中国稻田土壤镉污染及务农性暴露概率风险

为了解中国稻田土壤镉污染时空变异特征及其务农性接触的健康风险,对1991~2017年发表的205篇有关稻田土壤镉调查文献进行系统回顾,并采用USEPA推荐的健康风险评估概率模型对健康风险进行评估.结果表明,全国稻田土壤镉平均浓度[（0.54±1.38）mg/kg]显著高于全国表层土壤镉背景值（0.097mg/kg）.虽未见显著的时间变异（β=-0.002,95%置信区间：-0.025~0.022）,但不同地区和不同人为扰动下的稻田土壤镉浓度存在较大异质性：华南[（0.88±1.59）mg/kg]>西南[（0.46±0.85）mg/kg]>华东[（0.44±1.45）mg/kg]>华北[（0.36±1.05）mg/kg]>东北[（0.35±0.83）mg/kg]>西北[（0.01±0.05）mg/kg]和矿冶[（1.77±2.18）mg/kg]>其他工业活动[（0.64±1.22）mg/kg]>电子垃圾拆解[（0.59±0.87）mg/kg]>污灌[（0.57±1.26）mg/kg]>交通[（0.56±0.86）mg/kg]>常规稻田[（0.25±0.34）mg/kg].除西北地区外,各地区稻田土壤镉浓度均出现不同程度的超标现象,尤其华南地区34%条土壤镉浓度数据超过农用地土壤镉污染风险管制值（1.5mg/kg）.土壤镉务农性接触的非致癌风险（HQ<<1）处于可接受水平,其中皮肤接触是主要途径,女性是务农性土壤镉暴露的高风险人群,华南和西南地区是务农性土壤镉暴露的高风险地区.     

潘家口水库温室气体溶存、排放特征及影响因素

以大型深水水电类水库潘家口水库为例,于2020年春季（5月）、夏季（8月）在研究区设置33个采样点,采用顶空平衡-气相色谱法和经验模型法对水柱温室气体浓度和水-气界面扩散通量进行了观测及估算,并分析了潘家口水库温室气体浓度及通量的主要影响因素.结果表明：春季潘家口水库水-气界面CH₄、CO₂、N₂O平均通量分别为（1.11±1.60）μmol/（m²·h）,（1333.31±546.43）μmol/（m²·h）,（76.65±19.54）nmol/（m²·h）.夏季潘家口水库水-气界面CH₄、CO₂、N₂O平均通量分别为（0.62±1.13）μmol/（m²·h）,（746.08±1152.44）μmol/（m²·h）,（141.18±256.02）nmol/（m²·h）.潘家口水库温室气体排放呈现出大的时空异质性,空间上春季和夏季各温室气体通量均表现为干流大于支流;季节上CH₄与CO₂扩散通量表现为春季大于夏季,而N₂O扩散通量夏季大于春季.统计分析表明CH₄扩散通量主要受电导率、风速等环境因子影响,CO₂扩散通量受风速、pH及DOC影响,N₂O扩散通量主要受水柱NO₃^--N、NO₂^--N的影响.     

创新集聚空间分布模式对霾污染的影响

为了比较分析创新集聚空间分布单中心与多中心两种模式对霾污染的影响机制,本文构建了省域面板数据模型和中介效应模型进行实证检验.结果表明：创新集聚可通过规模效应降低霾污染;但创新集聚空间分布模式对霾污染的影响具有异质性.其中,单中心模式诱发了霾污染,存在创新集聚环境效应悖论;多中心模式对霾污染具有改善效应;随着创新集聚多中心的提高,其霾污染改善效应增强,但具有边际递减特征;能源利用效率是创新集聚空间分布模式影响霾污染的重要渠道之一.基于此,本文建议省级政府推进空间协同创新发展战略,建构省域多中心的创新网络空间组织体系,以此形成多中心协同治霾机制,破解创新集聚环境效应悖论.     

