Aluminium in UK rivers: a need for integrated research related to kinetic factors, colloidal transport, carbon and habitat

Dissolved aluminium concentrations ([Al]) in the <0.45 μm filtered fraction are described for 54 UK river sites covering rural, acidic/acid sensitive, agricultural and urban typologies, and wide pH range (4 to 11). High [Al] occurred under acidic conditions and for acid runoff neutralised by bicarbonate rich groundwater. Thermodynamic analysis indicates Al hydroxide/hydroxy-silicate oversaturation at circumneutral pH across the rivers, but undersaturation at lower/higher pH. The oversaturation reflects in part the presence of Al bearing colloids as indicated by (1) [Al] being correlated with components associated with both lithogenic (Fe, Ti and lanthanides) colloids and organic carbon, (2) baseflow studies using cross-flow ultrafiltration and (3) comparison of our data with Acid Waters Monitoring Network (AWMN) information on labile and non-labile Al. Tree harvesting and emission reductions of SO(x) in acidic and acid sensitive catchments in mid-Wales led to acidification reversal, lower [Al] and changing [H(+)] - [Al] relationships. The [Al] decline was confined to acidic conditions while [Al] increased during the later part of the monitoring period with a peak around 2002 for moorland and forested systems. Colloidal production across the flow range was indicated late in the record by comparison of our data with information collected by the AWMN for a site in mid-Wales. This production seems interlinked with organic carbon and with dissolved CO(2) changes. In order for further understanding of Al hydrogeochemistry in river systems there is a need to integrate research that moves from equilibrium to kinetic and colloidal consideration including the critical issues of organic and inorganic controls within the context of bioavailability and aquatic stress. The colloidal Al may well be of low environmental concern to fish and other factors such as habitat may well be critical.     

Atmospheric Deposition and Ozone Levels in Swiss Forests: Are Critical Values Exceeded?

Air pollution affects forest health through atmospheric deposition of acidic and nitrogen compounds and elevated levels of tropospheric ozone (O₃). In 1985, a monitoring network was established across Europe and various research efforts have since been undertaken to define critical values. We measured atmospheric deposition of acidity and nitrogen as well as ambient levels of O₃ on 12, 13, and 14 plots, respectively, in the framework of the Swiss Long-Term Forest Ecosystem Research (LWF) in the period from 1995 to 2002. We estimated the critical loads of acidity and of nitrogen, using the steady state mass balance approach, and calculated the critical O₃ levels using the AOT40 approach. The deposition of acidity exceeded the critical loads on 2 plots and almost reached them on 4 plots. The median of the measured molar ratio of base nutrient cations to total dissolved aluminium (Bc/Al) in the soil solution was higher than the critical value of 1 for all depths, and also at the plots with an exceedance of the critical load of acidity. For nitrogen, critical loads were exceeded on 8 plots and deposition likely represents a long-term ecological risk on 3 to 10 plots. For O₃, exceedance of critical levels was recorded on 12 plots, and led to the development of typical O₃-induced visible injury on trees and shrubs, but not for all plots due to (1) the site specific composition of O₃ sensitive and tolerant plant species, and (2) the influence of microclimatic site conditions on the stomatal behaviour, i.e., O₃ uptake.     

Linking groundwaters of high CO2 to aluminium levels in rivers: the case for the upper Severn in mid-Wales

Al is a critical ecotoxicant in surface waters impacted by acidic deposition. Apart from the most acidic surface waters, Al concentrations are often considered to be controlled by Al(OH)(3) or aluminosilicate (clay) solubility for modelling studies. For many UK rivers there is no clear evidence for such solubility controls even though there is the potential under moderately acidic/alkaline conditions. Here, Al solubility in ground and river water is compared for acid sensitive catchments in mid-Wales. The results reveal that there may be a solubility control within the groundwater but a more complex state of affairs within the river. The groundwater is of high CO(2) content and once in the river it degasses to raise pH. However, there is limited change in Al concentration and hence the solubility relationship is lost. The results flag the potential importance of groundwater solubility controls for Al and the potential for the groundwater zone to act as an Al filter. For positive alkalinity groundwaters, the high CO(2) levels depress the pH to near the value for minimum Al solubility. However, there is no simple groundwater end-member. Examining Al solubility controls solely within the rivers provides cryptic and misleading clues to the hydrogeological controls for Al within catchments. Assessing the within-catchment processes requires direct measurement with full consideration of both inorganic and organic attenuation.     

