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1.
This study provides an assessment of the transport of organic carbon and organic acids from typical Finnish forested catchments since the 1960's. The 21 study catchments (0.69–56 km2) are located over Finland excluding the northernmost regions. The mean annual total organic carbon (TOC) load from the catchments ranges from 2 600 to 8 800 kg/km2/a. Using a total acidity of 9.7 eq/mg DOC this would represent organic acid load of about 25–85 keq/km2/a which is higher than the mean annual deposition of strong acids in the highest deposition areas in southern Finland. The study demonstrates that organic acids dominate stream water acidity over large regions in Finland. In southern Finland minerogenic acidity is, however, more important. Organic acids exceeded mineral acids not only in autumn but also during spring snowmelt in 18 catchments. Moreover, the lowest pH values (25th percentile) were dominated by organic acids in 20 catchments. In most catchments TOC better explained pH than non-marine sulphate. In stepwise multiple regression base cations and TOC explained 67–83 % of the variation in pH for catchments divided into six groups according to season, deposition and peatland percentage; non-marine sulphate had minor contribution.  相似文献   

2.
Greater acidity and substantially higher annual deposition of the major ions, were recorded in the precipitation at Glencree (Co. Wicklow) on the east coast of Ireland compared to those recorded at the west coast sampling stations. The daily average deposition of hydrogen ions, non-marine sulphate and oxidized nitrogen was higher at all sampling locations when associated with air masses arriving from the east compared with those from the west, particularly at Glencree. The impact of emissions from the coal-fired power station at Moneypoint (Co.Clare) on the precipitation was negligible at all sampling locations except at Gortglass, a point 19 km to its east. At this sampling point the higher concentrations and deposition for hydrogen ion and non-marine sulphate were associated with air masses expected to show the influence of the Moneypoint power station.  相似文献   

3.
The primary objective of this monitoring is to detect long-term Long-Range Transboundary Air Pollution (LRTAP) induced changes in the water quality of small lakes, throughout Finland, with low conductivity. The monitored lakes (n=171, sampled every autumn since 1990 and in 1987) have a smaller watershed (usually headwater or seepage lakes), a larger lake/catchment ratio, and lower base cation concentrations, alkalinity and pH than Finnish lakes on average. The monitoring network provides background data for air pollution dose/response studies, critical load calculations and for the modelling of acidification scenarios. The declining sulphate deposition seems to be reflected in small headwater lakes all over southern and central Finland as a lowering of the sulphate concentration in the waters. Nitrate concentrations in these lakes have been typically low in the autumn. The base cation concentration is not generally declining, as it is in deposition in many areas. The sulphate concentration in lakes has declined more than base cations. Hydrologically, the recent years have been quite variable because of varying annual precipitation. The variation in alkalinity and pH in typical Finnish lakes is dependent on the content of humic material derived from catchments. The monitoring period is too short to reveal consistent trends in major ion chemistry. However, signs of improvement in recent years can be seen; in comparing 1993 to 1987, years with similar organic acidity and base cations, it seems that the sulphate decline in lakes monitored is compensated by a significant rise in both alkalinity and pH.  相似文献   

4.
Trends in the precipitation-weighted average concentrations and in the deposition of inorganic ions in daily precipitation samples at three Finnish background stations were calculated for a period extending from the seventies to 1988. During the period 1973–1988, S04 2? concentrations in wet deposition at the station in Central Finland decreased by 39% in accordance with the emission decrease of SO1 in Finland of 50% over the same period, and the 20% decrease in Europe from 1980 to 1988. However, due to the more significant decrease in alkaline ions (80% for Mg2+), H+ concentrations increased by 30%. At the two southernmost stations, overall concentrations are higher and the decrease of Mg2+ and Ca2+ is less important, but at the station in southeastern Finland the increase of N03 ? relative to NH4 + has doubled H+ concentrations during the period 1977–1988. Division of the data according to wind direction sectors showed generally decreasing concentrations in the sectors related to Scandinavia, but unchanging or increasing concentrations in the sectors related to eastern Europe. Acid deposition trends were estimated as H+, S04 2? - (Ca2+ + Mg2+), and H+ + NH4 + - N03 +. All these trends showed increasing acid deposition in central Finland and decreasing trends in western Finland. In eastern Finland the trends were opposing due to the increasing N03 + but decreasing NH4 ? trends. It is concluded that S04 2? deposition trends do not reflect acid deposition trends, and SO4 2? or N03 ? deposition do not geographically represent acid deposition.  相似文献   