室内木柴燃烧排放水溶性离子粒径分布特征

基于实验室模拟燃烧和稀释通道采样系统,采用荷电低压撞击采样器采集了6种典型木柴燃烧排放的14级粒径段颗粒物.采用离子色谱分析了8种水溶性离子,获得水溶性离子的分粒径排放因子和排放特征.结果表明,Ca²⁺的排放因子呈双峰分布,在0.25~0.38和2.5~3.6μm粒径段出现峰值,分别为0.14和0.16mg/kg.其余离子的排放因子为单峰分布.NH₄⁺、NO₃^-和SO₄^2-的排放因子在0.25~0.38μm粒径段出现峰值,分别为0.41、0.58和0.84mg/kg.K⁺和Cl^-的排放因子在0.15~0.25μm内出现峰值,分别为0.89和0.99mg/kg.木柴燃烧排放总水溶性离子的质量中值粒径为（0.30±0.07）μm,各离子的质量中值粒径范围为0.24~0.44μm.PM_0.094、PM_0.94、PM_2.5和PM₁₀中水溶性离子的排放因子变化范围分别为1.04~9.33、5.00~48.87、5.46~52.00和6.14~53.68mg/kg.木柴燃烧排放颗粒物中K⁺/Cl^-、K⁺/NO₃^-、K⁺/SO₄^2-和SO₄^2-/NO₃^-比值随粒径变化而变化,其排放初始值在应用于源解析和生物质燃烧排放气溶胶传输老化研究时需引起关注.木柴燃烧排放PM₁₀中的阴阳离子当量比值为0.80±0.11,颗粒物的酸度随颗粒物粒径而改变,亚微米颗粒物和细颗粒物的酸度高于超细颗粒物和粗颗粒物的酸度.本研究对构建生物质燃烧排放分粒径水溶性离子清单,更新和改进相关气候和空气质量模型的参数设置,识别烟气传输过程中的老化具有重要意义.     

基于摩擦纳米发电机的微塑料实时检测实验研究

采用基于自供电的摩擦纳米发电机(TENG)技术,设计开发了一种利用间断液柱检测水样内微塑料颗粒尺寸和丰度的实时快速检测方法和装置,并通过实验测试完成了对微塑料的尺寸形貌表征和化学元素组成的实时高效检测.研究发现,去离子水中加入微塑料颗粒时,溶液中zeta电位降低,改变了管壁表面的极化电场方向;随着水溶液中微塑料颗粒直径或丰度的增加,开路电压呈现减小趋势,50μm时减小了43.1%,0.250%浓度时减小了79.6%;微塑料颗粒对自来水的开路电压影响显著,以10μm微塑料颗粒为例,开路电压减小了20%,证明了TENG技术对海洋微塑料检测的可行性.     

利用CDOM吸收系数估算博斯腾湖水体表层DOC浓度

基于2021年夏秋两季西部干旱区博斯腾湖表层50个采样点位实测数据,通过对DOC特征的统计学分析、内外源因素影响的时空差异以及电导率相关性验证,将博斯腾湖划分为河口和非河口区域.然后以CDOM特征波长吸收系数a₂₅₀和a₃₆₅为自变量,以DOC浓度（c_DOC）为因变量,分别构建了基于CDOM的河口和非河口水域DOC浓度估算模型.结果表明：河流与湖泊进行水体交换的同时,会将大量陆源DOC输送到博斯腾湖中,使得河口区域DOC浓度明显高于非河口区域（t-tests,P<0.01）,河口区域的DOC浓度（c_DOC）约是非河口区域的2.2~2.3倍,且在河口区域c_DOC与电导率呈现显著相关关系（夏季：R²=0.81,P<0.01;秋季：R²=0.84,P<0.01）.本文构建拟合模型（c_DOC=α+β·α₂₅₀+γ·α₃₆₅）,并通过交叉验证的方法来检验模型精度.将夏季和秋季同区域数据统一建模,河口和非河口区域CDOM与DOC均存在较好的相关关系,且模型精度较高（河口区域：R²=0.60,RMSE=8.56%;非河口区域：R²=0.66,RMSE=8.77%）.本文所建立的模型可以在不增加环境因子变量的前提下提高精度,有利于实现卫星遥感反演.同时,本研究揭示了河流输入对博斯腾湖DOC分布和估算的时空影响,提出可利用CDOM估算DOC浓度,但需根据水文特征和c_DOC等因素区分河口和非河口区域.本研究对实现新疆水资源合理开发、有效保护以及综合治理提供科学依据,对我国西部干旱区湖泊DOC遥感动态监测具有重要意义.     

共代谢条件下荧蒽降解菌的差异蛋白质组学分析

以课题组筛选出的多环芳烃高效降解菌--蜡样芽孢杆菌(Bacillus cereus)DQ01菌株为研究对象,以荧蒽为目标污染物,以牛肉膏蛋白胨培养基(LB培养基)为共代谢基质,基于同位素相对和绝对定量技术(iTRAQ)比较细菌在无机盐培养基(MSM培养基)和MSM-LB培养环境中降解荧蒽的全蛋白表达水平,旨在揭示蜡样芽孢杆菌在共代谢过程中分子代谢水平上的变化.结果共检测到64个差异表达蛋白质,其中上调表达的蛋白质有28个,下调表达的蛋白质36个.鉴定到差异蛋白的功能集中在代谢、应激反应、信息传递和调控等方面,同时对比KEGG通路富集分析的结果,也显示细菌有关能量代谢和信息传递、调控的通路产生的变化.比较细菌在是否处于共代谢下的差异蛋白表达,推测细菌在降解多环芳烃过程中的关键环节是小分子代谢和适应外界环境的通路.     

