生活污水不同进水C/N比负荷对垂直潜流式人工湿地排放温室气体的影响

人工湿地处理的生活污水含氮量或者有机物含量很高时,可能会造成人工湿地在处理污水的过程中排放大量温室气体。研究了垂直潜流式人工湿地在人工合成的生活污水不同污染物进水C/N负荷条件下污水处理效果和温室气体(CO2和CH4)的排放量,利用现场测量和碳平衡模型估算分析了可以达到最佳污水净化效果和最少温室气体排放量的污染物进水C/N负荷条件。结果显示,在进水C/N负荷为C/N=6∶1~9∶1时可以得到最佳的污染物去除率。温室气体CH4排放量较CO2排放量可以忽略不计,而在进水C/N负荷为C/N=3∶1~6∶1时可以实现最少的温室气体排放。综上所述,最优的进水C/N负荷确定为C/N=6∶1,此时人工湿地可以得到较高的污染物去除率而排放较少的温室气体。     

Deposition and regional distribution of HCHs and p,p′-DDX in the western and southern Tibetan Plateau: records from a lake sediment core and the surface soils

Tibetan Plateau is the world’s highest plateau, which provides a unique location for the investigation of global fractionation of organochlorine pesticides (OCPs). In this study, deposition and regional distribution of HCHs and p,p′-DDX in the western and southern Tibetan Plateau were investigated by the records from a sediment core of Lake Zige Tangco and 24 surface soils. Concentration of ΣHCHs in the surface soils of the western Tibetan Plateau was much higher than that of the southern part. Maximum fluxes of α-, β-, and δ-HCH in the sediment core were 9.0, 222, and 21 pg cm^?2 year^?1, respectively, which appeared in the mid-1960s. Significant correlations were observed between concentrations of α- and β-HCH in both the surface soils and the sediment core. Concentrations of both α- and β-HCH increased with the inverse of the average annual temperature of these sites. γ-HCH became the dominant isomer of HCHs after the late 1970s, and reached the maximum flux of 160 pg cm^?2 year^?1 in the early 1990s. There were no significant correlations between concentrations of γ-HCH and the other isomers in both the surface soils and the sediment core. The results suggested that there was input of Lindane at scattered sites in this area. In contrast to ΣHCHs, concentration of Σp,p′-DDX in the surface soils of the southern part was much higher than that of the western part. Maximum flux of Σp,p′-DDX was 44 pg cm^?2 year^?1, which appeared in the mid-1960s. Local emission of p,p′-DDT was found at scattered sites. This study provides novel data and knowledge for the OCPs in the western and southern Tibetan Plateau, which will help understand the global fractionation of OCPs in remote alpine regions.     

Alterations in neurobehaviors and inflammation in hippocampus of rats induced by oral administration of microcystin-LR

Microcystin-LR (MC-LR) is a widely studied toxic peptide secreted by certain water blooms of cyanobacteria that exhibit hepatotoxicity and neural toxicity. This study aimed to observe the neurotoxic effects of low-dose MC-LR exposure by oral administration. Male Sprague-Dawley (SD) rats were administered orally every 2 days for 8 weeks with pure water and 0.2, 1.0, and 5.0 μg/kg MC-LR. The Morris water maze test was used to assess the spatial learning and memory capability of rats. The activation of astrocytes and nitric oxide synthase (NOS) was evaluated by immunohistochemistry, and concentrations of nitric oxide (NO) in rat hippocampus were analyzed. Slight liver dysfunction was observed in the 5.0 μg/kg MC-LR-treated rats. Impairment of spatial learning and memory was also observed in the 5.0 μg/kg MC-LR-treated rats. Astrocytes in the hippocampus of the 5.0 μg/kg MC-LR-treated rats showed enhanced activation and cell density; the inflammatory indicators, NOS and NO, increased in accordance with astrocyte activation. This study showed that oral exposure of MC-LR had adverse affects on neurobehaviors, and induced inflammation in memory-related brain regions.     