5.
1960-2009年青海省极端降水事件的变化特征   总被引:4,自引:0,他引:4  
利用1960-2009年青海省26个气象台站的降水资料,采用线性倾向估计法、反距离加权法、M—K突变检测等方法,研究了青海省50a来极端降水事件变化的空间分布以及时间变化特征。结果发现,近50a来,青海省极端降水天数、最大的1d和5d降水总量、中雨天数和逐年平均降水强度均表现为增加(强)趋势,只有极端降水天数通过了0.05的置信度检验;各极端降水指数变化趋势存在空间差异,祁连山地区极端降水天数、最大的1d和5d降水总量、中雨天数和逐年平均降水强度增加趋势明显,青海省东部地区增加不明显或呈微弱减少趋势;青海省极端降水事件在0.05的置信度下发生了明显的突变现象,且各极端降水指标与年降水总量有很好的相关性。  相似文献   

6.
李成    王让会    黄进 《水土保持研究》2013,20(6):117-124
根据天山北麓8个气象站1961—2010年气温和降水资料,采用线性趋势分析、Mann-Kendall检验、Hurst指数等方法,分析了天山北麓气温和降水的变化特征。结果表明:(1)50 a来,天山北麓年平均气温和年降水量均呈增加趋势,其变化率分别为0.26 ℃/10 a、15.67 mm/10 a;冬季增温最为明显,升温幅度达0.49℃/10 a左右,降水倾向率表现为夏季最大,为5.44 mm/10 a;(2)年平均气温和年降水量的突变年份分别在1996年和1983年;未来两者整体上呈增加趋势;(3)极端高(低)温指数在近50 a呈现增加(减少)趋势;极端降水指数中零降水日数和最长连续无降水日数呈不同程度的递减趋势,1日最大降水量和极端强降水日数以1.36 mm/10 a和1.81 d/10 a的速率递增,各极端气候指数空间差异明显;极端气温指数与年平均气温、极端降水指数与年降水量均有很好的相关性。  相似文献   

7.
Acid deposition and its effect on Andisols were investigated in the forest experimental station, the Rolling Land Laboratory (RLL), located in the Tama Hill region of Central Japan. The annual volume-weighted mean pH value of open bulk precipitation was 4.8 in the period 1990 to 1992. Nitrate deposition at RLL was larger than for sulfate, which was obviously different from results in Japan Environment Agency (JEA) stations or in study areas of Europe and North America. Abundant nitrate deposition was ascribed to the high emissions from a non-point source, mainly cars. Although sulfate concentration in throughfall fluctuated, its concentration in soil solution was kept at a low level. This was attributed to the high sulfate adsorption capacity of the Andisols.  相似文献   

8.
Snowpack quality has been systematically monitored in Finland since winter 1975/1976 by the Finnish Environment Agency. Snow samples have been taken at the 53 groundwater observation stations in nearly natural state areas, where the impacts of local emission sources have been negligible. Thus the concentrations of impurities in snow can be considered as background levels. Samples were analyzed for conductivity, pH, major ions and trace metals (Cd, Cu, Pb, Ni, Zn and Hg). The regional variation of the chemical composition of major ions in the snowpack was outlined by cluster analysis. Sampling sites were divided into six clusters by average linkage clustering method. The largest cluster — considered as the ‘mean cluster’ — was located in central and northern Finland. The lowest levels of the total amount of dissolved impurities occurred in the cluster formed by the most northern observation site exclusively. Highest rates of the acidifying components, sulphate (SO4), nitrate (NO3), ammonium (NH4) and hydrogen ions (H+), were encountered in southern Finland. Sampling locations of southern Finland were divided into three clusters. The acidity of snow varies among these clusters that in addition of deposition of SO4 and NO3 is considerably controlled by alkaline deposition. The results of chemical analyses of snow were converted to mean monthly depositions using the water equivalent of snow and the time of deposition. Deposition of SO4 during 1985–1993 was 32% lower compared with the period 1976–1984, which presumably results from 70% reduction of sulphur emissions in Finland since the beginning of the 1980s. The deposition level of NO3-N seemed to stay relatively stable during the whole 18 year period while the deposition of NH4-N has decreased 18%.  相似文献   

9.
The need to estimate the amount and pattern of air pollutants has resulted in the establishment of acid precipitation monitoring networks throughout northeastern North America. Information content measures are developed to examine the impact of station addition or removal on the ability of a network to estimate the deposition field. Also examined is the utility of standard precipitation network information to improve the acidic deposition estimates. The techniques are demonstrated through the estimation of the annual sulphate deposition field in southern Ontario for the years 1981 through 1984.  相似文献   

