Ozone pollution characteristics and sensitivity analysis using an observation-based model in Nanjing, Yangtze River Delta Region of China

Ground-level ozone (O₃) has become a critical pollutant impeding air quality improvement in Yangtze River Delta region of China. In this study, we present O₃ pollution characteristics based on one-year online measurements during 2016 at an urban site in Nanjing, Jiangsu Province. Then, the sensitivity of O₃ to its precursors during 2 O₃ pollution episodes in August was analyzed using a box model based on observation (OBM). The relative incremental reactivity (RIR) of hydrocarbons was larger than other precursors, suggesting that hydrocarbons played the dominant role in O₃ formation. The RIR values for NO_X ranged from –0.41%/% to 0.19%/%. The O₃ sensitivity was also analyzed based on relationship of simulated O₃ production rates with reductions of VOC and NO_X derived from scenario analyses. Simulation results illustrate that O₃ formation was between VOCs-limited and transition regime. Xylenes and light alkenes were found to be key species in O₃ formation according to RIR values, and their sources were determined using the Positive Matrix Factorization (PMF) model. Paints and solvent use was the largest contributor to xylenes (54%), while petrochemical industry was the most important source to propene (82%). Discussions on VOCs and NO_X reduction schemes suggest that the 5% O₃ control goal can be achieved by reducing VOCs by 20%. To obtain 10% O₃ control goal, VOCs need to be reduced by 30% with VOCs/NO_X larger than 3:1.     

Polycyclic aromatic hydrocarbons in benthos of the northern Bering Sea Shelf and Chukchi Sea Shelf

Eighteen polycyclic aromatic hydrocarbons (PAHs) were detected in benthos collected onboard the ‘Snow Dragon’ in the Northern Bering Sea Shelf and Chukchi Sea Shelf during the 6^th Chinese National Arctic Research Expedition (CHINARE 2014). Σ₁₈PAHs for all biota samples ranged from 34.2 to 128.1 ng/g dry weight (dw), with the highest concentration observed in fish muscle (Boreogadus saida) samples close to St. Lawrence Island. The PAH composition pattern was dominated by the presence of lighter 3 ring (57%) and 2 ring (28%) PAHs, indicating oil-related or petrogenic sources as important origins of PAH contamination. Concentrations of alkyl-PAHs (1-methylnaphthalene and 2-methylnaphthalene) were lower than their parent PAH (naphthalene) in all biological tissue, and their percentage also decreased significantly (p<0.05) compared with those in the corresponding sediment. There were no significant relationships between PAH concentrations and trophic levels, which is possibly due to the combined results of the complex benthic foodweb in the subarctic/Arctic shelf region, as well as a low assimilation/effective metabolism for PAHs. According to toxic potency evaluation results from TCDD toxic equivalents (TEQs) and BaP-equivalent (BaPE) values, whelk (Neptunea heros) and starfish (Ctenodiscus crispatus) are two macroinvertebrate species showing relatively higher dioxin-like toxicity and carcinogenic risk.     

Reviews of emission of biogenic volatile organic compounds (BVOCs) in Asia

Biogenic volatile organic compounds (BVOCs) in the atmosphere play important roles in the formation of ground-level ozone and secondary organic aerosol (SOA) in global scale and also in regional scale under some condition due to their large amount and relatively higher reactivity. In places with high plant cover in the tropics and in China where air pollution is serious, the effect of BVOCs on ozone and secondary organic aerosols is strong. The present research aims to provide a comprehensive review about the emission rate, emission inventory, research methods, the influencing factors of BVOCs emissions, as well as their impacts on atmospheric environment quality and human health in recent years in Asia based on the summary and analysis of literatures. It is suggested to use field direct measurement method to obtain the emission rate and model method to calculate the emission amount. Several recommendations are given for future investigation and policy development on BVOCs emission.     

