重金属复合污染场地对花背蟾蜍雄性性腺的毒性作用

以花背蟾蜍为研究对象,以包头市某尾矿库南侧受污染的水域湿地和相对无污染的小白河黄河湿地保护区为研究样地。对比分析雄性花背蟾蜍形态学指标、精巢脏器系数、精子动态参数、精子畸形率、性激素、红细胞微核率和DNA损伤等相关指标,研究重金属复合污染场地对花背蟾蜍雄性性腺的毒性效应。结果显示:与小白河湿地相比,尾矿库湿地花背蟾蜍条件因子和精巢脏器系数显著高于小白河湿地(P<0.01)。尾矿库花背蟾蜍精子的鞭打频率显著升高,而精子活力显著降低(P<0.05),精子畸形率、红细胞微核率和DNA损伤均显著高于小白河湿地(P<0.05)。结果表明:尾矿库复合污染通过降低精子质量,增加红细胞微核率和DNA损伤对花背蟾蜍的雄性性腺造成毒理学影响,花背蟾蜍通过升高条件因子和精巢脏器系数来缓解复合污染的毒性胁迫。该成果对重金属复合污染场地两栖类动物种群保护以及生态平衡维护有着积极作用。     

浙江省生态环境保护"十三五"规划中期评估与展望

《浙江省生态环境保护"十三五"规划》在改善全省生态环境质量方面发挥着重要的宏观引领作用。为查找规划实施薄弱环节、发现问题、提出建议,本研究采取定量评估与定性结合的方式,开展规划中期评估研究。结论表明:该规划的约束性指标和预期性指标均完成较好,"三大战役"进展明显,制度改革不断突破,"三大工程"扎实推进。针对管理制度、环境质量、基础能力等六方面的主要问题,提出了严格调度考核、打赢蓝天保卫战、实施碧水行动等八项对策建议。     

Comparative study of carbonic anhydrase activity in waters among different geological eco-environments of Yangtze River basin and its ecological significance

This study provides the presence of carbonic anhydrase(CA) activity in waters of the Yangtze River basin, China, as well as the correlation of CA activity with HCO-3 concentration and CO_2 sink flux. Different degrees of CA activity could be detected in almost all of the water samples from different geological eco-environments in all four seasons. The CA activity of water samples from karst areas was significantly higher than from non-karst areas(PP3-concentration(r = 0.672, P2 sink flux(r = 0.602, P = 0.076) in karst areas. This suggests that CA in waters might have a promoting effect on carbon sinks for atmospheric CO_2 in karst river basins. In conditions of similar geological type, higher CA activity was generally detected in water samples taken from areas that exhibited better eco-environments, implying that the CA activity index of waters could be used as an indicator for monitoring ecological environments and protection of river basins. These findings suggest that the role of CA in waters in the karst carbon sink potential of river basins is worthy of further in-depth studies.     

Effects of turbulence on carbon emission in shallow lakes

Turbulent mixing is enhanced in shallow lakes. As a result, exchanges across the air–water and sediment–water interfaces are increased, causing these systems to be large sources of greenhouse gases. This study investigated the effects of turbulence on carbon dioxide(CO_2)and methane(CH_4) emissions in shallow lakes using simulated mesocosm experiments.Results demonstrated that turbulence increased CO_2 emissions, while simultaneously decreasing CH_4 emissions by altering microbial processes. Under turbulent conditions, a greater fraction of organic carbon was recycled as CO_2 instead of CH_4, potentially reducing the net global warming effect because of the lower global warming potential of CO_2 relative to CH_4. The CH_4/CO_2 flux ratio was approximately 0.006 under turbulent conditions, but reached 0.078 in the control. The real-time quantitative PCR analysis indicated that methanogen abundance decreased and methanotroph abundance increased under turbulent conditions, inhibiting CH_4 production and favoring the oxidation of CH_4 to CO2.These findings suggest that turbulence may play an important role in the global carbon cycle by limiting CH4 emissions, thereby reducing the net global warming effect of shallow lakes.     

