湿法预处理对垃圾焚烧飞灰中重金属的形态及风险影响研究

以某典型城市生活垃圾焚烧飞灰为研究对象,采用X射线荧光光谱仪（XRF）、X射线衍射仪（XRD）和电感耦合等离子体光谱仪（ICP）测定了焚烧飞灰的主要成分、矿物学组成和重金属含量,探讨了湿法预处理工艺对飞灰的化学组成、矿物学形态、化学形态及风险水平的影响.结果表明,飞灰的主要化学组成为O、Ca、Cl、Na、K等,占飞灰总质量的93.54％,其次含有0.04％ ～0.68％的Zn、Pb、Cu、Cr等微量重金属元素;经过湿法预处理,飞灰中可溶性氯盐具有较好的去除效果,且几乎所有重金属元素的不稳定形态（弱酸提取态和可还原态）比例都有一定程度的减少,有效降低了重金属的毒性、生物有效性及环境风险水平.本研究有助于降低焚烧飞灰的环境风险和探寻其资源化的有效途径.     

Woody species Rhus chinensis Mill. seedlings tolerance to Pb: Physiological and biochemical response

Screening potential plant species is a crucial consideration in phytoremediation technology. Our previous study demonstrated that Rhus chinensis Mill. seedlings had potentials for phytoremediation of Pb contaminated soil. However, its bioaccumulation and tolerance characteristics remain unclear. Seedling growth, LMWOAs secreted by roots, Pb subcellular distribution and chemical forms, and mineral elements in R. chinensis tissues were evaluated under different Pb concentrations (0, 25, 50, 100, 200 and 400?mg/L) in culture solution at 14?days after planting. R. chinensis did not show visual symptoms of Pb toxicity under lower Pb treatments; however, Pb significantly declined the growth of seedlings under higher Pb treatments. Higher Pb stress also decreased the concentrations of nitrogen in leaves, but increased the concentrations of P and K in roots. Pb stress also decreased Mn concentrations in leaves. A great quantity of Pb was uptake and mostly retained in R. chinensis roots. Nonetheless, R. chinensis can still concentrate 459.3 and 1102.7?mg/kg Pb in leaves and stems, respectively. Most of Pb in R. chinensis tissues was stored in the cell wall with HAc-, HCl-, and NaCl-extractable form. LMWOAs secreted by R. chinensis roots showed a strong positive correlation with Pb concentrations in all plant tissues and with P in roots. Our results suggested that Pb deposited in the cell wall and integration with phosphate or oxalate might be responsible for the tolerance of R. chinensis under Pb stress in short period.     

Atmospheric photochemistry and secondary aerosol formation of urban air in Lyon, France

Photochemical aging of volatile organic compounds (VOCs) in the atmosphere is an important source of secondary organic aerosol (SOA). To evaluate the formation potential of SOA at an urban site in Lyon (France), an outdoor experiment using a Potential Aerosol Mass (PAM) oxidation flow reactor (OFR) was conducted throughout entire days during January-February 2017. Diurnal variation of SOA formations and their correlation with OH radical exposure (OHexp), ambient pollutants (VOCs and particulate matters, PM), Relative Humidity (RH), and temperature were explored in this study. Ambient urban air was exposed to high concentration of OH radicals with OHexp in range of (0.2–1.2)×10¹² molecule/(cm³?sec), corresponding to several days to weeks of equivalent atmospheric photochemical aging. The results informed that urban air at Lyon has high potency to contribute to SOA, and these SOA productions were favored from OH radical photochemical oxidation rather than via ozonolysis. Maximum SOA formation (36 µg/m³) was obtained at OHexp of about 7.4 × 10¹¹molecule/(cm³?sec), equivalent to approximately 5 days of atmospheric oxidation. The correlation between SOA formation and ambient environment conditions (RH & temperature, VOCs and PM) was observed. It was the first time to estimate SOA formation potential from ambient air over a long period in urban environment of Lyon.     

