辽东山溪河岸林群落特征对降雨再分配及其养分特征的影响

为明确不同物种组成和群落结构的河岸林对降雨再分配及其养分特征的影响,于2014年5—10月对辽东山地典型河岸林群落(落叶松林、蒙古栎林和槭树林)大气降雨、穿透雨和树干茎流过程及其水质特征进行研究。结果表明:落叶松林、蒙古栎林和槭树林穿透雨量分别占大气降雨量的81.9%,77.9%,73.1%,树干茎流量分别占大气降雨量的1.2%,4.4%,4.3%。与大气降雨相比,穿透雨和树干茎流中铵态氮、氯离子、硝态氮和总磷的浓度较高,不同林型铵态氮、氯离子、硝态氮和总磷的浓度和输入量差异显著。不同物种组成和群落结构的河岸林通过树木的形态特征及群落的结构特征对降雨进行再分配,通过林冠表层的物理特征、化学特征和生理特性等改变降雨理化性质,加之雨量、雨强的影响共同作用使铵态氮、氯离子、硝态氮和总磷的浓度和输入量发生改变。     

Intercomparison of snow Sampling and Analysis Within the Alpine-Wide Snowpack Investigation (SNOSP)

In order to investigate the seasonal and geographical distribution of snow concentrations anddeposition fluxes of environmentally relevant ionic species in the Alps, the international programSNOSP was initiated. In the framework of this program, intercomparisons of snow samplingtechniques and analytical methods to determine the ionic species C1^-, NO ₃ ^- ,SO ₄ ^2- , K⁺, Na⁺, NH4 ⁺, Mg²⁺, and Ca²⁺, as well as the pH and the specificconductivity were performed. The concentrations of these species in the snow samples collectedin the SNOSP program varied by orders of magnitude with, e.g., concentrations of NO ₃ ^- , SO ₄ ^2- , and NH4 ⁺ ranging from 0.2-60, 0.2-90, and 0.1-60 µeq L^-1,respectively. The intercomparisons revealed a reasonable agreement of the determinations of thespecies Cl^-, NO ₃ ^- , SO ₄ ^2- , Na⁺, and NH4 ⁺ in snow. Results were less satisfactory for K⁺, Mg²⁺, Ca²⁺,and H⁺, mainly due to the very low concentrations. In conclusion, recommendations areformulated for the reliable derivation of chemical inventories from snow packs.     

Precipitation Chemistry as an Indicator of Urban Air Quality in Mersin, North-Eastern Mediterranean Region

The chemical composition of precipitation in the city of Mersin on the Mediterranean coast of Turkey has been studied. Spatial and temporal variability of rainwater constituents have been determined from samples collected at two central and two suburban stations for the December 2003–May 2005 period. A total of 246 samples covering all precipitation events were analyzed to determine pH, conductivity, as well as major anion (Cl^?, ${\text{NO}}_3^ - $ , ${\text{SO}}_4^{2 - } $ ); major cation (H⁺, Na⁺, K⁺, Ca²⁺, Mg²⁺, ${\text{NH}}_4^ + $ ) and formaldehyde (HCHO) concentrations. The pH varied within a range of 4.8–8.5, with only 8 out of 246 samples being acidic (pH?<?5.6), and the remaining highly alkaline samples being neutralized by either ${\text{NH}}_4^ + $ in rainwater, or by CaCO₃ resulting from wet deposition of atmospheric dust. The volume weighted mean ΣAnion/ΣCation ratio was 0.49. The equivalent concentration of major ionic species followed the order: ${\text{Ca}}^{2 + } > {\text{HCO}}_3^ - > {\text{SO}}_4^{2 - } > {\text{Cl}}^ - > {\text{NH}}_4^ + > {\text{Na}}^ + > {\text{Mg}}^{2 + } > {\text{NO}}_3^ - > {\text{K}}^ + > {\text{H}}^ + $ . Formaldehyde concentrations varied in the range of 0.01–17.9 μM, and was found to be dependent on precipitation volume. Relatively higher ${\text{NH}}_4^ + $ , ${\text{SO}}_4^{2 - } $ , ${\text{NO}}_3^ - $ and HCHO concentrations, mainly of anthropogenic origin, measured near the city center suggest increased pollution from local anthropogenic sources, e.g., residential heating, industrial and/or traffic emissions. In general, the results of this study suggest local precipitation chemistry is more strongly influenced by natural (mineral dust and marine) sources compared to anthropogenic ones.     