Prevalence of multidrug-resistant,coagulase-positive Staphylococcus aureus in nasal carriage,food, wastewater and paper currency in Jalandhar city (north-western), an Indian state of Punjab

Eighteen sites impacted by abandoned mine drainage (AMD) in Pennsylvania were sampled and measured for pH, acidity, alkalinity, metal ions, and sulfate. This study compared the accuracy of four acidity calculation methods with measured hot peroxide acidity and identified the most accurate calculation method for each site as a function of pH and sulfate concentration. Method E1 was the sum of proton and acidity based on total metal concentrations; method E2 added alkalinity; method E3 also accounted for aluminum speciation and temperature effects; and method E4 accounted for sulfate speciation. To evaluate errors between measured and predicted acidity, the Nash-Sutcliffe efficiency (NSE), the coefficient of determination (R ²), and the root mean square error to standard deviation ratio (RSR) methods were applied. The error evaluation results show that E1, E2, E3, and E4 sites were most accurate at 0, 9, 4, and 5 of the sites, respectively. Sites where E2 was most accurate had pH greater than 4.0 and less than 400 mg/L of sulfate. Sites where E3 was most accurate had pH greater than 4.0 and sulfate greater than 400 mg/L with two exceptions. Sites where E4 was most accurate had pH less than 4.0 and more than 400 mg/L sulfate with one exception. The results indicate that acidity in AMD-affected streams can be accurately predicted by using pH, alkalinity, sulfate, Fe(II), Mn(II), and Al(III) concentrations in one or more of the identified equations, and that the appropriate equation for prediction can be selected based on pH and sulfate concentration.     

Critical Loads of Acidity for Forest Soils and Relationship to Forest Decline in the Northern Czech Republic

Critical load calculations in the Czech part of 'the Black Triangle' show exceedance of critical load in 75% of the forest area. A comparison with forest damage data shows an insignificant tendency toward more forest damage in areas with high exceedance. We conclude that high exceedance of critical load is a probable contributing factor to forest damage in the area.     

An assessment of the nutrient status of sugar maple in Ontario: indications of phosphorus limitation

Soil acidification, caused by elevated anthropogenic deposition, has led to concerns over nutrient imbalances in Ontario's sugar maple (Acer saccharum Marsh.) forests. In this study, soil chemistry, foliar chemistry, crown condition, and tree growth were measured at 36 sugar maple stands that included acidic (pH?相似文献   

Introduction of the Factor of Partitioning in the Lithogenic Enrichment Factors of Trace Element Bioaccumulation in Plant Tissues

Bioindicators are widely used in the study of trace elements inputs into the environment and great efforts have been conducted to separate atmospheric from soil borne inputs on biomass accumulation. Many monitoring studies of trace element pollution take into account the dust particles located in the plant surface plus the contents of the plant tissues. However, it is usually only the trace element content in the plant tissues that is relevant on plant health. Enrichment factor equations take into account the trace element enrichment of biomasses with respect soil or bedrocks by comparing the ratios of the trace element in question to a lithogenic element, usually Al. However, the enrichment equations currently in use are inadequate because they do not take into account the fact that Al (or whichever reference element) and the element in question may have different solubility-absorption-retention levels depending on the rock and soil types involved. This constrain will become critical when results from different sites are compared and so in this article we propose that the solubility factors of each element are taken into account in order to overcome this constrain. We analysed Sb, Co, Ni, Cr, Pb, Cd, Mn, V, Zn, Cu, As, Hg, and Al concentration in different zones of Catalonia (NE Spain) using the evergreen oak Quercus ilex and the moss Hypnum cupressiforme as target species. We compared the results obtained in rural and non industrial areas with those from the Barcelona Metropolitan Area. We observed differences in Al concentrations of soils and bedrocks at each different site, together with the differences in solubility between Al and the element in question, and a weak correlation between total soil content and water extract content through different sites for most trace elements. All these findings show the unsuitability of the current enrichment factors for calculating lithospheric and atmospheric contributions to trace element concentrations in biomass tissues. The trace element enrichment factors were calculated by subtracting the part predicted by substrate composition (deduced from water extracts from soils and bedrock) from total concentrations. Results showed that for most of the trace elements analysed, trace elements enrichment factors were higher inside the Barcelona Metropolitan Area than outside, a finding that indicates that greater atmospheric inputs occur in urban areas. The results show that the most useful and correct way of establishing a reference for lithospheric and atmospheric inputs into the plant tissues is, first, to analyse samples of the same plant species collected from a number of sites possessing similar environmental conditions (climate, vegetation type, soil type) and, second, to use this new enrichment factor obtained by subtracting from the total concentration in plant tissue the predicted contribution of soil or bedrock extracts instead of that of total soil or bedrock concentrations.     

