Respective contributions of point and non-point sources of E. coli and enterococci in a large urbanized watershed (the Seine river, France)

Because the large rivers of the Seine watershed have a low microbiological water quality, the main sources of fecal contamination were investigated in the present study. The inputs of the point (wastewater treatment plants (WWTPs) effluents) and non-point sources (surface runoff and soil leaching) of fecal bacteria were quantified for Escherichia coli and intestinal enteroccoci used as bacterial indicators. In order to assess the contamination through non-point sources, fecal indicators abundance was estimated in samples collected in small streams located in rural areas upstream from all point sources; these small rivers were characterized by the land use of their watershed. Bacterial indicator numbers were also measured in effluents of WWTPs, some using classical treatment (settling followed by activated sludge process) and some using an additional disinfection stage (UV irradiation). These data were used to estimate the respective importance of each type of source at the scale of the whole Seine river watershed taking into account the land use and the population density. It shows the predominant importance of the point sources of fecal indicator bacteria at the scale of the whole watershed. In a scenario in which activated sludge treatment would be complemented with UV in all WWTPs located in this watershed, the non-point sources of fecal indicator bacteria would be dominant.     

Assessment of the Water Quality and Ecosystem Health of the Great Barrier Reef (Australia): Conceptual Models

Run-off containing increased concentrations of sediment, nutrients, and pesticides from land-based anthropogenic activities is a significant influence on water quality and the ecologic conditions of nearshore areas of the Great Barrier Reef World Heritage Area, Australia. The potential and actual impacts of increased pollutant concentrations range from bioaccumulation of contaminants and decreased photosynthetic capacity to major shifts in community structure and health of mangrove, coral reef, and seagrass ecosystems. A detailed conceptual model underpins and illustrates the links between the main anthropogenic pressures or threats (dry-land cattle grazing and intensive sugar cane cropping) and the production of key contaminants or stressors of Great Barrier Reef water quality. The conceptual model also includes longer-term threats to Great Barrier Reef water quality and ecosystem health, such as global climate change, that will potentially confound direct model interrelationships. The model recognises that system-specific attributes, such as monsoonal wind direction, rainfall intensity, and flood plume residence times, will act as system filters to modify the effects of any water-quality system stressor. The model also summarises key ecosystem responses in ecosystem health that can be monitored through indicators at catchment, riverine, and marine scales. Selected indicators include riverine and marine water quality, inshore coral reef and seagrass status, and biota pollutant burdens. These indicators have been adopted as components of a long-term monitoring program to enable assessment of the effectiveness of change in catchment-management practices in improving Great Barrier Reef (and adjacent catchment) water quality under the Queensland and Australian Governments’ Reef Water Quality Protection Plan.     

酸/碱改性香蒲生物炭对水中磷的去除及其机制研究

雨水径流中存在的磷污染问题严重威胁生态环境,而传统的雨水径流处理设施,如雨水花园、渗滤沟等,对磷的去除率较低且成本较高.以湿地中收割的香蒲为原材料,酸改性后制备的生物炭（TH7）的除磷效果非常好,明显优于碱改性生物炭（TOH7）：与原生物炭（T7）相比,酸改性生物炭大大提高了磷的去除效率,可从T7的65%提高至94%,而碱改性生物炭无除磷效果.TH7的表面孔隙发达,比表面积高达434.2m²·g^-1,对磷的吸附符合Freundlich模型和伪二级动力学模型,其吸附属于物理化学吸附,具体的机制为孔隙填充、表面化学沉淀、氢键结合.研究表明,以香蒲为原料制备的改性生物炭是一种效果优越的除磷吸附剂,可应用于植草沟、雨水花园等以填料为主要吸附层的径流处理设施中.     