Deposition of air pollutants in a wind-exposed forest edge

The atmospheric deposition of air pollutants at a forest edge was studied by means of monitoring canopy throughfall at the edge and at five different parallel lines in the forest behind the edge. The investigation was carried out at a pine forest on the Swedish west coast. Throughfall and bulk deposition samples were analyzed for volume, SO ₄ ^2? , NO ₃ ^? , Cl^?, NH ₄ ⁺ , Na⁺, K⁺, Mg²⁺, Ca²⁺, and for pH. The results show that the throughfall flow at the edge was increased substantially for most ions. The ratios in throughfall flows between the edge and the line 50 m into the forest were for SO ₄ ^2? , 1.5, NO ₃ ^? 2.9, NH ₄ ⁺ 2.7, and Na⁺ 3.1. Since this effect is not only valid for forest edges but also for hillsides, hilltops, and edges between stands of different age, etc., there might be substantial areas which get much larger total deposition than the normally considered closed forest.     

Rainfall,Stemflow, and Throughfall Chemistry at Urban- and Mountain-facing Sites at Mt. Gokurakuji,Hiroshima, Western Japan

Rainfall, stemflow, and throughfall were collected from 1996 to 1999 at two types of forest sites: (1) forests near the traffic roads and urban areas and (2) forests away from the urban areas at Mt. Gokurakuji, Hiroshima, western Japan in order to estimatethe effects of anthropogenic activities on atmospheric deposition. Rainfall deposition for major ions showed small differences between the sites. The NO₃ ^- and SO₄ ^2-concentrations in stemflow were higher at the urban-facing slope than at the mountain-facing slope. Throughfall deposition of NO₃ ^- and SO₄ ^2- was also higher at urban-facing slopes. Net throughfall (NTF) deposition (throughfall minus rainfall) of NO₃ ^- and SO₄ ^2- accounted for 77 and50% of the total throughfall deposition on urban-facing slopes, respectively, while it accounted for 44 and 23% on themountain-facing slopes, respectively. These results indicated a higher contribution from dry deposition on urban-facing slopes compared to mountain-facing slopes. Atmospheric N (NO₃ ^- +NH₄ ⁺) deposition from throughfall was estimated to be around 17–26 kg N ha^-1 yr^-1 on urban-facing slopes, which was greater than the threshold of N deposition that could cause nitrogen leaching in Europe and the United States. The highload of atmospheric N deposition may be one of the factors bringing about the decline of pine forests on urban-facing slopesof Mt. Gokurakuji.     

Deposition and Leaching of Sulphate and Base Cations in a Mixed Boreal Forest in Eastern Finland

Monthly fluxes of sulphate (SO₄ ^2-) and base cations(Ca²⁺, Mg²⁺, K⁺) were studied from 1993 to 1996 as precipitation passed through forest vegetation and surfacesoil layers in an area receiving low and declining levels of atmospheric sulphate pollution. The canopy was dominated by mature Norway spruce (Picea abies Karsten) and the soilwas a podzol developed on glacial till material. The mean annual bulk deposition of SO₄ ^2- collected in the open was 136 mol_c ha^-1 and that of Ca²⁺, Mg²⁺ and K⁺ was 44, 11 and 25 mol_c ha^-1, respectively. The annual total throughfall deposition of SO₄ ^2- was 318 mol_c ha^-1 and that of Ca²⁺, Mg²⁺ and K⁺ was 151, 64 and 181 mol_cha^-1, respectively. Sulphate was the dominant anion accompanying the base cations leached from the canopy. More than half (58%) of the annual total throughfall deposition ofSO₄ ^2- was retained by the O-horizon and only 15% leached from below the B-horizon. The annual leaching of Ca²⁺, Mg²⁺ and K⁺ from below the B-horizon was14, 25 and 9% of the annual total throughfall deposition, respectively. The transport of base cations through the soil was predominantely countered by SO₄ ^2- anions.     

