中国西北地区黑河流域额济纳盆地地下水化学演化研究

Hydro-chemical characteristics of groundwater and their changes as affected by human activities were studied in the Ejin Sub-Basin of the Inner Mongolia Autonomous Region, China, to understand the groundwater evolution, to identify the predominant geochemical processes taking place along the horizontal groundwater flow path, and to characterize anthropogenic factors affecting the groundwater environment based on previous data. The concentrations of major ions and total dissolved solids （TDS） in the groundwater showed a great variation, with 62.5% of the samples being brackish （TDS ≥ 1 000 mg L^-l）. The groundwater system showed a gradual hydro-chemical zonation composed of Na^＋ -HCO3^-, Na^＋ -Mg^2＋ -SO4 ^2 -Cl^-, and Na^＋ -Cl^-. The relationships among the dissolved species allowed identification of the origin of solutes and the processes that generated the observed water compositions. The dissolution of halite, dolomite, and 2- gypsum explained, in part, the presence of Na^＋, K^＋, Cl^-, SO^4 , and Ca^2＋, but other processes, such as mixing, Na^＋ exchange for Ca^2＋ and Mg^2＋, and calcite precipitation also contributed to the composition of water. Human activity, in particular large-scale water resources development associated with dramatic population growth in the last 50 years, has led to tremendous changes in the groundwater regime, which reflected in surface water runoff change, decline of groundwater table and degeneration of surface water and groundwater quality. Solving these largely anthropogenic problems requires concerted, massive and long-term efforts.     

青海省北川河流域地下水水化学特征与水质评价

[目的]分析北川河流域地下水化学特征,从地下水的资源属性角度出发客观评价流域地下水水质状况,为区域地下水环境保护提供数据支撑。[方法]利用2019年北川河流域水文地质水资源调查所获取的189组地下水化学数据分析流域地下水化学成分的分布特征和来源。依据地下水富水性分级对单个样品点的水质类型赋予不同的系数,构建基于地下水富水性分级的区域水质评价方法。[结果]北川河流域地下水化学分布具有较大的空间变化。上游丘陵山区和河谷平原区广泛分布HCO₃~-型淡水,向下游逐渐出现SO₄^2-,Cl~-类型的微咸水、咸水以及指示人类活动影响的HCO₃·Cl-Na型淡水;碳酸盐岩和硅酸盐岩风化溶解对地下水水化学组分来源具有控制作用,局部区域因蒸发浓缩而富集;Al,Fe,Th等天然背景元素是造成流域地下水水质超标的主要指标,Pb,CCl₄、NO₃~-等典型污染组分在工业区和人口集中区地下水中超标更加明显,在人为污染及天然高背景双因素驱动下河谷区地下水质更加复杂;基于采样点数量统计的...     

HYDROCHEMISTRY OF THE AQUIFERS IN THE RIO LAS AVENIDAS BASIN,PACHUCA, HIDALGO,MEXICO

Groundwater in the Rio de las Avenidas sub-basin corresponds to the bicarbonate-sodium and bicarbonate-calcium hydrochemical facies, which result from the mineralization of water passing through alkaline rocks (andesites) which prevail in this basin. However, the presence of high concentrations of Na⁺ and K⁺ reveals the existence of an external inflow of these elements: the registered mean values are respectively 94.3 and 19.0 ppm, with the Tèllez and Tizayuca areas standing out with reported values of up to 142 ppm. As for the concentration of soluble water cations, we find in decreasing order: Na⁺, Ca²⁺, Mg²⁺, K⁺,along with the anions HCO₃ ^-, Cl^-, SO₄ ^2-, CO₃ ^-, which combine to form the NaHCO₃, NaCl, Ca(HCO_{3 2}, MgSO₄ and KCl salts. The presence of biological contaminants, P and detergents in the groundwater indicates that it may have been contaminated by waste water. In addition to the contaminants mentioned above, large quantities of Pb, B, Zn, Fe, Mn, Cr, Co were detected and although Fe, Pb, Zn, B,and Mn are closely related to the local lithology, the high concentrations of these elements along with the occurrence of Co, Cr, Cd, and Ni confirm the gradual degradation of the aquifers in the sub-basin. The water temperature indicates the existence of low temperature thermal processes in the area.     