Heavy metal concentrations in water and sediments in Tasik Chini, a freshwater lake, Malaysia

The purpose of this paper are to determine the concentration of heavy metals namely cadmium (Cd), copper (Cu) and lead (Pb) in water and sediment; and to investigate the effect of sediment pH and sediment organic matter on concentration of cadmium, copper and lead in sediment at oxidation fraction. For this purpose the concentration of heavy metals were measured in water and sediments at 15 sites from Tasik Chini, Peninsular Malaysia. The sequential extraction procedure used in this study was based on defined fractions: exchangeable, acid reduction, oxidation, and residual. The concentration of heavy metals in residual fraction was higher than the other fractions. Among the non-residual fractions, the concentration of heavy metals in organic matter fraction was much higher than other fractions collected from all sampling sites. The pH of the sediment in all sites was acidic. The mean pH ranges from 4.8 to 5.5 with the higher value observed at site 15. Results of organic matter analysis showed that the percentage of organic matter present in sediment samples varies throughout the lake and all sites of sediments were relatively rich in organic matter ranging from 13.0% to 34.2%. The highest mean percentage of organic matter was measured at sampling site 15, with value of 31.78%.     

Effects of roof and rainwater characteristics on copper concentrations in roof runoff

Copper sheeting is a common roofing material used in many parts of the world. However, copper dissolved from roof sheeting represents a source of copper ions to watersheds. Researchers have studied and recently developed a simple and efficient model to predict copper runoff rates. Important input parameters include precipitation amount, rain pH, and roof angle. We hypothesized that the length of a roof also positively correlates with copper concentration (thus, runoff rates) on the basis that runoff concentrations should positively correlate with contact time between acidic rain and the copper sheet. In this study, a novel system was designed to test and model the effects of roof length (length of roof from crown to the drip edge) on runoff copper concentrations relative to rain pH and roof angle. The system consisted of a flat-bottom copper trough mounted on an apparatus that allowed run length and slope to be varied. Water of known chemistry was trickled down the trough at a constant rate and sampled at the bottom. Consistent with other studies, as pH of the synthetic rainwater decreased, runoff copper concentrations increased. At all pH values tested, these results indicated that run length was more important in explaining variability in copper concentrations than was the roof slope. The regression equation with log-transformed data (R ² = 0.873) accounted for slightly more variability than the equation with untransformed data (R ² = 0.834). In log-transformed data, roof angle was not significant in predicting copper concentrations.     

Monitoring of Fogwater Chemistry in the Gulf Coast Urban Industrial Corridor: Baton Rouge (Louisiana)

