Metal pollutants in agricultural soils and the St. Louis urban rainfall anomaly

The existence of a rainfall anomaly downwind of the St. Louis urban-industrial areas prompted a survey of area soils for elevated heavy metal concentrations. The goals of this work were to measure concentrations of Zn, Cd, and Ph, and to evaluate the role of the urban rainfall anomaly in their accumulation, in potentially-affected soils. Samples from three soil layers were collected from agricultural fields at 21 sites along two NE-SW transects. The samples were analyzed for pH, texture, cation exchange capacity, and total organic carbon, in addition to the three metals. The highest metal concentrations were observed near Granite City, Illinois, and coincided with an area of maximum Zn deposition in rain found in an earlier study. Only slight increases of the metals over background were found in the area of rainfall anomaly. Present rates of atmospheric deposition can account for these slightly elevated metal concentrations. However, the maximum concentrations found near Granite City cannot be accounted for by present atmospheric deposition rates. Other kinds of sources, or larger atmospheric deposition rates, perhaps during the operation of a local Zn smelter which closed about 1960, must have contributed.     

县域尺度农田深层土壤有机质的估算及空间变异特征

县域是实施农业绿色发展的基本单元,农田土壤中不仅耕层的有机质含量会对土壤肥力产生影响,深层有机质的作用也不可忽略,精确估算基于县域尺度农田深层有机质含量具有重要意义。该研究选定位于山西省运城市的永济市农田为研究区,采用多点混合取样法,获取了8个样地剖面的18层数据,共144个混合土样的有机质含量数据,建立了表层(0～20 cm)有机质含量估算深层有机质含量的模型,并进行深层有机质含量的估算。基于半变异函数、空间自相关理论分析了0～30、30～60、60～90、90～120、120～150和150～180 cm土层有机质含量的空间相关性和聚集特征,并进行了相关性检验,采用克里格插值方法对研究区农田各土层的有机质含量进行了预测。结果表明:1)土壤有机质含量随深度的增加呈负指数递减(R2=0.80,P0.01),各土层的有机质含量变异系数介于35.89%～47.84%之间,处于中等变异程度。2)通过建立的估算模型可以通过表层有机质含量估算出任意深度的有机质含量,且拟合精度R2达到了0.90(P0.01)。3)指数模型是反映该区域有机质含量空间结构特征的最佳模型(R20.80,RSS0.001),各土层的有机质含量均表现出了中等程度结构性特征,和空间正相关性特征(Moran’s I=0.26,P0.01),并存在显著的空间聚集特征和异常值现象。4)克里格插值可以较好地进行研究区各层有机质含量的预测,预测精度较高,稳定性较好,为县域尺度深层有机质的估算,调整农艺措施、提高土壤肥力、达到土壤减肥增效、绿色增产增效提供依据。     

Atmospheric sulphur dioxide and rainwater at a coastal locality in N.W. England

The relationship between atmospheric SO₂ concentrations and rainwater pH is examined for a coastal locality in North Merseyside, England for the period 1978 to 1982. During this period rainwater pH has risen slightly but significantly while atmospheric SO₂ levels have fallen. The relationship between SO₂ levels, rainwater pH and wind frequency and wind run from eight sectors of the compass are analyzed. Higher SO₂ concentrations coincide with southerly, southeasterly and easterly winds from urban and industrial source areas. Slightly higher frequency and run of wind occur from the south and east during the winter season when SO₂ production is increased.     

Soil penetrometer resistance spatial variability in a Ferralsol at several soil moisture conditions

The penetrometer resistance (PR) spatial variability in a Ferralsol under different soil moisture conditions was characterized through statistical and geostatistical methods. PR measurements were made in a 10-row, 10-columns, 3-m spacing grid at 20–30 cm depth using a hand-pushing penetrometer. Measurements were made for dry soil conditions (before irrigation) as well as 2 and 24 h after irrigation. The soil bulk density (BD) and the relative topographical altitudes (RT) were measured at the same locations. The PR spatial variability is normally distributed for dry soil conditions and after irrigation-water redistribution. A normal distribution fits also to the BD spatial variability. PR mean and coefficients of variations are lower for wet soil conditions and vary notably according to the soil moisture condition. The PR semivariance values are much higher for dry soil conditions than those found for wet soil conditions. However, the semivariogram of PR before irrigation shows almost a pure nugget effect. Irrigation yields a spatial structure in PR measurements. Despite the differences in the shown spatial structure, the range of the PR semivariograms before and 24 h after irrigation is about 8–10 m, which is very similar to the range of the BD semivariogram. The correlation coefficients between PR and the other measured variables are very small before and after irrigation, which could lead to the conclusion that those variables are not related at all. However, according to the co-dispersion coefficients plotted as a function of the separation lag, the correlation between those variables changes according to the separation distance. Particularly, PR and the RT show correlation 24 h after irrigation only for lags between 5 and 12 m. The results pointed out that PR spatial variability depends on soil moisture condition, soil BD and on several local features as microtopography.     