10.
1960-2012年淮河流域极端气温变化特征   总被引:1,自引:0,他引:1  
基于1960-2012年淮河流域28个气象站点的逐日最高气温和最低气温观测资料,选取12个具有代表性的极端气温指数,采用线性倾向法、Mann-Kendall法和小波分析法研究淮河流域极端气温指数的变化特征.结果表明:(1)研究区冷夜、冰冻、霜冻曰数分别以4.08、0.78、5.10d·10a-1 (P<0.05)的速率下降,暖夜、夏季、热夜分别以1.87、2.08、2.82 d·10a-1 (P<0.05)的速率上升,日最高(低)气温的极小值、日最低气温的极高值的变化率分别为0.34 (0.62)、1.80℃·10a-1 (P<0.05),而冷昼、暖昼以及日最高气温极高值的变化并不显著.(2)28个气象站点极端气温指数的变化在空间分布上存在着较大的差异,冷指数中冷昼、冷夜、冰冻和霜冻曰数(日最高和最低气温的极低值)在淮河中下游地区的降幅(升幅)较大,上游地区站点的变化则相对较小.暖指数变化较大的站点主要分布在流域的东部和南部地区,西部与北部地区站点的变化不够明显.(3)冷指数的突变主要发生在20世纪80年代,而暖指数的突变则主要发生在2000年左右,与冷指数的突变相比,暖指数的变化表现出后延性、稳定性和持续性的特征.(4)冷、暖指数分别存在着4类和3类尺度的时间变化规律,暖指数的周期变化较冷指数更具稳定性,尤以10a时间尺度下的周期变化最为典型.  相似文献   

11.
利用修河流域主要控制站万家埠、晋坪和虬津水文站实测最大洪峰流量序列,采用Mann-Kendall检验法和小波分析等方法,对修河洪水极值流量的趋势性、突变性及周期性进行了分析,并探讨了洪水极值流量变化与厄尔尼诺-南方涛动(ENSO)、北大西洋涛动(NAO)、太平洋-北美型(PNA)、东亚夏季季风指数(EASMI)、南中国海夏季季风指数(SCSMI)、太阳黑子(SS)、西太平洋型(WP)等15个气候指标之间的相互关系。结果表明:万家埠站年最大流量表现为不显著减少趋势,晋坪和虬津2站年最大流量表现为不显著增加趋势。万家埠站年最大洪峰流量突变点为1972年,在1972年后最大洪峰流量发生由减少到增加的突变;晋坪站年最大洪峰流量突变点为1977年,在1977年后最大洪峰流量发生由增加到减少的突变;虬津站年最大洪峰流量突变点为1990年,在1990年后最大洪峰流量发生由减少到增加的突变。修河流域万家埠、晋坪和虬津站年最大洪峰流量系列在时频域中都存在着不同尺度的周期,既有2~8年的短振荡周期,也有超过20年的长振荡周期。除万家埠站最大洪峰流量存在22年显著周期,其余周期均不显著。修河流域年最大洪峰流量与ENSO,EASMI,PNA和WP均呈显著相关(p<0.05)。研究结果可为修河中长期洪水预报提供参考。  相似文献   

12.
Integrated assessment models were applied to analyze the side-benefits of structural changes in the energy systems of Finland and the EU to reduce acidity critical load exceedances in Finland. The acidification reduction potential of structural measures, induced by the need to restrict carbon dioxide (CO2) emissions, was compared with international agreements limiting acidifying emissions. The impacts of the UN/ECE Gothenburg protocol and the European Commission's proposal for a National Emission Ceilings (NEC) Directive were assessed together with domestic and bilateral policy scenarios. The study utilized point-source emission databases of Finland and the neighboring areas and a meso-scale deposition model together with the Europewide transfer matrices of the EMEP/MSC-W and European emission scenarios of IIASA. Further technical reduction measures in the adjacent large sulfur emission sources in Russia would reduce considerably deposition to nearby Finnish areas. Energy saving and shifts in the EU energy system towards less carbon-intensive fuels instead of further technical emission controls were found to have significant potential in limiting acidifying deposition. Implementation of the Kyoto protocol in the EU could reduce the Finnish areas at risk of acidification more than the Gothenburg protocol and the NEC Directive together.  相似文献   

