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1.
Carpet-forming bryophytes (mosses) have been used extensively since the late 1960's in assessing regional and temporal variability of atmospheric heavy-metal deposition. A large-scale decrease in heavy-metal deposition occurred during the 1970's in Sweden, probably also in other parts of northern Europe. The decrease was closely related to known changes in atmospheric emissions.  相似文献   

2.
渭河干流陕西段综合治理前后的水质变化与趋势   总被引：3，自引：1，他引：2  
[目的]讨论渭河干流陕西段综合整治项目启动以来河道水质的变化趋势,检验整治工程的治理成效,为后续河道的污染防治提供一定技术支持。[方法]基于2010—2016年渭河干流陕西段主要监测断面的水质数据进行水质综合评价,应用Mann-Kendall检验法阐述水质变化趋势,运用重标极差分析法(R/S分析法)查明水质的未来变化趋势。[结果]2016年渭河干流陕西段河道水污染已由2010年的重度污染转为轻度污染,劣Ⅴ类水质断面比例减少了58.8%,Ⅳ—Ⅴ类断面比例增加了55.5%,Ⅰ—Ⅲ类断面占比保持平稳;宝鸡市、咸阳市、西安市和渭南市4个出境断面枯水期化学需氧量(COD)、NH3-N浓度普遍高于丰水期,治理后西安市出境断面污染削减最为显著,但是西安市出境断面仍然是4个断面中污染最为严重的断面;4个出境断面NH3-N浓度均呈现高度显著下降趋势且未来持续性较强;咸阳、西安、渭南市出境断面COD浓度呈显著下降趋势,但是未来持续性较弱,宝鸡市出境COD浓度呈不显著上升趋势且会延续。[结论]综合治理后,河道污染程度明显减轻,水质变化明显,但部分断面污染物浓度有上升趋势,需引起特别关注。  相似文献   

3.
Dargall Lane is an acidic stream draining a moorland catchment in the Galloway Hills of southwest Scotland. This area has been receiving high atmospheric loadings of sulphur. The Dargall Lane catchment is underlain by a greywacke-shale sequence and by intrusive rocks of granodioritic-tonalitic composition. The shales have a sulphur concentration in the range 0.04–0.19 wt.%, whereas mudstones, greywackes and grandiorites rarely exceed 0.02 wt.% S. Calculations based on bedrock chemical composition, typical denudation rates of sedimentary and intrusive rocks, and the composition of surface water during baseflow, indicate that geogenic sulphur may account for a significant fraction of the sulphate hydrochemical budget. Sulphur mobilised by rock weathering of black shales is likely to be an important contributing factor causing the observed lack of a significant sulphate decrease in sulfate water despite the reported 30% reduction of sulphate in atmospheric precipitation during the past decade.  相似文献   

4.
Although the decline in fish populations due to acidicwater in Norway started as early as in the 1920's the most rapid losses appeared during the 1960–70's. Until 1978, the populations of Atlantic salmon had disappeared from the southernmost part of Norway, and in these areas, more than half of the brown trout populations had been lost. Today, in spite of no increase in acid depositions, the fishery problems seems to continue at the same speed. Data based on interviews of the local fish authority shows that lakes still holding a fish population in the late 70's, have experienced a 30% loss of brown trout populations and a 12% loss of perch in the period 1978–1983. This trend have been confirmed by testfishing in lake systems having long data series. Salmon rivers on the western coast of Norway have experienced several episodes of fish kills due to rapid changes in water quality. These fish kills have mainly affected smolts of Atlantic salmon. Spawning migrating salmon on entering their acidified home river have also been affected. In Sweden, several salmon populations along the western coast have been lost due to acidification with no positive trends so far in the 1980's. Areas in central Sweden and in some high mountain areas are still experiencing a continuous and increasing acidification with detrimental effects on invertebrates and fish. In Finland, an increase in acidic deposition during the last decades have occurred, leading to acidification in the most sensitive freshwater systems. Although some acidified freshwater lakes are reported to have lost their fish stocks, few data on fish population effects are available.  相似文献   