堆肥污泥重金属在黄土中的淋滤特征

堆肥污泥中所含重金属是污泥堆肥土地利用最大的障碍,实验选用北方贫瘠的黄土作为供试样品,通过室内土柱淋滤实验,对堆肥污泥重金属在黄土中的淋滤特征进行了研究。结果显示,在0～40 cm的浅层淋滤层,各种重金属在黄土中的纵向迁移能力为:Pb>Zn>Ni>Cu,而在50～55 cm的深层淋滤层,Cd在黄土中的迁移能力相对其他4种重金属是比较强的;各种重金属在50～60 cm深层淋滤层中会出现二次富集,出现明显富集层。研究揭示了堆肥污泥重金属在黄土中的迁移特征,为有效控制和消除堆肥污泥土地利用中重金属的污染研究提供了理论依据。     

Heavy metal pollution status in surface sediments of Swan Lake lagoon and Rongcheng Bay in the northern Yellow Sea

The national ‘Shandong Peninsula Blue Economic Zone Development Plan’ compels the further understanding of the distribution and potential risk of metals pollution in the east coast of China, where the rapid economic and urban development have been taken off and metal pollution has become a noticeable problem. Surface sediments collected from the largest swan habitat in Asia, the Swan Lake lagoon and the surrounding coastal area in Rongcheng Bay in northern Yellow Sea, were analyzed for the total metal concentrations and chemical phase partitioning of five heavy metals (Cu, Zn, Pb, Cd, and Cr). Metal contents in the studied region have increased significantly in the past decade. The speciation analyzed by the sequential extraction showed that Zn and Cr were present dominantly in the residual fraction and thus of low bioavailability, while Cd, Pb and Cu were found mostly in the non-residual fraction thus of high potential availability, indicating significant anthropogenic sources. Among the five metals, Cd is the most outstanding pollutant and presents high risk, and half of the surface sediments in the studied region had a 21% probability of toxicity based on the mean Effect Range-Median Quotient. At some stations with comparable total metal contents, remarkably different non-residual fraction portions were determined, pointing out that site-specific risk assessment integrating speciation is crucial for better management practices of coastal sediments.     

The treatment of black-odorous water using tower bipolar electro-flocculation including the removal of phosphorus,turbidity, sulfion,and oxygen enrichment

• An innovative bubble column tower BPE was designed to treat the black-odorous water. • PO₄³⁻, S²⁻ and turbidity were removed, and dissolved oxygen was enriched in the BPE. • An aluminum bipolar electrode gave the best oxygen enrichment and pollutant removal. • Changes of microorganisms confirmed the improvement in water quality achieved. The large amount of municipal wastewater discharged into urban rivers sometimes exceeds the rivers’ self-purification capacity leading to black-odorous polluted water. Electro-flocculation has emerged as a powerful remediation technology. Electro-flocculation in a bubble column tower with a bipolar electrode (BPE) was tested in an attempt to overcome the high resistance and weak gas-floatation observed with a monopolar electrode (MPE) in treating such water. The BPE reactor tested had a Ti/Ta₂O₅-IrO₂ anode and a graphite cathode with an iron or aluminum bipolar electrode suspended between them. It was tested for its ability to reduce turbidity, phosphate and sulphion and to increase the concentration of dissolved oxygen. The inclusion of the bipolar electrode was found to distinctly improved the system’s conductivity. The system’s electro-flocculation and electrical floatation removed turbidity, phosphate and sulphion completely, and the dissolved oxygen level improved from 0.29 to 6.28 mg/L. An aluminum bipolar electrode performed better than an iron one. Changes in the structure of the microbial community confirmed a significant improvement in water quality.     

钻井废液的超临界水氧化处理及动力学分析

在反应温度为500～600℃、压力为25～30 MPa、停留时间为30～600 s的条件下,在连续式反应器中研究了钻井废液的超临界水氧化反应.结果表明:钻井废液的COD去除率可达90.00%以上;在600℃、停留时间为600 s时,钻井废液氧化后,剩余收集液的COD＜120 mg/L,满足《污水综合排放标准》(GB 8978-1996)中的二级标准.用幂函数方程描述了氧化剂过量时钻井废液超临界水氧化的反应动力学规律,反应速率常数与温度的关系符合Arrhenius公式,随停留时间的增加、温度的升高,有机物的去除率显著增加;反应速率常数随压力升高而增加,但反应速率常数的增幅随压力的升高而减小,反应活化体积不是常数.在25 MPa时,反应活化能和频率因子分别为(17 745.430 40±1 114.983 42)kJ/mol和1.152 3×10-4s-1模型计算值与实验值的误差在±15%以内.     

