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1.
We applied trend analyses to data from the International Cooperative Programme forAcidification of Rivers and Lakes in an attempt to discover regional patterns of long-term changesin surface water chemistry both in Europe and North America, and to relate these changes totrends in deposition. Decreases in surface water SO 3 - concentrations predominated at European sites in theFederal Republic of Germany, The Netherlands, and in Norway, and at the North American sitesin Ontario, Canada, the Adirondacks and Catskill Mountains of New York, U.S.A. Otherpredominating trends in the European sites were decreasing Ca2+ concentrations at many of thesites in The Netherlands, Norway, and Sweden. Increases in NO 3 - were observed at several sites in southern Norway, and in theAdirondack and Catskill regions of eastern New York. This, combined with an increasedoccurrence of declining base cation concentrations may well be responsible for the lack ofdocumented surface water recovery from acidification. Despite region-wide trends in severalvariables of importance in acidification, no correlations between surface water trends and changesin deposition were found using these data.  相似文献   

2.
Regulatory measures in the United States, such as Title IV of the Clean Air Act Amendments of 1990, have primarily restricted sulfur dioxide emissions as a way to control acidic deposition. These restrictions, coupled with increasing concentrations of NH4 + in wet deposition in some regions of the U.S. and continued high emissions of nitrogen oxides have generated a significant shift in the chemistry of precipitation as measured at National Atmospheric Deposition Program/National Trends Network sites. Trends in precipitation chemistry at NADP/NTN sites were evaluated for statistical significance for the period 1981–1998 using a Seasonal Mann-Kendall Test, a robust non-parametric test for detection of monotonic trends. SO4 2? declines were detected at 100 of the 147 sites examined while no sites exhibited increasing SO4 2? trends. On average, SO4 2? declined 35% over the period 1981–1998 with downward SO4 2? trends being most pronounced in the north-eastern United States. In contrast, no consistent trends in NO3 ? concentrations were observed in precipitation in any major region of the United States. Although the majority of sites did not exhibit significant trends in NH4 + concentration, 30 sites exhibited upward trends. For Ca2+ concentration in precipitation, 64 sites exhibited a significant decreasing trend and no sites exhibited an upward trend.  相似文献   

3.
Monotonic trends in hydrogen (H+), sulfate (SO4 –2)and nitrate (NO3 –) were calculated using non-parametric techniques at four Canadian Air and Precipitation Monitoring Network (CAPMoN) sites and six nearby river systems in Atlantic Canada for the period 1983–1991. Over the whole interval, there were increasing nitrate concentrations and deposition trends at three of the four monitoring sites and no trends in SO4 –2 or H+ concentrations and deposition. We found that SO4 –2 concentrations increased at three of our six river sites, NO3 – increased at one site and H+ decreased at one site. River exports showed no trends in the entire study interval. The series were also analyzed in five year time windows, incremented by six months, to see if changes in trend presence or direction would occur, compared to trend analysis over the entire interval. We show that while trends in river chemistry do not contradict deposition patterns, the changes that occurred were not necessarily in step. We also found that the trends which we measured were the result of short-term changes as opposed to long-term continuous monotonic trends. The time lag between precipitation and chemistry trend changes seemed longer in basins dominated by softwoods than by hardwoods.  相似文献   

4.
During the last 20 years, emission reductions in Europe and North America have resulted in decreased atmospheric S-deposition of up to 50%, while N-deposition has stayed almost constant. Data from 98 ICP Waters sites were tested for trends in concentrations of major chemical components for the 10-year period 1989-1998 using the nonparametric seasonal Kendall test. The sites were grouped into regions and types for meta-analysis. All of the regions had highly significant downward trends in SO4 2?* concentrations. Nitrate concentrations, on the other hand, show no regional patterns of change. Concentrations of base cations declined in most regions. All regions showed tendencies of increasing DOC. The low ANC sites showed the largest rates of recovery. Neither the high NO3 ? or low NO3 ? groups of sites exhibited significant trends in NO3 ? concentrations. Alpine (non-forested) sites show clear and consistent signals of recovery in ANC and pH, and appropriate (relative to SO4 2?* trends) rates of base cation decline.  相似文献   