5.
California's 14-year, $25 million acidic deposition program has studied the causes and effects of acidic air pollutants. In contrast to the eastern United States where sulfur-derived (S-derived) by-products from coal combustion dominate precipitation chemistry, nitrogen-derived (N-derived) acids predominate in wet and dry deposition in California. Adverse effects on the human lung have not been observed after short-term exposures to acidity, but extended exposures to ambient acidity may pose a chronic risk. No irreversible, adverse effects on surface waters in the Sierra Nevada mountain range or to the state's forests have been found due to extant acidic inputs. The longer-term outlook for forests is less certain because the impacts observed elsewhere occurred after decades of S and N deposition, but at lower ambient ozone levels. Ozone is the major air pollutant stressor for forests, but atmospheric N has the potential to cause adverse changes in soil nutrient cycling. Impacts on man-made materials in southern California (e.g., galvanized steel) were found to be minor. While California does not have an ambient air quality standard for acidic air pollutants, emissions of precursors have declined since the 1960's due to changes in industrial practices, improvements in technology, and adoption of control measures for ozone. Lowering emissions from motor vehicles will be emphasized to prevent future increases in N deposition.  相似文献   

6.
White precipitates collected from stream bottoms and well tubes in the Senne area consist of amorphous aluminium hydroxide, coprecipitated with minor amounts of sulfate, phosphate and silica. The precipitates have presumably formed by the interaction of slightly alkaline water from calcareous subsoil sediments, with acidic water draining off sandy soils affected by high inputs of acidic atmospheric deposition. From many hydrochemical studies, precipitation of aqueous aluminium is known to occur in subsurface horizons of acid soils affected by acid rain. On the basis of presumed equilibrium with soil solutions, jurbanite, AlOHSO4 · 5H2O, is often assumed to be the secondary mineral involved. However, direct evidence for jurbanite from solid phase analysis is lacking. This first analysis of such a secondary phase does not support the jurbanite hypothesis, and shows that amorphous Al hydroxide can be formed instead.  相似文献   

7.
The perch population of Lake Vähä Valkjärvi, a two hectare clear-water lake in southern Finland, decreased due to acid precipitation during the 1980s. During the early 1990s a decrease in acidic deposition resulted in slight improvement of water quality of the lake. This was followed by recovery of the reproduction of perch starting in 1991. A mark and recapture experiment in spring 1995 indicated a hundred fold increase in the population size of perch in a four year period. A decrease in the abundance of aquatic invertebrates was recorded during 1989–1996. This decrease well coincided with the recovery of the perch population, suggesting that increased predation by fish was responsible for the decrease. The occurrence of goldeneye young also dropped in L. Vähä Valkjärvi since 1993. This was thought to be due to increased food competition with perch.  相似文献   

8.
Historical deposition rates of Hg were determined in 7 ombrotrophic bogs located far from direct sources in Sweden and Norway. The peat bog cores were dated using 210Pb. Based on the dating result 10 to 12 slices from each core were analyzed for Hg. In Southwestern Scandinavia (Rörvik) the deposition rate has increased from about 10 to about 30 μg Hg m?2 yr?1 since the beginning of this century. In Northwestern Norway (Överbygd) the deposition rate has increased from about 10 to about 35 μg Hg m?2 yr?1 since the 1960's. In Southeast Sweden (Aspvreten) the deposition rate decreased since the beginning of this century. There are no significant trends in the historical deposition rates at the two other stations in middle Scandinavia. A comparison between recent Hg deposition rates measured by peat bog analysis, wet precipitation and mosses shows good agreement at all stations except those in Northern Norway were local dry deposition of Hg may be an important source of Hg.  相似文献   

9.
The U.S. Environmental Protection Agency conducted the National Stream Survey (NSS) to provide unbiased estimates of the numbers and distribution of acidic and low acid neutralizing capacity streams in the Mid-Atlantic and Southeastern United States. The NSS employed a probability sample of 500 stream reaches to represent a target population of 64,300 stream reaches in the study area. All NSS samples were screened for acid mine drainage (AMD) influences, and population estimates of the regional extent of AMD impacts were made. Almost 10% of the stream reaches in the Northern Appalachians subregion were acidic during spring baseflow due to AMD. In the entire NSS, an estimated 4590 km (± 1670) of streams (2% of the total NSS length) were acidic due to AMD and another 5780 km (± 2090) of streams were strongly impacted, but not acidic. In subregions of the NSS with observed mine drainage effects, roughly the same number of streams were acidic during spring baseflow due to AMD as due to acidic deposition. The population estimates of mine drainage impact made in the NSS were similar to estimates made in previous surveys that attempted to census all of the streams in coal producing areas. These results demonstrate that a statistically based stream survey is a useful tool for evaluating regional water quality.  相似文献   

