典型产业承接区土壤砷含量的空间分布特征及影响因素

本文以揭阳市为研究区域,采集了1330个表层土壤(0—20 cm)样品和331个深层土壤(150—200 cm)样品,利用富集因子法分析了表层土壤中As的污染状况,通过GIS空间分析技术以及单因素分析法探究了土壤As的空间分布特征以及影响因素.结果表明,研究区表层土壤As含量的均值为6.03 mg·kg^-1,低于该区土壤背景值(7.16 mg·kg^-1)及农用地土壤污染风险管控值(20 mg·kg^-1),大部分土壤为轻微污染和中度污染.揭阳市表层土壤As含量高值区分布于揭阳市东北部、中部和西南部地区,低值区分布于西北部和东南部地区.土壤类型、成土母质和土地利用类型是影响表层土壤As含量的重要因素,在不同土壤类型中,黄壤和赤红壤As含量相对较高;不同成土母质中,粉砂岩母质土壤As含量显著高于其他母质;在不同土地利用类型中,农用地土壤As含量最高.     

砷尾矿污染土壤的细菌群落结构多样性及其相关环境影响因子分析

以湖南石门雄黄尾矿污染土壤为对象,研究纵向不同深度、横向不同距离土样中的重金属污染程度以及细菌群落结构变化规律,查明砷污染土壤的核心微生物组成并将其与土壤理化指标进行共存网络图分析。结果表明:该尾矿区的土壤各项重金属指标严重超标,尤以铅(626.54 mg·kg^?1,Ei=105.48)、砷(1804.75 mg·kg^?1,Ei=565.75)、镉(31.46 mg·kg^?1,Ei=7491.5)的生态危害性最强;土壤采样深度与重金属综合潜在生态风险指数(RI)呈显著正相关(r=0.79,P=0.000),而横向样品中RI与采样距离显著负相关(r=?0.85,P=0.000)。在污染土壤中,变形杆菌门(Proteobacteria,54.35%±17.16%)和放线杆菌门(Actinobacteria,22.39%±10.64%)占主导地位,属层级中假单孢杆菌属(Pseudomonas,16.47%±11.84%)、不动杆菌属(Acinetobacter,8.07%±7.11%)以及硫酸状杆菌属(Acidithiobacillus,7.53%±14.68%)相对丰度较高;而26个共享类群占据了该尾矿污染土壤中微生物群落总平均相对丰度90%以上,尽管不同属的具体相对丰度在不同样品间的分布趋势差异较大。纵剖采集的污染土样中,铁原体属(Ferroplasma)、硫酸状杆菌属(Acidithiobacillus)、硫化杆菌属(Sulfobacillus)、乳杆菌属(Lactobacillus)和硝化螺旋菌属(Nitrospira)占优势,与理化的共存网络图分析(相关系数|r|≥0.6,P<0.05)显示部分类群与亚铁、游离态砷和镉成显著正相关,而与pH成显著负相关;横向采集的土样中,以嗜酸菌属(Acidiphilium)、假单孢杆菌属(Pseudomonas)、棒状杆菌属(Corynebacterium)、硫杆菌属(Thiobacillus)等为主,部分类群与总砷、铅成显著正相关,而与结合态或包蔽型砷成显著负相关。综上,该研究不仅对目标区域尾矿不同重金属污染程度进行了分析,同时探讨了污染土壤中核心响应类群的组成多样性,为筛选潜在重金属抗性菌群或工程菌群提供理论基础。     