5.
Long-term atmospheric deposition of Pb has been measured using lake sediment cores. The average ‘whole-lake’ Pb burden was measured for several lakes in each of four regions located throughout Ontario and Quebec, Canada. Since the regions were remote to any point source of Ph, large scale variation in atmospheric transport could be studied. The results indicate that Pb deposition is highest in South-Central Ontario, where lake burdens ranged from 312 to 432 mg m?2, and that it decreases in an eastward direction into Quebec. Lowest deposition was at the site farthest north, Schefferville, Quebec, where fallout was 31 to 42 mg m?2, less than one-tenth of that previously observed in South-Central Ontario. Lead-210 dating of sediment cores from the northern site showed that input to these remote lakes has occurred over the same time period as in the southern sites.  相似文献   

6.
We monitored the chemistry of 603 small water bodies in three acid-sensitive regions of central Ontario, Canada (Algoma n=235, Muskoka n=216, Sudbury n=152) between 1988-1996 to determine whether they have responded to recent SO2 emission reductions, and whether any chemical changes were related to lake characteristics. During the study, 27-56% of lakes declined in SO4 2- concentrations, 41-57% declined in base cation concentrations, but only 26-28% increased in pH or ANC (acidity status). Increases in pH were greatest in lakes with low ANC, but had weak relationships to lake color or volume. No consistent trends were observed for DOC, NO3 - or TP concentrations. Clearly, the long-term biological recovery of these sensitive aquatic ecosystems will depend on interactions among several environmental stressors, including acidification.  相似文献   

7.
Atmospheric deposition and surface water chemistry have been monitored intensively at 5 geologically “sensitive” sites in southeastern Canada. The sites receive differing acid inputs that span the entire range found in Canada. Surface water data collected at 9 stations from 1981 to 1993 for SO 4 2? , NO 3 ? , Alkalinity, DOC, pH, Ca2+ and Mg2+ have been analyzed to detect monotonic trends. Similarities between the temporal patterns and trends for SO 4 2? in deposition and surface water suggest that they are strongly linked at our sites. Our 13-year datasets showed significant negative SO 4 2? trends at the 3 Ontario sites and a positive trend in Nova Scotia. A climatically-induced SO 4 2? increase in northwestern Ontario has been reversed. Mobilization and export of adsorbed SO 4 2? and/or reoxidized S from the basins of central Ontario sites is delaying their recovery. Two of our 9 stations (in Quebec and central Ontario) are continuing to acidify. The 2 Nova Scotia stations have the highest DOC levels and both exhibit a decreasing trend. Ionic compensation for declining SO 4 2? varies from station to station, sometimes involving an Alk increase, sometimes a base cation decrease, and sometimes more complex combinations. Additional factors (e.g. climatic variation) also influence variable trends, and data records longer than those presently available will be needed to unequivocally verify acidification recovery.  相似文献   

8.
A three month experimental study to evaluate the relative performance of three different designs of ‘event’ precipitation chemistry samplers was carried out at Woodbridge, Ontario beginning in August 1979. The samplers evaluated were an automatic Aerochem Metrics, ‘wet-only’ type (A), a funnel-and-bottle type (F), and a large-mouth plastic bucket with a specially-fabricated polyethylene bag insert (S). Each sampler was run in duplicate, with a sampling period of 24 hr. The results show that at sites where dry deposition is important, bulk samplers (‘F’ and ‘S’ types) yield significantly different results from the wet-only collector including rainfall amount, H+ , SO4 ?, NO3 ?, Na+, K+, Ca++, and Mg++. However, the bulk samplers, especially the ‘S’ type, are found to be satisfactory under certain conditions. For conditions which correspond to daily rainfall less than 2.8 mm and windier and drier sampling, there is even evidence of dry contamination of the wet-only type sampler.  相似文献   