外来调水对华北低平原区地表水和地下水 水化学特征的影响* ——以河北省南皮县为例

华北低平原区有着巨大的粮食增产潜力,同时也是粮食生产和农业水资源矛盾突出的地区。外来调水与浅层微咸水的联合利用是解决区域水资源问题的有效途径之一,同时也将引起区域水循环和水环境的改变。为明确外来调水对华北低平原区地表水和地下水水化学特征的影响,本研究在华北低平原区河北省南皮县域内对调水后不同季节地表水和地下水进行调查和采样,利用水文地球化学和氢氧(d~2H、d~(18)O)稳定同位素相结合的方法,研究外来调水对地表水和地下水转化及其水化学特征的影响。研究结果表明,11月至翌年7月,受蒸发作用的影响,地表水电导率(EC)和钠吸附比(SAR)增加,d2H、d18O同位素不断富集;由于地表水和周围土壤的交换吸附作用使其水化学类型向Na~+、Cl~-和SO_4~(2-)增加、HCO_3~-减少的咸水转变。调水改变了地表水和浅层地下水之间的补给关系,11月至翌年3月,沟渠附近浅层地下水受外来调水直接或者灌溉补给,使得3月浅层地下水EC降低,埋深变浅,部分采样点分布在外来调水的SAR-EC区域。受调水影响,3月沟渠附近浅层地下水水化学类型为Na·Mg·Ca-Cl·SO_4、Na·Mg-Cl·SO_4·HCO_3、Na·Mg-SO_4·Cl·HCO_3等,是11月调水(Na·Mg·CaSO_4·HCO_3·Cl)和浅层地下水(Na·Mg-Cl·SO_4)的过渡类型。3月至7月浅层地下水补给沟渠水,地下水埋深变深,7月浅层地下水水化学类型与3月相似。调水可以季节性地改善区域内沟渠水及其附近的浅层地下水水质,而对深层地下水和坑塘水的水质无改善作用。调水对沟渠水水质的改善体现在调水季节,对浅层地下水水质的改善存在滞后性,2014年11月调水之后,2015年3月浅层地下水的水质得到改善。因此,采用调水和浅层地下水、坑塘水混合灌溉,对合理开发利用区域咸淡水资源以及深层地下水压采,恢复地下水位意义重大。     

Evaluation of On-site Wastewater Disposal Systems in Mississippi Coastal Areas

Groundwater and surface water contamination have been linked to inadequate or failing on-site residential wastewater treatment and disposal systems. The potential for groundwater contamination in coastal areas with shallow water tables is higher; subsequently the ability of soil, microorganisms, and vegetation to mitigate pollutants may be reduced. This study evaluated the performance of the four types of on-site wastewater treatment and disposal systems predominantly used on the Mississippi Gulf Coast. One type of system was deemed inappropriate for this region as none of the dozens of installations examined were functioning acceptably. Of the remaining three types, subsurface water samples were collected from representative sites using lysimeters and monitoring wells. Apart from general performance evaluation of these systems, seasonal changes translating into possible variation in disposal efficiencies and groundwater contamination were investigated. Statistical analysis of variations in organics (COD and BOD₅), nitrogen (TKN and NH ₄ ⁺ ?CN), and fecal coliform concentrations was used to identify probable deficiencies in systems tested and to recommend changes to governing standards.     