锌在不同磷源条件下对铜绿微囊藻生长与产毒的影响

针对磷和微量元素对藻类生长的共同作用,研究不同磷源条件下锌对藻细胞生长与产毒的影响。实验选用铜绿微囊藻为藻种,分别以无机磷磷酸氢二钾(K_2HPO_4)、小分子有机磷甘油磷酸钠(NaGly)和大分子有机磷卵磷脂(LEC)为磷源,研究不同锌(Zn~(2+))含量对藻细胞的藻密度、碱性磷酸酶活性(alkaline phosphatase activity,APA)以及胞内藻毒素(MC-LR)的影响。研究发现:以NaGly为磷源时微量元素锌对藻细胞生长的促进效果显著,而以K_2HPO_4或LEC为磷源时,锌含量的变化对藻细胞生长无显著影响。APA不仅与磷源有关而且与锌含量相关,以LEC为磷源时的APA显著高于以K_2HPO_4或NaGly为磷源时的APA,且锌含量越低APA越低,以K_2HPO_4为磷源时锌含量越低APA越高,而锌对以NaGly为磷源时的APA几乎没有影响。磷源与微量元素锌对藻细胞的产毒均产生影响,NaGly有利于藻毒素的产生; LEC不利于藻细胞的产毒,但锌含量越低藻细胞的产毒量越多。综上所述,磷源与微量元素锌共同作用对藻细胞的生长与产毒产生影响,小分子有机磷NaGly与锌的效果显著。     

渤海湾入海溶解无机氮总量控制研究

基于渤海湾近岸海域的实际调查结果,采取生态物理耦合模型,对渤海湾的主要污染物-溶解无机氮(DIN)的基准环境容量和极小剩余海洋环境容量进行了计算。结果表明,渤海湾DIN的极小剩余海洋环境容量在Ⅰ类和Ⅱ类水质标准下均为负值,渤海湾的DIN已经超标。结合实际的海水功能区水质管理目标,应重点控制非点源的排放,加强上游携带入境污染物的处理,从总量上控制DIN入海污染通量,改善渤海湾水质。     

Arsenic residue in residential area after cleanup of pesticide illegal dumping sources in Thanh Hoa province,Central Vietnam

In Vietnam, Nicotex's site is perhaps the most infamous case of illegal disposal of toxic pesticides near residential areas. In 2013, affected villagers discovered illegal burials of around 1,000 tons of expired pesticides in the Nicotex factory. Organic pesticides were detected in illegal burial areas (IBAs) around 60 times greater than acceptable levels, but no attention was paid to contamination of metals, metalloids, and other classes of organic contaminants, which could be co-contaminants in pesticide formulation. This study assessed the contaminants remaining in the IBAs and surrounding residential areas two years after the source removal conducted in 2014. Additionally, a preliminary health risk assessment from residual contaminants was performed. Nine classes of chemicals including parental pesticides, inorganic and organic degradation byproducts, and metals and metalloids, comprising 123 chemicals were quantified in soil, sediment, and water samples from Nicotex and surrounding residential areas. Although concentrations of organic pesticides were below acceptable levels, arsenic contamination in the soil in a Nicotex IBA named NCT5 and Nap village (NV) exceeded the acceptable level. The enrichment factor and log-probability plot indicate that arsenic enrichment at NV is not from natural sources but is associated with arsenic contamination in NCT5. Arsenic may be a co-contaminant in pesticide manufacturing or an arsenical pesticide, such as monosodium methanearsonate. Arsenic found in NV was toxic arsenate for which the preliminary risk assessment yielded an unacceptable excess carcinogenic risk (1 × 10^?4). While all attention was paid to investigate and treat contamination of organic pesticides, it turns out that arsenic is the major existing threat which poses an unacceptable cancer risk in good agreement with the high cancer rate claimed by villagers near Nicotex. This justifies the need for further investigation of the extent of the arsenic contamination and restoration of the contaminated land.     