Modelling spatial and temporal variability of denitrification

Summary Denitrification shows both spatial and temporal variability. Any attempt to model the process must take this into account. A model has been developed in which the soil is treated as a large assembly of potentially denitrifying microsites (a modification of the hot-spot concept). Chemical and biological heterogeneity is represented by a log-normal distribution of microsite respiration potential. Structural heterogeneity (where present) is accommodated by associating individual microsites with soil aggregates, the radius of which varies log-normally. Spatial variation arises naturally from the existence of microsites. Model microsites are assumed to be in a state of pseudo-equilibrium (a steady state). This means that they respond rapidly to any perturbation; it does not imply that they are static. A pseudo-equilibrium model can readily encompass temporal variation provided that the response time of the system is relatively short. Examination of the response times of typical model microsites, by numerical solution of the partial differential equations governing the transient processes occurring within them, suggests that in soils with few large (greater than 10^-2m in radius) denitrifying microsites the steady-state approximation is probably adequate. Where denitrification occurs predominantly in large microsites, however, a pseudo-equilibrium model is inappropriate.     

Analysis of rainwater quality variability on mesoscale: Case of the montreal island

During summer of 1989, a network for the analysis of spatial variability of rainwater quality was operated on Montréal Island. Six bulk samplers distributed on the territory were used for this purpose. A total of 97 storm-station events have been analyzed for pH, conductivity, Total Organic Carbon, nitrate, sulphate, calcium and magnesium. A canonical discriminant analysis shows that as a whole, there is no statistically significant discrimination between stations. However, Tukey's test for means shows that mean pH is significantly different between downtown and peripheric stations. The pH is higher in downtown. Finally, a variance analysis shows that variations with respect to time are greater than those on a spatial basis. Thus, the Montréal Island can be considered as spatially homogeneous for most rainwater quality parameters.     

Discriminating factors of the spatial variability of soil quality parameters at landscape‐scale

The aim of the study was to evaluate the spatial variability pattern of some soil quality parameters at landscape‐scale, particularly soil microbial biomass‐C (C_mic) and ‐N (N_mic), and soil microbial activity (respiration) as well as soil organic carbon (C_org), and hot water extractable carbon (C_hwe) by multivariate analyses of variance and canonical discriminant analyses (CDA). The study area was the Trier region, Rhineland‐Palatinate, which is characterized by a wide range of soil types developed from various parent materials. Additionally, the investigated fields differed in soil management intensity (conventional, integrated, organic farming) and crops grown. Within the whole study area CDA revealed a separation into three sub‐areas. Within the sub‐areas the soil quality parameters were significantly influenced by the soil management systems and the crops grown. Despite the spatial variability and the relationship to soil management, the contents of C_mic could be predicted by stepwise multiple linear regression models, both for arable and grassland soils. The explained variance for the regression models were 72 % for arable soils and 63 % for grassland soils, respectively. Regression models for predicting N_mic and microbial activity revealed an explained variance between 30 and 58 %.     

牧草氮素产量的时空变异研究

以英国Hillsborough农业研究所附近的一块7.9hm2的牧草田为研究区,采用地统计方法研究分析连续3年的牧草氮素产量在3个收割季节的空间变异,并研究了第一、二季其空间分布的变异在时间上的稳定性。结果表明,试验区牧草氮素产量在单个田块间存在较大的空间变异,而且这种变异在不同的生长季呈现有规律变化,变量施肥是必要的;牧草氮素产量的空间分布与地形有很大的关系,可以根据地形将试验区分片管理。     

畦面微地形时空变异分布状况试验研究

畦面微地形时空变异分布状况对畦灌性能的影响较为显著,该文依据从典型试验畦块获得的畦面相对高程实测数据,借助统计学方法分析评价田间耕作措施和地面灌溉对畦面微地形时空变异分布状况的影响。结果表明：农田机耕、围畦打埂等田间耕作措施对畦面微地形整体分布状态和畦面相对高程空间分布状况的影响显著;而地面灌溉虽对畦面相对高程空间分布状况有一定影响,但对畦面微地形整体分布状态的影响却较小;田间耕作和地面灌溉等人为生产活动对较小规格畦块的畦面微地形时空变异分布状况的影响明显一些,围畦打埂和入畦单宽流量是影响土地精平后畦面微地形分布状况发生变化的主要影响因素;对较大规格的畦块,除上述影响因素外,还应关注机耕作业留下的车轮压痕对畦面平整状况产生的负面作用。     

