首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
The discharge of nutrients is investigated in relation to their sources and effects in two case studies. The reduction of 47% in the phosphorus load from Denmark to marine areas between 1989 and 1993 has resulted in significantly lower phosphorus concentrations in most Danish coastal waters, and tendency to decrease can be seen in the Belt Sea and Kattegat as well. No general changes in nitrogen concentrations have been observed. This is due to the fact that more than 80% of the nitrogen load in Danish waters originate from diffuse agricultural sources.In the Pomeranian Bight strong nutrient gradients are generated by the mixing of Odra river water and coastal water. The spreading of the river plume could be exactly observed especially in winter, when biological activity is low. In general, different types of distribution, transport and modification patterns can be described.The annual input of nutrients from the catchment area to the Baltic Sea was estimated to be around 1000 kt N and 46 kt P. As a result, winter concentrations of phosphate and nitrate are characterized by positive overall trends in the surface layer in all subregions of the Baltic Proper for the period 1969 to 1993. These trends stem mainly from the strong increase in the 1970ies and early 1980ies. Thereafter, the concentrations of both nutrients fluctuate strongly around a high level. The drastic decrease in fertilizer consumption since the late 1980ies mainly caused by the great economic changes in the countries of the former East Bloc is not yet significantly reflected in decreasing winter concentrations, but first signs already have been found in the decrease in averaged phosphate concentrations in winter, especially in the Arkona and Bornholm Seas.  相似文献   

2.
The flood in the Odra river in 1997 has led to considerable additional pollution of the Stettin Lagoon and the Baltic Sea with contaminated suspended solids. For some priority substances, the pollutant entries via suspended solids during the flood period are estimated to be approximately 1/3 of the usual annual load. Among these priority pollutants there are total organic carbon (TOC), nitrogen, and the heavy metals Cu, Pb and Zn. For the concentrations of the priority pollutants in suspended solids accumulation factors from 2 to 4 in the comparison with normal conditions were observed. On the basis of the analysis of sediments sampled after the flood, main sources of the pollutants should be evaluated. As reference area with an industrial background as well as a typical pollutant pattern the region around Glogow/Legnica is proposed.  相似文献   

3.
The discharge of organic matter, nutrients, and heavy metals from the river Odra into the Baltic Sea is compared with the combined discharge of the same substances from other Polish rivers into the Baltic during 1988–1997. The impact of the summer flood of 1997 is also discussed. The discharges of organic matter, nitrogen and phosphorus compounds were closely correlated with the flow rate. The annual loads of these nutrients measured in 1988 and 1996 under similar flow conditions decreased by 15 to 40% in these rivers as a result of the reduction of point sources. A steady decrease in the heavy metal load, independent of weather conditions, has been recorded during the past decade. Zinc decreased by up to 85% in the Odra and 99% in the Wisła. Although the water outflow from the Odra was half that of the Wisła, it transported a proportionally higher load of chemical compounds. Despite the differences in flow rates, the contribution of both rivers to the total riverine phosphorus discharge was approximately the same. The total water outflow during the flood (from 1 July to 28 August 1997) increased by 65% near the mouth of the Odra in comparison to 1996. The phosphate discharge increased by 34%, that of nitrite nitrogen by 88%  相似文献   

4.
Rona Vink  Horst Behrendt 《水文研究》2002,16(16):3227-3244
Pollutant transport and management in the Rhine and Elbe basins is still of international concern, since certain target levels set by the international committees for protection of both rivers have not been reached. The analysis of the chain of emissions of point and diffuse sources to river loads will provide policy makers with a tool for effective management of river basins. The analysis of large river basins such as the Elbe and Rhine requires information on the spatial and temporal characteristics of both emissions and physical information of the entire river basin. In this paper, an analysis has been made of heavy metal emissions from various point and diffuse sources in the Rhine and Elbe drainage areas. Different point and diffuse pathways are considered in the model, such as inputs from industry, wastewater treatment plants, urban areas, erosion, groundwater, atmospheric deposition, tile drainage, and runoff. In most cases the measured heavy metal loads at monitoring stations are lower than the sum of the heavy metal emissions. This behaviour in large river systems can largely be explained by retention processes (e.g. sedimentation) and is dependent on the specific runoff of a catchment. Independent of the method used to estimate emissions, the source apportionment analysis of observed loads was used to determine the share of point and diffuse sources in the heavy metal load at a monitoring station by establishing a discharge dependency. The results from both the emission analysis and the source apportionment analysis of observed loads were compared and gave similar results. Between 51% (for Hg) and 74% (for Pb) of the total transport in the Elbe basin is supplied by inputs from diffuse sources. In the Rhine basin diffuse source inputs dominate the total transport and deliver more than 70% of the total transport. The diffuse hydrological pathways with the highest share are erosion and urban areas. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