Seventeen fog events were sampled in Baton Rouge, Louisiana during 2002–2004 as part of characterizing wet deposition by fogwater in the heavily industrialized corridor along the Louisiana Gulf Coast in the United States. These samples were analyzed for chemical characteristics such as pH, conductivity, total organic and inorganic carbon, total metals and the principal ion concentrations. The dominant ionic species in all samples were NH₄⁺, NO₃⁻, Cl⁻ and SO₄²⁻. The pH of the fogwater sampled had a mean value of 6.7 with two cases of acidic pH of 4.7. Rainwater and fogwater pH were similar in this region. The acidity of fogwater was a result of NO₃⁻ but partly offset by high NH₄⁺. The measured gaseous SO₂ accounted for a small percentage of the observed sulfate concentration, indicating additional gas-to-particle conversion of SO₂ to sulfate in fogwater. The gaseous NO_x accounted for most of the dissolved nitrate and nitrite concentration in fogwater. The high chloride concentration was attributable to the degradation of chlorinated organics in the atmosphere. The metal composition was traced directly to soil-derived aerosol precursors in the air. The major metals observed in fogwater were Na, K, Ca, Fe, Al, Mg and Zn. Of these Na, K, Ca and Mg were predominant with mean concentrations > 100 μM. Al, Fe and Zn were present in the samples, at mean concentrations < 100 μM. Small concentrations of Mn (7.8 μM), Cu (2 μM), Pb (0.07 μM) and As (0.32 μM) were also observed in the fogwaters, and these were shown to result from particulates (PM_2.5) in the atmosphere. The contribution to both ions and metals from the marine sources in the Louisiana Gulf Coast was minimal. The concentrations of all principal ionic species and metals in fogwater were 1–2 orders of magnitude larger than in rainwater. Several linear alkane organic compounds were observed in the fogwater, representing the contributions from petroleum products at concentrations far exceeding their aqueous solubility. A pesticide (atrazine) was also observed in fogwater, representing the contribution from the agricultural activities nearby.     

Linkages of P and Al Export at High Discharge at the Bear Brook Watershed in Maine

Phosphorus chemistry in streams was evaluated at the paired watershed study at the Bear Brook Watershed, Maine. The West Bear catchment has been treated bimonthly since 1989 with 1,800 eq (NH4)2SO4 ha-1 yr-1. East Bear was the untreated reference watershed. During 1993, concentration of total phosphorus (P) in weekly samples from East and West Bear Brook ranged from 0 to 15 g L-1. The median values were 2 and 4 g L-1 for East and West Bear, respectively. During a high discharge event in January of 1995, the concentration of dissolved P remained relatively constant ( 3 g L-1) as pH decreased from 5.63 to 5.08 and from 5.14 to 4.75 in East and West Bear, respectively. The concentration of total P increased to ca. 60 g L-1 during the rising limb of the hydrograph in West Bear, four times the value in East Bear, total P then declined rapidly as discharge remained high followed by an increase. Dissolved Al increased in both streams during the episodic acidification. West Bear, the more acidic, had concentrations of dissolved Al four times those of East Bear (maximum of 1.1 mg L-1 versus 0.25 mg L-1). Acid-soluble particulate Al increased to 0.2 and 4.2 mg L-1 for East and West Bear, respectively, in parallel to total P (but was 102 greater than total P) and then declined in parallel to total P while discharge remained high. Total P, dissolved P, and particulate Al did not relate to pH. Total P and particulate Al and Fe were strongly correlated. Concurrently, base cations remained relatively constant or decreased slightly. Particulate acid-soluble Al exceeded particulate acid-soluble base cations. We hypothesize that the particulate P was occluded in, or adsorbed on, acid-soluble particulate Al(OH)3. This Al(OH)3. This Al(OH)3 precipitates as emerging acidic groundwater degasses CO2 and pH rises. The export of Al and P is greater from the treated watershed because the induced acidification is translocating more Al from soils to the stream. Most of the export of P is related to acid-soluble Al particulate material.     

Distribution and sources of mercury in soils from former industrialized urban areas of Beijing, China

Fifty-seven typical surface soils and 108 deeper soils were collected from five former industrial sites in Beijing and concentrations of total Hg (SigmaHg) as well as pH, total carbon (TC), total nitrogen (TN), total sulfur, and dissolved organic carbon concentrations determined. The mean concentration of SigmaHg in surface soils was significantly greater than background concentrations in the vicinity of Beijing. Forty-eight percent of the samples exceeded the "critical" concentration of 1.0 mg Hg/kg, dry weight in soils, which has been established by the Chinese government. At depths of 0-80 cm in the soil, profile concentrations of SigmaHg also exceeded the background value. There were significant correlations between concentrations of SigmaHg, TC, and TN in the industrial soils. The greater concentration of SigmaHg in most soils could have been due in part to combustion of coal and leakage from industrial processes.     

