氧化石墨烯的水环境行为及其生物毒性

氧化石墨烯是一类石墨烯衍生物,性质独特,应用广泛,生产量急剧增加,其环境风险日益引起关注.氧化石墨烯具有高亲水性和表面活性,在水中易分散,易随水流发生迁移转化,可能对水环境和水生生物造成不利影响.因此,明确氧化石墨烯的水环境行为及其生态效应,对于正确理解和评估其环境风险,合理规划其使用和回收具有重要意义.目前,该领域的研究涵盖了氧化石墨烯在水环境中的分散/团聚、吸附、还原、降解、沉积等行为,及对微生物、浮游动物、藻类和鱼类等水生生物的毒性表现.本文综述了相关研究成果,分析了当前研究面临的挑战并展望其研究前景.     

Simulation of long-term nutrient removal in a full-scale closed-loop bioreactor for sewage treatment: an example of Bayesian inference

In this study, the performance of nitrogen and phosphorus removal in a full-scale closed-loop bioreactor (oxidation ditch) system was simulated using the ASM2d model. Routine data describing the process for two years were compiled for calibration and validation. To overcome the identifiability problem, the classic Bayesian inference approach was utilized for parameter estimation. The calibrated model could describe the long-term trend of nutrient removal and short-term variations of the process performance, showing that the Bayesian method was a reliable and useful tool for the parameter estimation of the activated sludge models. The anoxic phosphate uptake by polyphosphate accumulating organisms (PAO) contributed 71.2% of the total Poly-P storage, which reveals the dominance of denitrifying phosphorus removal process under the oxygen limiting conditions. It was found that 58.7% of the anoxic Poly-P storage and denitrification by PAO in the reactor was achieved in the aerated compartment, implying that the PAO’s anoxic activity was significantly stimulated by the low dissolved oxygen (DO) level in this compartment due to the oxygen gradient caused by brush aerator.     

沉水植物黑藻腐解过程中营养盐释放过程

为探究沉水植物衰亡过程中营养盐的释放规律,采用黑藻(Hydrilla verticillata Royle)作为研究用沉水植物,在实验室内模拟了黑藻在初春温度下腐解过程中的主要营养盐碳、氮、磷的释放过程.结果表明:黑藻在试验初期迅速腐解,该过程中向水体释放大量碳(81.31%)、氮(81.62%)、磷(85.94%).但随着时间的推移,黑藻向水体释放的磷大部分沉积进入底泥,而氮有部分沉积进入底泥,同时有部分以气体形式移出水体.黑藻腐烂分解产生的厌氧条件以及高TOC供给促进水体反硝化作用加快氮素移出水体.但是较大生物残留量会引起水体缺氧,植物残体分解加剧,导致水质严重恶化,因此需要适时收割水生植物来控制水体残留生物量.     

长江三角洲流域保护水生生物优先控制农药品种筛选

以长江三角洲流域为研究区域,首先明确了以保护水生生物为目标的优先控制农药品种的筛选原则,并以模型预测为基础,根据农药对水生生物的风险性,筛选形成了长江三角洲流域保护水生生物优先控制农药品种名录。名录共包含15种农药有效成分,一方面可为我国地表水农药生态基准的制定提供优先次序,另一方面对于长江三角洲流域地表水体农药污染控制具有重要的指导意义。     

珠江河网水产品中菊酯类农药残留调查及健康风险评价

2012年8月在珠江河网采集水产品样品(13种鱼,4种虾和2种贝),采用超声波提取-气相色谱法对样品中菊酯类农药(PYRs)进行残留检测,并对鱼类PYRs暴露水平进行健康风险评价。结果显示,鱼类肌肉、虾类和贝类中PYRs质量分数分别介于ND~3.05μg·kg-1、0.05~1.13μg·kg-1和0.69~1.20μg·kg-1(ND为未检出,以湿重计),平均值分别为0.90μg·kg-1、0.41μg·kg-1和0.99μg·kg-1。虾类和贝类中PYRs的检出率均很高,除联苯菊酯在虾类体内检出率为75%外,其他菊酯均为100%,鱼类肌肉中氯菊酯检出率最高,达到100%。氯菊酯在鱼类肌肉和贝类中的检出量最高,分别占总菊酯质量分数的52.2%和55.4%,溴氰菊酯在虾类中检出量最高,分别占总菊酯质量分数的33.0%;对居民通过食物摄入的PYRs进行食用暴露风险评估,结果表明,珠江河网水产品中PYRs人体健康危害的年总风险评价介于3.96×10-13~1.21×10-10a-1,水产品的安全消费量为5.54×104kg·d-1,水产品中的PYRs的健康危险风险很小。     

长江流域水生态评价指标初步研究

通过调研20世纪90年代以来国外主流水生态评价项目中采用的生境指标,统计了14个类型生境指标的使用频率,并针对不同的河流类型,筛选出物理形态特征、河岸带状况、生境组成、生境复杂性、人类干扰和水质状况等6个类型的11项评价指标,推荐作为长江流域河流生境评价指标.随后,利用层次分析法对国外水生生物评价指标进行了统计分析,并...     