lead contamination of GROUNDWATER in an INDUSTRIAL complex

The objectives of this study were to investigate Pb contamination of a shallow groundwater aquifer underneath an industrial complex and Pb chemical forms that may be found in the study area. Concentrations of Pb in the groundwater samples ranged between 0.04 to 1570.12 µg L^-1 (10^-9.4 to 10^-5.1 mole L^-1), with an average of 88.2 µg L^-1 (10^-6.4 mole L^-1). The results of analysis of variance showed that sampling locations had significantly (p <0.05) affected Pb concentrations in the groundwater samples. Contour map of Pb concentrations and Pb/Cl ratios indicated that Pb contamination of groundwater could be associated to the seepage of irrigation water, corrosion of buried metallic structure (largely of iron), and leachate from the industrial dust pile. Thermodynamic modeling approach was used to speciate total Pb concentrations in the groundwater samples. The results of these computations revealed that, in the very dilute groundwater (salinity < 1 parts per thousand, i.e., ppt), Pb²⁺ and Pb-OH complexes were the most significant chemical forms. Groundwater salinities between 1 to 5 ppt, Pb²⁺, Pb-OH, Pb-Cl, Pb-HCO₃, and Pb-SO₄ were present in appreciable concentrations, depending on their respective anionic concentrations. Over 80% of the total Pb in water was present in Pb-Cl complexes in groundwater samples with salinities >40 ppt. A comparison of the calculated activities of Pb²⁺ and the thermodynamic solubility isotherms of Pb minerals suggested that mineral Pb(OH)₂(c) was too soluble to precipitate in these water samples. The distribution trend in Pb²⁺ activities do not support equilibrium with Pb₃(PO₄)₂(c). Formation of PbCO₃(c) and Pb₂CO₃Cl₂(c) in the groundwater samples appeared to be the most logical option. From the foregoing, it was concluded that Pb-CO₃ minerals can limit Pb solubility in saline groundwaters.     

Nitrogen Isotope Study on Nitrate-Contaminated Groundwater in the Sichuan Basin, China

We investigated the expansion of NO₃ ^?-contaminated groundwater in the Sichuan Basin, China. Nitrogen concentrations and isotopic ratios of NH₄ ⁺ and NO₃ ^? were analyzed in groundwater and rain collected from four areas in this basin in order to evaluate the sources of nitrogen pollution. NH₄ ⁺ in rain, for which δ¹⁵N values are strongly negative to slightly positive ?13.4 to + 2.3‰, appears to originate from fertilizers and excretory waste. NO₃ ^? in rain (δ¹⁵N: ?10.2 to ?4.4‰) was attributed to NO _x from automobile exhaust gas. In the studied area, well water sampled from farmyards was found to have the highest δ¹⁵N_NO3 (average: +9.7 ± 4.7‰), indicating contamination by domestic sewage as animal excrement. The lowest δ¹⁵N_NO3 (?0.2 ± 3.7‰), found in spring water, indicates that the studied groundwater samples are widely affected by air contaminants (mainly as nitrogen oxides) resulted from fuel combustions. The δ¹⁵N_NO3 (+3.7 ± 2.1‰) values of well water from farmland are between these levels, suggesting that NO₃ ^? contamination results primarily from cultivation using nitrogen fertilizers, although the contribution from animal excrement cannot be excluded. These results demonstrate that the studied groundwater is widely polluted by locally derived nitrogen sources.     

克拉玛依人工碳汇林区景观地球化学特征与规律

以克拉玛依人工碳汇林区的土壤可溶性盐分离子、地下水矿化度和植被为研究对象, 综合运用描述性统计和相关性分析等方法, 研究其景观地球化学特征, 旨在通过对克拉玛依人工碳汇林区的景观地球化学特征的研究, 为这一地区盐渍化土壤改良和沙漠化防治提供理论依据。结果表明: 克拉玛依人工碳汇林区土壤Cl^-、SO₄^2-、Ca²⁺在0~80 cm范围内变异系数较大, 80~100 cm范围内, 土壤总盐和各离子变异系数相对较小; 盐分表聚现象严重; 该地区盐土类型主要是硫酸盐型, 其中SO₄^2-和Na⁺+K⁺为土壤可溶性盐的主要成分。研究区地下水呈弱碱性, 除HCO₃^-外, 其他离子和矿化度表现出较强的变异性; 地下水的化学类型主要为Cl·SO₄-Na, 矿化度和Cl^-、SO₄^2-、Na⁺+K⁺相关系数较为显著。种植人工碳汇林后, 除土壤HCO₃^-含量有轻微上升外, 其他离子均有所下降, 其中SO₄^2-含量的降低趋势最为明显。俄罗斯杨林分土壤含盐量随种植年限的增长明显降低, 种植后的土壤盐渍化状况有明显改善。     