9.
The Experimental Watershed Liming Study (EWLS) evaluated the application of CaCO3, to a forested watershed to mitigate the acidification of surface water. During October 1989, 6.9 Mg CaCC3/ha was applied by helicopter to two subcatchments of about 50% (102.5 ha) of the Woods Lake watershed area. The EWLS team investigated the response to treatment of soils (chemistry and microbial processes), vegetation, wetland, stream and lake waters, and phytoplankton and fish, and applied the Integrated Lake Watershed Acidification (ILWAS) model in predicting a watershed treatment duration of up to 50 years. Observations showed a gradual change in pH, acid neutralizing capacity (ANC) and Ca2+ in the water column; direct lake additions of CaCO3 (three different times) were characterized by abrupt changes following base addition and subsequent rapid reacidification. Moreover, the watershed treatment eliminated the snowmelt acidification of the near-shore region of the lake observed during direct lake treatments. Positive ANC water in the tributary and near-shore area improved conditions for fish reproduction and for a viable fish population. Budgets for 12-month periods before and after the watershed treatment showed that the lake shifted from a source of ANC to a sink due to retention of elevated inputs of Ca2+ from the watershed CaCO3 application.  相似文献   

10.
The Upper Midwest contains a large concentration of low alkalinity lakes located across a west to east gradient of increasing deposition acidity. We present temporal trends in the chemistry of 28 lakes (4 in Minnesota, 13 in Wisconsin, and 11 in Michigan) representative of the acid-sensitive resource of the region. Lakes were sampled three times per year between 1983 and 1989. Temporal trends in SO4 2? were all negative in direction, consistent with a regional decline in SO2 emissions and atmospheric SO4 2? deposition. However, these trends occurred predominantly in higher ANC (100 to 225 Μeq L?1), non-seepage lakes and were associated with increases in ANC and pH in only one of the 8 lakes. ANC decreased in a second group of lakes, usually in concert with decreased [Ca2++Mg2+], a response we associate with a severe drought. Disruptions in hydrologic flowpaths caused one lake to acidify rapidly after inputs of ANC-rich groundwater ceased and appeared to cause ANC and [Ca2++Mg2+] declines in a second lake by reducing stream-water inflow. Our analysis was thus complicated by hydrochemical effects of climatic variability, which confounded trends related to acidic deposition. Periods longer than 6 yr are needed to transcend climatic signals and verify subtle trends related to atmospheric pollutants.  相似文献   

11.
Between 1983–94, as acid deposition rates declined, SO4 2? concentrations decreased in 18 of 28 lakes monitored by the upper Midwest LTM program. The expected recovery of ANC and pH was less common, however. Differences in climate may account for divergent trend patterns across the region. Only in Minnesota, where climatic shifts were less pronounced, did we observe a general pattern of increasing lake ANC and pH accompanying declines in SO4 2?. In contrast, the widespread negative trends in lake SO4 2? in the upper Michigan lakes were generally not associated with recovery of ANC and pH, but with decreases in Ca+Mg. These cation decreases may be linked to decreased groundwater inputs during the drier climatic conditions characterizing the study period and decreases in Ca+Mg in atmospheric deposition. In many of the Wisconsin lakes, an overall decline in SO4 2? was precluded by SO4 2? increases during a 4-year drought midway through the study period. During the drought, declining lake water level and volume caused evaporative concentration of solutes, and may have decreased the areal extent of sulfate reduction. Despite controls on sulfur emissions across the region, recovery of pH and ANC has been hindered by climatic shifts and concurrent decreases in atmospheric deposition of cations.  相似文献   