Measurement of heterogeneous uptake of NO2 on inorganic particles, sea water and urban grime

Heterogeneous reactions of NO₂ on different surfaces play an important role in atmospheric NO_x removal and HONO formation, having profound impacts on photochemistry in polluted urban areas. Previous studies have suggested that the NO₂ uptake on the ground or aerosol surfaces could be a dominant source for elevated HONO during the daytime. However, the uptake behavior of NO₂ varies with different surfaces, and different uptake coefficients were used or derived in different studies. To obtain a more holistic picture of heterogeneous NO₂ uptake on different surfaces, a series of laboratory experiments using different flow tube reactors was conducted, and the NO₂ uptake coefficients (γ) were determined on inorganic particles, sea water and urban grime. The results showed that heterogeneous reactions on those surfaces were generally weak in dark conditions, with the measured γ varied from <10^?8 to 3.2 × 10^?7 under different humidity. A photo-enhanced uptake of NO₂ on urban grime was observed, with the obvious formation of HONO and NO from the heterogeneous reaction. The photo-enhanced γ was measured to be 1.9 × 10^?6 at 5% relative humidity (RH) and 5.8 × 10^?6 at 70% RH on urban grime, showing a positive RH dependence for both NO₂ uptake and HONO formation. The results demonstrate an important role of urban grime in the daytime NO₂-to-HONO conversion, and could be helpful to explain the unknown daytime HONO source in the polluted urban area.     

Horizontal and vertical gene transfer drive sediment antibiotic resistome in an urban lagoon system

Rapid urbanization has resulted in pervasive occurrence of antibiotic resistance genes (ARGs) in urban aquatic ecosystems. However, limited information is available concerning the ARG profiles and the forces responsible for their assembly in urban landscape lagoon systems. Here, we employed high-throughput quantitative PCR (HT-qPCR) to characterize the spatial variations of ARGs in surface and core sediments of Yundang Lagoon, China. The results indicated that the average richness and absolute abundance of ARGs were 11 and 53 times higher in the lagoon sediments as compared to pristine reference Tibetan lake sediments, highlighting the role of anthropogenic activities in ARG pollution. Co-occurrence network analysis indicated that various anaerobic prokaryotic genera belonging to Alpha-, Deltaproteobacteria, Bacteroidetes, Euryarchaeota, Firmicutes and Synergistetes were the potential hosts of ARGs. The partial least squares-path modeling (PLS-PM) analysis revealed positive and negative indirect effects of physicochemical factors and heavy metals on the lagoon ARG profiles, via biotic factors, respectively. The horizontal (mediated by mobile genetic elements) and vertical (mediated by prokaryotic communities) gene transfer may directly contribute the most to drive the abundance and composition of ARGs, respectively. Furthermore, the neutral community model demonstrated that the assembly of sediment ARG communities was jointly governed by deterministic and stochastic processes. Overall, this study provides novel insights into the diversity and distribution of ARGs in the benthic habitat of urban lagoon systems and underlying mechanisms for the spread and proliferation of ARGs.     

污水厂尾水受纳河段沉积物磷形态及释放风险效应

2018年10月～2019年4月,在合肥市板桥河的蔡田铺污水厂尾水排放口上、下游河道4个采样点位,按照每两个月采样一次的频率采集沉积物和上覆水样,分析尾水排放对河道沉积物磷形态及磷平衡浓度(EPC_0)的影响,解析沉积物磷平衡浓度及磷释放风险的外源碳(乙酸钠)响应.结果表明,板桥河水体沉积物磷素受污水厂尾水影响较大,排放口上、下游沉积物总磷均值分别为789. 39 mg·kg~(-1)和854. 41 mg·kg~(-1),生物有效性磷均值分别为157. 19 mg·kg~(-1)和173. 37 mg·kg~(-1); 4个采样点的EPC_0值大小排序为:SP1 SP2 SP3 CP,表明尾水排入提高了河流EPC_0,致使河流沉积物磷释放风险增加;外源碳的添加明显降低沉积物的EPC_0值,特别是紧邻排放口的SP1下降最为显著,表明外源碳添加对降低沉积物磷释放风险有效.     