基于MGWR的黄河流域土壤有机碳密度和影响因素分析

土壤有机碳作为最大陆地碳库,其空间分布特征和影响因素对于全球碳循环过程具有重要影响.基于土壤有机碳密度数据,结合环境因子,使用多尺度地理加权回归（MGWR）模型预测了黄河流域土壤有机碳密度（SOCD）和影响因素.结果表明：①黄河流域0~20 cm和0~100 cm的SOCD范围分别为0~14.82 kg ·m^-2和0~32.39kg ·m^-2,均值分别为3.48 kg ·m^-2和8.07kg ·m^-2,储量则分别为2.76 Pg和6.48 Pg;②各生态系统类型中,0~20 cm的SOCD从大到小依次为：森林>水体与湿地>其他>草地>农田>聚落>荒漠,0~100 cm的SOCD从大到小依次为：水体与湿地>森林>其他>草地>农田>聚落>荒漠,SOCR从大到小皆为：草地>农田>森林>荒漠>水体与湿地>聚落>其他;③黄河流域SOCD的分布主要受常数项、剖面曲率、NDVI和降水的影响,曲率和粉砂对深层的SOCD的分布也具有重要影响;此外,降水、NDVI和常数项（除森林外）是影响各生态系统的主要因素,曲率和粉砂则仅对荒漠和其他生态系统具有重要影响.研究结果得出了黄河流域SOCD的空间分布和影响因素,可为黄河流域碳平衡、土壤质量评价和生态治理恢复与巩固提升提供科学依据.     

HYDROCLIMATIC VARIABILITY IN THE ROCKY MOUNTAINS1

ABSTRACT: The spatial and temporal variability of hydroclimatic elements were investigated in the central and northern Rocky Mountains (Colorado, Idaho, Montana, Utah, and Wyoming) during the 1951–1985 period. The three hydroclimatic elements studied were total water-year (October 1-September 30) streamflow (ST), winter (October 1-March 31) accumulated precipitation (PR), and April 1 snowpack (SN). An analysis of 14 virgin watersheds showed wide spatial djfferences in the temporal variability of SN, PR, and ST, and these were found to be caused largely by basin exposure to moist air flows. The more stable (low variability) basins were those exposed to prevailing northerly to westerly flow, while unstable (high variability) basins were exposed to occasional southwesterly to southeasterly moist flow. Snowpack was the better indicator of ST in 11 of the 14 watersheds, explaining 37 to 87 percent of the ST variance. Analysis of the spatial variability, based on all SN and PR data from across the study area, revealed 11 discrete climatic regions. Both SN and PR exhibited coherent regions of stable and unstable temporal variability. The average variability between stable and unstable regions differed by a factor of two, and the differences were best explained by the exposure of the mountain barrier to moist air flows.     

MINIMIZING THE IMPACT OF URBANIZATION ON LONG TERM RUNOFF1

Increasing concern about the problems caused by urban sprawl has encouraged development and implementation of smart growth approaches to land use management. One of the goals of smart growth is water resources protection, in particular minimizing the runoff impact of urbanization. To investigate the magnitude of the potential benefits of land use planning for water resources protection, possible runoff impacts of historical and projected urbanization were estimated for two watersheds in Indiana and Michigan using a long term hydrological impact analysis model. An optimization component allowed selection of land use change placements that minimize runoff increase. Optimizing land use change placement would have reduced runoff increase by as much as 4.9 percent from 1973 to 1997 in the Indiana study watershed. For nonsprawl and sprawl scenarios in the Michigan watershed for 1978 to 2040, optimizing land use change placement would have reduced runoff increase by 12.3 percent and 20.5 percent, respectively. The work presented here illustrates both an approach to assessing the magnitude of the impact of smart growth and the significant potential scale of smart growth in moderating runoff changes that result from urbanization. The results of this study have significant implications for urban planning.     

柱型水力旋流器对硅切割废砂浆分离性能的研究

为了研究废砂浆中碳化硅粉和硅粉的分离情况,选用混合模型对柱型水力旋流器多相流流场进行数值模拟。模拟结果表明:柱型水力旋流器的分离效率与入口速度、进口浓度等因素有关,并分析出一定条件下当主、次相的入口速度均为1.1m/s时颗粒分离效果较好,分离效率较高,实验检测分离性能较好,为进一步实验研究提供一定的指导。     