10.
Concern about acidification in upland areas has brought about the need to model the stream hydrochemical response to deposition and land-use changes and calculate critical loads. Application of dynamic models such as MAGIC are preferable to steady-state methods, since they are able to produce an estimate of the time scale required to meet some water chemistry target given a reduction in acid deposition. These models typically consider annual changes in stream chemistry at one point. However, in order to protect biota from 'acid episodes', quantification of temporal variability needs to encompass event responses; in addition spatial variability across the catchment also needs to be considered. In this paper, modelling of both spatial and temporal variability is combined in a new framework which enables quantification of catchment hydrochemical variability in time and space. Both low and high flow hydro-chemical variability are quantified in terms of statistical distributions of ANC (Acid Neutralisation Capacity). These are then input as stochastic variables to an EMMA (End-Member Mixing Analysis) model which accounts for temporal variability and ANC is hence predicted as a function of time and space across the whole catchment using Monte-Carlo simulation. The method is linked to MAGIC to predict future scenarios and may be used by iteration to calculate critical loads. The model is applied to the headwaters of the River Severn at Plynlimon, Wales, to demonstrate its capabilities.  相似文献   

11.
近58年天山降雪/降水量比率变化特征及未来趋势   总被引：2，自引：1，他引：1  
降雪/降水量比率(S/P)能够反映不同形态降水特征,对气候变化十分敏感。该文基于天山及周边49个气象台站观测数据和IPCC-CMIP5气候情景数据,分析了近58 a来中国天山山区冷季(10-4月)降雪量、降水量和S/P时空变化特征,并预估在RCP4.5排放情景下各指标的未来变化趋势。结果表明:天山山区冷季S/P受地形影响,呈山区大于盆地,北坡大于南坡的分布格局,与海拔显著正相关。1961—2018年天山山区平均冷季降雪量、降水量均显著增加,S/P变化不大,在0.35~0.67之间波动,以-0.016%/10a的速率呈微弱减少趋势;平均气温变化是引起S/P变化的重要因素。在RCP4.5气候情景下,天山山区未来冷季降雪量缓慢减少,降水量显著增加,S/P显著减少。相比基准期(1986—2005年),到2050s冷季降雪量平均减少8.9%,降水量增加10.1%,S/P减少14.7%。该研究对科学认识全球变暖背景下天山地区水文响应以及区域水资源调控具有重要意义。  相似文献   

12.
Forest soils having low exchangeable calcium (Ca) and other nutrient base cation (BC) reserves may induce nutrient deficiencies in acid-sensitive plants and impact commercially important tree species. Past and future depletion of soil BC in response to acidic sulfur (S) deposition, forest management, and climate change alter the health and productivity of forest trees. This study used a process model (Model of Acidification of Groundwater in Catchments [MAGIC]) to address a number of questions related to soil BC status for a group of 65 streams and their watersheds in the southern Blue Ridge physiographic province of the southern Appalachian Mountains. Future S deposition to the study watersheds used for the Base Scenario was specified according to proposed reductions in S emissions at the time of this study, representing a reduction of 42 % of ambient S deposition by 2020. Twenty additional simulations were considered, reflecting four alternate S deposition scenarios (6 %, 58 %, 65 %, and 78 % reduction), and various changes in timber harvest, temperature, and precipitation. Base Scenario soil exchangeable Ca and % base saturation showed decreasing trends from 1860 to 2100. Changes in tree harvesting had the largest effect on stream sum of base cations (SBC) and soil BC supply. Each of the scenario projections indicated that median year 2100 soil exchangeable Ca will be at least 20 % lower than pre-industrial values. The simulations suggested that substantial mass loss of soil BC has already occurred since pre-industrial times. Nearly the same magnitude of BC loss is expected to occur over the next 145 years, even under relatively large additional future reductions in S deposition.  相似文献   

