Räumliche Variabilität von Stoffkonzentrationen am Grundwasserspiegel bei einem grundwasserfernen Sandstandort unter Kiefern

Spatial variability of groundwater solute concentrations at the water table under a pine stand on sandy soil with deep groundwater Aim of the study was to prove the evidence of a direct influence of solute input pattern (induced by canopy throughfall) on the pattern of groundwater solute concentration at the water table even at sites with groundwater table of 4–5 m below surface. The test site was a weakly buffered sandy soil with groundwater table ca. 4.3 m below surface (Podzol soil with some features of former gley process) under a cultivated pine stand (age ca. 60 years). Groundwater at the water table was sampled in between two rows of trees along a 30 m transect at 0.5 m intervals. As example, the results for sulfate concentration (the key solute of soil and groundwater acidification) show rather high variation along the transect. But a thorough stochastic analysis of empirical data sets reveals cyclic oszillations occurring synchronous and with same period length for sulfate concentration at the water table and for canopy coverage of the ground (and therefore for solute input). An additional long-periodic oscillation is strongly superimposing in the case of sulfate concentration. Thus the results indicate a direct influence of the pattern of canopy throughfall on the pattern of sulfate concentration at the water table. However, this influence is rather weakly pronounced at this deep groundwater site compared to corresponding shallow groundwater sites.     

Spatial variability of groundwater solute concentrations at the water table under arable land and coniferous forest. Part 2: Field data for arable land and statistical analysis

The spatial variability of groundwater solute concentrations at the water table beneath a fine to medium sandy soil (Gleyic Podzol) under arable land was investigated. Samples were taken in March (within a period of high seepage) within the first decimeter below the groundwater table at horizontal intervals of 0.5 m along a 30 m transect perpendicular to the direction of plowing. At the time of sampling the field was fallow, the preceding crop was maize. Nitrate, sulfate, potassium, and calcium concentrations, as well as electrical conductivity were determined and analyzed by geostatistical and spectral analysis methods. Semivariance analysis shows spatial dependence between measurements (except for potassium) within a range of about 6 m. Spectral and cospectral analysis show a pattern of periodic variations with a period of 12 m for nitrate, sulfate, calcium, and electrical conductivity. This pattern is related to the manner in which the mineral fertilizer is spread (width of a single application = 12 m). The periodic variation of sulfate is 180° out-of-phase and has a phase shift of 0.4 m with respect to nitrate, calcium, and electrical conductivity, which is probably due to separate application. The concentration of potassium shows a spatial trend, presumably due to a trend in the amount of potassium fertilizer applicated from one side of the field to the other.     

Evaluation of models to upscale the small scale variability of Cd sorption in a case study

Cadmium sorption, basic soil properties and water retention were jointly analyzed in an acidic sandy podzol under pine forest in the North of Germany. Samples were taken along a 10 m transect at a depth of 0.15 m with a sample-support of 0.15 m. The small-scale Cd sorption variability was upscaled in two steps. Firstly, it was simplified and, secondly, aggregated from the sample to the pedon scale. We evaluated different models to simplify Cd sorption variability at different levels of spatial aggregation. Our evaluation method was the numerical simulation of Cd transport in the topsoil where the variability of Cd sorption is the key input.We described Cd sorption with the Freundlich parameterization and tested three models to simplify its spatial variability. The reference model (model 1) had two and the simplified models only one spatially variable sorption parameter. Model 2 varied the parameter K_f of the Freundlich parameterization and set the exponent constant. Model 3 expressed only the linear variability of sorption. Each sample had a scaling factor that related to a constant sorption reference function. The Freundlich parameter K_f of the third simplification model (model 4), was derived by a local pedotransfer function. Its variability was, therefore, filtered by the available variation of a limited number of basic soil properties.The average sorption was at all aggregation levels not significantly different between the models. However, the corresponding uncertainty was smallest for model 3, intermediate for model 4 and largest for model 2. We evaluated the different sorption variability models with the simulation of Cd transport. The mean Cd concentrations in the topsoil predicted by the different models were statistically not different. However, at all support scales, the uncertainties of the predicted mean Cd concentrations and the RMSE's were smallest when model 3 was used, where the error was about 20% at the sample scale and decreased to below 10% at the pedon scale. Therefore, if measurements of sorption isotherms are available, we recommend to use model 3 to derive the mean sorption behavior with minimal uncertainty.     