Monitoring and assessment of surface water acidification following rewetting of oxidised acid sulfate soils

Large-scale exposure of acid sulfate soils during a hydrological drought in the Lower Lakes of South Australia resulted in acidification of surface water in several locations. Our aim was to describe the techniques used to monitor, assess and manage these acidification events using a field and laboratory dataset (n?=?1,208) of acidic to circum-neutral pH water samples. The median pH of the acidified (pH?<?6.5) samples was 3.8. Significant (p?<?0.05) increases in soluble metals (Al, Co, Mn, Ni and Zn above guidelines for ecosystem protection), SO₄ (from pyrite oxidation), Si (from aluminosilicate dissolution) and Ca (from carbonate dissolution and limestone addition), were observed under the acidic conditions. The log of the soluble metal concentrations, acidity and SO₄/Cl ratio increased linearly with pH. The pH, alkalinity and acidity measurements were used to inform aerial limestone dosing events to neutralise acidic water. Field measurements correlated strongly with laboratory measurements for pH, alkalinity and conductivity (r ²?≥?0.97) but only moderately with acidity (r ²?=?0.54), which could be due to difficulties in determining the indicator-based field titration endpoint. Laboratory measured acidity correlated well with calculated acidity (r ²?=?0.87, acidity present as Al^III?>>?H⁺?≈?Mn^II?>?Fe^II/III) but was about 20 % higher on average. Geochemical speciation calculations and XRD measurements indicated that solid phase minerals (schwertmannite and jarosite for Fe and jurbanite for Al) were likely controlling dissolved metal concentrations and influencing measured acidity between pH 2 and 5.     

Mobilization of aluminum by the acid percolates within unsaturated zone of sandstones

The area of the Black Triangle has been exposed to extreme levels of acid deposition in the twentieth century. The chemical weathering of sandstones found within the Black Triangle became well-known phenomenon. Infiltration of acid rain solutions into the sandstone represents the main input of salt components into the sandstone. The infiltrated solutions–sandstone percolates–react with sandstone matrix and previously deposited materials such as salt efflorescence. Acidic sandstone percolates pH?3.2–4.8 found at ten sites within the National Park Bohemian Switzerland contained high Al-tot (0.8–10 mg?L^?1) concentrations and high concentrations of anions SO₄ (5–66 mg?L^?1) and NO₃ (2–42 mg?L^?1). A high proportion (50–98 %) of Al-tot concentration in acid percolates was represented by toxic reactive Alⁿ⁺. Chemical equilibrium modeling indicated as the most abundant Al species Al³⁺, AlSO₄ ⁺, and AlF²⁺. The remaining 2–50 % of Al-tot concentration was present in the form of complexes with dissolved organic matter Al-org. Mobilization and transport of Al from the upper zones of sandstone causes chemical weathering and sandstone structure deterioration. The most acidic percolates contained the highest concentrations of dissolved organic material (estimated up to 42 mg?L^?1) suggesting the contribution of vegetation on sandstone weathering processes. Very low concentrations of Al-tot in springs at BSNP suggest that Al mobilized in unsaturated zone is transported deeper into the sandstone. This process of mobilization could represent a threat for the water quality small-perched aquifers.     

Acid soil indicators in forest soils of the Cherry River Watershed, West Virginia

Declining forest health has been observed during the past several decades in several areas of the eastern USA, and some of this decline is attributed to acid deposition. Decreases in soil pH and increases in soil acidity are indicators of potential impacts on tree growth due to acid inputs and Al toxicity. The Cherry River watershed, which lies within the Monongahela National Forest in West Virginia, has some of the highest rates of acid deposition in Appalachia. East and West areas within the watershed, which showed differences in precipitation, stream chemistry, and vegetation composition, were compared to evaluate soil acidity conditions and to assess their degree of risk on tree growth. Thirty-one soil pits in the West area and 36 pits in the East area were dug and described, and soil samples from each horizon were analyzed for chemical parameters. In A horizons, East area soils averaged 3.7 pH with 9.4 cmol_c kg^???1 of acidity compared to pH 4.0 and 6.2 cmol_c kg^???1 of acidity in West area soils. Extractable cations (Ca, Mg, and Al) were significantly higher in the A, transition, and upper B horizons of East versus West soils. However, even with differences in cation concentrations, Ca/Al molar ratios were similar for East and West soils. For both sites using the Ca/Al ratio, a 50% risk of impaired tree growth was found for A horizons, while a 75% risk was found for deeper horizons. Low concentrations of base cations and high extractable Al in these soils translate into a high degree of risk for forest regeneration and tree growth after conventional tree harvesting.     

