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1.
Diatoms were identified and enumerated from a surface sediment calibration set of 50 lakes in northwestern Québec. The relationship
between species composition and environmental variables was examined using canonical correspondence analysis (CCA). Forward
selection and Monte Carlo permutation tests in CCA indicated that diatom species distributions in the data set are most strongly
correlated to lakewater pH. A strong (r
2
boot = 0.83) weighted averaging calibration model, that includes bootstrapped error estimates, was developed for inferring past
lakewater pH. Using this model, temporal changes in pH were reconstructed for two kettle lakes, Lac de la Pépinière and Lac
Perron. Based on limnological data, both the study lakes were expected to have recently acidified due to increased acidic
precipitation and increases in anthropogenic metal loading. However, our long-term pH inference data indicate that these lakes
were naturally acidic during pre-industrial times. Nonetheless, the rate of acidification, particularly in Lac de la Pépinière,
has accelerated in the last ∼75 years. These long-term pH records developed for the dilute lakes in northwestern Québec suggest
that the region has received increased atmospheric pollutants from the nearby Horne smelter in Rouyn-Noranda. The pH inference
profiles are markedly different from many other paleolimnological studies in acid-sensitive regions of Canada that have become
acidic primarily as a result of industrial activities.
Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users. 相似文献
2.
Significant population growth over the last three decades, as well as efforts to improve surface-water quality mandated by the Clean Water Act, potentially have had opposing influences on aquatic ecosystems in the U.S. Because historical data on water-quality trends are limited over this time period, we developed a diatom-based transfer function to reconstruct chloride, color, acid neutralizing capacity (ANC), total phosphorus (TP), and pH in 55 Minnesota lakes. The lakes span three different ecoregions, as well as the Twin Cities metropolitan area, and differ in their history of settlement and land use, and in surficial geology, climate, and vegetation. Lakes in the Northern Lakes and Forest ecoregion are nearly pristine, whereas those in the other regions likely are strongly affected by urban or agricultural pollutants. Reconstructions of water-chemistry trends since 1970 suggest that recent human activities have had substantial impacts in both urban and rural areas. Chloride concentrations have increased in many Metro lakes, which may be due to road salts, and phosphorus levels have been steady or rising in agricultural regions. The majority of Metro lakes show some decline in TP, although many of the changes are not statistically significant based on our reconstruction techniques. There is no evidence that atmospheric deposition of sulfate or nitrate has caused acidification or changes in trophic state for remote lakes in the northeastern part of the state. 相似文献
3.
J.?GuoEmail author R.?D.?Vogt X.?Zhang Y.?Zhang H.?M.?Seip H.?Tang 《Environmental Geology》2004,45(8):1148-1153
Exchange reactions between Ca2+, H+ and Al species and their effects on the aluminium mobility in two Chinese acidic forest soils were studied. The study was based on a batch experiment using extractant solutions with different base cation (calcium) concentrations and pH. The experimental data showed that increased Ca2+ concentrations increased the release of soil hydrogen—and aluminium ions, especially from the more acid soil. In agreement with a cation exchange process, the treatment with Ca2+ extracts gave significantly decreased soil aluminium saturation (AlS) and increased calcium saturation (CaS) on the ion exchanger. Geochemical calculation using AlCHEMI program showed that activities of Al3+ in the extracts were all strongly under-saturated with respect to any gibbsite mineral in the studied pH region (i.e. below 4.1). There were instead apparently two different mechanisms controlling the activities of Al3+ in extracts. At pH between about 4.1 and 3.7, the Al3+ activity did not change significantly with pH. This is especially the case in the more acid soil. Apparently there are no sizeable pools available to release Al in this pH region. At pH below 3.7 (induced by higher Ca2+concentration) the activity of Al3+ increased with H+ though not in a pattern that complies with a gibbsite solubility control. An increase of base cation deposition would therefore mainly enhance the release of hydrogen ions between pH 4.1 and 3.7 and aluminium ions below pH 3.7 from Chinese mature acidic soils. This will cause an increased acidity of soil water in the short term and a decrease in the soil acidity in the long term. More attention should be paid to this fact in Chinese acid rain studies and control options. 相似文献
4.
