Solid partitioning and solid-liquid distribution of Po and Pb in marine anoxic sediments: roads of Cherbourg at the northwestern France

A sequential extraction protocol has been used to determine the solid-phase partition of ²¹⁰Po and ²¹⁰Pb in anoxic marine sediment from the roads of Cherbourg (France) in the central English Channel. Measurements were also obtained in pore waters, in which ²¹⁰Po activities range between 1 and 20 mBq L⁻¹ and ²¹⁰Pb activities between 2.4 and 3.8 mBq L⁻¹, with highest activities in the topmost layer. These activities are higher than in seawater, suggesting that sediment act as a source of both ²¹⁰Po and ²¹⁰Pb for overlying water. The ²¹⁰Po profile in the pore waters is apparently correlated with those obtained for Fe, Mn and SO₄²⁻, suggesting an influence of early diagenetic processes on the ²¹⁰Po solid-liquid distribution. In the sediment, ²¹⁰Po is predominantly bound to organic matter or chromium reducible sulphides, and residuals (clay minerals and refractory oxides). Our results indicate that ²¹⁰Po is not significantly bound to AVS, i.e. acid volatile sulphides: bioturbation could play a role by the early redistribution of ²¹⁰Po bound to acid volatile sulphides in the sediment. ²¹⁰Po, ²¹⁰Pb and Pb exhibit differences in terms of distribution, probably due to a different mode of penetration in the sediment. This work provides information on solid and liquid distribution of ²¹⁰Po and ²¹⁰Pb in marine sediment. These data are very scarce in the litterature.     

Water Quality in the Near Coastal Waters of the Gulf of Mexico Affected by Hurricane Katrina: Before and After the Storm

Water quality was assessed following Hurricane Katrina in the affected waters of Alabama, Mississippi, and Louisiana. Post-landfall water quality was compared to pre-hurricane conditions using indicators assessed by EPA’s National Coastal Assessment program and additional indicators of contaminants in water and pathogens. Water quality data collected after Hurricane Katrina suggest that the coastal waters affected by the storm exhibited higher salinity and concentrations of chlorophyll a, dissolved inorganic phosphorus, and total suspended solids following the storm compared to the previous 5-year averages. Higher bottom dissolved oxygen concentrations and light attenuation were also observed. Contaminant concentrations measured in the water column were very low or undetectable, as were the presence of pathogens. Overall water quality did not significantly differ from water quality assessed in the five years preceding the storm. Statistical analyses indicate that use of a probabilistic survey design is appropriate for making pre-storm and post storm comparisons for water quality condition on an areal basis. The information in this article has been funded wholly (or in part) by the U.S. Environmental Protection Agency. It has been subjected to review by the National Health and Environmental Effects Research Laboratory and approved for publication. Approval does not signify that the contents reflect the views of the Agency, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. This is contribution number 1280 from the Gulf Ecology Division.     

An Ecological and Economic Assessment Methodology for Coastal Ecosystem Management

An adaptation of the Drivers-Pressure-State-Impact-Response methodology is presented in this work. The differential DPSIR (ΔDPSIR) was developed to evaluate impacts on the coastal environment and as a tool for integrated ecosystem management. The aim of the ΔDPSIR is to provide scientifically-based information required by managers and decision-makers to evaluate previously adopted policies, as well as future response scenarios. The innovation of the present approach is to provide an explicit link between ecological and economic information related to the use and management of a coastal ecosystem within a specific timeframe. The application of ΔDPSIR is illustrated through an analysis of developments in a Southwest European coastal lagoon between 1985 and 1995. The value of economic activities dependent on the lagoon suffered a significant reduction (ca. −60%) over that period, mainly due to a decrease in bivalve production. During that decade the pressures from the catchment area were managed (ca. 176 million Euros), mainly through the building of waste water treatment plants. Notwithstanding this, the ecosystem state worsened with respect to abnormal clam mortalities due to a parasite infection and to benthic eutrophication symptoms in specific problematic areas. The negative economic impacts during the decade were estimated between −565 and −315 million Euros, of which 9–49% represent the cost of environmental externalities. Evaluation of these past events indicates that future management actions should focus on reducing the limitation on local clam seeds, which should result in positive impacts to both the local socio-economy and biodiversity.     