13.
The Galloway region of Southwest Scotland has been subject to decades of acidic deposition which has resulted in damage to soils, surface waters and aquatic biota. A survey of lochs was conducted in 1979, 1988, and 1993, over which time there have been dramatic changes in total sulphur and nitrogen deposition. The MAGIC model successfully reproduced the major chemical changes in water chemistry from 1979 to 1988 during which time there was a rapid decline in sulphur deposition. A new coupled sulphur and nitrogen model (MAGIC-WAND) has been used to evaluate the regional hydrochemical response to changing patterns of N & S deposition from the period 1988 to 1993. Details of the model structure and parameterisation are discussed. The model under-predicts the response of non-marine sulphate in the region suggesting that there has been a slight increase in deposition over this period. Future hydrochemical responses to different nitrogen deposition scenarios are presented, indicating that the potential increase of nitrogen in surface waters is closely linked to the age and extent of different mosaics of commercial afforestation within the individual catchments.  相似文献   

14.
An evaluation of the influences of acidic deposition and forest development on nutrient cycling and conifer productivity at the Charles Lathrop Pack Demonstration Forest, near Warrensburg, New York, was made. This site has a known land use history and is the source of 60 years of soils and silviculture research. Soils were characterized by a nutritional imbalance and support conifer plantations that exhibited declining growth. Historical and contemporary evaluations of nutrient cycling in 47- to 57-yr-old red pine plantations provided no evidence that acidic deposition has had an adverse influence on nutrient cycling. Ap horizon pH decreased from 1949 to 1962 but remained the same from 1962 to 1985. In the B horizon, pH was stable from 1962 to 1985. Exchangeable potassium levels in the Ap horizon fluctuated but did not significantly change from 1949 to 1985: in the B horizon it increased during the period 1962 to 1985. Levels of potassium in the foliage of red pine in unfertilized plots increased from 1949 to 1985, paralleling increases in B horizon potassium levels during that period. There was no increase in cation leaching from the mineral soil that could be attributed to anthropogenic inputs of NO3 ? and SO4 2? due to retention of N and S in this ecosystem. Soil solution K+ chemistry was similar between the 1960's and the 1980's. Mineral soil pH and base cation status were differentially influenced by tree species since 1930. In general, temporal and contemporary trends of mineral soil pH and base cation status of the soil and foliage indicated that forest development has been the dominant factor influencing nutrient cycling in these conifer plantations. While results of these studies do not conclusively preclude involvement of acidic deposition effects as part of a forest decline syndrome, they indicate the importance of recognizing and measuring natural variability in forest soil processes due to differential species effects and forest aggradation. Because these effects may have a greater impact on stand productivity than the effects of acidic deposition, they can confound interpretation of acidic deposition research if not clearly understood.  相似文献   

15.
Sulphur deposition has diminished by about half during the last decade. For Sweden consistent estimates of total deposition are available for 1991, and 1994–97. Based on these estimates and using GIS the deposition for large drainage areas during one decade are calculated. These values are compared with the measured S transport in rivers covering about 85% of the Swedish territory, thus enabling the construction of a S budget for Sweden. The majority of the drainage areas have a net loss of S, which can be attributed to desorption of S in the soil. During the period of high deposition in the 1980:s (>60 meq m?2 yr?1 in southern Sweden) S was adsorbed, and retarded acidification. There still seems to be some S-adsorption in the northern parts of the country, where the deposition is less (now <20 meq m?2 yr?1).  相似文献   

16.
The deposition of sulphyr (S) has decreased considerably during the last decade and is now at levels below those recorded in the middle of the 1950s in Sweden. However, the sulphate concentrations in surface waters have not decreased to the extent that could be expected from the decreased S deposition. Catchment studies have shown a net S output, indicating a soil-derived S source besides the atmospheric S input. This study was performed in three small, forested catchments in southern and central Sweden, that are part of the national, integrated monitoring program for forests. The aim was to assess S levels and fluxes in and between the different compartments of the ecosystems in order to trace the possible sources of excess S in runoff. The sulphate concentrations in soil water indicate that the excess S originates from mineralization and oxidation of organically bound S in humus and peat, as well as from desorption of sulphate from Fe and Al oxohydroxides in the B-horizon. The latter process will quickly respond to changes in S deposition, while the former probably is independent of S deposition in a short time perspective. This will have implications for the modelling of recovery from soil and surface water acidification.  相似文献   