河北曲周盐渍土区的地下水化学特征

对河北曲周县盐渍土区浅层地下水的水化学类型、基本化学性质、主要化学组分及其形式和微量元素的状况及分布等化学特征进行了分析和研究。资料表明，该区地下水化学类型以Cl-SO4型为主，其次为SO4-Cl型。阳离子以Ca∧2 为主，其次为Na∧ 。各地下水化学类型可用于3种特征指标，即rHCO3/r（Cl SO4)、rSO4/rCl和rNa/r（Ca Mg），加以区分。地下水矿化度平均3.11gL∧-1，最高达17gL∧-1。以Cl-SO4和SO4-Cl型的矿化度和离子强度较高。全区纳吸附比较低，基本上无钠害问题。饱和指数表明，地下水中石膏和硬石膏呈非饱和状态，而方解石、霰石呈过饱和状态。除主要游离子外，化学组分形式中CaSO∧04、MgSO∧04、CaHCO∧ 3和MgHCO∧ 3等配合物和配离子的相对浓度较高。地下水中微量元素Cr、Cd和Fe的含量较高，应注意其水质问题，除Zn外，各微量元素浓度均与矿化度呈极显著（或显著）相关。     

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.     

Effects of tile drainage repair on nutrient leaching from a field under ordinary cultivation in Sweden

Leaching losses of nitrogen (N), phosphorus (P) and potassium (K) from arable land can be high, with N and P contributing significantly to the eutrophication of lakes and coastal waters. This study examined whether agriculture management and drain repair changed the chemical properties of shallow groundwater and affected nutrient leaching in the field. The hydrology of a subsurface-drained agricultural observation field included in the Swedish water quality monitoring programme was simulated for the period 1976–2006 using the process-based, field-scale model DRAINMOD. On the assumption that the drainage system operated similarly before and after repair, 54% more water was assigned to low-moderate flow events. Measured concentrations of sulphate-sulphur (SO₄-S), sodium (Na), chloride (Cl) and potassium (K) were significantly lower in shallow groundwater in the period before drainage system repair (1980–1998) than afterwards (1998–2010). The concentrations were also significantly correlated with the corresponding concentrations in near-simultaneously sampled drain water. A similar connection was not observed for Na and Cl in the period before drain repair. Elevated concentrations of nitrate-nitrogen (NO₃-N) were recorded both in shallow groundwater and in drainage water from 1998 to 2010, especially after incorporation of chicken manure into the soil in 1998. Based on simulated discharge (assuming a functioning measuring station throughout), estimated flow-weighted mean NO₃-N concentration in drainage water increased from 5.6 mg L^?1 (1977–1998) to 15.7 mg L^?1 in the period 1998–2000. Simultaneously, mean NO₃-N concentration in shallow groundwater increased from 0.2 to 4.0 mg L^?1, and then to 4.8 mg L^?1 in the period 2000–2012. It was estimated that after drain repair, a greater proportion of infiltrated NO₃-N entered the receiving stream directly via the outlet of the tile drainage system close to the field's monitoring station than was the case before repair.     