Contribution of dissolved organic nitrogen to N leaching from four German agricultural soils

Dissolved organic nitrogen (DON) substantially contributes to N leaching from forest ecosystems. However, little is known about the role of DON for N leaching from agricultural soils. Therefore, the aim of our study was to quantify the contribution of DON to total N leaching from four agricultural soils. Concentrations and fluxes of DON and mineral N were monitored at two cropped sites (Plaggic Anthrosols) and two fallow plots (Plaggic Anthrosol and Gleyic Podzol) from November 1999 till May 2001 by means of glass suction plates. The experimental sites were located near the city of Münster, NW Germany. Median DON concentrations in 90 cm depth were 2.3 mg l^—1 and 2.0 mg l^—1 at the cropped sites and 1.6 mg l^—1 and 1.3 mg l^—1 at the fallow sites. There was only a slight (Anthrosols) or no (Gleyic Podzol) decrease in median DON concentrations with increasing depth. Total N seepage was between 19 kg N ha^—1 yr^—1 and 46 kg N ha^—1 yr^—1 at the fallow sites and 16—159 kg N ha^—1 yr^—1 at the cropped sites. For the fallow plots, DON seepage contributed 10—21 % to the total N flux (4—5 kg DON ha^—1 yr^—1), at the cropped sites DON seepage was 6—21 % of the total N flux (6—10 kg DON ha^—1 yr^—1). Thus, even in highly fertilized agricultural soils, DON is a considerable N carrier in seepage that should be considered in detailed soil N budgets.     

Carbon emission from the soil surface in a mature blueberry pine forest of the middle taiga (Republic of Komi)

Data on the input of plant falloff and organic matter decomposition on the surface of the peaty podzolic-gleyic humus-illuvial (Gleyic Podzol) soil under a mature blueberry pine forest in the middle taiga are presented. The fractional composition of the falloff was determined, and constants of decomposition for its components were calculated. The carbon flux to the atmosphere due to the mineralization of plant residues is estimated at 251 g/m². A close positive correlation (r = 0.71; P < 0.05) was found between the carbon dioxide emission measured using a gas analyzer and the soil temperature at the depth of 10 cm. The CO₂ emission for a growing period calculated from the data on its dependence on soil temperature in different years varied from 243 to 313 g C/m² and was related to weather conditions.     

宁夏固原云雾山天然草坡土壤电阻率和含水率的关系及其空间变异

为了解黄土区坡面土壤水分的空间分布,于2010年5月初选择宁夏固原云雾山2个典型草坡上利用多电极电阻仪法(ERT)测定了土壤电阻率的坡面空间分布。分别在长约400m的东南坡向坡面和圆丘坡面的4个长约100m坡向上设置纵向样线,并在样线上多点同步地测定了土壤含水率和电阻率,结果表明:土壤电阻率沿纵向坡面的空间连续性和变异性总体较好,阴坡半阴坡(西北、东北)的土壤电阻率小于阳坡半阳坡(东南、西南),并随土层深度增加而逐渐增大。同时,土壤电阻率随着体积含水率增大而几乎线性降低,其相关关系较好,说明利用土壤电阻仪测定值计算土壤含水率的空间连续发布是定量了解黄土坡面土壤水分空间分布非破坏性的一个适合技术途径。     

Field-scale study of the variability in pesticide biodegradation with soil depth and its relationship with soil characteristics

