The concentrations, distribution and sources of PAHs in agricultural soils and vegetables from Shunde, Guangdong, China

The concentrations, distribution and sources of 16 polycyclic aromatic hydrocarbons (PAHs) were determined in 30 agricultural soil and 16 vegetable samples collected from subtropical Shunde area, an important manufacturing center in China. The total PAHs ranged from 33.7 to 350 μg/kg in soils, and 82 to 1,258 μg/kg in vegetables. The most abundant individual PAHs are phenanthrene, fluoranthene, chrysene, pyrene and benzo(b)fluoranthene for soil samples, and anthracene, naphthalene, phenanthrene, pyrene and chrysene for vegetable samples. Average vegetable–soil ratios of total PAHs were 2.20 for leafy vegetables and 1.27 for fruity vegetables. Total PAHs in vegetable samples are not significantly correlated to those in corresponding soil samples. Principal component analyses were conducted to distinguish samples on basis of their distribution in each town, soil type and vegetable specie. Relatively abundant soil PAHs were found in town Jun’an, Beijiao, Chencun, Lecong and Ronggui, while abundant vegetable PAHs were observed in town Jun’an, Lecong, Xingtan, Daliang and Chenchun. The highest level of total PAHs were found in vegetable soil, followed by pond sediment and “stacked soil” on pond banks. The PAHs contents in leafy vegetables are higher than those in fruity vegetables. Some PAH compound ratios suggest the PAHs derived from incomplete combustion of petroleum, coal and refuse from power generation and ceramic manufacturing, and paint spraying on furniture, as well as sewage irrigation from textile industries. Soil PAHs contents have significant logarithmic correlation with total organic carbon, which demonstrates the importance of soil organic matter as sorbent to prevent losses of PAHs.     

集中式饮用水源地邻苯二甲酸酯类物质分布特征与健康风险评估

以某地区7个集中式饮用水源地为研究对象,采用固相萃取气相色谱-质谱法(SPE-GC-MS)对水体中16种邻苯二甲酸酯的分布特征和溯源进行了研究,并利用健康风险评估模型对水体PAEs进行了健康风险评价。结果表明:邻苯二甲酸二正丁酯、邻苯二甲酸二(2-乙基己基)酯、邻苯二甲酸二异丁酯和邻苯二甲酸二正辛酯在所有PAEs同系物中含量丰富,而所有样品均无邻苯二甲酸二(2-甲氧基)乙酯和邻苯二甲酸二戊酯的检出;二水厂和亨达水务断面Σ_(16)PAEs浓度最高,四水厂和五水厂断面Σ_(16)PAEs浓度最低;水体12种PAEs共提出3个主成分,揭示了91%的影响因子;层次聚类分析表明:7个采样断面聚为2类,分别代表了内河和长江水体。水体中PAEs的致癌风险值和非致癌风险值均远低于参考值,说明研究水体PAEs不会对居民构成致癌风险或其他明显的健康风险,但需加强该地区PAEs使用的规范与监管,强化末端处理,以规避风险。     

博斯腾湖富营养化状态水平调查

通过水质特征和生物学特征的一个水文年规范化实地调查,采用Scirgesew参数分类标准和相关加权综合营养状态指数,对博斯腾湖水体富营养化状态水平进行了调查和评价。     

南京市郊设施蔬菜重金属含量及健康风险分析

采用火焰原子吸收光谱法测定了南京市郊2个设施蔬菜栽培基地蔬菜中的重金属含量,并与国内蔬菜标准进行比较;运用目标危害系数(the target hazard quotient,THQ)方法评价了当地居民摄食蔬菜导致的健康风险,并比较了成人和儿童居民THQ值大小.结果表明,蔬菜中Pb、Cd、Zn和Cu的平均含量分别是0.1...     