Acidification of freshwater ecosystems changes phytoplankton biomass and reduces species composition. However, there are contradictory statements with respect to the occurrence of cyanobacteria below pH 4.5. Textbooks have not reported cyanobacteria in acid and very acid environments, whereas only a few papers on acidification of lakes through acid precipitation noted the occurrence of cyanobacteria in those environments. In a phytoplankton survey of 10 lakes in the Bavarian Forest as well as the lignite mining districts of Bavaria (Upper Palatine) and Lusatia, covering a pH gradient from 8.0 to 2.8, we demonstrate that acid-tolerant cyanobacteria do exist. Most strikingly, one of the most acid lakes (pH 2.9), Lichtenauer See (Lusatia), was inhabited by two populations of filamentous cyanobacteria, resembling Oscillatorial/Limnothrix and Spirulina spp. Eukaryotic phytoplankton was almost absent in this lake at the time. In contrast to filamentous cyanobacteria, picoplanktic ones were totally lacking where pH < 4.5. This indicates that members of coccal picoplanktic cyanobacteria and filamentous cyanobacteria have different acid tolerances. At present, it is not known how the acid-tolerant cyanobacteria described here maintain a strong transmembrane pH gradient. 相似文献
5.
Environmental impact of uncontrolled waste disposal in mining and industrial areas in Central Germany 总被引:7,自引:0,他引:7
P. Schreck 《Environmental Geology》1998,35(1):66-72
The present-day landscape in Central Germany, in particular the region of Leipzig, Halle and Bitterfeld, is characterized
by the scars of former industrial activities. Vast districts have been devastated by lignite strip mining. Industrial and
domestic waste, residues from ore smelting, and highly toxic waste products from petrochemical plants and pesticide production
were deposited in abandoned pits near population centers. The chief effects of waste on the environment are the contamination
of groundwater by dissolved pollutants, the acidification of soil and water by the oxidation of pyrite-containing mining waste,
and the salinization of shallow aquifers by rising brines from adjacent confined groundwater affected by mining. The consequences
for the region are serious: mining lakes used for recreational purposes are contaminated by leachates from adjacent waste
dumps. Pyrite-containing refuse from lignite mining under oxidation gives rise to the acidification of surface and groundwater,
a basic condition for pollutant mobilization. In former metal mining districts, metalliferous and radioactive residues from
smelting jeopardize public health. These effects are described in detail using three case studies.
Received: 30 July 1996 · Accepted: 24 February 1997 相似文献
6.
C. Neal S. Lofts C. D. Evans B. Reynolds E. Tipping M. Neal 《Aquatic Geochemistry》2008,14(3):263-288
Iron distributions in rainfall, streams, soils and groundwaters are described for the Upper River Severn catchment of mid-Wales.
Iron is mainly supplied from within-catchment sources with highest concentrations occurring under reducing conditions. Iron
concentrations have doubled over the past 20 years (~5.0 μg yr−1 for the forest and ~3.7 μg yr−1 for the moorland). For the forested sites, the gradients are particularly high post-1993. UK rivers/lakes monitored by the
UK Acid Waters Monitoring Network show similar increases. Generally, Fe correlates with dissolved organic carbon (DOC). The
greatest rates of Fe increase coincide with those for DOC. Thermodynamic modelling using WHAM/Model VI indicates that Fe(III)
is mainly in microparticulate form (probably oxyhydroxides) apart from under reducing conditions. It is proposed that Fe increases
for surface waters are associated with increased microparticulate Fe(III) due to stabilisation against aggregation by binding
of DOM to its surface. The results relate to acidification declines and deforestation leading to land disturbance and wetter
conditions within the soil. There will be greater acidification reversal following tree harvesting due to lowering of atmospheric
SOx scavenging and this may have resulted in the greater increase in Fe in the later years of the study. 相似文献
7.
J. Sjöström 《Environmental Geology》1993,21(4):219-226
The groundwater chemistry of 14 shallow wells and 10 springs in Halland, southwest Sweden, and precipitation have been studied in trilinear diagrams. Ionic strength and saturation index (SI) for selected minerals have been calculated. Five springwaters have similar chemical composition to that of the precipitation, which indicates surficial and rapidly recharged water. The SI of the groundwaters is out of equilibrium (undersaturated) with respect to primary silicates such as mafic minerals, feldspar, K-mica and chlorite, but in equilibrium with solid SiO2 (quartz, cristobalite, or chalcedony). The SI shows oversaturation conditions for kaolinite, hydroxy-Al interlayered vermiculite, Na,K,Mg-beidellite, Mg-montmorillonite, and AB-montmorillonite. Concentrations of soluble Al and Si can be governed by Mg,Fe-beidellite, BF-montmorillonite, or Ca-montmorillonite at four springs, and by halloysite at two wells on the coastal plain. For these groundwaters, clay minerals may act as H+ buffers and thus have an influence on pH and toxic Al, i.e., parameters affecting the drinking water quality and environment. The study shows that the soil catena are intensily weathered at the investigated sites. It is further concluded that neither cation exchange nor primary silicate weathering will keep up with buffering the acidic loads into the soils. A general prediction of groundwater quality is presented. 相似文献
8.