餐厨垃圾生物有机肥对贫瘠黄褐土改良的研究

为了阐明餐厨垃圾生物有机肥改良贫瘠土壤的作用机制,以贫瘠黄褐土为研究对象,通过不施肥、长期（>5 a）施用化肥、中长期（5 a）施用少量餐厨垃圾生物有机肥和短期（1 a）施用大量餐厨垃圾生物有机肥4种施肥方式,分别记为CK组、CF组、LOF-5组和MOF-1组,对比分析不同施肥方式对土壤OM（有机质）、活性有机碳、营养元素和团聚体等的影响.结果表明:①施用餐厨垃圾生物有机肥可显著提高土壤OM、活性有机碳含量,其中,MOF-1组提高效果最显著,与CK组相比,w（OM）可提高173.29%,w（ROC）（ROC为易氧化有机碳）增加了39.17%,w（POC）（POC为颗粒有机碳）和w（DOC）（DOC为可溶性有机碳）分别是CK组的13.85和10.32倍.②中长期（5 a）施用少量餐厨垃圾生物有机肥可增加土壤中较大粒径团聚体的占比,且更有利于提高土壤团粒结构的稳定性,LOF-5组>2 mm粒级的团聚体占比是CK组的4.68倍;与CK组相比,LOF-5组MWD（平均重量直径）增加了100.00%,GMD（几何平均直径）增加了82.98%,>0.25 mm水稳定性团聚体质量占比（DR_0.25）增加了27.20%.③中长期（5 a）施用少量餐厨垃圾生物有机肥可增加土壤中w（TN）（TN为全氮）和w（AN）（AN为速效氮）,与CK组相比,LOF-5组w（TN）和w（AN）分别增加了77.42%和20.82%.施用餐厨垃圾有机肥也可同时增加土壤中w（AP）（AP为速效磷）和w（AK）（AK为速效钾）,MOF-1组增加效果较佳,w（AP）和w（AK）分别是CK组的9.43和3.39倍.研究显示,中长期（5 a）施用少量餐厨垃圾生物有机肥可提升土壤固碳能力,提高土壤养分利用的有效性,从而提升耕地土壤质量,减少化肥施用量,是我国贫瘠黄褐土改良的有效施肥模式.      

不同制备温度下污泥生物炭对Cr(Ⅵ)的吸附特性

以城市剩余污泥为原料,于300,400,500,600 ℃温度条件下制备生物炭,通过单因素静态吸附实验探讨制备温度对生物炭吸附Cr（Ⅵ）的影响。结果表明:在500 ℃以内随着温度上升制备的生物炭对Cr（Ⅵ）的吸附量增加,制备温度高于500 ℃后变化不明显;扫描电镜（SEM）、比表面积（BET）、傅里叶红外光谱（FTIR）表征结果显示,热解温度对生物炭表面形貌和官能团组成有显著影响;等温模型及动力学拟合结果表明,生物炭吸附Cr（Ⅵ）为单分子层吸附、物理-化学复合吸附。热解温度对污泥制备生物炭吸附Cr（Ⅵ）的性能有显著影响,最佳制备温度为500 ℃,在此条件制备的生物炭对Cr（Ⅵ）的理论吸附量可达7.93 mg/g。     

污泥与不同pH值渗滤液联合厌氧发酵产氢分析

以污泥与垃圾焚烧厂渗滤液为原料,通过小瓶批式试验,考察了垃圾渗滤液的添加量以及渗滤液初始pH对联合厌氧消化产氢的影响。结果表明:未添加污泥的渗滤液本身也可以在厌氧发酵过程中产氢。而污泥与垃圾渗滤液联合厌氧发酵,当渗滤液初始pH为5.20时,添加90%的渗滤液体系产氢量最大,为201.58 mL,最大产氢速率也最高,为9.56 mL/h;当初始渗滤液pH为4.47时,最大产氢量出现在渗滤液添加剂量为60%的样品,为57.73 mL,随后减小,但最大产氢速率在添加40%的渗滤液达到峰值,为5.11 mL/h。     

我国燃煤电厂大气汞控制技术综合评估与对策探讨

采用模糊综合评价法与层次分析法或专家判定法相结合,对我国燃煤电厂非常规污染物大气汞控制技术进行了综合评估,以筛选出最佳控制技术.建立了环境、经济和技术为一级指标的三层指标体系,共22个评价指标;初步筛选出洗选煤+烟气净化协同脱除技术、烟气净化协同脱除技术、烟气净化协同脱除技术+活性炭吸附技术等七项技术及技术组合并对其开展评估.结果表明:强调环境因素的层次分析法综合评估结果表明,超低排放协同脱除技术+活性炭吸附技术得分最高（0.797 0）,为最佳控制技术.而专家判定法与强调经济因素的层次分析法的综合评估结果一致,洗选煤+烟气净化协同脱除技术最具经济优势,是专家认可的最佳可用技术（BAT）和最佳环境实践（BEP）.研究显示,我国现阶段可采用洗选煤+超低排放协同脱除技术对燃煤电厂的大气汞污染进行控制,但为达到发达国家的严格排放标准,必须采用超低排放协同脱除技术+活性炭吸附技术.      