Chemical Elements and their Source Apportionment of PM10 in Beijing Urban Atmosphere

Ecological health in a temperate stream impacted by acid mine drainage (AMD) was evaluated by using a multimetric approach of the Index of Biological Integrity (IBI) based on natural fish assemblage. Recently, this approach has been widely used in many developed countries as a tool for ecological risk assessments of water environments. We used 10 metric systems, instead of 12 metrics suggested by Barbour, M. T., Gerritsen, J., Snyder, B. D., & Stribling, J. B. (1999). Rapid Bioassessment Protocols for Use in Streams and Wadeable Rivers: Periphyton, benthic Macroinvertebrates and Fish, 2nd edn. EPA 841-B-99-002. Washington, DC: U.S. Environmental Protection Agency, Office of Water, for a development of the regional IBI model, and used trophic guilds, habitat guilds, and richness variables for the calculation of IBI values. In the model, the attributes of four of 11 metrics were modified for the regional application. IBI values in the stream averaged 20.6 (n = 5), indicating a “poor condition” in terms of ecological health according to the modified criteria of U.S. EPA (1993). Fish Field and Laboratory Methods for Evaluating the Biological Integrity of Surface Waters. EPA 600-R-92-111. Environmental Monitoring systems Laboratory – Cincinnati office of Modeling, Monitoring systems, and quality assurance Office of Research Development, U.S. EPA, Cincinnati, Ohio, 45268. In particular, mean IBI values in the impacted areas of sites 2 and 3 were 13, and this health condition was categorized as “very poor condition.” IBI values in the impacted sites were significantly lower than the values found in the control. Also, we found that fishes in site sites 2 and 3 were not present during the study, and morphological deformity of Rhynchocypris oxycephalus was observed in site 4, influenced directly by sites 2 and 3, indicating a chemical impact in the sites. From the results of experiments in which AMD was treated with marine shells at stagnant condition, pH increased up to 6.0 from 3.1, and Fe and Al were removed up to 99% within 6 h. In the reactor experiment considering field application, pH of effluent maintained around 7.0. In addition, concentrations of Fe, Al, and heavy metals decreased remarkably in the effluents, and bottom-opened screen between neutralizer basins showed high effectiveness in the treatment of AMD.     

Reactivity, interactions and transport of trace elements, organic carbon and particulate material in a mountain range river system (Adour River, France)

The background levels, variability, partitioning and transport of eleven trace elements-Ag, Al, As, Cd, Co, Cr, Cu, Mn, Pb, Zn and U-were investigated in a mountain range river system (Adour River, France). This particular river system displayed a turbulent hydrodynamic regime, characterized by flash-transient discharge conditions leading to fast shifts in suspended particulate matter (SPM) concentrations as high as two orders of magnitude (12 to 600 mg l(-1)). The distribution of SPM was accurately predicted with a "hysteresis" transport model, indicating that about 75% of the annual solids load was exported within 20 to 40 days. Dissolved and particulate concentrations of most trace elements were low compared to their concentrations in other reference river systems expect for Pb and Cr, associated with historical anthropogenic activities. Although dissolved and particulate metal concentrations were steady for most elements during low and average discharge conditions, significant changes were observed with increasing river discharge. The changes in trace element concentrations in the two compartments was found to induce a partitioning anomaly referred to as the particulate concentration effect. This anomaly was significant for Cr, Mn, Pb, Zn, Cu and organic carbon (p < 0.03). The processes driving this anomaly were possibly linked to the modification and/or increase of colloidal organic and inorganic vectors, suggested by the significant increase of DOC (p < 0.001) and dissolved Al concentrations (p < 0.05) during flood conditions. A complementary process linked to the influence of coarse particles of low complexation capacity and transported mainly during high discharge may also effect trace element concentrations. Annual metal fluxes transported by this river system were estimated using the hysteresis SPM model with consideration of these fate processes. Metals in the Adour River system are primarily exported into the Bay of Biscay (Atlantic Ocean).     