Simulation of flow patterns and ion-exchange in soil percolation experiments

An increased understanding of ion-exchange processes in raw-humus was obtained by simulations using quantitative mathematical models. The work is based on a series of percolation experiments with a water flow of about 1 mm min^?1 through raw-humus samples of 4 cm thickness. For the input solutions consisting of 10^?3 N H₂SO₄, HNO₃, HCl and NaCl the results indicate that cation-exchange reactions are the most important processes for the chemical composition of the run-off. Since a large part of the water flows quickly through the soil, both the water residence time and the ion-exchange kinetics must be taken into account. As a basis for the chemical model, a hydrologic sub-model reproducing the residence time distribution of the flow in the soil is used. Considering the ions H⁺, M⁺ (monovalent metal ions) and M²⁺ (divalent metal ions), four different chemical models were tried but only one of them gave satisfactory agreement with the experimental results. This model has 5 independent parameters and consists of first and second order chemical processes.     

Specific features of the chemical composition of groundwater in floodplain soils of the Selenga River delta (Lake Baikal region)

The chemical composition of groundwater has been studied at several test plots in the Selenga River delta. The fresh groundwater containing calcium bicarbonates favors the formation of nonsaline soils in the delta and, hence, contributes to preservation of fresh water in Lake Baikal. The role of groundwater as a source of dissolved organic matter, iron compounds, phosphorus, and other elements is discussed. It is shown that the depth and chemical composition of the groundwater in particular areas depend on the character of the mesotopography, the drainage of the area, and the soil properties. After the flood period, the concentrations of Ca²⁺, HCO ₃ ^? , Fe³⁺, and SO ₄ ^2? in the groundwater increase with the rise in the soil temperatures. In the dry periods, the concentrations of Na⁺ and Cl^? ions increase, whereas the concentration of C_total decreases.     

Groundwater Contamination by Landfill Leachates in a Karstic Aquifer

The contamination of a karstic aquifer by the leachate from the urban solid waste landfill of La Mina (Marbella, south of Spain) has been monitored. A characterization of the karstic media and the different storages of water in the carbonate rock have been deduced by the study of the hydrodynamic and hydrochemical variations in water points of the study network. The chemical compositions of four springs, three pumping wells and five piezometers in the surroundings of the landfill, yield two patterns of hydrochemical behaviour at the contaminated points: (1) the contamination at the piezometers, measured by the concentration of Cl^? and by electrical conductivity, increased over time, but was associated with the precipitation of calcite, evidenced by a reduction in the concentration of HCO₃ ^? and Ca²⁺; (2) at points near the landfill, contamination also increased, but the CO₂ from the landfill provoked an additional dissolution of carbonate minerals, a process reflected in the high concentrations of hydrogen carbonate, calcium and magnesium. The contaminated points were irregularly distributed, the most distant piezometer presenting the greatest impact, whereas no traces of contamination were detected at one piezometer close to the landfill. The irregular distribution of these processes is explained by the heterogeneity of the karstic media, with different types of storage (conduits, fractures/fissures and matrix) and a difference in density between the leachate and the groundwater.     

Is salt stress of faba bean (Vicia faba) caused by Na+ or Cl– toxicity?

The effect of sodium chloride (NaCl), sodium sulfate (Na₂SO₄), and potassium chloride (KCl) on growth and ion concentrations of faba bean (Vicia faba L. cv. Troy) was studied. After 14 or 15 d of isoosmotic treatment with 100 mM NaCl or 75 mM Na₂SO₄, respectively, plants developed toxicity symptoms. These symptoms were characterized by local and nonchlorotic wilting spots, which later turned to black, necrotic spots. In contrast to NaCl or Na₂SO₄ treatment, plants treated with 100 mM KCl did not show these symptoms. The symptoms occurred on those leaves that accumulated highest concentrations of Na⁺ and showed highest Na⁺ : K⁺ ratios. Our results indicate that Na⁺ toxicity inducing K⁺ deficiency is responsible for the spot necrosis of faba bean. Additionally, chlorotic symptoms occurred. The concentrations of Na⁺ and Cl^– were determined in chlorotic leaves and in isolated chloroplasts. The reduction of chlorophyll in leaves after NaCl exposure may be explained in terms of high Cl^– concentrations in the chloroplasts and appears to depend on high Na⁺ concentrations. Chlorotic toxicity symptoms can be avoided by additional Mg²⁺ application.     