Restoration of hyper-eutrophic water with a modularized and air adjustable constructed submerged plant bed

A modularized and air adjustable constructed submerged plant bed (CSPB) which can be used to restore the eutrophic water is introduced in this paper. This plant bed helps hydrophyte grow under poor conditions such as frequently changed water depth, impaired water transparency, algae bloom and substantial duckweed in summer, which are not naturally suitable for growing hydrophyte. This pilot study in Waihuan River of Tianjin, China, revealed that reduction of Chemical Oxygen Demand (COD), Total Nitrogen (TN) and Total Phosphorus (TP) by the use of CSPB could be reached 30%–35%, 35%–40%, 30%–40% respectively in the growing season (from March to October) and 5%–10%, 5%–15%, 7%–20% respectively in the winter (from November to February) when the detention time was 6 d. The relationships between the concentration of COD, TN, TP and the detention time fit the first-order kinetic equation well and the coefficients of determination (R²) were all above 0.9. The attenuation coefficients k of the kinetic equation were a function of the water temperature. When the water temperature was quite low or quite high, k was not significantly changed with increasing or decreasing water temperature. While when the temperature was in a moderate range, an increase or decrease of water temperature would lead to a rapid increase or decrease in k.     

太湖悬浮物对水体生态环境的影响及其高光谱反演

利用太湖水质参数数据、水面以下实测光谱数据以及水-气界面辐射传输模型,计算得到了水体漫射衰减系数和水面以上遥感反射比,探讨了悬浮物对水体中营养盐以及水下光照等水体环境因子的影响,在此基础上,利用水面以上遥感反射率建立了悬浮物浓度的定量反演模型.研究结果表明:悬浮物浓度与水体下行漫射衰减系数具有很好的相关性,在可见光波段相关系数达到0.8以上,与真光层深度具有很好的负指数关系;水面以上遥感反射比与悬浮物浓度对数(In(Tss))具有很好的相关性,在500～600nm范围内呈负相关,在620-882nm范围呈正相关,最大负相关出现在522nm附近,最大正相关出现在692nm附近;选用Rra(522nm)、Rra(692nm)以及其比值作为变量建立悬浮物反演模型,得出的单波段线性对数模型能够较好地反演悬浮物浓度.     

Metals contamination in the foraging area of Milky Stork: evidence of anthropogenic inputs in the aquatic environment of Kuala Gula,Malaysia

The rapid decline of the wild Milky Stork population in Malaysia has led to the reintroduction of the captive bred species in Kuala Gula, Perak. The area is known as an important migratory stopover and sanctuary for both visitors and resident birds. Although Kuala Gula and its adjacent areas are regarded as pristine and unpolluted, recent study suggested that accumulation of certain pollutants is occurring in the aquatic environment of the area. Surface sediment samples from five foraging areas considered important to the reintroduced Milky Storks have been analyzed for metals contamination. The results show that elevations of Cu, Zn, and Pb ranging from 9.7 to 57 mg kg^?1, 71 to 120 mg kg^?1, and 28 to 47 mg kg^?1 have occurred, except for Cd (0.9–1.7 mg kg^?1). The accumulation of these metals is site-specific which reflects continuous anthropogenic inputs into the aquatic environment of Kuala Gula. In addition, metal levels in some areas have exceeded the effects range low values, and thus urgent action is needed to ensure good practice and sustainable management of Kuala Gula by responsible parties.     

Bioavailability of copper and cadmium in sediment of nanjing section of Changjiang river to aquatic organisms

Bioavailabilities of metals in sediment to aquatic organisms depend on the strength of metal bonding to particulates. The accumulation tests of Cu and Cd in carp and in snails have been studied in vitro with the solution containing semisynthetic sediment samples in which the contents of various speciation of metal in sediment have been extended. For carp, the accumulation of Cu and Cd is related to the concentration of dissolved metal which in turn is affected by the distributions of speciations in sediment under given environmental conditions. It is another pattern for snails, various speciations of metal in sediment can contribute indirectly to metal accumulation. The contribution ratio, or relative importance of various speciations of metal in sediment can be expressed by multiple linear regression formulas. The contribution of ion‐exchangable speciation and coprecipition with carbonate speciation is 10⁵ times larger than that of residue speciation in sediment.