Uncertainty assessment of mapping mercury contaminated soils of a rapidly industrializing city in the Yangtze River Delta of China using sequential indicator co-simulation

Accurate characterization of heavy-metal contaminated areas and quantification of the uncertainties inherent in spatial prediction are crucial for risk assessment, soil remediation, and effective management recommendations. Topsoil samples (0–15 cm) (n = 547) were collected from the Zhangjiagang suburbs of China. The sequential indicator co-simulation (SIcS) method was applied for incorporating the soft data derived from soil organic matter (SOM) to simulate Hg concentrations, map Hg contaminated areas, and evaluate the associated uncertainties. High variability of Hg concentrations was observed in the study area. Total Hg concentrations varied from 0.004 to 1.510 mg kg⁻¹ and the coefficient of variation (CV) accounts for 70%. Distribution patterns of Hg were identified as higher Hg concentrations occurred mainly at the southern part of the study area and relatively lower concentrations were found in north. The Hg contaminated areas, identified using the Chinese Environmental Quality Standard for Soils critical values through SIcS, were limited and distributed in the south where the SOM concentration is high, soil pH is low, and paddy soils are the dominant soil types. The spatial correlations between Hg and SOM can be preserved by co-simulation and the realizations generated by SIcS represent the possible spatial patterns of Hg concentrations without a smoothing effect. Once the Hg concentration critical limit is given, SIcS can be used to map Hg contaminated areas and quantitatively assess the uncertainties inherent in the spatial prediction by setting a given critical probability and calculating the joint probability of the obtained areas.     

The epiphytic lichen hypogymnia physodes as a biomonitor of atmospheric nitrogen and sulphur deposition in Norway

Hypogymnia physodes was sampled from 179 sites of Scots pine forests regularly distributed throughout Norway. The purpose was to map the nitrogen and sulphur contents of lichen thalli on a large-scale geographical basis, and to relate these values to differences in atmospheric deposition and climate.The lichen nitrogen and sulphur concentrations showed large differences; the highest concentration values being 4–5 times greater than the lowest. The highest nitrogen and sulphur values occurred along the coast of southern Norway and on some sites in the inland of southern Norway. There was a close correlation between the two elements. The lichen N/S ratio decreased with increasing latitude.The nitrogen and sulphur contents ofHypogymnia physodes were both significantly correlated to estimated atmospheric deposition of these two elements in Norway. The degree of explanation improved when climatic variables such as temperature sum, altitude, annual precipitation and temperature were included. Factors promoting growth, such as high bark pH, mild winters, hot summers, high precipitation, high ammonium deposition and high evapotranspiration, were all associated with lower lichen nitrogen and/or sulphur concentrations. Unfavourable growth conditions, such as at high altitude, was related to higher concentrations than expected from deposition models. This indicates that differences in element concentration between nearby localities might be related to local differences in climate and lichen growth conditions. This should be taken into consideration whenever using lichens for biomonitoring.     

Effects of decaying wood on eluviation,podzolization, acidification,and nutrition in soils with different moisture regimes

One possible impact of large accumulations of decaying wood on forest sites is an increase in (1) eluviation, podzolization and acidification of, and (2) leaching and loss of nutrients from, the soil directly under decaying wood. As an exploratory investigation, we sampled soils beneath forest floors with and without large accumulations of decaying wood (lignic and algnic forest floors respectively) on three soil moisture regimes. Nine sites were located, three in each of central British Columbia, east Vancouver Island, and east of Vancouver. Among the moist sites, there were no differences in Ae horizon thickness between the alignic and lignic forest floors. However, the Ae horizon was thicker beneath the lignic forest floors (mean 4.2 cm) compared to the alignic forest floors (mean 0.7 cm) in slightly dry and fresh sites. Lignic and alignic forest floors differed (p<0.01) in pH, total C, total N, mineralizable N, available S, available P, extractable Mg, K and Ca, lipids, C in fraction B (soluble polysaccharide fraction), C in humic acid, C in fulvic acid, and polyphenol C in fulvic acid for all soil moisture regimes. There were no significant differences in the measures of nutrients or indicators of podzolization as measured by organically complexed Fe and Al, the total non-crystalline Fe and Al, and the poorly crystalline Fe and Al, in the underlying 10 cm of the Bf horizon between the two substrates regardless of the soil moisture regime. Further investigations are needed to establish the relationships between soil productivity and the observed soil chemical measures.