Monitoring and Modeling Nitrate Persistence in a Shallow Aquifer

A modeling study on fertilizer by-products fate and transport was performed in an unconfined shallow aquifer equipped with a grid of 13 piezometers. The field site was located in a former agricultural field overlying a river paleochannel near Ferrara (Northern Italy), cultivated with cereals rotation until 2004 and then converted to park. Piezometers were installed in June 2007 and were monitored until June 2009 via pressure transducer data loggers to evaluate the temporal and spatial variation of groundwater heads, while an onsite meteorological station provided data for recharge rate calculations via unsaturated zone modeling. The groundwater composition in June 2007 exhibited elevated nitrate (NO ₃ ^? ) and chloride (Cl^?) concentrations due to fertilizer leaching from the top soil. The spatial distribution of NO ₃ ^? and Cl^? was heterogeneous and the concentration decreased during the monitoring period, with NO ₃ ^? attenuation (below 10?mg/l) after 650?days. A transient groundwater flow and contaminant transport model was calibrated versus observed heads and NO ₃ ^? and Cl^? concentrations. Cl^? was used as environmental tracer to quantify groundwater flow velocity and it was simulated as a conservative species. NO ₃ ^? was treated as a reactive species and denitrification was simulated with a first order degradation rate constant. Model calibration gave a low denitrification rate (2.5e^?3 mg-NO ₃ ^? /l/d) likely because of prevailing oxic conditions and low concentration of dissolved organic carbon. Scenario modeling was implemented with steady state and variable flow time discretization to identify the mechanism of NO ₃ ^? attenuation. It was shown that transient piezometric conditions did not exert a strong control on NO ₃ ^? clean up time, while transient recharge rate did, because it is the main source of unpolluted water in the domain.     

Hydrochemical modelling of a stream dominated by organic acids and organically bound aluminium

An existing hydrogeochemical model, the Birkenes model (BIM), has been extended to include production of dissolved organic carbon (DOC) in the soil/water system and its chemical interactions with H⁺ and A1³⁺. The model has been calibrated and verified using precipitation and runoff data from the Svartberget catchment in northern Sweden. The catchment is impacted by moderate amounts of sulphur deposition (6 kg S ha^?1 a^?1; the stream is high in DOC (7–35 mg L^?1) and experiences episodically low pH-values (～4.0). The refined BIM is able to simulate the main variations in major chemical components of the stream water (H⁺, Ca²⁺, Mg²⁺, Al_i, Al₀, Cl^?, SO₄ ^?2 and DOC), as well as stream discharge and ¹⁸O, while Na⁺ is not well reproduced. Although very simplified relationships are used for the chemical interactions between DOC and H⁺ and aluminium, the model shows that these interactions are essential to stream acidity and aluminiumspecies content. Some of the model parameters are poorly determined by calibration with runoff data only. Soil and soil water investigations may contribute to the evaluation and development of the model structure and the representation of chemical processes. Further improvements of the model should emphasize DOC-production/absorption, detailed studies on DOC chemical behaviour and hydrological structure.     

Leaching of nutrients and major ions from an arable field with an unfertilized fallow as infield buffer zone