The extent of within-field spatial variability of pesticide degradation was characterised in topsoil and subsoil, using the compounds isoproturon, bentazone and mecoprop, which are major contaminants of groundwater and surface freshwater in Europe. Twenty topsoil samples from 0 to 15 cm depth and twenty subsoil samples from 50 to 60 cm depth were collected from a single agricultural field within a 160×90 grid. It was shown that degradation rates of all compounds declined with soil depth. Variability of pesticide degradation rates, pesticide sorption and formation of non-extractable pesticide residues was higher in subsoil relative to topsoil. Furthermore, in the subsoil, there was variation in large scale soil physicochemical composition, which did not occur in topsoil. The greater variability in pesticide degradation rates in subsoil relative to topsoil could be the result of a greater range of degradation kinetics, which could reflect greater spatial variability in the distribution and/or activities of pesticide metabolising communities.     

艾比湖干涸湖底盐漠土壤环境特征分析

在艾比湖东南部历史时期干涸湖底上选择一块长1 500 m,宽1 000 m的植被类型较丰富的采样带,用土钻分别采集深度为0—30 cm和30—60 cm的土壤样品,研究了新疆准噶尔盆地西部艾比湖干涸湖底沉积土壤的盐分、主要离子和有机质的季节性变化和空间分布特征。结果表明:（1）干涸湖底表层（0—30 cm）沉积物盐分平均值占整个采样层（0—60 cm）沉积物盐分平均值的73.3％,沉积物盐分垂直分布呈现出强烈的表聚性。（2）5—10月份土壤盐分的空间分布发生了很大的变化,在垂直剖面上自下向上盐分增加,在水平剖面上秋季盐分大于春季,蒸发作用对干涸湖底的土壤盐分分布有很大的作用。（3）艾比湖干涸湖底不同离子空间变异的一般规律是除了Ca²⁺离子以外,表层土壤比深层土壤的变异系数大。（4）土壤的有机碳和有机质含量10月份较5月份略有升高,盐漠植物在生命活动中对其地表有机碳和有机质的调节作用使其分布格局发生了一定的变化。     

A State‐Space Analysis of Soil Organic Carbon in China's Loess Plateau

An accurate estimation of soil organic carbon (SOC) is important for the evaluation and management of carbon (C) flux in terrestrial ecosystems. However, there is little work on the spatial variability of SOC in deep soils and its driving factors. Thus, the objective of the study was to derive the primary factors dominating the spatial distribution of SOC in different soil layers with the use of the autoregressive state‐space approach. The concentration of SOC was measured to the depth of 500 cm (n  = 86) along a south–north transect of China's Loess Plateau. The mean SOC of the 500‐cm soil profile generally decreased from south to north following the decreasing rainfall gradient. Based on the investigated factors, the state‐space model was able to capture 90.3–99.9% of the spatial variability of SOC in the various soil layers. According to the coefficients in the optimal state‐space model for each soil layer, climatic factors such as precipitation and temperature had a dominant control over the spatial distribution of SOC at shallow depths. However, both climatic and edaphic (e.g. soil texture) factors, and to a small extent land use, influenced the spatial behavior of SOC at the 40–200 cm soil depth. For soil layers below 200 cm, the importance of land use was revealed, and the spatial characteristics of SOC were together driven by land use, climatic and edaphic factors. This is critical for the management of soil C flux in deep soils and the C stock and cycle in terrestrial ecosystems. Table SI. Basic properties of soils and climate and elevation under three land uses along the south–north transect on the Loess Plateau (mean ± standard deviation). Note that SWC is gravimetric soil water content. Copyright © 2016 John Wiley & Sons, Ltd.     

Migration of Cesium-137 in typical soils of North Germany ten years after the Chernobyl accident

Ten years after the Chernobyl disaster the Cs-137 migration of typical soils of North Germany (Folic Histosol, Haplic Podzol, Dystric Gleysol, Eutric Fluvisol) has been investigated and compared to their Cs distribution in 1986. In 1986 nearly 90% of the Cs-137 occurred in the upper 1–5 cm soil sections, whereas it was 50–70% in 1996. The more regular distribution ten years after the accident shows that migration processes have taken place. The Podzol presented a high migration with marked Cs-137 losses in the top soil. The Gleysol showed the lowest migration down to 10 cm depth. A nearly similar pattern at the top was found within the Histosol, however, a ratio of 10% Cs-137 in the 10–15 cm section indicated a deeper migration. Despite the large clay content, the Fluvisol showed a regular Cs distribution within its profile, probably resulting from cattle steps and/or peloturbation.     