城市污水处理厂及其受纳水体中5种典型PPCPs的赋存特征和生态风险

以5种药品及个人护理用品(pharmaceuticals and personal care products,PPCPs)包括氯贝酸、酮洛芬、萘普生、双氯芬酸和布洛芬为目标物,初步研究了它们在上海某生活污水处理厂不同污水处理单元中的赋存特征和去除特性,探讨了污水处理厂受纳河流中5种PPCPs的分布情况,并对其在受纳水体中的生态风险进行了初步评估.结果表明,5种PPCPs在污水处理厂进水中均被检出,表明生活污水是污水处理厂中PPCPs的来源之一.5种PPCPs在整个污水处理工艺中不能全部去除,微生物转化/降解是主要降解机制.受纳污水河流中5种PPCPs的分布特征与污水处理厂出水中的相似,且排污口下游水体中目标物浓度普遍高于上游,反映出污水处理厂排放可能是其受纳水体中PPCPs的主要来源之一.初步风险评估结果表明,受纳水体中双氯芬酸存在高生态风险,而酮洛芬、萘普生、氯贝酸和布洛芬的生态风险相对较低.     

珠江三角洲印刷行业VOCs组分排放清单及关键活性组分

根据珠江三角洲地区印刷行业活动数据和不锈钢罐采样-气质联用技术,获取了印刷工艺VOCs成分谱,建立了该地区2010年印刷行业VOCs组分排放清单,研究了不同工艺排放的臭氧生成潜势. 结果表明:该地区2010年印刷行业VOCs排放总量达8591.26t,深圳、东莞、佛山排放量较大.凹印是印刷行业主要VOCs排放工艺,排放量达5762.01t;平印和凸印次之,分别为1954.01和37.82t.不同工艺排放的VOCs组分差异较大,平印工艺排放的VOCs成分中异丙醇含量最多(306.58t),其次为正庚烷(115.87t);苯和甲苯是凸印工艺排放的VOCs成分中含量最大的2种化合物,分别达5.58和4.83t;乙酸乙酯是凹印工艺排放的VOCs成分中的首要化合物,达2482.85t.凸印工艺排放的VOCs单位浓度臭氧潜势最大,达1.30μg/m3,平印和凹印较小,分别为0.89和0.72μg/m3,各工艺排放的含氧有机物对臭氧生成潜势的贡献均为最大.      

东平湖DOM荧光特征及与氢氧同位素指标的相关性

本研究在运用三维荧光光谱示踪平水期东平湖DOM荧光特征的基础上,进一步分析其与氢氧同位素指标的相关性,并在此基础上尝试对大气降水的DOC贡献进行估算,以期为东平湖的污染控制及治理提供依据.结果表明,东平湖平水期DOM主要由类蛋白组分（C1和C4）和类腐殖质组分（C2和C3）构成,以类酪氨酸组分C1为主,C1所占比重将近50%.平水期东平湖DOM同时受陆源、内源及大气降水的影响,但以内源输入为主;外源输入中大气降水补给与大汶河输入所占比例相当;大气降水中的溶解性有机碳输入可能会对东平湖DOM产生不可忽视的影响,需进一步系统研究.氢氧稳定同位素与溶解态有机碳以及类腐殖质荧光之间呈显著相关关系,可以在一定程度上指示DOM的变化趋势.     

1,4-二氯苯对小白菜种子萌发和幼苗的毒性

采用室内模拟染毒法,研究1,4-DCB(1,4-二氯苯)对3种小白菜种子(矮青6号、上海青和秦白2号)萌发和蔬菜幼苗的毒性作用. 结果表明:1,4-DCB作用后,3种小白菜种子的发芽势、种子发芽率、发芽指数和活力指数均降低,并呈现一定的剂量-效应关系;种子受1,4-DCB胁迫后,小白菜幼苗的根和苗生长都受到了抑制,根长和苗高降低,根苗比显著下降;随着ρ(1,4-DCB)的升高,受胁迫后的幼苗叶片的w(游离脯氨酸)呈现先升高后降低的趋势,而MDA(丙二醛)含量逐渐升高,与ρ(1,4-DCB)呈正相关;幼苗叶片SOD(超氧化物歧化酶)活性在ρ(1,4-DCB)为5 mg/L时升高,在ρ(1,4-DCB)为10和50 mg/L时明显降低;与对照组相比,各处理组幼苗叶片POD(过氧化物酶)活性均升高,但是ρ(1,4-DCB)为50mg/L时酶活性比ρ(1,4-DCB)为10 mg/L时下降. 表明水体中1,4-DCB污染对蔬菜种子萌发和幼苗生长产生毒性,其毒性机制与膜脂质过氧化有关.      