5.
The retention of particulate matter of the Odra River in flooded areas was estimated by determining suspended particulate matter (SPM) elimination and particle-bound nutrient retention in a polder area of the Lower Odra Valley national park. Water and suspended matter samples collected before, during, and after the 1997 summer flood at the inlet and the outlet of the investigated polder (Polder A/B close to Schwedt) offer the opportunity to balance the matter retention inside the floodplain. The maximum level of retained SPM (more than 80%) was calculated for the record flood of summer 1997, while in ordinary winter floods retention differs between 33% and 70%. Basic properties of the flowing particles like settling velocity, density, loss on ignition etc. change on their way through the polder area. In the investigated Polder A/B a retention of at least 50% of particle-bound phosphorus which was independent of the incoming suspended matter load from the Odra River was observed. The retention of particle-bound nitrogen and carbon varied seasonally to different extents. The presented balance demonstrates that particle-bound nutrient retention in polders is an important factor in the self-purification process of the river system. Some additional effort was done to study changes of plankton composition: during a joint field experiment in spring 1998, the authors determined biological parameters (abundance and biomass of phytoplankton and zooplankton) of water samples at polder inflow and outflow points.  相似文献   

6.
This paper presents results of a study on the concentration of adsorbable organic halogens (AOX) in water samples of the Oder River and its tributaries collected from 1998 to 2002. The Vistula River water for AOX was analysed in the period 2001–2002. The investigated waters of the Vistula near the mouth (Kiezmark) were more contaminated with AOX than the Oder near the mouth (Widuchowa, Krajnik Dolny). In general, AOX levels in the Polish rivers are comparable to the values found in the European rivers, e.g. the Rhine and the Ton. The research has shown that AOX were correlated with pH, total suspended solids, and the riverine flow. No relation between dissolved oxygen and redox potential and AOX was found out. During the flood period AOX, inorganic halogens (TIX), and mineral substances (sulfates) were analysed.  相似文献   

7.
The water quality along the River Kennet, in the Thames basin of southern England, was examined in terms of the influence of point- and diffuse-nutrient inputs. The river is supplied mainly from a Cretaceous Chalk aquifer and hence the waters are of a calcium bicarbonate type. The nitrate largely comes from agricultural sources, with concentrations decreasing downstream due to plant uptake and probable denitrification. In contrast, soluble reactive phosphorus (SRP) is largely associated with sewage inputs and concentrations increase downstream in line with effluents from major towns such as Newbury and Reading. Adjacent to the river in the lower half of the catchment is the Kennet and Avon Canal and the two are in places hydrologically connected. The canal inputs may influence calcium carbonate (calcite) precipitation and increase suspended sediment and particulate phosphorus concentrations in the river. Monitoring upstream and downstream of Marlborough sewage treatment works (STW) showed that SRP concentrations in the effluent were highly variable due to variable efficiency of P stripping and still sufficiently concentrated to dominate downstream river SRP with potential impacts on stream ecology. Biological recovery in this river following P stripping at STWs is complex and controlling those spikes in SRP that are above a threshold of 100 μg l−1 may be a critical requirement. More stringent effluent targets than are currently recommended may be needed (less than 800 μg RP l−1) to achieve good ecological status in this river depending on SRP concentrations upstream.  相似文献   

8.
Excessive inputs of phosphorus and nitrogen are the main reasons of eutrophication of inland waters and coastal areas. Large efforts have been made to control phosphorus, but the measures to reduce nitrogen emissions failed at least partly. While it was possible to reduce nitrogen emissions from industry and municipal wastewater treatment plants, diffuse sources are showing only very minor decline. Examples of limnetic, marine and coastal systems are given to review the current knowledge about nitrogen transformation and the effects of nitrate in the environment. When N is the limiting nutrient in a particular water body, this does not necessarily mean that phytoplankton is controllable by NO3– removal. In systems with problems due to a high redox‐sensitive internal phosphorus load and under certain constraints, nitrate may be used as an ecotechnological measure to prevent anaerobic phosphorus release from sediments. Model simulations are used to demonstrate this. A schematic model of redox‐mediated temporal phosphorus storage in riverine lake sediments with short retention time is proposed. We conclude that while anthropogenic nitrogen emissions are a global problem, no fast and simple single solution exists. Additional nitrogen removal in wastewater treatment will have no effect, as long as diffuse sources and nitrate concentrations in groundwater remain at a high level. Emission reductions should be achieved in an integrated way, taking direct and indirect effects into account. In this sense, case by case decisions and a new definition of “sensitive areas” are required.  相似文献   