六盘山华北落叶松坡面土壤饱和导水率空间异质性及其影响因素

为深入理解森林坡面土壤饱和导水率的空间变异,利用经典统计学和地统计学的方法研究六盘山华北落叶松人工林坡面不同土层土壤饱和导水率的空间异质性,并基于相关性分析揭示其空间变异的主要因素。结果表明:(1)随土层的加深,土壤饱和导水率逐渐增加,不同土层土壤饱和导水率的空间变异程度存在差异,表现为40—60 cm土层土壤饱和导水率为强变异,其他土层均为中等变异。(2)不同土层土壤饱和导水率的空间结构也存在差异,20—40,40—60,60—80 cm土层土壤饱和导水率表现为强烈的空间自相关性,0—20,80—100 cm土层土壤饱和导水率表现为中等空间自相关性。(3)坡面土壤饱和导水率与石砾含量、非毛管孔隙度、毛管持水量、田间持水量和毛管孔隙度显著相关。综上,研究坡面土壤饱和导水率具有较强的空间变异,石砾含量和土壤物理性质是影响研究坡面土壤饱和导水率空间分布的主要因素。     

Soil microbial properties down the profile of a black earth burie by colluvium

The activity and biomass of soil microorganisms were determined in samples at 0—140 cm depth taken from an arable site, where the soil has been developed by erosion and colluvial deposition overlaying a black earth at 70—110 cm depth. The central aim was to get an insight into the breakdown of increasingly old and thus recalcitrant soil organic matter down the profile, effects on the availability of C to microorganisms and the microbial community structure. From 0 to 140 cm depth, microbial biomass C decreased by 96%, biomass N by 97%, the adenylates ATP, ADP, and AMP as well as the basal respiration rate by 89%. No ergosterol was measured at 120—140 cm depth. All soil biological properties decreased in distinct steps after 30 cm and 50 cm depth. At 30—90 cm depth, the amounts of soil organic C and microbial biomass C per hectare of the present colluvium exceeded nearly three‐fold those in undisturbed aeolian loess sediments. The cation exchange significantly affected the relationships between microbial biomass C, biomass N, and the adenylates. As a consequence, none of the ratios between the soil microbial biomass properties revealed constant gradients throughout the profile. The adenylate energy charge (AEC) varied between the different soil layers insignificantly around a mean of 0.71. It was the most stable ratio down the profile showing absolutely no depth gradient, the lowest depth‐to‐depth variation, and also the lowest within depth variability. The other ratios between soil organic C, basal respiration, ergosterol, microbial biomass C and biomass N also did not reveal any marked changes in the microbial community structure.     

Spatial variability of water retention parameters and saturated hydraulic conductivity in a calcareous Inceptisols (Khuzestan province of Iran) under sugarcane cropping

The objective of this study was to quantify inherent spatial variability and spatial cross-correlation of the van Genuchten retention parameters and saturated hydraulic conductivity (K_s) of surface and subsurface layers in a calcareous Inceptisols (Khuzestan province, Iran) under sugarcane cropping. Measurements were performed on 100-cm³ undisturbed soil cores collected at 94 locations along a 30-m-long transect with horizontal sampling distance intervals of 0.3 and 1 m at soil depths of 0–40 and 40–80 cm, respectively. Spatial variability was investigated using conventional statistics and geostatistical techniques. Coefficient of variation (CV) varied from 8.2% (for shape parameter, n at 40–80 cm depth) to 256.7% (for K_s at 0–40 cm depth). The n parameter and saturated water content, θ_s, showed a small-scale spatial heterogeneity with a maximum CV of 11.3% for the first depth and 9.2% for the second depth. Most of the hydraulic parameters at both depths showed a spatial structure and convex experimental semivariograms with dominant spherical models with the influence range of 3.2–41 m. In most cases, the extent of spatial correlation scales of cross-semivariograms for pairs of cross-correlated hydraulic variables was found to be different with reference to those relating to the direct semivariograms of correlated variables.     