13.
The causal factors for episodic deposition of acidic material in rainfall cannot be fully understood from conventional daily network data. A brief review of the meteorological conditions leading to episodes is given. A definition of ‘episodicity’ was considered and applied to a 6 month data set collected at high temporal resolution using a microprocessor based acid rain monitor at a site in south-east England. The deposition was highly episodic for all of the measured variables when data from individual rain events were considered. Combining the data into daily averages resulted in changes of episodicity classification for several chemical species. A large percentage of the total deposition recorded during the field experiment occurred in a 5 day period when there was an independent report of ecological damage at other locations in England. Nitrate deposition showed the highest degree of episodicity with 51% of the 6 month total occurring during the 5 day episode. Meteorological details of the transport and wet deposition processes during this period were examined. Back trajectory analysis indicated that the episode was the result of pollutant loading in eastern and central Europe of the air masses reaching the site together with an absence of upwind precipitation scavenging.  相似文献   

14.
黄河流域极端气温指数的气候演变特征分析   总被引:1,自引:0,他引:1  
利用黄河流域1963-2013年59个站点日最高和最低气温资料,结合线性拟合、M-K检验、Morlet小波分析、主成分分析及相关性分析等方法,研究了该流域极端气温的时空变化特征。结果表明:(1)整体上看,黄河流域冷日、冷夜、冰日、霜冻、冷持续日数分别以1.06、1.93、2.40、3.36、1.12d·10a-1 (P<0.001)的趋势减少,而暖日、暖夜、夏日、热夜、暖持续日数、生物生长季分别以1.56、2.22、2.66、1.56、1.48、3.47d·10a-1 (P<0.001)的趋势增加,日最低气温极小(大)值、日最高气温极小(大)值及气温日较差的变化率分别为0.25(0.4)、0.18(0.27)、-0.09℃·10a-1 (P<0.05)。(2)研究区内6个子区域的极端气温指数的变化趋势相一致,宁夏中北部、内蒙古中南部极端气温事件变化趋势最为显著。(3)夜指数(暖夜、冷夜)变化幅度大于昼指数(暖日、冷日),冷指数(极端最低、最高温度极小值)变化幅度小于暖指数(极端最低、最高温度极大值)。(4)黄河上中游比下游地区对极端气温变化更敏感。(5)WMO发布的16个指数均有3a、7a左右的短周期和26a左右的长周期,而暖(冷)持续日数、气温日较差、生物生长季还拥有一个16a左右的中长周期。(6)除日最低气温极小值、气温日较差、冷持续日数外,其余各项指数的突变年份均发生在20世纪90年代。  相似文献   

15.
The St. Lawrence North Shore region (Québec) is subject to acid precipitation entailing sulphate deposition (17 to 22 kg SO4 2? ha?1 yr?1) which poses a threat to sensitive aquatic ecosystems. Physicochemical surveys conducted in 1982–1983 revealed the extreme sensitivity of the region owing to weak mineralization of the waters (mean alkalinity of 55 μeq L?1 and conductivity of 17 μS cm?1). Calculation of the annual loads of S discharged from 21 rivers throughout the region shows atmospheric deposition as the principal source of sulphate. A decreasing west-east gradient in the concentration is interpreted in terms of the impact of long-range airborne transport, although certain local sources of S emission are not to be overlooked. Analysis of the seasonal variation in the sulphate load balance, conducted in a small drainage basin (40 km2), revealed that the sulphate anion plays a part in lowering the water pH in spring. The spring pH depression is apparently intensified by an additional input of sulphate stemming from the release of this element subsequent to accumulation in the drainage basin during summer and fall. Organic acids play a measurable role in the chemical equilibrium of surface waters in the region, particularly in the eastern sector where there is less S fallout. Low pH levels in this sector (5.5 to 6.0) point to some degree of organic acidification.  相似文献   

