: Insights from stable isotope data

Achievement of at least “good ecological status” in all waterbodies under the EU Water Framework Directive by 2015 will in some cases be a challenge. The twin challenge is to manage expectations of policy makers for such waterbodies as to a realistic length of time required for improvement in water quality. Hence, understanding the source, transformation processes and residence time of nitrate in a hydrological system is an essential part of meeting such challenges. On a dairy farm with 24 shallow groundwater wells, the dual isotopic composition of nitrate (δ¹⁵N and δ¹⁸O) was used to clarify nitrate sources, to assess spatial and temporal variability in nitrate concentrations and to determine if and where denitrification was occurring. Vertical travel time was estimated to correlate nitrate concentrations with management practices. Organically derived nitrogen was the predominant source contributing to groundwater nitrate concentrations. Denitrification was identified as prevalent within specific regions of the study site. The distinct low temporal variability in the isotopic data suggests constancy among nitrate sources and processes over time across the study site. Vertical travel times of up to 3 years were estimated on site indicating the influence of recent management practices on nitrate concentrations. Very slow horizontal migration of groundwater (decades) indicates a legacy of older management practices. Stable isotope techniques, together with an understanding of time lag, provide an extra mechanism to test the efficacy of monitoring and mitigation programmes.     

崇明岛生态风险源分析及其防范对策研究

上海市城市总体规划（1999~2020年）中提出了要将崇明岛建成生态岛的发展目标,而保障崇明岛的生态安全,规避生态风险是实现这一目标以及实现经济可持续发展的重要内容。崇明岛地处长江的河口和经济最发达的长江三角洲,而且东邻东海,地理位置十分特殊,区域生态风险来源十分复杂。因此,深入分析崇明岛的生态风险源类型、来源和特征,是进一步开展生态风险评价和正确制定风险防范对策的基础。通过对崇明历史资料的分析和现状的评价,辨识出26种生态风险源,这些风险源按性质分可分为自然风险源和人为风险源两类,按来源分可分为来自流域、来自周边区域、来自海洋和来自岛屿内部4类;通过对风险源的发生概率、强度分析结果,结合各风险源的特点,筛选出咸水入侵、台风、暴雨、风暴潮、生物入侵为崇明岛的主要风险源,并分析了其对生态系统的干扰和危害。在上述分析的基础上,提出了具体的风险防范对策。