Deposition gradients and foliar and soil leachate concentrations of air pollutants in Scots pine stands of S.-E. Finland and the Karelian Isthmus,N.-W. Russia

Bulk precipitation and throughfall analyses in 50–100-year-old Scots pine stands revealed decreasing sulphur, nitrogen, calcium and magnesium deposition gradients, which extend from the St. Petersburg-Leningrad region and N.-E. Estonia to S.-E. Finland. The Ca and Mg deposition alleviate the acidifying effect of sulphur and nitrogen. The Scots pine canopies acted as a sink for ammonium and nitrate, while the canopy interactions increased sulphur, calcium and magnesium content in throughfall. Foliar S, N and Ca concentrations correlated positively with the corresponding deposition loads. In contrast, low foliar magnesium concentrations were detected in the vicinity of St. Petersburg. The results indicate that the sulphur and calcium deposition may have increased soil leachate S and Ca concentrations in the most polluted Scots pine stands.     

Ausfilterung von Schwefelverbindungen aus der Luft durch einen Buchenbestand

Filtering of Sulfur compounds from air by beech forest In a mature beech (Fagus silvatica) forest the amounts of sulfate-S per ha and year in open land precipitation, throughfall, stem flow and seepage in 100 cm soil depth have been measured from 1969 to 1976. From the fluxes measured quantitative data on plant leaching and dry deposition in the form of plant filtering are derived. Dry deposition amounts to 26kg S · ha^?1 · y^?1 and is of the same size as wet deposition (24 kg). The leaching of sulfate takes place only in autumn and amounts to ca. 3 kg S. The acid soil in the range of Al-buffering increases its sulfate storage annually by ca. 17 kg S/ha.     

Fate of Nitrogen Compounds Deposited to Spruce (Picea Abies Karst.) and Pine (Pinus Silvestris L.) Forests Located in Different Air Pollution and Climatic Conditions

Measurements were made of NO₃-N and NH₄-N in bulk deposition, throughfall and soil solution on six permanent plots in pine and spruce stands located along a transect from the south to the north of Poland. Location differed both in the level of air pollution level and in climatic parameters. The total N load calculated from throughfall ranged from 12.5 to 34 kg^{-1a -1}. The load of NH₄-N exceeded the NO₃-N contribution. Differences in total N load were not reflected in foliar N concentration. Present forest health status of stands determined by defoliation class, and do not appear to be related to their N deposition.     

锡林河流域土壤有机碳空间变异分析

为了探索锡林河流域土壤有机碳的空间变异规律,基于半方差函数理论和普通克里格插值研究了0-10 cm,20-30 cm,40-50 cm土壤有机碳变异特征及分布格局。结果表明,（1）0-10 cm,20-30 cm,40-50 cm层土壤有机碳的最优拟合模型依次是高斯模型、高斯模型、指数模型。（2）随着土层深度的增加,土壤有机碳空间分布相关性增强,0-10 cm层土壤有机碳存在中等空间分布相关性,20-30 cm与40-50 cm层土壤有机碳具有强烈的空间分布相关性,自相关距离分别为25.81 km,20.26 km,45.00 km。（3）各向异性分析表明:各方向土壤有机碳变异程度随着土层深度增加而减弱,同层不同方向半方差变化明显,各向异性显著,不同层西南-东北45°方向以及东南-西北135°方向半方差变化最为明显,而各层45°方向变异程度却表现出相似性。（4）各层土壤有机碳分布具有一致性,流域南部边缘到东部以及东北部为土壤有机碳含量较高区域,北部、西北部以及上游的中南部是全流域土壤有机碳含量最低的区域,西部以及西南部土壤有机碳含量处于相对中等水平,流域地形与植被分布特征决定了土壤有机碳这种分布特点。     