Abstract

Leaching of nutrients and major ions from a tile-drained arable field was evaluated over a 25-year period (1980–2005). The soil, classified as a Gleyic Cambisol, received moderate applications of fertilizers. During later years the soil was more frequently under ley, and since 2002, an area of ravine (29% of the total field) has been managed as a permanent fallow with annual cutting without removing the grass material. A decrease in the concentration of nitrate nitrogen (NO₃?N) in the drainwater was estimated in 1980–2005, based on non-parametric tests on concentrations flow-normalized with a robust fitting curve procedure. The average concentration of soluble reactive phosphorus after pre-filtration (RP_f) of 0.030 mg l^?l corresponded to a calculated degree of phosphorus saturation (DPS) of 6% in acid extract of ammonium lactate from the topsoil. Between 1995 and 2005, concentrations of suspended solids (SS), RP and total organic carbon (TOC) decreased significantly in the drainage water from the entire field. Throughout the entire period, there was a negative net accumulation of the major ions to the soil. The order of decrease in relative terms was calcium (Ca²⁺)>magnesium (Mg²⁺)>sulphate (SO₄ ^2?)>chloride (Cl^?)>potassium (K⁺). In addition, the soil phosphorus (P) balance was negative. A significant reduction in ion concentrations in the drainwater, including sodium (Na⁺) and hydrogen carbonate HCO₃ ^?, was estimated. The order of reduction in relative terms was: SO₄ ^2?>Mg²⁺>Ca²⁺>HCO₃ ^?>Cl^?>NO₃ ^?>Na⁺>HPO₄. Altogether these trends were equal to approximately 0.1 mmol_c l^?1. yr^?1 of positively and negatively charged ions. Based on measured concentrations, decreasing trends in SO₄ ^2? and Ca²⁺ were also observed in the shallow groundwater (3.6 m below the soil surface), while K⁺, Na⁺ and HCO₃ ^? tended to increase. Trends of cations in deeper groundwater (5.8 m below the soil surface) were in some cases the opposite of the trends in the drainwater.     

Links Between Runoff Generation,Climate and Nitrate-N Leaching from Forested Catchments

To assess links between hydroclimatological factors and NO₃ ^- concentrations in streamflow from boreal forests with shallow soils, data from two catchments were analyzed. TOPMODEL was used to calculate the surface runoff fraction, daily dynamics of soil moisture, groundwater levels, and extensions of saturated areas. The stable isotope 18O was used for isotopic hydrograph separation (IHS) during one snowmelt season. Air-temperature and flow increase were the dominating factors explaining annual NO₃ ^-dynamics. Correlation also was found between NO₃ ^- concentrations and the surface runoff fraction. Increased concentrations during times of shallow groundwater were found both during cold and warm periods in one catchment. In the other, shallow groundwater was correlated to decreasing concentrations during cold periods, and increasing concentrations during warm periods. A two component model of event and pre-event water fractions and corresponding NO₃ ^- concentrations was set up for the snowmelt season. Model predictions mirrored NO₃ ^- concentrations during the first five days of the snowmelt. After that, the model overestimated NO₃ ^- concentrations, which indicates retention of NO₃ ^- in the event water fraction, originating from the snowmelt. The highest concentrations occurred during the initiations of flow increase, which indicates flushing of surficial NO₃ ^-.     

Effect of Environmental Conditions on Chemical Profile of Stream Water in Sanctuary Forest Area

This study reports the evaluation of chemical composition of a Black Vistula and White Vistula streams’ waters taking into consideration both geological conditions of the stream’s catchment area and different water’ level related to seasonal variations in particular catchment ecosystem (high stage: beginning of the vegetation period; medium stage: vegetation period; low stage: final time of vegetation period). The complex data matrix (744 observations), obtained by the determination of major inorganic analytes (Cl^?, NO₃ ^?, SO₄ ^2?, NH₄ ⁺, Na⁺, K⁺, Ca²⁺, Mg²⁺) in water samples by ion chromatography was treated by linear discriminant analysis and non-parametrical testing. In case of both streams obtained results indicate presence of two discriminant functions (DFs). The data variance explained by DFs is as follows: Black Vistula stream—first DF: 93.5%, second DF: 6.5%; White Vistula stream—first DF: 66.3%, second DF: 33.7%. In case of Black Vistula stream first DF allows distinction of medium, high and low waterstage related samples while second DF between high/low and medium water stage related samples. In case of White Vistula stream first DF allowed to distinguish between medium/high and low water stage related samples while second DF between medium and high water level samples. In case of both streams, the most informative DFs were related to geological conditions of investigated catchments (contents of Cl^?, Na⁺, K⁺, Mg²⁺, Ca²⁺, SO₄ ^2?), while the second to nutrient biocycle (mainly NH₄ ⁺ and NO₃ ^?) related to slope’s exposition and inclination.