A study of peroxyacetyl nitrate at a rural site in Beijing based on continuous observations from 2015 to 2019 and the WRF-Chem model

•PAN concentrations at a rural site near Beijing were monitored from 2015 to 2019. •PAN concentrations exhibited high values in spring and low values in winter. •Anomalously southerlies induced extreme high PAN concentration in spring 2018. Peroxyacetyl nitrate (PAN) is one of the most important photochemical pollutants and has aroused much concern in China in recent decades. However, few studies described the long-term variations in PAN in China. In this study, we continuously monitored the PAN, O₃ and NO_x concentrations at a regional background site near Beijing from August 2015 to February 2019. Based on the observed concentrations and climate data, we analyzed the seasonal PAN variations. The results revealed that the monthly mean PAN concentration ranged from 0.33–2.41 ppb, with an average value of 0.94 ppb. The PAN concentration exhibited a distinct seasonal variation, with high values in spring and low values in winter. After analyzing the corresponding meteorological data, we found that stronger ultraviolet (UV) radiation, a relatively longer lifetime and a higher background PAN concentration contributed to the high PAN concentrations in spring. In addition, with the utilization of the WRF-Chem (Weather Research and Forecasting with Chemistry) model, the cause of the extremely high PAN concentration in spring 2018 was determined. The model results demonstrated that an anomalously low pressure and the southwesterly winds in northern China might be the main causes of the increased PAN concentration in Beijing and its surrounding area in spring 2018.     

Removal of anaerobic soluble microbial products in a biological activated carbon reactor

The soluble microbial products (SMP) in the biological treatment effluent are generally of great amount and are poorly biodegradable. Focusing on the biodegradation of anaerobic SMP, the biological activated carbon (BAC) was introduced into the anaerobic system. The experiments were conducted in two identical lab-scale up-flow anaerobic sludge blanket (UASB) reactors. The high strength organics were degraded in the first UASB reactor (UASB1) and the second UASB (UASB2, i.e., BAC) functioned as a polishing step to remove SMP produced in UASB1. The results showed that 90% of the SMP could be removed before granular activated carbon was saturated. After the saturation, the SMP removal decreased to 60% on the average. Analysis of granular activated carbon adsorption revealed that the main role of SMP removal in BAC reactor was biodegradation. A strain of SMP-degrading bacteria, which was found highly similar to Klebsiella sp., was isolated, enriched and inoculated back to the BAC reactor. When the influent chemical oxygen demand (COD) was 10,000 mg/L and the organic loading rate achieved 10 kg COD/(m 3 ·day), the effluent from the BAC reactor could meet the discharge standard without further treatment. Anaerobic BAC reactor inoculated with the isolated Klebsiella was proved to be an effective, cheap and easy technical treatment approach for the removal of SMP in the treatment of easily-degradable wastewater with COD lower than 10,000 mg/L.     

甲基汞水环境安全阈值研究及生态风险分析

甲基汞是影响水生生物的毒性物质,其在淡水环境中的安全阈值研究非常少。查阅国内外数据库,搜集筛选了中国淡水水生生物藻类、溞类、鱼类的12种生物甲基汞急性毒性数据、5种生物慢性数据,采用加拿大开发的评估因子法推算淡水水生生物的甲基汞的安全阈值。结合甲基汞典型易生物富集的特点,搜集甲基汞生物富集因子数据,引入最终残留值综合比较,得出甲基汞水生生态系统安全阈值为1.22 ng/L。基于此数据,利用生态风险评估商值法对目前报道的主要流域地表水溶解态甲基汞检出值做出风险评估,结果表明,大部分水域不存在甲基汞带来的风险,只有贵州的乌江渡水库和阿哈水库存在甲基汞带来的食用鱼风险。     

6种重金属对3种海水养殖生物的急性毒性效应

以主要海水养殖动物菲律宾蛤仔、刺参、褐牙鲆为研究对象,采用静水毒性法评价了重金属对海洋生物的毒性效应,分别将受试动物暴露于不同浓度梯度的重金属Cd、Cr、Cu、Zn、Hg及As单种试液中,概率单位法求得半致死质量浓度。结果表明,同一种重金属对3种不同养殖生物的毒性存在明显差异(P0.05),Hg对菲律宾蛤仔、刺参及褐牙鲆3种养殖生物的96 hLC50分别为0.134 mg·L~(-1)、0.0246 mg·L~(-1)及0.238 mg·L~(-1);Cu为0.323 mg·L~(-1)、0.0499 mg·L~(-1)及0.975 mg·L~(-1);As为2.464 mg·L~(-1)、0.301 mg·L~(-1)及8.345 mg·L~(-1);Cd为2.843 mg·L~(-1)、1.111 mg·L~(-1)及6.787 mg·L~(-1);Zn为30.246 mg·L~(-1)、0.449 mg·L~(-1)及17.114 mg·L~(-1);Cr为32.591 mg·L~(-1)、2.205 mg·L~(-1)及95.137 mg·L~(-1)。6种重金属对菲律宾蛤仔毒性强弱:HgCuAsCdZnCr;对刺参毒性:HgCuAsZnCdCr;对褐牙鲆毒性:HgCuCdAsZnCr。综合结果表明:Hg、Cu毒性最强,Cd、As及Zn次之,Cr毒性最弱。研究结果可为海水增养殖区重金属风险评价提供理论依据。     