国内外滨海地区先进环保经验对江苏沿海开发的启示

调研了国内外滨海地区环保管理的经验,结合江苏沿海地区环境的特点,对江苏沿海开发中的环保管理提出了建议和展望。     

Bankfull Regional Curves for North and Northwest Florida Streams1

Abstract: Regional curves, which relate bankfull channel dimensions and discharge to watershed drainage area, are developed to aid in identifying the bankfull stage in ungaged watersheds, and estimating the bankfull discharge and dimensions for river studies and natural channel design applications. This study assessed 26 stable stream reaches in two hydro‐physiographic regions of the Florida Coastal Plain: the Northwest Florida Coastal Plain (NWFCP) and the North Florida Coastal Plain (NFCP). Data from stream reaches in Georgia and Alabama were also used to develop the Florida regional curves, since they are located in the same hydro‐physiographic region. Reaches were selected based on the presence of U.S. Geological Survey gage stations and indicators of limited watershed development (e.g., <10% impervious surface). Analyses were conducted to determine bankfull channel dimensions, bankfull discharge, average channel slope, and Rosgen stream classification. Based on these data, significant relationships were found between bankfull cross‐sectional area, width, mean depth, and discharge as a function of drainage area for both regions. Data from this study suggested that bankfull discharges and channel dimensions were larger from NWFCP streams than from Coastal Plain streams in North Carolina and Maryland. Bankfull discharges were similar between NFCP and Georgia coastal plain streams; therefore, the data were combined into one regional curve. In addition, the data were stratified by Rosgen stream type. This stratification strengthened the relationships of bankfull width and mean depth as a function of drainage area.     

Assessing the steady-state [·NO<Subscript>2</Subscript>] in environmental samples

Based on available literature data of [NO₂ ⁻], steady-state [·OH], and ·OH generation rate upon nitrate photolysis in environmental aqueous samples under sunlight, the steady-state [·NO₂], could be calculated. Interestingly, one to two orders of magnitude more ·NO₂ would be formed in photochemical processes in atmospheric water droplets compared to transfer from the gas phase. The relative importance of nitrite oxidation compared to nitrate photolysis as an ·NO₂ source would be higher in atmospheric than in surface waters. The calculated levels of ·NO₂ could lead to substantial transformation of phenol into nitrophenols in both atmospheric and surface waters.     

Comparative study of different advective schemes: Application to the MECCA model

A 3-D version of the MECCA model (Model of Estuarine and Coastal Circulation Assessment) is used to simulate the dynamics of the Eastern part of the English Channel. This area is characterized by a strong tidal turbulent regime and a frontal zone identified near the French coast by a low-salinity band. The model uses the upwind scheme to approximate the advective terms. Results show that the model overestimates the band width of the frontal zone and that this anomaly is definitely caused by the numerical diffusion introduced by the so-called upwind scheme (first-order approximation). In this paper, we study the flux-limiter schemes as an alternative to the upwind method in order to reduce this non-physical diffusion. To illustrate the improvements provided by this type of schemes, a comparison in 2-D schematic cases is made between the upwind and centered scheme with more recent higher-order schemes combined with limiter namely Minmod, Superbee, Van Leer and Monotonized Centered (MC) (called also MUSCL scheme). Respecting the CFL condition, our numerical simulations show that the flux-limiter schemes reduce the numerical diffusion and eliminate the oscillations caused by the non-limited higher-order schemes. For the schematic and realistic cases, the Superbee limiter is a good compromise between shape preservation and computational cost.     

基于MODIS的烟台近海水体叶绿素浓度分布

利用实测光谱数据及水体叶绿素浓度数据建立了基于MODIS数据的叶绿素反演模型,并利用MODIS L1B数据对研究区的叶绿素浓度进行了反演。通过分析烟台近海水体叶绿素浓度分布得出,烟台近海水体叶绿素浓度由沿岸向海延伸,叶绿素的浓度逐渐增加;通过不同月份的叶绿素浓度分布状况发现,夏季水体叶绿素浓度含量最高,冬季最低。     

近岸海域水质自动监测质量保证和质量控制

根据实际工作经验,阐述了近岸海域水质自动监测系统运行过程中的质量保证与质量控制措施,包括建立规章制度、实验室条件、设备维护和校准、数据检查和审核、记录等方面的要求,通过实例介绍了设备维护和校准周期的确定、设备维护效果的影响和数据有效性的判别等,为近岸海域连续自动监测系统的有效管理提供依据。     

江苏某县乡镇饮用水中挥发性有机物的检测及其风险评价

在江苏某癌症高发县5个乡镇10个村进行布点取样,采集深层地下水与浅层地下水共计20个水样。采用吹扫捕集与气相色谱-质谱联用方法测定水样中14种挥发性有机物(VOCs),检出二氯甲烷、1,3-二氯丙烷、三氯甲烷、苯和四氯化碳5种VOCs,其质量浓度分别为0.14～1.71、ND～50.98、0.29～90.02、0.09～2.35、0.18～3.45μg/L。2个水样中的三氯甲烷和6个水样中四氯化碳超过《生活饮用水卫生标准》(GB 5749—2006)规定的限值。采用优化的美国环保局风险评价模型进行人体健康风险评价,其非致癌风险指数为0.000 7～0.072,致癌风险水平1.70×10-7～2.03×10-5,70%水样的致癌风险水平超过10-6水质监控值,2个浅层地下水的致癌风险水平较高。四氯化碳和三氯甲烷对非致癌风险指数和致癌风险水平贡献较大。