成都市施工扬尘排放特征研究

采用DustTRAK TM气溶胶（粉尘）监测仪对成都市112个不同类别的房建、市政工地施工扬尘进行测试,研究了不同类别施工扬尘的排放特征,分析了下风向扬尘浓度的变化趋势,并采用CALPUFF对成都市新都区某建筑工地的排放进行了模拟.结果表明：（1）成都市施工扬尘排放浓度约为0.13~2.91mg/m³,其中房建类施工平均浓度约为0.94mg/m³,高于市政施工;大型工地扬尘平均浓度约为0.61mg/m³,低于中型和小型工地;土方施工阶段平均浓度约为1.21mg/m³,远高于地基建设、主体建设、装饰阶段.（2）成都市施工扬尘呈现出高低浓度交替的周期性变化,其中房建工程土方施工阶段的高低浓度差值可达到0.6mg/m³以上.（3）施工扬尘在场界外下风向5~15m范围内会出现浓度增加的趋势,随后逐渐下降,在50m附近逐渐趋于稳定,稳定浓度介于0.1~0.2mg/m³.（4）CALPUFF模型能较好地从宏观角度来模拟成都地区施工扬尘的扩散趋势,但难以捕捉施工扬尘在下风向近距离的扩散特征.     

长治市沙尘天气污染特征及传输路径解析

以2018年3次沙尘天气为研究对象,分析了PM_2.5和PM₁₀浓度、水溶性离子组分、气象条件和气溶胶光学特征,研究了长治市沙尘天气的典型污染特征和传输路径.结果表明：长治市2018年共8d为受沙尘天气影响日,其中4月份最多（5d）,这与春季大气环流调整,冷暖空气活动频繁有关.沙尘污染发生前一般受西方或西北方冷空气影响,大气层结不稳定,大气环流转为经向环流,平均风速达4m/s以上;沙尘污染过程中PM_2.5/PM₁₀均低于0.3,环境空气中粗颗粒物占比较大,水溶性离子总浓度在PM_2.5中占比下降,Ca²⁺浓度为沙尘污染发生前的4倍以上.冬季沙尘为近地面扩散传输,春夏季沙尘为高空沉降传输,影响范围大,区域传输贡献明显.长治市沙尘重要潜在源区为蒙古国、哈萨克斯坦中部和新疆中北部的荒漠地区,传输路径主要为西北路径和正北路径,其中西北路径为哈萨克斯坦—新疆中北部—内蒙古西部—长治以及新疆中北部—内蒙古西部—长治两条路径,正北路径为蒙古国—内蒙古中部—山西北部—长治.     

矿山排水污染稻田土壤胶体对砷的吸附研究

为研究矿山排水污染土壤胶体对砷的吸附影响,文章以高砷污染区和背景区土壤的胶体在不同的pH、离子强度以及好氧/厌氧淹水条件下对As(Ⅴ)的吸附进行对比试验。结果表明:土壤胶体对As(Ⅴ)的吸附量随pH的增大而减少,且污染区胶体比背景区胶体对As(Ⅴ)的吸附量大;离子强度越大,胶体对As(Ⅴ)的吸附量越大,Ca(NO_3)_2浓度从0.001 mol/L增至0.1 mol/L时,污染区与背景区胶体对As(Ⅴ)的吸附量分别增加了30.57%、50.25%;厌氧淹水后的胶体对As(Ⅴ)的吸附量低于好氧条件下的胶体,解吸量较高,且厌氧淹水后污染区胶体与背景区胶体相比无明显吸附优势,而好氧条件下污染区胶体的解吸率低于背景区胶体,说明厌氧淹水后的胶体不易吸附且易释放As(Ⅴ)。因此,低p H和高离子强度以及好氧的条件有利于土壤胶体对砷的吸附。