梯级水库建设对怒江与澜沧江沉积物氮形态分布的影响

为探究梯级水库建设对沉积物氮形态分布的影响,通过分级浸取方法得到沉积物的离子交换态氮（IEF-N）、弱酸提取态氮（WAEF-N）、强碱提取态氮（SAEF-N）以及强氧化剂提取态氮（SOEF-N）,对比研究了有梯级水库建设的澜沧江和干流无水电站建设的怒江沉积物中氮形态的分布特征,分析了可转化态氮的主要影响因素.结果表明,两条流域沉积物赋存环境存在差异,进而使沉积物的理化性质呈现明显的差异,最终导致沉积物可转化态氮的含量及空间分布也不同,澜沧江沉积物可转化态氮的含量高于怒江,且澜沧江的空间变化也大于怒江,怒江IEF-N、WAEF-N、SAEF-N与SOEF-N含量范围分别为1.56~2.55,16.91~46.42,1.83~10.66,486.61~719.27mg/kg,澜沧江IEF-N、WAEF-N、SAEF-N与SOEF-N含量范围分别为1.55~14.35,20.77~83.08,1.36~92.15,562.61~1404.82mg/kg.两条河流的可转化态氮含量大小排列顺序一致,均为SOEF-N > WAEF-N > SAEF-N > IEF-N,怒江与澜沧江上游自然河段可转化态氮含量及空间分布基本一致,但在澜沧江的梯级水库段上,4种可转化态氮空间分布特征发生了较明显的变化,产生这种现象的原因主要是水库的建设导致了沉积物理化性质的改变,总有机碳、粒度、氧化还原电位对可转化态氮的影响不同.     

深圳市洪涝灾害的数值模拟与分析

深圳市自建特区以来,沿河沿海低地迅速城市化,流域内大规模的开发活动加剧了水土流失,河道淤塞严重,行洪能力降低,新增市区防洪排涝设施不足,使深圳市洪涝灾害更趋频繁,经济损失急剧增长,为配合深圳市制定新的防洪(潮)规划,本研究开发了城市洪水演进一、二维不恒定流混合模型,分现状与规划措施实施后两种情况对各典型年暴雨、高潮的组合在深圳市可能造成的洪涝灾害进行了模拟和分析,其结果为深圳市合理评价防洪(潮)规划提供了依据。     

天然红土与苦草联合控制沉积物中磷释放

运用天然红土和苦草（RS+VS）的原位联合修复技术,探究单一及联合修复对污染底泥磷去除的影响.结果表明,RS与VS联合对沉积物P的去除能力高于两者单一修复,在37d的批量实验中,覆盖RS+VS组沉积物释放到上覆水中的磷被抑制了91%,与无覆盖RS+VS组的底泥释放磷相比,上覆水中溶解态活性磷（SRP）从1.41mg/L降至0.12mg/L.RS+VS联合修复对沉积物磷的固定作用显著,将不稳定的亚铁磷（Fe （II）-P）和铁铝结合磷（CDB-P）转变成惰性的钙磷（Ca-P）,沉积物中的Ca-P含量增加了51%,Fe （II）-P,CDB-P分别降低了1%和24%,有效降低了底泥磷释放到上覆水的风险.综上,RS+VS联合可以应用于处理富营养化水域的内部磷负荷,实现两者协同去除沉积物磷,同时RS和VS两者价廉且广泛分布可作为一种潜在高效益的磷酸盐吸附剂应用于实际工程中.     

Multiple environmental burdens and neighborhood-related health of city residents

Urban living environments are known to influence human well-being and health; however, little is known about the multidimensionality of different environmental burdens. The aim of this study is to examine the relations between multiple burdens and self-rated health of city residents in Berlin. A spatial analysis was conducted to determine neighborhood street blocks with high versus low levels of three environmental burdens (traffic noise, air pollution, lack of public green space) as study sites for a cross-sectional household questionnaire. Burden level served as a dichotomous predictor to compare residents' self-reports of neighborhood satisfaction, life satisfaction, health behavior, and psychological and physical health symptoms. Residents from high-burden blocks appraised the environmental conditions more stressful, reported poorer health behavior and were less satisfied with their neighborhood than residents from low-burden blocks. However, they did not differ in regard to more general health symptoms. Three other burdens (behavior-related noise, litter and dirt in public space, lack of urban vegetation), which could not be varied objectively, were assessed by their perceived intensity. Regression analyses of the relations between the perceived levels of all six burdens and outcomes in the total sample revealed the following: Neighborhood satisfaction could be predicted from multiple stressors and resources that co-occur independently, while more general health symptoms were related only to perceived air pollution. The results have implications for both urban planning and public health.