三相流化床电Fenton法预处理硝基苯废水试验研究

采用铁碳微电解固定床、铁碳微电解流化床、电絮凝、电氧化等不同的组合方法,处理难降解的硝基苯类废水,找出最佳的组合工艺,即三相流化床组合电絮凝,配合后续间接电芬顿,能将难降解废水COD435ppm处理到COD小于90ppm,色度小于2倍,很有推广价值。     

Concentrations and source characteristics of airborne carbonyl compounds measured outside urban residences

This paper presents the analysis of ambient air concentrations of 10 carbonyl compounds (aldehydes and ketones) measured in the yards of 87 residences in the city of Elizabeth, NJ, throughout 1999-2001. Most of these residences were measured twice in different seasons; the sampling duration was 48 hr each time. The authors observed higher concentrations for most of the measured carbonyl compounds on warmer days, reflecting larger contributions of photochemical reactions on warmer days. The estimated contributions of photochemical production varied substantially across the measured carbonyl compounds and could be as high as 60%. Photochemical activity, however, resulted in a net loss for formaldehyde. The authors used stepwise multiple linear regression models to evaluate the impact of traffic sources and meteorological conditions on carbonyl concentrations using the data collected on colder days (with lower photochemical activities). They found that the concentrations of formaldehyde, acetaldehyde, acrolein, propionaldehyde, crotonaldehyde, benzaldehyde, glyoxal, and methylglyoxal significantly decreased with increasing distance between a measured residence and one or more major roadways. They also found significant negative associations between concentrations for most of the measured carbonyl compounds and each of the following meteorological parameters: mixing height, wind speed, and precipitation.     

活性炭氯乙烷防护时间测定方法的改进

活性炭氯乙烷防护时间是用于表征活性炭对难吸附有机物的物理吸附性能。本文对活性炭吸附法测定氯乙烷浓度进行了试验,试验表明,测浓管使用的最佳时间是20-40min。针对活性炭吸附法的不足．本文提出了使用红外光谱技术检测氯乙烷浓度,研究表明,红外光谱仪检测氯乙烷浓度是现实可行的。     

民用燃煤、焦化厂和石油沥青工业多环芳烃源成分谱的比较研究

利用模拟实验采集了民用燃煤污染源样品，在现场采集了焦化帮石油沥青两类污染源样品，用GC/MS联用技术测定了样品中13种多环芳烃，对分析结果进行归一化处理后确定以上3类污染源多环芳烃源成分谱，在此基础上，对民用燃煤，焦化厂和石油沥青污染源的排放水平，轮廓图特征，排放特征和特征比值进行了比较。     

环境影响评价中停车场CO排放量的计算

现在的建设项目大多建设停车场,其排放的污染物中一氧化碳的浓度最大,但是,鉴于经费制约,实测比较困难.确定排放量最关键的参数为等速工况单车排放因子,本文用五种方法对其进行拟和,并通过结果的比较,认为小型车适用指数法,大中型车适用多项式法(二次),并给出了CO等速工况单车排放因子拟和公式,相关系数均在99%以上.最后给出了停车场CO排放量的计算公式,希望对广大环评工作者有所裨益.     

基于绿色全要素生产率的“两山”转化效率测度方法

为探讨“绿水青山”转化为“金山银山”的转化途径,评估不同地区“两山”转化效率,通过在以资本、劳动力测算TFP（全要素生产率,Total Factor Productivity）的过程中,加入“绿水青山资源”作为生产要素投入,界定了体现环境资本的GTFP（绿色全要素生产率,Green Total Factor Productivity）概念,构建了基于Malmquist-DEA模型的GTFP测算方法.以拥有全国最多“两山”实践基地称号的浙江省为研究对象,构建基于2005—2016年面板数据,具有地表水达到或优于Ⅲ类（GB 3838—2002《地表水环境质量标准》）的断面比例、环境空气优良天数比例、森林覆盖率等7项投入以及地区生产总值1项产出的“两山”转化效率测度评估指标体系.计算对比2005—2016年浙江省全省及其各地市TFP和GTFP的结果表明:12年间浙江省全省TFP平均技术效率变动值为0.980,总体处于下降趋势,考虑GTFP后的平均技术效率变动值为0.976.“两山”实践创新基地——衢州市、湖州市的平均GTFP分别为0.980和0.962,“绿水青山资源”与资本、劳动力资源效率相当,相对稳定;杭州市、宁波市、金华市的平均GTFP分别为1.006、0.992、0.983,在浙江省位居前列.从技术效率变动角度来看,2005—2016年衢州市、金华市、丽水市历年GTFP稳定、技术效率持续增长,“绿水青山资源”作为要素投入可推动技术效率提升与经济增长,佐证了“绿水青山就是金山银山”的论断;嘉兴市GTFP累计下降了37%,“绿水青山资源”匮乏成为其短板.研究显示,在“绿水青山资源”供给水平较高的浙江省,良好的生态资源能够推动经济发展,在GTFP指数累积上升的地市中能够发挥比传统的劳动力与资本更高的资源配置效率.