Canopy and Soil Retention of Nitrogen Deposition in a Mixed Boreal Forest in Eastern Finland

Nitrogen deposition, leaching, and retention were monitored in a mature spruce (Picea abies Karsten) dominated mixed boreal forest in eastern Finland. Bulk precipitation, throughfall, stemflow, and percolation through the podzolic soil profile were monitored from 1993 to 1996. Mean annual bulk deposition of total N was 3.83 kg ha^-1, of which 33% was NH₄ ⁺, 26% was NO₃ ^- , and 41% was organic N. Throughfall+stemflow flux of total N was 2.93 kg ha^-1 yr^-1. Sixty-four % of NH₄ ⁺ and 38% of NO₃ ^- in bulk precipitation was retained by tre three canopy. Organic N was released (0.27 kg ha^-1 yr^-1) from the tree canopy. Nitrate-N was retained and organic N was leached as the water passed through the ground vegetation and soil O-horizon. Ammonium-N and organic N were retained mainly in the E-horizon. The output of total N from the E-horizon was only 5% of the total N deposition in the forest stand during the study period and it was mainly as organic N. The output of inorganic N forms from under B-horizon was seasonal and occurred mainly at spring snowmelt.     

Comparison of Long-Term Precipitation Chemistry Measurements at the Hubbard Brook Experimental Forest,New Hampshire

From 1978 through 1989, a wet-onlyprecipitation collector operated for the NationalAtmospheric Deposition Program, an independantwet-only collector, and a bulk precipitation collectorwere co-located at the Hubbard Brook ExperimentalForest (HBEF) in central New Hampshire. A secondbulk precipitation collector was maintained at anotherlocation within the HBEF. There were statisticallysignificant differences between the chemistry fromco-located wet-only collections for Ca²⁺,K⁺, NH₄ ⁺, pH, and NO₃ ^-. Thedifferences for K⁺ and pH though statisticallysignificant were very small but consistant. Thedifferences for Ca²⁺ were related to earlycontamination problems, and differences inNH₄ ⁺ and NO₃ ^- were related toepisotic events. Bulk precipitation was significantlyricher in K⁺ than wet-only precipitation. Therewere no differences for any ions between the bulkcollections at the two locations. While there wereminor differences, after 1981 when the contaminationproblems had been resolved, data from all collectorsat all locations adequately characterized theprecipitation chemistry of the site.     

Nutrient Fluxes in Planted Norway Spruce Stands of Different Age in Southern Poland

The fluxes of N–NO ₃ ^? , N–NH ₄ ⁺ , S–SO ₄ ^2? , Na⁺, K⁺, Ca²⁺ and Mg²⁺ from bulk precipitation to throughfall, stemflow and soil water surface flows were studied during 1999–2003 in planted Norway spruce forest stands of different ages (11, 24, 91 and 116 years in 1999). Also, runoff from the corresponding Potok Dupniański Catchment in the Silesian Beskid Mts was studied. N deposition was above the critical load for coniferous trees. The interception increased with stand age as well as leaf area index and so did the leaching from the canopy of almost all the analysed elements, but especially S–SO ₄ ^2? , H⁺ and K⁺. The nutrient fluxes varied with age of the spruce stands. Throughfall showed a high amount of S and of the strong acids (S–SO ₄ ^2? and N–NO ₃ ^? ) deposited to the soil, especially in older spruce age classes. Decomposition of organic matter caused a rise in water acidity and an increase in the concentrations of all the analysed ions; the leaching of minerals, however, was low (under 1%). The horizontal soil water flow showed an increase in the amount of water and amount of ions and contributed to a further decrease of pH at the soil depth of 20 cm. Element concentrations and their amounts increased with water penetrating vertically and horizontally on the slopes. Considerable amounts of ions, especially S and alkaline cations, were carried beyond the reach of the root system and then left the catchment. In the long term, these mineral losses will adversely affect health and growth of the spruce stands, and the increased acidity with stand age will presumably have negative effects on the runoff water ecosystem.     