天然Na基膨润土吸附处理高浓度PAM废水的研究

研究了PAM在天然钠基膨润土上的吸附行为,将其应用于含高浓度PAM（100～200 mg/L）的生产废水处理。静态条件下,膨润土的吸附平衡时间为1.5 h,最有效的吸附材料投加量为100 mg/100 mL水样。实验证明,低温度变化范围和弱酸、弱碱条件对PAM的吸附行为不产生显著影响。在最佳吸附动力学条件下,以活性炭做参比,利用实验的结论对化工厂中PAM生产废水进行吸附处理,结果表明,在对PAM废水中对PAM的吸附量分别可达到30.1和22.4 mg/g,膨润土是性价比较高的吸附处理材料。     

武汉城市湖泊表层底泥汞分布、风险评价及影响因素

底泥作为汞重要的"汇"及二次"源"，在湖泊系统汞生物地球化学循环中起到了重要作用。本文以武汉主要城市湖泊为研究对象，探究了表层底泥中总汞（THg）和甲基汞（MeHg）的分布特征、潜在生态风险及主要影响因素。结果表明，武汉15个城市湖泊表层底泥THg平均浓度为152±170 ng/g （24~611 ng/g），与国内其它湖泊系统相比处于较高水平；MeHg浓度为52.0±46.8 pg/g （ND~161.0 pg/g），低于其它湖泊系统。空间分布上，底泥THg浓度呈现由武汉市中心向外逐渐递减的趋势，MeHg含量并未呈现类似THg的分布趋势。潜在生态风险评价（PERI）结果显示，所有采样点位中汞潜在生态风险极高和高风险等级占比均为5.7%，且主要分布在市中心附近，说明武汉市中心附近湖泊底泥汞污染程度较重，而市中心外围湖泊底泥汞生态风险较低。相关性分析结果显示，有机质可能是影响武汉城市湖泊底泥THg分布的重要因素之一，而MeHg主要受控于无机汞的原位甲基化过程。底泥THg浓度-湖泊距市中心距离间显著的负相关关系、THg浓度-湖泊所在区GDP/人均GDP间的显著正相关关系均表明人为活动对武汉城市湖泊汞分布影响明显。     

工业园区和城区VOCs组成及化学活性的空间差异对清远大气臭氧污染分布的影响

工业化与城镇化交替演进使珠三角及其周边地区土地利用类型较为复杂。快速的城市化进程使城市建成区与大量村镇工业园区互相交错。这种变化势必会增加挥发性有机物(VOCs)在组分构成和空间分布上的复杂性,并对臭氧(O₃)污染的时空变化产生影响。为厘清这种排放的空间异质性特征及其对O₃污染分布的影响,分别选取可以代表清远市典型工业园区和城市建成区的站点开展观测研究。结果表明:工业园区和城市建成区VOCs浓度水平和污染特征有较大的空间差异,其中代表村镇工业园区的龙塘站VOCs日均浓度为30.42×10^-9,高于代表城市建成区的技师学院站(17.32×10^-9)。龙塘站二甲苯和甲苯的臭氧生成潜势(OFP)比技师学院站高57.6×10^-9,且该值相当于技师学院站排名前10位物种OFP的总和。气象分析表明:2个站点之间并非彼此的上、下风向,而是共同受到局地气团的影响。源解析结果表明:源排放是造成这种空间异质性的内因,其中交通源对技师学院的贡献更高,而工业相关排放源对龙塘的贡献更高。该研究进一步比较了周边站点O₃时间序列的一致性,并模拟2个站点的O₃生成速率。研究发现O₃在局地范围内变化较小,高VOCs排放的地点对局地O₃有较高的贡献,局地内不同地点的O₃生成过程也存在较大差异。据此,笔者提出O₃污染防控建议:短期内可通过技术手段和观测数据发现O₃污染的重要贡献点,并进行针对性的"散乱污"清理整治和涉VOCs行业综合整治,长期看应科学合理规划城市发展布局和产业布局,预留城市通风廊道,以有效减少O₃污染。