9.
《Water Policy》1998,1(3):283-303
This paper reports on a pilot study of water quality management strategies for the Upper and Middle Odra River basin in Poland. The study was undertaken to test an approach for setting targets for compliance with European Union directives in the water sector, focusing particularly on urban wastewater. These interim targets are important for the government and the EU to be able to monitor whether Poland is making adequate progress towards full compliance. The study shows clearly that an approach based solely on specifying effluent control standards and corresponding treatment technologies for various sources of pollution is extremely expensive relative to the amount of environmental improvement achieved. Applying least cost solution for meeting specific water quality standards in the Odra river costs significantly less. Adopting a least cost strategy for meeting specific water quality objectives therefore offers great potential for both reducing compliance costs in the interim period and accelerating the environmental benefits that will result.  相似文献   

10.
Environmental conditions of the lower river Odra and its estuary show a high variability of chemical and biological parameters, related to the dynamics of the river, its mouth area, the Lake Dabie-Szczecin Lagoon system, and the Pomeranian Bay. Water chemistry, affected by the total sum of industrial, urban, and agricultural pollution discharged from the direct drainage area is discussed. This pollution load influences the composition and ecological structures of terrestrial, frequently unique, phytal communities associated with aquatic areas, phyto- and zooplankton, benthos, fish fauna, and avifauna. The current status of the terrestrial and aquatic ecosystems is described; elements of cultural infrastructure existing within the Lower Odra Valley in Western Pomerania are mentioned as well.  相似文献   

11.
The distribution and fate of polycyclic aromatic hydrocarbons (PAHs) were investigated in surface sediments (0...2 cm) and fluffy layer material of the internal and external coastal waters of the Odra river estuary (north-eastern Germany). The area includes the Odra Lagoon (Oderhaff), the Greifswalder Bodden, the Pomeranian Bight, and the Arkona Basin. Elevated concentrations were observed in the surface sediments of the internal coastal waters with highest concentrations in the Odra Lagoon. This indicates a significant contribution of river discharge to the contamination of sediments with PAHs. During the exceptional Odra flood in the summer of 1997 significantly higher concentrations of PAHs were found in the fluffy layer material of the Odra Estuary. The distribution of the individual PAH compounds varies widely depending on their structure and molecular weight. A concentration gradient of the lower molecular weight PAHs was found from the Odra Lagoon to the open sea areas. The concentrations decreased rapidly from the Oder Haff to the Arkona Basin. These results were found in both sediments and fluffy layer material. This is attributed to the degradation of the lower molecular weight PAHs during transport from the urban regions to the sedimentation basins. A decrease of this magnitude was not found for the higher molecular weight PAHs (i.e. benzo(a)pyrene) due to their higher persistence. An enrichment of these compounds was measured in the Arkona Basin.  相似文献   

12.
Over ninety surface sediment samples (0...3 cm) were collected in the Odra river estuarine system – from the Oderhaff, the Pomeranian Bight, the Peenestrom, the Greifswald Bodden – and the Arkona Basin between 1994 and 1996 and analysed for polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/F) and biphenyls (PCB), and p,p′-dichlorodiphenyl-trichloroethane (DDT) including their metabolites. The contents of all investigated organochlorines in the sediments of the western part of the Oderhaff (Kleines Haff) were only slightly higher and more homogenously distributed compared to the values of the Pomeranian Bight and the Greifswald Bodden. PCB contents (sum of 23 congeners) in surface sediments ranged between <130 and 9 550 pg/g (given for dry weight, dw). The results of individual PCB congeners showed that high contents of hexa- and heptachlorinated compounds (PCB 138, 153, 180) were present in the entire area investigated. Generally, low levels of PCDD/F were found in surface sediments of the Odra river estuarine system due to small industrial activities in the catchment area. Contents of PCDF (sum) and PCDD (sum) varied from 2.5 to 820 pg/g (dw) and from 13 to 2 991 pg/g (dw), respectively. The congener contents of PCDF showed a nonuniform picture between the Oderhaff and the Arkona Basin. In contrast, the congener profiles of PCDD showed approximately similar patterns at nearshore and offshore stations, with highest values of OCDD (octa CDD). We assume that most of the particulate-bound micro-contaminants (PCB, PCDD/F) are deposited in the eastern part of the Oderhaff (Stettin Lagoon), which acts as a temporary trap and opurificationπ basin for the suspended particulate matter (SPM). One pathway for further transport of the particles seems to be the way on a small sedimentation strip along the island of Usedom via the “Saßnitz-trough” into the deeper parts of the western Baltic Sea.  相似文献   