Vegetation,soils, and ion transfer through the forest canopy in two Nova Scotia lake basins

Characterization of the forest vegetation and soils in two adjacent; contrasting headwater lake basins located in Kejimkujik National Park, Nova Scotia was completed in 1980. Precipitation chemistry was studied during May to November, 1981–83 at two forested plots in each basin. There were 2012 stems ha^-1 in Beaverskin basin and 1816 stems ha^-1 in Pebbleloggitch basin. Beaverskin species composition was predominantly coniferous (72% of stems) while Pebbleloggitch was predominantly deciduous (52% of stems). Thickness and mass of organic soil layers were greater in Beaverskin. Mineral soil cation concentrations were similar. There were no differences between the basins in mean incident bulk precipitation pH. Mean volume-weighted pH for the period (73 collections) was 4.80. Sixteen percent of collections had a pH < 4.25. Sulphate deposition in incident bulk precipitation (May – November) ranged from 5.4–8.5 kg ha^-1 during 1981–83 while NO _inf3 ^sup- ranged from 0.04–0.93 kg ha^-1. The partitioning of incident precipitation into throughfall varied considerably (69%–38%) year-to-year. Temporal flux of ions did not differ significantly. Amounts of all major ions in throughfall especially SO _inf4 ^sup2- and base cations(Ca²⁺ + Mg²⁺ + K⁺ + Na⁺) were enriched.     

Sources of acidity in forest-floor percolate from a maple-birch ecosystem

Ion concentrations in water collected within a forest of sugar maple and yellow birch at the Turkey Lakes Watershed near Sault Ste. Marie, Ontario were examined from 1982 to 1984 to determine sources of acidity and the extent of cation leaching from forest floor horizons. Volume-weighted concentrations and ion fluxes in throughfall and forest-floor percolate during the growing and dormant seasons were calculated. Hydrogen ion content of the forest-floor percolate decreased in relation to that of throughfall in the dormant season and increased in the growing season. Hydrogen ion deposition in throughfall could account for 100% of the flux of H⁺ through the forest floor in the dormant period, and 40% of the flux during the growing season. In forest-floor percolate, Ca²⁺ concentrations were positively correlated with those of SO₄ ^2-, NO₃ ^- and organic anions during both dormant and growing seasons. Sources of NO₃ ^- and organic anions within the ecosystem and major external inputs of NO₃ ^- and SO₄ ^2- were critical factors that influenced cation mobility in the forest floor.     

Effective Removal of Toxic Heavy Metal Ions from Aqueous Solution by CaCO<Subscript>3</Subscript> Microparticles

Heavy metals are a common contaminant in water supplies and pose a variety of serious health risks to nearby human populations. A promising approach to heavy metal decontamination is the sequestration of heavy metal ions in porous materials; however, current technologies involve materials which can be difficult to synthesize, are high-cost, or are themselves potentially toxic. Herein, we demonstrate that rapidly synthesized calcium carbonate (CaCO₃) microparticles can effectively remove high quantities of Pb²⁺, Cd²⁺, and Cu²⁺ ions (1869, 1320, and 1293 mg per gram of CaCO₃ microparticles, respectively) from aqueous media. The CaCO₃ microparticles were characterized with powder X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Brunauer–Emmett–Teller (BET) N₂ sorption–desorption. It was found that the Ca²⁺ ions of the microparticles were replaced by the heavy metal ions, leading to partially recrystallized nanoparticles of new compositional phases such as cerussite (PbCO₃). The adsorption, surface dissolution/re-precipitation, and nucleation/crystal growth mechanisms were determined by investigating the Ca²⁺ released, along with the changes to particle morphology and crystal structure. Importantly, this study demonstrates that the porous CaCO₃ microparticles performed well in a system with multiple heavy metal ion species: 100% of Cu²⁺, 97.5% of Pb²⁺, and 37.0% Cd²⁺ were removed from an aqueous solution of all cations with initial individual metal concentrations of 50 mg/L and 1.5 g/L of CaCO₃ microparticles. At this concentration, the CaCO₃ microparticles significantly outperformed activated carbon. These results help to establish CaCO₃ microparticles as a promising low-cost and scalable technology for removing heavy metal ions from contaminated water.