不同类型生态浮床对富营养河水脱氮效果及微生物菌群的影响

通过设施大棚内容积为1.5 m3的人工模拟池试验,研究了框式与传统旱伞草浮床对富营养河水氮素转化及微生物菌群的影响. 传统浮床是以聚乙烯泡沫板为载体,栽植陆生植物来削减水体氮磷和有机物质等,从而达到净化水质的效果. 框式浮床是以塑料镂空支架为载体,除种植陆生植物外还添加填料等组件的新型浮床. 结果表明:①2种浮床对水体中TN,NH₄+-N和NO₃--N均有显著的去除效果,其中框式浮床和传统浮床的NH₄+-N去除率分别高达91%和86%,TN去除率也分别达到74%和64%,NO₃--N去除率分别为49%和31%. ②2种浮床系统有效地提高了水体中微生物和氮循环细菌总数和种群数量,尤其是框式浮床不同时期均比空白对照高出2～3个数量级. ③氮循环细菌的数量跟水体氮素去除有显著相关性. 其中水体ρ(NH₄+-N)和氨化菌数量呈显著正相关,ρ(NH₄+-N)和硝化菌数量呈极显著负相关,ρ(NO₃--N),ρ(TN)和反硝化菌数量之间呈极显著负相关. ④框式浮床的独特结构使之比传统浮床的去氮能力更强. 其中,填料系统吸附贡献率为8%,植物吸收的去氮贡献为16.5%,微生物系统脱氮则为75.5%;而传统浮床植物系统吸收贡献率为31.8%,微生物系统脱氮贡献率为68.2%. 说明浮床系统中植物吸收只是系统去氮的一种途径,微生物脱氮在2种浮床脱氮途径中占主导作用.      

Nanoencapsulation of hexavalent chromium with nanoscale zero-valent iron: High resolution chemical mapping of the passivation layer

Solid phase reactions of Cr(Ⅵ) with Fe(0) were investigated with spherical-aberration-corrected scanning transmission electron microscopy(Cs-STEM) integrated with X-ray energy-dispersive spectroscopy(XEDS). Near-atomic resolution elemental mappings of Cr(Ⅵ)–Fe(0) reactions were acquired. Experimental results show that rate and extent of Cr(Ⅵ) encapsulation are strongly dependent on the initial concentration of Cr(Ⅵ) in solution. Low Cr loading in nZⅥ(1.0 wt%) promotes the electrochemical oxidation and continuous corrosion of n ZⅥ while high Cr loading(1.0 wt%) can quickly shut down the Cr uptake. With the progress of iron oxidation and dissolution, elements of Cr and O counter-diffuse into the nanoparticles and accumulate in the core region at low levels of Cr(Ⅵ)(e.g., 10 mg/L). Whereas the reacted n ZⅥ is quickly coated with a newly-formed layer of 2–4 nm in the presence of concentrated Cr(Ⅵ)(e.g., 100 mg/L). The passivation structure is stable over a wide range of pH unless pH is low enough to dissolve the passivation layer. X-ray photoelectron spectroscopy(XPS) depth profiling reconfirms that the composition of the newly-formed surface layer consists of Fe(Ⅲ)–Cr(Ⅲ)(oxy)hydroxides with Cr(Ⅵ) adsorbed on the outside surface. The insoluble and insulating Fe(Ⅲ)–Cr(Ⅲ)(oxy)hydroxide layer can completely cover the n ZⅥ surface above the critical Cr loading and shield the electron transfer. Thus, the fast passivation of nZⅥ in high Cr(Ⅵ) solution is detrimental to the performance of nZⅥ for Cr(Ⅵ) treatment and remediation.