13.
Fourteen polycyclic aromatic hydrocarbons (PAH), six monosaccharides (SA) formed following the hydrolysis of polysaccharides, as well as water and organic matter contents were determined in river sediments sampled in thirteen points in the Odra basin after the catastrophic flood of 1997. The water content is related to the water absorbing capacity of the soil in the Odra catchment area. The PAH content increases together with the increase in the organic matter (OM) content which suggests that these species are mainly of anthropogenic origin. On the other hand, SA and OM contents decrease with increasing water content, which implies that both enhance biological life. The PAH content tends to decrease when the SA content increases. This relation goes hand in hand with the quality of water resources, which is greater when the quantity of polysaccharides is higher.  相似文献   

14.
The water quality in Biscayne Bay has been significantly affected by past and continuing coastal and watershed development. The nutrient concentrations in the Bay have been dramatically changed by the conversion of natural creeks and sheet flow freshwater inputs to rapid and episodic canal inputs from the large and rapidly expanding Miami metropolitan area. This study is an evaluation of nutrient loadings to Biscayne Bay for 1994-2002 from canal, atmospheric, and groundwater sources. Dissolved inorganic nitrogen (DIN, as nitrate, nitrite, and ammonium) and total phosphorus (TP) loadings by the canals were influenced by their geographic locations relative to discharge amount, watershed land use, stormwater runoff, and proximity to landfills. Annual budgets showed that canals contributed the bulk of N loading to the bay as 1687.2 metric ton N yr(-1) (88% total load). Direct atmospheric DIN load for Biscayne Bay was only 231.7 ton N yr(-1), based on surface area. Of the canal DIN load, nitrate+nitrite (NO(x)(-)) loading (1294.5 ton N yr(-1)) made up a much greater proportion than that of ammonium (NH(4)(+), 392.6 ton N yr(-1)). In the urbanized north and central Bay, canal DIN load was evenly split between NO(x)(-) and NH(4)(+). However, in the south, 95% of the DIN load was in the form of NO(x)(-), reflecting the more agricultural land use. Contrary to N, canals contributed the only 66% of P load to the bay (27.5 ton P yr(-1)). Atmospheric TP load was 14 ton Pyr(-1). In the north, canal P load dominated the budget while in the south, atmospheric load was almost double canal load. Groundwater inputs, estimated only for the south Bay, represented an important source of N and P in this zone. Groundwater input of N (141 ton N yr(-1)) was about equal to atmospheric load, while P load (5.9 ton P yr(-1)) was about equal to canal load.  相似文献   

15.
Gaschromatographic Determination of Diethylenetriaminepentaacetic Acid in Surface Water. A method for the determination of diethylenetriaminepentaacetic acid (DTPA) is reported. The determination is based on the preconcentration on a strong base anion exchange resin, esterification with n-propanol and following gaschromatographic separation using a N-selective detector. The sensitivity of the method, including enrichment, is 1 μg/L in river water. The identity of DTPA in river water was proved by mass spectrography. The method can be used also for the quantitative determination of nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), cyclohexanediaminetetraacetic acid (CDTA) and ethyleneglycolbis-(2-aminoethylether)-N,N,N′,N′-tetraacetic acid (EGTA). The method was used to examine river water. An investigation along the river Rhine, taking grab samples from January and february 1992 showed that DTPA was present in some sampling places in similiar concentrations as NTA and EDTA.  相似文献   

16.
Sources and fate of nutrients in a subtropical reservoir   总被引：1，自引：0，他引：1  
This study examined the sources and fate of nutrient inputs from two principal tributaries to the eutrophic subtropical Wivenhoe reservoir: an unregulated river and a dammed river with regular releases, during a period of declining reservoir water levels. Nutrient budgets were constructed over a period of 6 years, and combined with short-term data on nutrient concentrations and forms, and δ15N stable isotope data. Our study found that over a 6 year period, there was net retention of phosphorus (P) in the reservoir, with 60% of inputs retained. Most of the P input load came from the unregulated river, with an agricultural catchment, during periods of high flow. During one event half of the total TP load from the unregulated river in the study period was delivered in only 12 days. Much of the P was dissolved inorganic P (DIP) and was derived from high P concentrations in soils and sediments. This highlights the importance of appropriate catchment management practices to reduce P losses from terrestrial systems because retention of P in reservoir sediments reduces the availability of this nutrient for agricultural production. In contrast, there was negligible retention of nitrogen (N). The unregulated river was an important source of N derived from N fixation in the river and adjacent soils, while the source from the dammed river was mostly reprocessed N. The high retention of P relative to N is consistent with relatively higher accumulation of P in sediments.  相似文献   