土壤水盐空间变异尺度效应的研究

水文学和土壤学中的尺度问题是目前水土科学研究的前沿课题之一。该文利用空间信息科学——地质统计学、根据设计的各种田间网格，在一维和二维(平面)空间中初步研究了黄河河套平原长胜试验区中小尺度的土壤水分和盐分随采样尺度所表现出的空间变异(结构性)的某些规律，表明采样尺度的划分和选取与水分和盐分的空间变异性大小有密切关系，尺度效应的研究对于指导农业技术研究中野外采样系统设计、节省外业调查的工作量及科学地进行内业计算、评估和揭示农业工程中具有地学特征的区域性自然规律有重要作用。     

Small-scale spatial variability of selected soil biological properties

A strategy for sampling soil from intact monolith lysimeters was established based on measurements of spatial heterogeneity within the lysimeter area. This was part of an ongoing study to determine relationships between soil microbial diversity and nutrient loss by leaching. The sampling protocol had to allow collection of soil on a regular basis (as opposed to destructive sampling) and ensure high spatial independence of subsamples. On each of the two sites (one developed under organic crop management and the other under conventional crop management), ten 15 cm soil cores (sampling points) were taken from three areas (replicates) of 50 cm diameter (lysimeter surface area) and separately analysed for biotic (microbial biomass carbon and nitrogen; arginine deaminase activity) and abiotic (total carbon and nitrogen) soil properties. The data were tested for variability, expressed as coefficient of variance (biotic and abiotic), and spatial heterogeneity using geostatistics (biotic properties). The biotic soil properties showed significant differences among sampling points, whereas the abiotic parameters were useful in differentiating on a larger scale, i.e. between sites. For all soil properties tested, the differences among the replicates were smaller than those between the sites or among points indicating that, in the main experiment, all treatments can be sampled following the same pattern. Geostatistical analysis and fitting of an exponential model showed that a spatial structure exists in the biotic soil properties and that the samples are independent beyond separation distances of 25-30 cm. A revised sampling pattern consisting of 11 samples per lysimeter is described.     

土壤钾素空间变异性和空间插值方法的比较研究

通过研究土壤养分的空间变异性和空间插值方法 ,获取田间土壤养分的连续分布图是当前精确施肥技术的工作基础。本研究以英国Hillsborough农业研究所附近的一块 7.9hm2 的牧草田为研究区 ,区内以 25m25m网格点采样 ,共 125个采样点。以土样的钾素含量为研究对象 ,采用移动平均、趋势面拟合、样条插值、点状克立格、逆距离加权等各种空间插值方法对一部分离散的采样点进行连续插值而获取土壤钾素空间分布图。同时以另一部分的采样点数据来对各种插值方法的结果进行均差和均方差的比较分析。研究结果表明 ,克立格、逆距离加权两种方法总体效果最好 ,其中克立格方法中又以指数模型为佳 ,逆距离加权插值法以二次方为佳     

Divergent evolution and the spatial structure of soil landscape variability

The spatial structure of soil variability at the landscape scale was examined on adjacent geomorphic surfaces dating from 80 to 200 ka in eastern North Carolina. The purpose was to determine whether there is evidence at broader scales (distances of 10²–10⁴ m) for the divergent evolution observed in the field at very detailed scales (distances of 10⁰–10² m). The state probability function (SPF), which measures spatial dependence for categorical environmental data along a transect, was applied to soil series mapped at a 1:24,000 scale. The older Talbot Terrace and younger Pamlico Terrace surfaces showed distinctly different patterns of spatial variability. The range of spatial dependence was shorter on the older surface (about 200 vs. 300 m), and the SPF was higher at any given distance, indicating more variability. The SPF for the Pamlico surface also indicates a periodicity related to fluvial dissection of the landscape, which is not readily detectable on the Talbot transect despite its greater degree of dissection. The results confirm earlier field studies which suggest that pedogenesis is marked by divergence, whereby differences in initial conditions or local perturbations persist and increase to produce a more variable soil cover.     

土壤钾素空间变异性和空间插值方法的比较研究

通过研究土壤养分的空间变异性和空间插值方法 ,获取田间土壤养分的连续分布图是当前精确施肥技术的工作基础。本研究以英国Hillsborough农业研究所附近的一块 7.9hm2 的牧草田为研究区 ,区内以 25m×25m网格点采样 ,共 125个采样点。以土样的钾素含量为研究对象 ,采用移动平均、趋势面拟合、样条插值、点状克立格、逆距离加权等各种空间插值方法对一部分离散的采样点进行连续插值而获取土壤钾素空间分布图。同时以另一部分的采样点数据来对各种插值方法的结果进行均差和均方差的比较分析。研究结果表明 ,克立格、逆距离加权两种方法总体效果最好 ,其中克立格方法中又以指数模型为佳 ,逆距离加权插值法以二次方为佳     