三峡库区典型退耕还林模式土壤养分流失控制

选择三峡库区典型退耕还林模式,包括园地(茶园)及林地(板栗)与原有坡耕地对照,观测并分析其土壤养分(氮磷)输出途径及数量情况,以评估实施退耕还林工程对流域土壤养分输出的影响.结果表明:1退耕后土壤养分氮磷年流失量(包括随泥沙和地表径流流失的量)减少;总氮(TN)年输出量从大到小依次为坡耕地(2 444.27 g·hm-2)茶园地(998.70g·hm-2)板栗林地(532.61 g·hm-2);总磷(TP)为坡耕地(1 690.48 g·hm-2)茶园地(488.06 g·hm-2)板栗林地(129.00 g·hm-2);与坡耕地比较,退耕还林模式(园地、林地)总氮、总磷年输出载荷分别减少了68.68%和81.75%.2茶园地、板栗林地与坡耕地相比,土壤养分速效态氮流失量明显减少,硝态氮(NO-3-N)输出总量依次为坡耕地(113.79g·hm-2)茶园地(73.75 g·hm-2)板栗林地(56.06 g·hm-2);铵态氮(NH+4-N)养分输出次序为茶园最大(69.34 g·hm-2),坡耕地次之(52.45 g·hm-2),板栗林地最小(47.23 g·hm-2).3硝态氮、铵态氮主要通过地表径流输出,所占总量比例分别为91.4%和92.2%;总氮和总磷主要通过泥沙输出,所占总量比例分别为86.6%和98.4%.通过退耕还林等措施,该地区地表径流以及土壤侵蚀输出明显减少,土壤养分流失得到有效控制.     

路面径流生态阻控技术研究——以改性麦饭石透水沥青路面为例

为强化透水沥青路面对路面径流中氮、磷的控制效果,采用铁盐联合碱热技术制备了涂层负载改性麦饭石蓄水层集料,并运用场发射扫描电子显微镜(SEM)、能谱分析仪(EDS)和X射线衍射(XRD)等手段对改性后麦饭石集料的表面形态、特征和化学成分进行了表征.同时,通过静态吸附试验对TP的吸附效果及其作用机理进行了对比研究.最后将改性麦饭石作为蓄水层集料应用于透水沥青路面中,通过模拟降雨和周期蓄水试验探究其净化机制.结果表明:相比于天然麦饭石,铁盐联合碱改性麦饭石的表面性状发生了明显变化,最大饱和吸附容量明显提高,对氨氮和磷酸盐的吸附容量分别从1.32 mg·g~(-1)和1.48 mg·g~(-1)提升到12.82 mg·g~(-1)和6.38 mg·g~(-1);降雨全过程中改性蓄水层路面对NH~+_4-N的整体去除效率可提高20%左右,对TP的净化效率至少可提高15%,蓄水阶段较模拟降雨阶段污染物的去除效果显著提高,改性后麦饭石蓄水层24 h后的出水水质均可达III类水标准,强化蓄水层和提高蓄水时间是提高路面径流净化效率的有效措施.因此,本实验中铁盐联合碱热技术制备的改性麦饭石可推荐用于海绵城市生态处理设施透水沥青路面中削减氨氮和总磷的污染负荷.     

京津冀地区高分辨率PM2.5浓度时空变化模拟与分析

为了全覆盖、高分辨率和高精度识别京津冀地区大气PM_2.5质量浓度时空变化,选取多角度大气校正算法遥感反演的1km AOD为主要预测因子,多种气象要素和土地利用要素为辅助预测因子,构建了混合效应模型+地理加权回归模型的两阶段统计模型,并针对京津冀地区PM_2.5污染较严重的特点,模型中引入了AOD²等独特预测因子.通过上述两阶段模型定量预测了研究区2017年1 km²空间分辨率的每日PM_2.5质量浓度.结果表明,模型交叉验证的决定系数R²为0.94,斜率为0.95,均方根预测误差为13.14 μg·m^-3,在前人基础上预测精度进一步提升,可用于PM_2.5浓度时空变化预测与分析.2017年,京津冀地区PM_2.5浓度年均值为44.96 μg·m^-3,年均值范围在0~89.89 μg·m^-3之间.PM_2.5浓度时空变化差异性明显,整体上呈现"平原西南部浓度高、平原东北部浓度中等和山区高原浓度低"的空间分布格局以及"冬季浓度高、夏季浓度低和春秋过渡"的季节变化特点.模型预测结果的高时空分辨率可以支持流行病学研究在较小区域的暴露评估和识别小尺度污染源的时空变化,分析发现在大气污染防治行动计划实施以来,污染较严重的冀中南山麓平原区可能出现了重要污染源的空间变化.模型预测与分析结果可以为京津冀大气污染防治提供科学支撑.