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Effects of Land Use on Hydrochemistry and Contamination of Karst Groundwater from Nandong Underground River System, China

The Nandong Underground River System (NURS) is located in Southeast Yunnan Province, China. Groundwater in NURS plays a critical role in socio-economical development of the region. However, with the rapid increase of population in recent years, groundwater quality has degraded greatly. In this study, the analysis of 36 groundwater samples collected from springs in both rain and dry seasons shows significant spatial disparities and slight seasonal variations of major element concentrations in the groundwater. In addition, results from factor analysis indicate that NO ₃ ^? , Cl^?, SO ₄ ^2? , Na⁺, K⁺, and EC in the groundwater are mainly from the sources related to human activities while Ca²⁺, Mg²⁺, HCO ₃ ^? , and pH are primarily controlled by water–rock interactions in karst system with Ca²⁺ and HCO ₃ ^? somewhat from anthropogenic inputs. With the increased anthropogenic contaminations, the groundwater chemistry changes widely from Ca-HCO₃ or Ca (Mg)-HCO₃ type to Ca-Cl (+NO₃) or Ca (Mg)-Cl (+NO₃), and Ca-Cl (+NO₃+SO₄) or Ca (Mg)-Cl (+NO₃+SO₄) type. Concentrations of NO ₃ ^? , Cl^?, SO ₄ ^2? , Na⁺, and K⁺ generally show an indistinct grouping with respect to land use types, with very high concentrations observed in the groundwater from residential and agricultural areas. This suggests that those ions are mainly derived from sewage effluents and fertilizers. No specific land use control on the Mg²⁺ ion distribution is observed, suggesting Mg²⁺ is originated from natural dissolution of carbonate rocks. The distribution of Ca²⁺ and HCO ₃ ^? does not show any distinct land use control either, except for the samples from residential zones, suggesting the Ca²⁺ and HCO ₃ ^- mainly come from both natural dissolution of carbonate rocks and sewage effluents.     

湘江流域岳麓山周边地区地表水体水化学特征及灌溉适宜性

[目的] 对湘江流域岳麓山地区地表水体进行水化学特征分析及灌溉适宜性评价,为该地区的生态环境保护及水资源综合管理的科学决策提供理论支持。[方法] 以岳麓山周边地区为研究区,从2020年12月至2021年11月采集降水、山涧溪水和湘江河水水样,利用Piper图、Gibbs图、端元图等方法,分析各水体水化学特征以及影响因素。[结果] 降水主要阴阳离子为Ca²⁺,K⁺,SO^2-₄和NO^-₃,无明显水化学类型;山涧溪水主要阴阳离子为Ca²⁺和NO^-₃,主要水化学类型为Cl-Ca·Mg型和Cl-Ca型;湘江河水主要阴阳离子为Ca²⁺和HCO^-₃,主要水化学类型为HCO₃-Ca型。山涧溪水主要受大气降水输入和碳酸盐岩风化控制;湘江河水受碳酸盐岩风化作用影响较大。[结论] Na⁺离子含量,SAR和RSC指标以及其绘制USSL图和Wilcox图分析结果较好,山涧溪水和湘江河水适合用于灌,不易引起盐害或碱害。     

The role of organic horizons and canopy to modify the chemistry of acidic deposition in some forest ecosystems