上海市规模经营农场的土壤养分与水稻产量空间变异特征

运用经典统计和地统计学结合的研究方法，探讨了规模化经营农场田块内的作物产量及土壤有效养分含量等空间变异特征。结果表明，土壤pH有较小变异和较强的空间结构性。作物产量变异较小而且是随机因素引起的没有明显空间结构性，和土壤养分含量及pH值等属性也没有明显的相关。有效磷、有效硫也表现为纯块金效应，全部变异由随机因素引起。其它观测项目均有不同程度的空间自相关，有效养分含量之间也有较为显著的相关性。     

方正县土壤全硒空间变异研究

为了明确富硒水稻主产县方正县土壤中全硒的含量、分布等特征,以方正县农业土壤为研究对象,运用地统计学和Arc GIS相结合的方法研究土壤全硒含量的空间异质性和分布格局,并探讨硒浓度变异与土壤理化性质之间的关系。结果表明,土壤全硒含量变异函数符合指数模型,空间异质性指数Q=0.125,说明全硒含量的变异主要由结构性因素引起,空间自相关性较强。用普通克里格法(OK法)绘制全县的土壤全硒分布图,发现研究区绝大多数土壤(69.3%)属于足硒土壤,硒含量高值区出现在研究区中部及西南部,而低值区主要分布在研究区东北部。不同土壤类型中,泥炭土全硒含量最高(0.267 mg·kg-1),而沼泽土全硒含量最低(0.153 mg·kg-1);不同土地利用方式下,稻田土全硒含量(0.230 mg·kg-1)略高于旱地土(0.217 mg·kg-1)。影响土壤全硒含量的主要因素为土壤有机碳、粘粒及粉粒含量。     

Temporal and spatial variability of soil respiration in a boreal mixedwood forest

Temporal and spatial variability of soil respiration (R_s) was measured and analyzed in a 74-year-old, mixedwood, boreal forest in Ontario, Canada, over a period of 2 years (August 2003–July 2005). The ranges of R_s measured during the two study years were 0.5–6.9 μmol CO₂ m⁻² s⁻¹ for 2003–2004 (Year 1) and 0.4–6.8 μmol CO₂ m⁻² s⁻¹ for 2004–2005 (Year 2). Mean annual R_s for the stand was the same for both years, 2.7 μmol CO₂ m⁻² s⁻¹. Temporal variability of R_s was controlled mainly by soil temperature (T_s), but soil moisture had a confounding effect on T_s. Annual estimates of total soil CO₂ emissions at the site, calculated using a simple empirical R_s–T_s relationship, showed that R_s can account for about 88 ± 27% of total annual ecosystem respiration at the site. The majority of soil CO₂ emissions came from the upper 12 to 20 cm organic LFH (litter–fibric–humic) soil layer. The degree of spatial variability in R_s, along the measured transect, was seasonal and followed the seasonal trend of mean R_s: increasing through the growing season and converging to a minimum in winter (coefficient of variation (CV) ranged from 4 to 74% in Year 1 and 4 to 62% in Year 2). Spatial variability in R_s was found to be negatively related to spatial variability in the C:N ratio of the LHF layer at the site. Spatial variability in R_s was also found to depend on forest tree species composition within the stand. R_s was about 15% higher in a broadleaf deciduous tree patch compared to evergreen coniferous area. However, the difference was not always significant (at 95% CI). In general, R_s in the mixedwood patch, having both deciduous and coniferous species, was dominated by broadleaf trees, reflecting changing physiological controls on R_s with seasons. Our results highlight the importance of discerning soil CO₂ emissions at a variety of spatial and temporal scales. They also suggest including the LFH soil layer and allowing for seasonal variability in CO₂ production within that layer, when modeling soil respiration in forest ecosystems.     

The spatial variability of the oil contamination level in technogenic transformed podzolic soils at the northeast of Sakhalin Island

The vertical and lateral microvariability of total petroleum hydrocarbon (TPH) in technogenic soils is considered in this work. An autocorrelation and cross-correlation analysis of the TPH along a transect in the lateral direction is carried out. Statistical parameters of TPH for various industrial sites, oil spills, and natural exits are described and the normal or lognormal law of distribution of petroleum hydrocarbons in technogenic soils is confirmed. The percentage of the total spatial variability of TPH contributed by hierarchical sampling levels (10 cm, 0.25 ha, and 20 km2) is estimated. Planning the volumes of the samples that are necessary for an assessment of the average level of pollution in soils for separate sites and the entire territory of the oil field is carried out.     

利用MATLAB研究土壤水分空间变异初探

本文利用强大的数据计算分析软件MATLAB对土壤水分空间变异进行分析,并通过对样地数据插值和趋势面分析,方便地得出了样地土壤水分的变化趋势,计算分析结果对水土保持和农田灌溉都有很好的指导作用。