17.
Total mercury (Hg) deposition and input/output relationships were investigated in an 11-ha deciduous forested catchment in northern Vermont as part of ongoing evaluations of Hg cycling and transport in the Lake Champlain basin. Atmospheric Hg deposition (precipitation + modeled vapor phase downward flux) was 425 mg ha-1 during the one-year period March 1994 through February 1995 and 463 mg ha-1 from March 1995 through February 1996. In the same periods, stream export of total Hg was 32 mg ha-1, respectively. Thus, there was a net retention of Hg by the catchment of 92% the first year and 95% the second year. In the first year, 16.9 mg ha-1 or about half of the annual stream export, occurred on the single day of peak spring snowmelt in April. In contrast, the maximum daily export in the second year, when peak stream flow was somewhat lower, was 3.5 mg ha-1 during a January thaw. The fate of the Hg retained by this forested catchment is not known. Dissolved (< 0.22 µm) Hg concentrations in stream water ranged from 0.5-2.6 ng L-1, even when total (unfiltered) concentrations were greater than 10 ng L-1 during high flow events. Total Hg concentrations in stream water were correlated with the total organic fraction of suspended sediment, suggesting the importance of organic material in Hg transport within the catchment. High flow events and transport with organic material may be especially important mechanisms for the movement of Hg through forested ecosystems.  相似文献   

18.
Northern Sweden has been regarded as unaffected by acid deposition, but many surface waters in the region fall within the definition of acid surface water (pH < 6.0, alkalinity < 50 mmolc m?3) permanently or during episodes. Approximatly 100 MSEK in spent annually on liming in northern Sweden. This paper summarizes our conclusions from a workshop on natural versus anthopogenic acidification held in February 1995. It was shown that organic substances have a key role in determining the acidity of surface waters in the region, although anthropogenic effects are documented in some coastal systems and in the southern mountain range. Sulfide oxidation occurs by the coast. It appears clear that many surface waters that were naturally acidic have been limed to unnatural pH levels. New criteria to screen liming candidates should be developed, and one such model based on water chemistry data is proposed.  相似文献   

19.
Mercury (Hg) was measured in stream water and precipitation in the Loch Vale watershed in Rocky Mountain National Park, Colorado, during 2001–2002 to investigate processes controlling Hg transport in high-elevation ecosystems. Total Hg concentrations in precipitation ranged from 2.6 to 36.2 ng/L and showed a strong seasonal pattern with concentrations that were 3 to 4 times higher during summer months. Annual bulk deposition of Hg was 8.3 to 12.4 μ g/m2 and was similar to deposition rates in the Midwestern and Northeastern U.S. Total Hg concentrations in streams ranged from 0.8 to 13.5 ng/L and were highest in mid-May on the rising limb of the snowmelt hydrograph. Stream-water Hg was positively correlated with dissolved organic carbon suggesting organically complexed Hg was flushed into streams from near-surface soil horizons during the early stages of snowmelt. Methylmercury (MeHg) in stream water peaked at 0.048 ng/L just prior to peak snowmelt but was at or below detection (< 0.040 ng/L) for the remainder of the snowmelt season. Annual export of total Hg in Loch Vale streams ranged from 1.2 to 2.3 μ g/m2, which was less than 20% of wet deposition, indicating the terrestrial environment is a net sink of atmospheric Hg. Concentrations of MeHg in stream water and corresponding watershed fluxes were low, indicating low methylation rates or high demethylation rates or both.  相似文献   

20.
Acidification of surface waters in northern Europe due to anthropogenic sulphur (S) deposition has led to new emission restrictions based on Critical Loads (CL). There is likely to be considerable interest in documenting the effect resulting S deposition changes have on surface water quality. This paper will focus on how the chemistry of 134 reference lakes in Sweden has changed between 1988 and 1993 in response to a decline in S deposition. Only 10% of the reference lakes had significant declines in sulphate during the 5 year study period. A similar number of lakes had an increase in the acid neutralizing capacity (ANC), but few of those with an increase in ANC were also lakes with significant sulphate decreases. Since there is good evidence that S deposition decreases will eventually result in ANC increases, a five year period is probably too short for evaluating the S protocol in terms of changes in lake chemistry. It takes a number of years to equilibriate to new deposition levels, and weather patterns may also obscure longer term trends.  相似文献   

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