Temperature effect on photolysis decomposing of perfluorooctanoic acid

Perfluorooctanoic acid(PFOA)is recalcitrant to degrade and mineralize.Here,the effect of temperature on the photolytic decomposition of PFOA was investigated.The decomposition of PFOA was enhanced from 34% to 99% in 60 min of exposure when the temperature was increased from 25 to 85°C under UV light(201–600 nm).The limited degree of decomposition at 25°C was due to low quantum yield,which was increased by a factor of 12 at 85°C.Under the imposed conditions,the defluorination ratio increased from 8% at 25°C to 50% at85°C in 60 min.Production of perfluorinated carboxylic acids(PFCAs,C7–C5),PFCAs(C4–C3)and TFA(trifluoroacetic acid,C2)accelerated and attained a maximum within 30 to 90 min at 85°C.However,these reactions did not occur at 25°C despite extended irradiation to180 min.PFOA was decomposed in a step-wise process by surrendering one CF2unit.In each cyclical process,increased temperature enhanced the quantum yields of irradiation and reactions between water molecules and intermediates radicals.The energy consumption for removing eachμmol of PFOA was reduced from 82.5 k J at 25°C to 10.9 k J at 85°C using photolysis.Photolysis coupled with heat achieved high rates of PFOA degradation and defluorination.     

Ca and OH release of ceramsites containing anorthite and gehlenite prepared from waste lime mud

Lime mud is a kind of solid waste in the papermaking industry, which has been a source of serious environmental pollution. Ceramsites containing anorthite and gehlenite were prepared from lime mud and fly ash through the solid state reaction method at 1050°C. The objective of this study was to explore the efficiency of Ca^2 + and OH⁻ release and assess the phosphorus and copper ion removal performance of the ceramsites via batch experiments, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that Ca^2 + and OH⁻ were released from the ceramsites due to the dissolution of anorthite, gehlenite and available lime. It is also concluded that gehlenite had stronger capacity for Ca^2 + and OH⁻ release compared with anorthite. The Ca^2 + release could be fit well by the Avrami kinetic model. Increases of porosity, dosage and temperature were associated with increases in the concentrations of Ca^2 + and OH⁻ released. Under different conditions, the ceramsites could maintain aqueous solutions in alkaline conditions (pH = 9.3–10.9) and the release of Ca^2 + was not affected. The removal rates of phosphorus and copper ions were as high as 96.88% and 96.81%, respectively. The final pH values of both phosphorus and copper ions solutions changed slightly. The reuse of lime mud in the form of ceramsites is an effective strategy.     

Preparation of MgCr<Subscript>2</Subscript>O<Subscript>4</Subscript> from waste tannery solution and effect of sulfate,chloride, and calcium on leachability of chromium

This paper presents a study regarding the preparation of MgCr₂O₄ from waste tannery solution, and chromium leaching behavior is also investigated with varying amounts of sulfate, chloride and calcium. The phase transformation, crystallinity index and crystallite diameter were characterized using XRD, FT-IR and thermal analysis. A well-crystallized MgCr₂O₄ was successfully prepared at 1400 °C. The sintering temperature had a major impact on the formation of MgCr₂O₄ compared with sintering time. The MgCr₂O₄ phase was observed initially at 400 °C and its crystallite diameter increased with increasing temperature. The concentration of total chromium leached and Cr(VI) decreased gradually with increasing temperature. The considerable amount of Cr(VI) was found in the leachate at 300–500 °C caused by Cr(VI) intermediary products. Sulfate and chlorine could impact the transformation efficiency of chromium adversely, and chlorine has a more significant effect than sulfate. The presence of calcium disturbed the formation of MgCr₂O₄ and new chromium species (CaCrO₄) appeared, which resulted in a sharp increase in the concentration of leached Cr(VI). Incorporating Cr(III) into the MgCr₂O₄ spinel for reusable products reduced its mobility significantly. This was demonstrated to be a promising strategy for the disposal of chromium containing waste resource.     

Preparation, characterization and performance of poly(m-phenylene isophthalamide)/organically modified montmorillonite nanocomposite membranes in removal of perfluorooctane sulfonate

Nanocomposite membranes containing poly(m-phenylene isophthalamide) (PMIA) and organically modified montmorillonite (OMMT) were prepared by a combination of solution dispersion and wet-phase inversion methods, and the effects of OMMT addition on the properties and performance of fabricated nanofiltration membranes were investigated. The membranes were characterized by contact angle measurements, scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis, and zeta potential. The performance of the membranes was elucidated by the removal of perfluorooctane sulfonate (PFOS) at neutral pH. Increasing OMMT concentration improved the thermal stability and hydrophilicity of the membranes. The permeation and rejection of PFOS were significantly improved. The performance of fabricated nanofiltration membranes in removal of PFOS varied depending on the solute and membrane properties as well as solution conditions. Finally, a comparison between fabricated membranes and a commercial NF membrane (ESNA1-K1, Hydecanme) proved that the OMMT addition is a convenient procedure for producing nanocomposite membranes with superior properties and performance.