12.
为了了解高原湖泊流域“3类空间”的布局结构,探析流域在发展过程中“3类空间”的格局变化及其变化趋势,本文以抚仙湖流域为研究对象,从土地功能空间分类的角度研究抚仙湖流域“3类空间”分类体系,并分析了2005—2015年流域“3类空间”时空格局变化特征,为抚仙湖流域生态环境保护决策和国土空间格局优化研究提供理论参考。结果表明:（1）2005—2015年抚仙湖流域城镇空间呈上升趋势,10 a增加了71.37%,农业空间呈下降趋势,10 a减少了6.38%,生态空间先升后降,总体增加了0.48%;（2）2005年、2010年和2015年抚仙湖流域“3类空间”格局基本一致,以生态空间为主,但城镇空间格局、农业空间格局和生态空间格局的分布存在明显差别,城镇空间和农业空间主要分布于抚仙湖流域的北部,而生态空间除抚仙湖湖泊水面外在流域四周均有分布;（3）从变化程度上看,“3类空间”格局变化差异显著,城镇空间和农业空间格局变化主要发生在流域北部,而生态空间则在湖泊中部沿岸地区。  相似文献   

13.
Twenty surface soils from four main Soil Groups in Malawi and their sub-soils were divided into three groups based on cation exchange capacity (group I, CEC < 50; group II, 50–100; and group III > 100μeq g–1). In each soil group the maximum amounts of K removed by successive extraction with 0.005 M CaCl2 solution were well related to the potassium potential pK–0.5p(Ca + Mg), exchangeable K, ‘step K’, and the quotient ‘step K’/CR.K, where CR.K is ‘constant-rate’potassium. In Group III soils only, ‘step K’/CR.K values were significantly correlated with pH, clay, and CEC, and this suggested that the soils were relatively rich in K+ specific binding sites. In 27 soils from an NPK factorial experiment on tea, the rate of depletion of extractable K reserve increased with ammonium sulphate treatment, whereas K fertilizers tended to off-set significantly (P= 0.001) the depletion of K reserve. The values for the change in free energy ΔG =RT In aK/ (a(Ca+Mg)) ½, ranged from –12 to –16 kJ mol–1, and field observations showed that tea plants growing on soils having ΔG values less than –15 kJ mol–1 responded to K fertilizers. The investigation has indicated that heavily cropped soils are likely to show crop responses if the intensive cropping system does not include supplementation of K.  相似文献   

14.
Yiyong  Zhou  Jianqiu  Li  Chunlei  Song  Xiuyun  Cao 《Water, air, and soil pollution》2004,159(1):395-407
Total alkaline phosphatase activity (APA) and soluble reactive phosphorus (SRP) concentrations were measured in municipal wastewater, and a shallow Chinese freshwater lake receiving it. Activities of Dissolved alkaline phosphatase (ADAP) in overlying and interstitial water were also analyzed monthly at three sites for several years. The lake was enriched with SRP and alkaline phosphatase by discharge of the wastewater, indicating that the inclusion of APA for estimating water pollution was reasonable. Annual data showed that APA in coarser fraction was significantly higher at the site receiving more wastewaters, both in surface and overlying water, suggesting that resuspension of enzyme most likely occurred in the basin heavily discharged. ADAP was an order of magnitude higher in the wastewater than those in lake waters, and was generally higher in interstitial water, a feature more striking at the site receiving more discharges. Besides, it was irrespectively inhibited by Na2WO4, L-cysteine and EDTA-Na, but stimulated by Cu2+, Zn2+, CTAB and Triton X-100 in interstitial, overlying and surface waters. This similarity of responding patterns to the stressors indicated an analogy between dissolved alkaline phosphatase in water column and that in interstitial water, supporting the hypothesis that the polluted sediments act as source of dissolved alkaline phosphatase in eutrophic lakes.  相似文献   

