性畸变在三丁基锡污染的生物监测中的应用

该文概述三丁基锡在海洋防附着涂料中的应用及其环境效应，综述因TBT污染而导致某些螺类雌性个体中发育出雄性性征的性畸变现象发生情况，探讨性畸变在TBT污染生物监测中的应用。并以香港地区性畸变的发生为例，论证性畸变在生物监测中的应用，同时比较香港及世界其他地区性畸变的程度。     

渭河干流浅层地下水与地表水中重金属Cd污染特征及风险评价

为了解渭河流域水体重金属污染现状及健康危害风险,沿渭河干流采集浅层地下水和地表水水样,采用单因子指数法和美国环境保护署(USEPA)健康风险评价模型揭示了水体中重金属Cd污染现状和健康风险。结果表明:2018年渭河干流地下水和地表水中Cd浓度分别为426.40~1104.27 ng·L^-1和224.70~1154.12 ng·L^-1;参照《地下水质量标准》(GB/T 14848-2017)和《地表水环境质量标准》(GB 3838-2002)得知,地下水和地表水中Cd浓度均在GB/T 14848—2017和GB 3838-2002Ⅰ~Ⅲ类标准限值内;水体中Cd浓度表现出明显的空间分异性,沿河流流向均表现为逐渐增加的趋势;地下水与地表水中Cd浓度高值区相一致,即集中分布于陕西省兴平市和渭南市临渭区;由水体中Cd浓度单因子指数评价结果可知,渭河干流水体中Cd污染属于清洁水平;沿河流流向,渭河中游和下游水体中Cd浓度单因子污染指数远高于上游;水体中重金属Cd对成人和儿童产生的致癌风险分别为(1.48~2.05)×10^-4和(1.84~2.55)×10^-4,说明水体中Cd对人体可能会产生一定的健康风险。     

The sudestadas: a hydro-meteorological phenomenon that affects river pollution (River Luján,South America)

Abstract

The “sudestadas” are short-term hydro-meteorological phenomena that produce a “hydraulic plug”, preventing the normal drainage of the water courses in the Río de la Plata Estuary. The purpose of this study was to analyse the influence of the sudestadas on the water quality of the Lower River Luján, which discharges into the Río de la Plata Estuary (59°37′W; 34°43′S). Samplings were conducted from November 1998 to July 2001 at six sites on the lower stretch of river. Physical and chemical variables were measured and a nonparametric test was applied to each variable, grouping samples affected and non-affected by sudestadas, which further diminish the water quality of the river. The frequency and intensity of sudestadas are predicted to increase as a consequence of the Earth's warming; thus, this research suggests that the environmental risk produced by the effects of global change, will be greater.     

Nitrate transport in the unsaturated zone: a case study of the riverbank filtration system Karany,Czech Republic

Nitrate transport in the unsaturated zone of a riverbank filtration (RBF) system in Karany, Czech Republic, was studied. Previous study of the system estimated RBF recharge as 60% riverbank filtrate and 40% local groundwater contaminated by nitrates. Nitrate concentrations observed in RBF recently cannot be explained by simple groundwater contamination and a new conception of groundwater recharge is suggested. A two‐component model based on water ¹⁸O data modelled recharge of local groundwater. One component of groundwater recharge is rainfall and irrigation water moving through the unsaturated zone of the Quaternary sediments in piston flow. The second component is groundwater from the Cretaceous deposits with a free water table. Both the components of groundwater recharge have different nitrate concentrations, and resulting contamination of groundwater depends on the participation of water from Quaternary and Cretaceous deposits. Nitrates' origins and their mixing in the subsurface were traced by ¹⁵N data. Nitrate transport from the unsaturated zone is important and time variable source of groundwater contamination. Copyright © 2011 John Wiley & Sons, Ltd.     

TOPCAT‐NP: a minimum information requirement model for simulation of flow and nutrient transport from agricultural systems

Future catchment planning requires a good understanding of the impacts of land use and management, especially with regard to nutrient pollution. A range of readily usable tools, including models, can play a critical role in underpinning robust decision‐making. Modelling tools must articulate our process understanding, make links to a range of catchment characteristics and scales and have the capability to reflect future land‐use management changes. Hence, the model application can play an important part in giving confidence to policy makers that positive outcomes will arise from any proposed land‐use changes. Here, a minimum information requirement (MIR) modelling approach is presented that creates simple, parsimonious models based on more complex physically based models, which makes the model more appropriate to catchment‐scale applications. This paper shows three separate MIR models that represent flow, nitrate losses and phosphorus losses. These models are integrated into a single catchment model (TOPCAT‐NP), which has the advantage that certain model components (such as soil type and flow paths) are shared by all three MIR models. The integrated model can simulate a number of land‐use activities that relate to typical land‐use management practices. The modelling process also gives insight into the seasonal and event nature of nutrient losses exhibited at a range of catchment scales. Three case studies are presented to reflect the range of applicability of the model. The three studies show how different runoff and nutrient loss regimes in different soil/geological and global locations can be simulated using the same model. The first case study models intense agricultural land uses in Denmark (Gjern, 114 km²), the second is an intense agricultural area dominated by high superphosphate applications in Australia (Ellen Brook, 66 km²) and the third is a small research‐scale catchment in the UK (Bollington Hall, 2 km²). Copyright © 2007 John Wiley & Sons, Ltd.     