Trace elements and microbiological parameters in farmed Nile tilapia with emphasis on muscle,water, sediment and feed

Fish may bioaccumulate contaminants from the aquatic environment and extend them to the food chain provoking risks to human health. This study evaluated the microbiological parameters of the pond´s water and trace elements concentrations in samples of water, sediment, feed and muscle of farmed Nile tilapia used for human consumption in southern Brazil. A total of 240 fish were collected from 12 tilapia farms. Sediment, tank water and dry ration used in the animals' diet were collected for analysis. Analysis were performed by Energy Dispersion X-ray Fluorescence (EDXRF), Inductively Coupled Plasma Mass Spectrometer (ICP-MS), Induced Coupled Plasma Optical Emission Spectrometer (ICP-OES), and Atomic Absorption Spectrometer (AAS-VGA). In addition, the microbiological analysis of the water was carried out. The concentrations of Se, I, Fe, Cu and Zn in fish muscle were higher than the recommended by the Brazilian legislation, considering the advised daily intake for adults. The arsenic element had concentrations above the limit stipulated by the present Brazilian legislation, observed in all samples of muscle, sediment and tank water highlighting a possible environmental and fish contamination by the toxic element. Moreover, the arsenic concentration in the water presented a positive correlation (ρ?=?0.33) with arsenic in the muscle, suggesting that tilapia is a good environmental bioindicator, once they properly reflect the levels of arsenic in the water. It is suggested to perform an arsenic speciation for quantification of the inorganic form and accurate assessment of the degree of toxicity in the muscle samples and risks it can bring to human health. Regarding the other potentially toxic elements (Hg, Pb and Cd), and microbiological analysis of water it was verified that the consumption of the fish in question does not raise risks, since the values are within a quality benchmark established by law. The concentration of total and fecal coliforms in pond´s water in the facilities was in agreement with the microbiological indexes required by the legislation of CONAMA class II. Western region presented the lowest concentrations of fecal coliforms when compared to the other regions. There was no significant difference in the microbiological counts of total heterotrophic bacteria, Vibrio spp. and Pseudomonas spp. among the regions.     

安阳市冬季观测期间PM2.5污染特征及来源解析

为探究安阳市冬季PM_(2.5)的污染特征及来源,于2019年11月19—26日在安阳市3个站点(柏庄镇政府、红庙街小学、安阳师专)采集PM_(2.5)样品,并对PM_(2.5)质量浓度和无机元素、水溶性离子进行测定,利用正定矩阵因子模型(PMF)并结合大气污染源排放清单进行源解析。结果表明:观测期间安阳市的PM_(2.5)平均质量浓度为104.09μg/m~3,水溶性离子平均质量浓度为48.9μg/m~3,占PM_(2.5)质量浓度的46.9%。PMF解析结果为二次源58.9%、燃煤源15.7%、机动车排放源9.2%、扬尘源8.6%、工业源2.5%、其他源5.1%。结合2018年安阳市大气污染源排放清单对二次源贡献进行重新分配,得到安阳市PM_(2.5)主要贡献来自燃煤源29.8%、工业源28.5%、机动车源27.1%。后向轨迹聚类结果显示,安阳市气团输送路径主要有远距离传输、城市间输送和本地运输3类,其中本地运输占比最大,其次为正南和东南方向上的城市间输送。     

优势微生物菌群消减有机污泥作用效果分析

本文阐述用优势微生物菌群消解有机污泥的作用效果及原因,指出了优势菌群的构成类别和消解特点。实验结果表明,污泥消解率可达到55%,且过程对出水水质不产生负面影响,水质指标均符合GB18918-2002要求。     

地表水和地下水中的砷、硒同时测定

通过利用双道原子荧光法,同时对地表水和地下水样品中砷、硒进行测定,具有操作更加简单、监测分析速度快、节省试剂等优点。     

柠檬酸对砷污染土壤的萃取优化条件实验研究

论文以新邱矿矸石山排土场土壤为研究对象,以去离子水做空白试验,选取尿素、十二烷基磺酸钠、碳酸氢钠、醋酸、柠檬酸等12种化学试剂做了萃取剂初选试验;并以柠檬酸为萃取剂进行了三因素三水平L9(33)正交实验。实验结果表明:柠檬酸和氢氧化钠可作为砷污染土壤的萃取剂,具有良好的萃取效果。柠檬酸作为砷污染土壤萃取剂的最优化条件是液土比为10mL/g,萃取时间为12h,萃取剂浓度为0.1mol/L。实验结果可为砷污染土壤的治理提供参考。