The Holocene diatom and pollen records from Kelly’s Lough have been analysed to determine the timing and extent of the acidification
in this upland lake. The pollen data during the early Holocene reflect the typical vegetation changes that occur in sediments
throughout Ireland during this period. The diatom record begins by being dominated by circumneutral and acidophilous benthic
forms. Later tychoplanktonic Aulacoseira species begin to expand and dominate indicating increased water transparency following the stabilization of catchment soils.
Peatland development in the catchment is evident from approximately 6,450 cal year BP. The main change in the diatom assemblages
at this time is the decline of Aulacoseira species and expansion of periphytic species. At around 1,450 cal year BP, loss-on-ignition (LOI) values, Calluna pollen and microscopic charcoal all increase suggesting the initiation of a major phase of peat erosion and an increased
inwash of organic matter to the lake. Lake acidity changed significantly although the initial acidification is very subtle
as indicated by the diatom-inferred pH record. Changes in the diatom assemblages might be largely the result of increasing
erosion and inwash of organic matter from the catchment to the lake leading to reduced water transparency and more acidic
conditions. The diatom flora remains relatively stable until the mid-twentieth century when more acidibiontic species increase.
These diatom changes result in the reconstructed pH curve showing a moderate recent acidification from pH 5.7 to 5.1. About
half of the total change in pH took place by around the late 1960s. The lowest diatom-inferred pH value occurs in the late
1970s, and parallels the peak in SO2 emissions in Ireland. Acidic conditions seem to have prevailed in Kelly’s Lough throughout its entire history and alkalinity
has been low or absent for much of the time. However, soil acidification and inwash of organic acids from peatlands are not
a sufficiently effective mechanism to explain the low pH levels found today in Kelly’s Lough. The effect of acid deposition
on the waters of Kelly’s Lough is clear and it has probably caused these already naturally acid waters to acidify further. 相似文献
9.
Liming placed in a long-term perspective: a paleolimnological study of 12 lakes in the Swedish liming program 总被引:1,自引:0,他引:1
Since the 1970s liming has been practised on a large scale in Sweden to mitigate acidification and several thousand lakes
and streams are limed repeatedly. The Swedish monitoring program ISELAW (Integrated Studies of the Effects of Liming Acidified
Waters) studies the long-term effects of liming. This paper summarizes the paleolimnological part of the program. Sediment
cores from 12 lakes were analysed to study the development of the lakes from pre-industrial time until the present, and address
questions about natural conditions and the effects of early human impact, acidification, and liming. Diatoms were used to
reconstruct the pH history and to study shifts in species composition due to acidification and liming. Analyses of lead and
spheroidal carbonaceous particles were applied for indirect dating and as indicators of the atmospheric deposition of pollutants
associated with acid rain. Pollen analysis was performed in eight of the lakes to study the vegetation and agricultural history.
The natural pH (prior to human disturbance) was between 5.3 and 6.5 in the eight lakes where the complete post-glacial sediment
sequence was recovered. Pollen from anthropochores and apophytes indicated early agricultural land use in the vicinity of
the lakes from 1000 to 2000 years ago, and pH increased with land use in six of these lakes. Five of the lakes have been acidified
during recent decades, and in all 12 lakes some effects of liming were recorded in the diatom assemblage. The lakes show different
responses to liming, including a return to a pre-acidification diatom composition or a shift to a state previously not recorded
in the lake’s histories. This study accentuates the complexity of biological response to acidification and liming, and highlights
the importance of historical perspectives to assess the current state of a lake’s ecosystem and to establish adequate restoration
goals. 相似文献
10.
In this study, variations of the chemical composition of precipitation in Nanjing, China, over a 12-year period (1992–2003) are presented. The average annual concentration of pH value was 5.15, ranging from 4.93 to 5.36, and there was no significant trend in the acidity of precipitation. SO42−, Cl− and NO3− were the main anions, while Ca2+, NH4+ and Mg2+ were the main cations. The concentrations of these main ions were very high compared to those reported in many other areas around the world. Most of the ions came from anthropogenic and crustal sources. High correlations were found among dust-derived cations Ca2+, Mg2+and K+, between Cl− and SO42−, between Cl− and NH4+ and between acidic anions and dust-derived cations, such as SO42− and Ca2+, SO42− and K+, Cl− and Ca2+, Cl− and K+, F− and Mg2+ and F− and K+. A significant decreasing trend was observed in concentration of SO42− because of the abatement strategies for SO2 emissions and energy policy change, while a significant increasing trend was found in the contribution of NO3− to acidification due to the rapidly growing number of motor vehicles. A significant decreasing trend was found in dust-derived cation Ca2+ due to more stringent controls of industrial dust emissions and rapid urbanization reducing the amount of open land, while the contribution of NH4+ to neutralization increased relatively. 相似文献