盛行梯度风下热力环流对近地空气质量的影响研究

以中纬度沿海城市上海为代表,采用数值模拟方法,分析了海岸线附近污染源排放的大气污染物在盛行梯度风和热力环流耦合作用下的扩散和输送特征,并与忽略海陆温差的理想情况作了对比.结果表明,即使在盛行梯度风主导城市风场时,海陆温差引起的热力环流对海岸线附近流场仍有重要影响,并使近地面污染物浓度时空分布与海陆无温差时截然不同.海陆无温差时,污染物仅向盛行梯度风的下风向区域扩散.而在海陆有温差时,污染物的扩散却可能是双向的.陆地最高和最低气温出现的时间分别对应着沿海城市污染物最不利释放时段(RTS-16:00和RTS-04:00),造成的污染总时长和日平均浓度均最大,不仅部分近地面污染物被海陆热力环流携带至盛行梯度风的上风向区域,并且下风向区域的日平均浓度最高达海陆无温差时的4~5倍.因此,即使在盛行梯度风较强时忽略海陆温差形成的热力环流影响,也会明显低估非海陆风日的实际污染强度和污染范围.     

Competing pathways of cresol formation in toluene photooxidation: OH-toluene adducts react with NO2 or with O2?

Methyl-hydroxy-cyclohexadienyl radicals (OTAs) are the key products of the photooxidation of toluene, with implications for the fate of toluene. Hence, we investigated the photooxidation mechanisms and kinetics of three main OTAs (o-OTA, m-OTA, and p-OTA) with NO₂ using quantum chemical calculations as well as the fate of OTAs under the different concentration ratios of NO₂ and O₂. The mechanism results show that the pathway of H-abstraction by NO₂ to anti-HONO (anti-H-abstraction) is more favorable than the syn-H-abstraction pathway, because the strong interaction between OTAs and NO₂ is formed in the transition states of the anti-H-abstraction pathways. The branching ratios of the anti-H-abstraction pathways are more than 99% in the temperature range of 216−298 K. The total rate constant of the OTA-NO₂ reaction is 9.9 × 10⁻¹² cm³/(molecule∙sec) at 298 K, which is contributed about 90% by o-OTA + NO₂, and the main products are o-cresol and anti-HONO. The half-lives of the OTA-NO₂ reaction in some polluted areas of China are 35 times longer than those of the OTA-O₂ reaction. In the atmosphere, the NO₂- and O₂- initiated reactions of OTAs have the same ability to form cresols as [NO₂] is up to 142.1 ppmV, which is impossible to achieve. It implies that under the experimental condition, the [NO₂]/[O₂] should be controlled to be less than 7.8 × 10⁻⁵ to simulate real atmospheric oxidation of toluene. Our results reveal that for the photooxidation of toluene, the yield of cresol is not affected by the concentration of NO₂ under the atmospheric environment.     

Response of PM2.5-bound elemental species to emission variations and associated health risk assessment during the COVID-19 pandemic in a coastal megacity

The coronavirus (COVID-19) pandemic is disrupting the world from many aspects. In this study, the impact of emission variations on PM_2.5-bound elemental species and health risks associated to inhalation exposure has been analyzed based on real-time measurements at a remote coastal site in Shanghai during the pandemic. Most trace elemental species decreased significantly and displayed almost no diel peaks during the lockdown. After the lockdown, they rebounded rapidly, of which V and Ni even exceeded the levels before the lockdown, suggesting the recovery of both inland and shipping activities. Five sources were identified based on receptor modeling. Coal combustion accounted for more than 70% of the measured elemental concentrations before and during the lockdown. Shipping emissions, fugitive/mineral dust, and waste incineration all showed elevated contributions after the lockdown. The total non-carcinogenic risk (HQ) for the target elements exceeded the risk threshold for both children and adults with chloride as the predominant species contributing to HQ. Whereas, the total carcinogenic risk (TR) for adults was above the acceptable level and much higher than that for children. Waste incineration was the largest contributor to HQ, while manufacture processing and coal combustion were the main sources of TR. Lockdown control measures were beneficial for lowering the carcinogenic risk while unexpectedly increased the non-carcinogenic risk. From the perspective of health effects, priorities of control measures should be given to waste incineration, manufacture processing, and coal combustion. A balanced way should be reached between both lowering the levels of air pollutants and their health risks.