17.
The atmospheric chemistry and deposition model has been applied for calculation of nitrogen and sulphur depositions to the entire North Sea area for the year 1999. The total atmospheric nitrogen and sulphur depositions to the North Sea area were determined to 709 kton (kt) N and 551 kt S, respectively. Since the North Sea area was calculated to be 747,988 km2, this is equivalent to an average deposition of 0.9 ton N km?2 and 0.7 ton S km?2, respectively. The depositions decrease strongly from the south end (about 2–3 kt N km?2) to the north end (about 0.2 kt N km?2) of the North Sea, due to increasing distance to the large source areas in the northern part of the European continent. The territorial waters of Belgium, the Netherlands and Germany receive about 50% higher deposition densities than the average value for the entire North Sea area. For the remaining territorial waters of the North Sea the depositions follow more or less the fraction of the area. The results furthermore show that about 60% of the total nitrogen deposition is related to emissions from combustion sources (nitrogen oxides) and about 40% from emissions related to agricultural activities (ammonia).  相似文献   

18.
Abstract

Abstract Current research suggests that strategies to control sediment and phosphorus loss from non-point sources should focus on different runoff components and their spatial and temporal variations within the river basin. This is a prerequisite for determining effective management measures for reducing diffuse source pollution. Therefore, non-point source models, especially in humid climatic regions, should consider variable hydrologically active source areas. These models should be able to consider runoff generation by saturated overland flow, as well as Hortonian overland flow. A combination of the hydrological model WaSiM-ETH and the erosion and P-transport model AGNPS was chosen for this study. The models were run in the WaSiM runoff generation mode (Green & Ampt/TOPMODEL or Richards equation approach) and the SCS curve number mode to assess the effect of these different runoff calculation procedures on the dissolved phosphorus yield. A small and a medium-sized river basin, of the area of 1.44 and 128.9 km2, respectively, in central Germany were selected for the investigation. The results show that the WaSiM–AGNPS coupling produces more accurate results than the SCS curve number method. For the spatial distribution, the more physically-based model approach computed a much more realistic distribution of water and phosphorus yield-producing areas.  相似文献   

19.
Human activity has resulted in increased nutrient levels in rivers and coastal seas all over Europe. Models that can describe nutrient fluxes from pollution sources to river outlets may help policy makers to select the most effective source control measures to achieve a reduction of nutrient levels in rivers and coastal seas. Part I of this paper describes the development of such a model: PolFlow. PolFlow was specially designed for operation at the river basin scale and is here applied to model 5‐year average nitrogen and phosphorus fluxes in two European river basins (Rhine and Elbe) covering the period 1970–1995. Part II reports an error analysis and model evaluation, and compares PolFlow to simpler alternative models. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

20.
《国际泥沙研究》2020,35(1):69-78
Bed sediment carbon to nitrogen(C/N) ratio is one of the essential variables reflecting sources of organic matter in river basins.In order to explore the spatial variability in sources of sediment C/N ratios,and the influence of land use and land cover(LULC) changes on the Betwa River basin in Peninsular India,51 river bed sediment samples were collected in December 2016.The coefficient of variation(CV) was35%indicating highly variable biogeochemical parameters.The sediment C/N ratio varied from 2.94 to 10.09.3.21-56.40,and 6.50-76.97 in upstream,mid-stream,and downstream regions,respectively,indicating a progressive change in sources of organic matter and depositional environment.The positive correlation between total carbon(TC) and C/N ratio was increasing in the downstream direction [upstream(+0.560) mid-stream(+0.603) downstream(+0.838)],which is an indication of high deposition and slow decomposition of sedimentary terrigenous organic matter distant from the regions of urban pollution.The LULC change analysis done by remote sensing and Geographic Information System(GIS)methods revealed an adverse change for the forests and barren land and a positive change for the agricultural land and built-up areas.The sediment C/N ratio mapping showed the impact of LULC changes on the sediment quality.The spatial distribution of bed sediment C/N ratio in the Betwa River basin has important reference value for managing organic matter transport in the downstream Yamuna River and Ganga River basin.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号