To clarify the mechanisms of pH buffering in forest ecosystems, field observations of pH and ionic concentrations in precipitation (R), throughfall (Tf), stemflow (Sf), and leachates from organ c horizons (Lo) were conducted for three years at three stands in Tomakomai (TK) and Teshio (TS) in Hokkaido, northern Japan. Weighted mean rates of H⁺ input as wet deposition at TK and TS were estimated in the range from 0.3 to 1.0 and 0.4–0.6 kmol_c ha^?1 y^?, respectively. While the net H⁺ flux was reduced significantly by the forest canopy, net fluxes of other ions by throughfall, especially for Na⁺, Cl^?, and SO₄ ^2?, were apparently greater than those by precipitation. The canopy modification of the H⁺ flux was more remarkable under deciduous stands than under coniferous stands, suggesting that the efficiency of conifers as the collectors of dry deposition is greater than that of deciduous ones. More than 50% of H⁺ flux due to throughfall was absorbed by the organic horizons and the weighted mean pH of Lo at TK and TS was in the range from 4.9 to 5.5 and 5.0–5.5, respectively. Results from field observation and field leaching experiments, showed that the major H⁺ sinks of the organic horizons are exchange reaction of Ca²⁺, Mg²⁺ and K⁺. Organic acids or organo-metallic complexes of lower pK(=5.0–5.5) played a significant role as counter anions in O horizons leachate in coniferous forests. Our results indicate the importance of biogeochemical modifications in the canopy and organic horizon in acid buffering mechanisms of forest ecosystems.     

Dry Deposition to the Forest Canopy and Surrogate Surfaces in Two Mediterranean Holm Oak Forests in Montseny (NE Spain)

The fluxes recovered from washing branches and surrogatesurfaces were compared for two holm oak (Quercus ilex L.)forests in the Montseny mountains (NE Spain) differentiallyexposed to pollution. For 5 periods in May and June 1996 afterexposures ranging between 68–189 hr, 6 metacrylate plates and 8branches were extracted with distilled water. Also, a sequentialwashing of branches was undertaken, with 5 min separationsbetween the 3 initial washes, one hour between the 3rd and the4th, and 6 hr between the 4th and the last one. The compositionwas analysed for PO₄ ^3-, SO₄ ^2-,NO₃ ^-, Cl, F, NH₄ ⁺,Ca²⁺, Mg²⁺, Na⁺, K⁺, Cu, Pb, Mn, Co, Ni and Zn. The applied techniques were consistent in that dry deposition would accountfor the throughfall fluxes of NO₃ ^-, Cl^-,Cu and Zn. Potassium and Mn would derive mostly from leaching and their fluxes were strongly related with the holm oak flower growth. ForMg²⁺ and SO₄ ^2- either leaching or impaction of small particles or gases (for SO₄ ^2-) could account forthe recovered fluxes. Also for Na⁺ and Ca²⁺ the experiments did not produce conclusive results. Ammonium, F, Pb,Co, and Na were under the detection limit of analyticaltechniques in the plate-wash. The exposed site presented higherleaf-wash and plate-wash fluxes for all elements. This wasattributed to its higher exposure to pollutants, and forleaching-derived elements, to its higher site fertility.     

日光温室番茄缺镁与土壤盐分组成及离子活度的关系

研究了石灰性土壤日光温室不同栽培年限及番茄不同程度缺镁的土壤水溶盐分中离子组成、比例及Mg2+、Ca2+、K+离子活度等的变化及关系.结果表明:随着栽培年限的增加,温室土壤水溶盐分中Ca2+、K+、NO3-含量显著增加;水溶性盐分中阳离子以Ca2+为主,栽培5 a后NO3-成为阴离子主要成分;土壤中NO3-含量的增加是导致土壤盐分累积的主要因素.随番茄缺镁程度的加剧,土壤水溶性盐中Ca2+、K+、NO3-、全盐量及Ca2+/Mg2+、K+/Mg2+摩尔比均呈增加趋势,番茄出现缺镁的土壤含盐量达到盐渍化水平.随着土壤盐分含量增加,Ca2+、Mg2+活度均呈指数下降趋势,番茄缺镁的土壤溶液中Mg2+和Ca2+活度显著低于不缺镁土壤,(K+)/(Mg2+)、(Ca2+)/(Mg2+)活度比显著高于不缺镁土壤,(K+)/(Mg2+)活度比随缺镁程度加剧达显著差异,番茄缺镁的土壤溶液(K+)/(Mg2+)活度比大于1.盐分累积使Mg2+活度大幅降低以及K+富集对植物吸收Mg2+的拮抗作用是石灰性土壤上番茄缺镁的主要诱因.     