15.
The recovery potential of stream acidification from years of acidic deposition is dependent on biogeochemical processes and varies among different acid-sensitive regions. Studies that investigate long-term trends and seasonal variability of stream chemistry in the context of atmospheric deposition and watershed setting provide crucial assessments on governing biogeochemical processes. In this study, water chemistries were investigated in Noland Divide watershed (NDW), a high-elevation watershed in the Great Smoky Mountains National Park (GRSM) of the southern Appalachian region. Monitoring data from 1991 to 2007 for deposition and stream water chemistries were statistically analyzed for long-term trends and seasonal patterns by using Seasonal Kendall Tau tests. Precipitation declined over this study period, where throughfall (TF) declined significantly by 5.76?cm?year?1. Precipitation patterns play a key role in the fate and transport of acid pollutants. On a monthly volume-weighted basis, pH of TF and wet deposition, and stream water did not significantly change over time remaining around 4.3, 4.7, and 5.8, respectively. Per NDW area, TF SO4 2- flux declined 356.16?eq?year?1 and SO4 2- concentrations did not change significantly over time. Stream SO4 2- remained about 30???eq L?1 exhibiting no long-term trends or seasonal patterns. SO4 2- retention was generally greater during drier months. TF monthly volume-weighted NH4 + and NO3 - concentrations significantly increased by 0.80???eq L?1?year?1 and 1.24???eq L?1?year?1, respectively. TF NH4 + fluxes increased by 95.76?eq?year?1. Most of NH4 + was retained in the watershed, and NO3 - retention was much lower than NH4 +. Stream monthly volume-weighted NO3 - concentrations and fluxes significantly declined by 0.56???eq L?1?year?1 and 139.56?eq?year?1, respectively. Overall, in NDW, inorganic nitrogen was exported before 1999 and retained since then, presumably from forest regrowth after Frazer fir die-off in the 1970s from balsam wooly adelgid infestation. Stream export of NO3 - was greater during winter than summer months. During the period from 1999 to 2007, stream base cations did not exhibit significant changes, apparently regulated by soil supply. Statistical models predicting stream pH, ANC, SO4 2-, and NO3 - concentrations were largely correlated with stream discharge and number of dry days between precipitation events and SO4 2- deposition. Dependent on precipitation, governing biogeochemical processes in NDW appear to be SO4 2- adsorption, nitrification, and NO3 - forest uptake. This study provided essential information to aid the GRSM management for developing predictive models of the future water quality and potential impacts from climate change.  相似文献   

16.
Acid sensitive headwater lakes (n=163) throughout Finland have been monitored during autumn overturn between 1987–1998. Statistically significant decline in sulphate concentration is detected in 60 to 80 percent of the lakes, depending on the region. Median slope estimates are from ?1.1 µeq L?1 in North Finland to ?3.3 µeq L?1 in South Finland. The base cation (BC) concentrations are still declining especially in southern Finland (slope ?2.5 µeq L?1), where every second lake exhibits a significant downward trend. The BC slope is steeper for lakes with less peatlands, more exposed bedrock, longer retention time and southerly location, but these factors are inter correlated. Gran alkalinity slope medians for the three regions range from 1.4 to 1.8 µeq L?1 yr?1. No significant negative alkalinity trends were detected. The similarity in the slopes of SO4, BC and alkalinity in this data compared to seasonal sampling data from Nordic Countries can be regarded as indirect evidence that autumnal sampling is representative for long term monitoring for these ions. There are no indications of increased organic carbon in lakes, as found in some recent trend analyses of similar regional data sets. Although the processes behind the positive development in these lakes have to be revealed with site- specific intensive studies, this data suggests, that the initial recovery from lake acidification in Finland is a regional phenomenon.  相似文献   

17.
The effects of artificial precipitation with different pH levels on soil chemical properties and element flux were studied in a lysimeter experiment. Cambic Arenosol (Typic Udipsamment) in monolith lysimeters was treated for 6 1/2 yr with 125 mm yr?1 artificial rain in addition to natural precipitation. Artificial acid rain was produced from groundwater with H2SO4 added. pH levels of 6.1, 4 and 3 were used. ‘Rain’ acidity was buffered, mainly due to cation exchange with Ca2+ and Mg2+, which were increasingly leached due to the acid input. The H+ retention was not accompanied by a similar increase in the output of Al ions, but a slight increase in the leaching of Al ions was observed in the most acidic treatment. The net flux of SO4 2? from the lysimeters increased with increasing input of H2SO4, but in the most acidified lysimeters significant sorption of SO4 2? was observed. The sorption was, however, most likely a concentration effect. The ‘long-term’ acidification effects on soil were mainly seen in the upper O and Ah-horizons, where an impoverishment of exchangeable Ca2+ and Mg2+ was observed. An increased proportion of Al ions on exchange sites in the organic layer was observed in the pH 3-treated soil. By means of budget calculations the annual release of base cations due to weathering was estimated to be between 33 and 77 mmolc m?2.  相似文献   