Measurement of residues and simulation of the movement of atrazine in deeper soil layers after long-term application in agriculture

The herbicide atrazine [2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine] was applied to corn at recommended rates over a period of 18 years until 1988. The investigated field was sampled down to a depth of 10 m in 1989 and 1991. In both years residues of atrazine were determined down to 10 m depth by HPLC-analysis of soil extracts in concentrations of up to 12 μg/kg. Batch-experiments were conducted to establish sorption isotherms of various soil layers. Numerical simulations of the migration of atrazine, based on the Richards-equation and the convection-dispersion-equation with first-order degradation were performed and compared to the measurements. Depth-dependent distribution of atrazine residues could be roughly reproduced by calculations, but the calculated depth-profiles of atrazine concentrations varied strongly within the variability of the sensitive parameters. The deterministic model used was therefore not able to predict the amount of pesticide residues in groundwater recharge precisely.     

How representatively can we sample soil mineral nitrogen?

Spatial distribution of soil mineral‐N content (N_min) is a scale‐variant process. Precision farming assumes knowledge about the spatial distribution of N_min. Moreover, sampling in management zones is based on the assumption of spatial dependence between sampling points. In the present study, variability structure of N_min and the sources of variability were investigated. Within an agricultural landscape, N_min was investigated across a field in a nested design over four consecutive years. Temporally unstable structure of individual nests require a sampling with several nests in the field. In the investigated field, 35%–49% of the total variability derived from small‐scale variability observed at spatial distances of <5 m and from sampling and analytical errors. Differences between 10 and 26 kg N ha^–1 for the soil depth increment 0–60 cm can be expected. Uncertainty due to analytical errors were in the order of 5–10 kg N ha^–1 for a 0–60 cm layer.     

盐渍化灌区土壤水盐时空变异特征分析及地下水埋深对盐分的影响

针对盐渍化灌区土壤盐渍化问题,以河套灌区下游乌拉特灌域为研究区,通过野外实测与室内试验分析结合,采用统计学方法地质统计学原理分析表层土壤(0-20,20-40 cm)及深层土壤(40-100 cm)含水率与盐分(EC值)时空分布和变异规律,以及探求地下水埋深对土壤盐分的影响。结果表明:(1)除6月0-20 cm(9.779%)外,表层土壤含水率变异系数均在12.384%~19.667%,属于中等变异性,深层土壤含水率变异系数较小,在3.513%~9.757%,属于弱变异性;表层土壤盐分(EC值)变异系数在100.845%~129.279%,属于强变异性,深层土壤盐分变异系数均在83.685%~98.853%,属于中等变异性;随着土壤深度的增加,含水率和盐分的变异性都相对减弱。(2)不同时期土壤含水率和盐分在一定范围内具有空间结构特征,均可用高斯模型模拟,各层土壤含水率空间相关度在0.038%~20.408%,各层土壤盐分空间相关度在0.043%~8.374%,均小于25%,说明具有强烈的空间相关性,可以认为主要是受结构性因素的影响,其自相关引起的空间变异性较强。(3)试验区土壤盐分主要集中在北侧盐荒地,由于蒸发强烈,包气带毛细水上升,把深层土壤以及地下水中的可溶性盐类带到土壤表层,致使盐分升高,属于典型的盐分表聚型土壤,需及时防治与治理,同时土壤盐分受地下水埋深的影响较大,随着地下水埋深减小而增大,荒地地下水埋深与土壤盐分满足线性关系,耕地地下水埋深与土壤盐分满足指数关系。荒地0-20 cm土壤盐分含量随地下水埋深变化趋势较大,20-40,40-100 cm土壤盐分含量随地下水埋深变化趋势较小,耕地地下水埋深在1~1.6 m时,土壤盐分含量随着地下水埋深变化趋势较大,当地下水埋深大于1.6 m时,土壤盐分含量随着地下水埋深变化趋势较小。研究结果为河套灌区下游盐渍化土壤的防治与改良提供了重要的理论基础和参考依据。