Changes of Some Components of Precipitation in East Germany after the Unification

A network of 15 sites of precipitation monitoring was built-up to characterize the spatial and temporal changes of pollutants over East Germany. Rain water samples were analysed and characterized regarding their acidity, conductivity, main water soluble components (Cl^-, NO₃ ^-, SO₄ ^2-, Na⁺, NH₄ ⁺, K⁺, Ca²⁺, Mg²⁺), volume and the meteorological parameters. Dependent on the changes of emission of pollutants, resulting from the reformation of industry, the decrease of stock farming, and increase of traffic (by the factor of ≈1.5) in East Germany, a drop could be observed with the sulphate and calcium concentrations in the precipitation by 20 to 50 and 30 to 70%, respectively. An increase could not be ascertained with the nitrate concentration and the acidity.     

Changes in the chemical composition of water percolating through the soil profile in a moderately polluted catchment

Throughfall (TF), stemflow (SF), soil solution below the organic layer (SS_org) and at 50 cm depth (SS₅₀), and output with stream water (SW) were measured and analyzed for four years in a moderately polluted forest catchment in southern Poland. The input of water with stemflow was ca. 6% of input with TF. However, due to higher concentrations of most ions in SF, the input of most elements with SF was from 8% to 9%. Sulphate (SO₄ ^2–), chloride (Cl^–) and magnesium (Mg²⁺) were the only ions steadily increasing in concentrations in water percolating through the soil profile. Nitrogen reached the forest floor mainly as ammonium (NH₄ ⁺). In the soil organic layer the NH₄ ⁺ concentration decreased, while concentrations of nitrate (NO₃ ^–) and hydrogen (H⁺) increased, probably due to nitrification. For NO₃ ^–, sodium (Na⁺) and calcium (Ca²⁺), the highest concentrations were found in SS_org and SW. This indicates both efficient cycling in the biotic pool of the ecosystem and intensive weathering processes in the mineral soil below the plant rooting zone. The latter was especially pronounced for Mg and Ca. Concentrations of zinc (Zn), lead (Pb) and cadmium (Cd) were the highest in SS_org and SS₅₀. As this was accompanied by a low pH and constant input of H⁺, NH₄ ⁺ and heavy metal ions to the catchment area, it may pose a serious threat to forest health.     

Precipitation chemistry at sinhagad-a hill station in India

The chemistry of precipitation in remote sites such as mountain tops is of interest in the study of atmospheric pollution and acid rain. The chemical composition measured at mountain site which is away from industrial and urban areas is useful as a reference level and it allows to determine the extent of anthropogenic contamination. Hence, rain water samples were collected at Sinhagad (18°21N, 73°45E, 1450 m asl during the monsoon season (June-September) of 1992 and were analysed for major ions. The precipitation samples collected at Sinhagad were alkaline in nature and pH values ranged between 5.9 to 6.76. The ionic composition was dominated by soil dust The concentration of Ca²⁺ was highest among all the ions. The concentrations of excess SO₃ ^2– and NO₄ ^– were small (23.8 and 15.2 eq l^–1 respectively) compared to the values of polluted regions in India. The correlation coefficient between the ions and pH values was calculated and it was found to be maximum in case of Ca²⁺. Precipitation samples collected at Sinhagad were alkaline owing to higher concentration of Ca²⁺ and lower levels of acidic pollutants (SO₄ ^2– and NO₃ ^–).