Agricultural land use and hydrology affect variability of shallow groundwater nitrate concentration in South Florida

South Florida's Miami‐Dade agricultural area is located between two protected natural areas, the Biscayne and Everglades National Parks, subject to the costliest environmental restoration project in history. Agriculture, an important economic activity in the region, competes for land and water resources with the restoration efforts and Miami's urban sprawl. The objective of this study, understanding water quality interactions between agricultural land use and the shallow regional aquifer, is critical to the reduction of agriculture's potentially negative impacts. A study was conducted in a 4‐ha square field containing 0·9 ha of corn surrounded by fallow land. The crop rows were oriented NW–SE along the dominant groundwater flow in the area. A network of 18 monitoring wells was distributed across the field. Shallow groundwater nitrate–nitrogen concentration [N‐NO₃^?] was analyzed on samples collected from the wells biweekly for 3 years. Detailed hydrological (water table elevation [WTE] at each well, groundwater flow direction [GwFD], rainfall) and crop (irrigation, fertilization, calendar) data were also recorded in situ. Flow direction is locally affected by seasonal regional drainage through canal management exercised by the local water authority. The data set was analyzed by dynamic factor analysis (DFA), a specialized time series statistical technique only recently applied in hydrology. In a first step, the observed nitrate variation was successfully described by five common trends representing the unexplained variability. By including the measured hydrological series as explanatory variables the trends were reduced to only three. The analysis yields a quantification of the effects of hydrological factors over local groundwater nitrate concentration. Furthermore, a spatial structure across the field, matching land use, was found in the five remaining common trends whereby the groundwater [N‐NO₃^?] in wells within the corn rows could be generally separated from those in fallow land NW and SE of the crop strip. Fertilization, masked by soil/water/plant‐delayed processes, had no discernible effect on groundwater nitrate levels. Copyright © 2006 John Wiley & Sons, Ltd.     

Source of and potential bio-indicator for the heavy metal pollution in Ny-(A)lesund, Arctic

Three kinds of tundra plant samples including Dicranum angnstum(a type of boreal bryophyte) , PuccineUia phryganodes (a type of fringy p/ant),Salix polaris (a type of vascular plant) and surface soil were samples in 200 at Ny-Alesund of the Arctic.The levels of eight heavy metal elements (Hg, Pb, Cd, Cu, Zn, Ni, Fe and Mn) and three metal-like dements (As, Se, Sr) in the plant and soil samples of the areas within previous coal mining activities are significantly higher than those of other areas.The relative accumulation of these elements in these tundra plant samples is consistent with the one in the soft samples, especially in the areas affected by previous coal-mining activities.Thus, the pollution is apparently from local coal mining activity.Dicranum angustum has the highest concentrations among those elements, and it can be a good bio-indicator for heavy metal pollution in Ny(A)lesund.Though Ny(A)lesund is less polluted by heavy metal than nearby Northern European human living areas, but much more than the tundras of the Alaska, Greenland and the Antarctic.     

Sensitivity of nitrate concentration-discharge patterns to soil nitrate distribution and drainage properties in the vertical dimension

We propose a conceptual model that examines the ‘variable source area’ (VSA) and ‘nitrate flushing’ hypothesis in the vertical direction, and use this approach to explain nitrate concentration–discharge relationships in a semi-arid watershed. We use an eco-hydrology simulation model (RHESSys) to show that small changes in the vertical distribution of nitrate mass and their interaction with soil hydraulic conductivity can result in abrupt changes in the nitrate concentration–discharge relationship. We show that the estimated concentration–discharge relationship is sensitive to the parameters governing soil vertical nitrate distribution and soil hydraulic conductivity, at both patch scale and watershed scale, where lateral redistribution of water and nitrate is also accounted for. Given heterogeneity in nitrogen inputs, uptake processes, soil drainage and storage processes, substantial variation in parameters that describe rate of changes in vertical distribution of soil nitrate and hydraulic properties is likely both within and between watersheds. Thus, we argue that vertical ‘variable source area’ processes may be as important as lateral VSA in determining concentration discharge relationships.     

洛美沙星和诺氟沙星对水中生物反硝化过程的影响模拟试验

近年来水环境中硝酸盐污染与抗生素污染的现象引起了人们的广泛关注,但目前复合抗生素污染对反硝化过程产生的影响并不明确。本研究以水环境中检出率较高的诺氟沙星和洛美沙星为代表进行模拟实验,探究ng级的两种抗生素复合对反硝化过程的影响。硝氮和亚硝氮的降解情况表明,实验浓度条件下,洛美沙星、诺氟沙星单用与二者联用对水环境中的反硝化过程存在不同的抑制作用。洛美沙星单用前期轻微促进反硝化,后期表现抑制作用,而诺氟沙星单用始终表现出抑制作用;洛美沙星和诺氟沙星联用抑制作用小于诺氟沙星单用,联用表现为拮抗作用。各体系的抑制作用大小为诺氟沙星>诺氟沙星+洛美沙星>洛美沙星。该模拟试验条件虽与实际条件有所差异,但在一定程度上表明抗生素联用表现出拮抗作用与反硝化体系内微生物数量、活性,反硝化酶活性,反硝化菌优势物种Achromobacter xylosoxidans、Acinetobacter baumannii、Pseudomonas sp.KY及功能基因nosZ和aac的丰度的变化有关。抗生素加入反硝化体系后会产生持续的影响,随反应时间的增加,反硝化菌逐渐适应有低浓度抗生素存在的环境,喹诺酮类抗生素耐药基因数量增加,微生物的耐药性增强,反硝化菌在数量和活性、反硝化酶活性及微生物群落层面均有回升趋势。