16.
The results of rainwater analyses collected at five sampling sites within Kvarner Bay area are presented for the period 1984–1991. The samples were collected on a daily basis in open buckets thus representing bulk samples. Although measurements are referred to as wet deposition samples, they are actually an upper limit for the wet deposition. The rainwater was initially analysed for pH, sulphate and nitrate content, while during the period March 1990 — May 1991 the analyses were extended to major ion concentrations: hydrogen, sulphate, nitrate, chloride, ammonium, sodium, potassium, calcium and magnesium. The pH frequency distribution, pH medians and precipitation weighted average (PWA) concentrations of hydrogen, sulphate and nitrate are presented, as well as wet deposition rates of sulphur (as sulphate) and nitrogen (as nitrate). The dependence of hydrogen, sulphate and nitrate mean concentrations on wind directions and seasons for Site 1 is also given. The highest precipitation acidity is obtained at urban and industrial Site 1 (city of Rijeka) because of the local washout of the atmosphere and influence of dry deposition, and at remote Site 4 (Lake Vrana) due to long-range transport. The neutralizing potential of sea salt and soil dust is responsible for partial neutralization of rainwater at other sites. The influence of sea salt on chemical composition of rainwater is observed at all sites. The estimated wet deposition rates of sulphate and nitrate are close to the values reported for Southeast Europe. The wet deposition rate for ammonium ion at Site 1 is almost double comparative regional values.  相似文献   

17.
The Kostomuksha mining complex in Russian Karelia is a major emission point source surrounded by large forest areas near the Finnish border. The sulphur dioxide emissions of the complex are almost 60 000 tonnes and dust emissions about 5 000 tonnes a year. Research into the effects of emissions on the surrounding forests were started in a Finnish-Russian co-operation project in 1992. Deposition measurements during the two first years indicate that the effects of the emissions extend about 30 km to the west of the complex. The annual sulphur deposition near the mining complex has been about 300 mg/m2 in bulk precipitation and about 500 mg/m2 in throughfall. Sulphur emissions sometimes extend the eastern parts of Finland, but there the deposition is clearly smaller than near to the mining complex. The high calcium emissions neutralize the acidifying effect of sulphur near to the mine and smelter. The iron concentration in precipitation also increased near the complex. Sulphur and calcium decreased in percolation water on moving westwards.  相似文献   

18.
The characteristics of acidic deposition at Kejimkujik National Park, a rural site in south-central Nova Scotia, were determined for the period from May 1979 to December 1983. The acidifying pollutants investigated were H+, sulphate ion and nitrate ion. Thirty per cent of the total annual amount of acidifying pollutants deposited by precipitation at Kejimkujik was deposited by only about 8% of the precipitation events during the year. These occasions of large deposition are referred to as episodes and occurred, on average, about five times per year, usually between March and November. The precipitation events that produced episodes were almost always rain events. The major meteorological feature producing deposition episodes at Kejimkujik is the sequence of a large high pressure area from mid-continent moving south of Nova Scotia, producing a prolonged southwesterly to westerly flow over the site, and then a weak frontal system, usually from south of the Great Lakes region, bringing moderate amounts of precipitation to the site. Since deposition episodes were almost always preceded by the above sequence of events, the ability to predict episodes was investigated. The results indicate that many “false alarms” could be anticipated because this sequence also occurs for non-episodes.  相似文献   

19.
近45年来浏阳河流域极端降水变化   总被引:1,自引:0,他引:1  
利用1969—2013年浏阳河流域12个雨量站的降水资料,结合百分位方法定义极端降水阈值,采用线性回归、滑动平均、Mann-Kendall检验、累积距平联合滑动t检验和Morlet小波分析等方法分析了极端降水指数的演变规律。结果表明:(1)极端降水量、极端降水强度、极端降水比率表现为上升趋势,10年上升率分别为7.3mm,9.5mm/d,0.3%,极端降水日数表现为下降趋势,下降率为-0.054d/10a。(2)极端降水量、极端降水强度分别在1991年、1992年存在明显突变,极端降水日数、极端降水比率突变不显著。(3)极端降水指数均存在7~8a,10~11a和25~27a的主周期,且丰枯交替变化明显。研究结果对于指导浏阳河流域的防洪减灾具有重要意义。  相似文献   

20.
黑河流域上游水沙变化特征及成因分析   总被引:2,自引:1,他引:1  
[目的]研究黑河流域上游干流的水沙时空变化特征及其成因,为流域生态保护和水资源开发利用提供科学依据。[方法]选取黑河上游干流主要水文站近60a的实测径流、输沙及降雨资料,通过采用Mann-Kendall秩相关检验法、累积距平法和相关分析法,研究水沙变化特征及驱动因子。[结果]黑河上游干流径流量总体上从20世纪80年代以后呈增加趋势;输沙量从20世纪70年代开始呈不显著增加趋势,但莺落峡水文站输沙量从2001年开始呈显著下降趋势。[结论]降水增加是影响黑河上游径流量增多的重要原因;水土流失导致了札马什克站和祁连站输沙量的增加,而水库拦沙是莺落峡水文站输沙量显著减少的主要原因。  相似文献   

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