18.
The International Cooperative Programme on Integrated Monitoring (ICP IM) is part of the effects monitoring strategy of the UN/ECE Convention on Long-Range Transboundary Air Pollution. We calculated input-output budgets and trends of N and S compounds, base cations and hydrogen ions for 22 forested ICP IM catchments/plots across Europe. The site-specific trends were calculated for deposition and runoff water fluxes and concentrations using monthly data and non-parametric methods. The reduction in deposition of S and N compounds, caused by the new Gothenburg Protocol of the Convention, was estimated for the year 2010 using atmospheric transfer matrices and official emissions. Statistically significant downward trends of SO4, NO3 and NH4 bulk deposition (fluxes or concentrations) were observed at 50% of the ICP IM sites. Implementation of the new UN/ECE emission reduction protocol will further decrease the deposition of S and N at the ICP IM sites in western and northwestern parts of Europe. Sites with higher N deposition and lower C/N-ratios clearly showed an increased risk of elevated N leaching. Decreasing SO4 and base cation trends in output fluxes and/or concentrations of surface/soil water were commonly observed at the ICP IM sites. At several sites in Nordic countries decreasing NO3 and H+ trends (increasing pH) were also observed. These results partly confirm the effective implementation of emission reduction policy in Europe. However, clear responses were not observed at all sites, showing that recovery at many sensitive sites can be slow and that the response at individual sites may vary greatly.  相似文献   

19.
We examined the influence of a forested landscape on the quality of water in a stream originating on an urban landscape and flowing through National Forest lands. Sample sites included an urban stream (URB), a site on the same stream but within a National Forest (FOR) and 2 km downstream from the URB site, and a small, undisturbed, forested reference tributary of the main stream (REF). We monitored stream water quality from March 2002 through June 2003. Average base flows for the three stream sites were URB = 184 L s?1, FOR = 420 L s?1, and REF = 17 L s?1. We analyzed weekly stream water samples for NO3 ?, NH4 +, PO4 +, Cl?, K, Ca, Mg, SO4, SiO2, pH, conductivity, total suspended solids (TSS), and bacteria on a monthly basis. Most solutes were higher in concentration at the URB site, as were conductivity, TSS, and bacteria counts. Reductions in NO3 ?, NH4 +, and PO4 + concentrations between the URB and FOR sites were inferred from changes in nutrient:chloride ratios. Bacteria populations were greater and more responsive to stream temperature at the URB site. Water quality responses to changes in stream discharge varied among sites but were greater at the URB site. By all measures, water quality was consistently higher at the FOR site than at the URB site.  相似文献   

20.
In 1986 Lake Langedalstjenn in southern Norway was a weakly acidified lake with a pH of 5.2–5.6, and an average concentration of SO4 of 330 μeq L?1. The total Al concentration varied between 10 and 20 μeq L?1 (expressed as Al3+). The lake supported populations of brown trout and perch and had supplied about 100 people with drinking water until the late 1980's. During 1986–1989, a dramatic change in the water chemistry occurred because of blasting of and weathering of sulphidic gneisses in the watershed. The oxidation of sulphide to sulphate (sulphuric acid) caused an increase in the SO4 concentration of the draining stream of up to ≈ 4800 μeq L?1. Weathering and/or cation exchange of Ca and Mg neutralized approximately 52% of the protons from the sulphuric acid production, while about 46% were consumed by mobilization of aluminium and iron. Nevertheless, about 2% of the hydrogen ions from the sulfuric acid were still present, which resulted in a stream pH of 4.0. In the lake, the pH was 4.4, and the concentrations of all major cations and anions were significantly lower than in the heavily affected stream. Mixing of the stream water with lake water, formation of aluminium-sulphate complexes and coprecipitation of Ca may explain the resulting concentrations of major ions in the lake.  相似文献   

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