小尺度下茶园土壤有效态微量元素空间变异特征及其影响因素分析

  【目的】  开展小尺度下茶园土壤有效态微量元素空间变异及影响因素研究,以指导茶园养分管理和土壤培肥。  【方法】  于2020年,在四川雅安名山区中峰镇面积约2 km2的生态茶园,采用随机布点法布设94个采样点,每个采样点取 0—30 cm 表层土壤,分析土壤pH、有机质以及有效铁、有效锰、有效铜和有效锌4种微量元素含量,用阈值法(平均值±3倍标准差)对分析数据进行异常值处理。采用地统计学与GIS空间分析技术相结合的方法,探讨了小尺度下茶园土壤有效铁、有效锰、有效铜和有效锌4种有效态微量元素的空间异质性,并运用相关性分析和回归分析方法探究其影响因素。  【结果】  研究区土壤有效铁、有效锰、有效铜和有效锌平均含量分别为56.0、28.0、1.2和1.8 mg/kg,变异系数分别为52.59%、89.95%、38.81%和32.90%,属于中等程度变异。有效铁、有效铜和有效锌含量均服从正态分布,而有效锰含量服从对数正态分布。土壤有效铜呈纯块金效应,全局Moran’s I指数为负值;有效铁、有效锰以指数模型为最优拟合模型,有效锌以球面模型为最佳,块基比在36.57%～61.85%,均呈中等空间相关性,全局Moran’s I指数均为正值,且有效铁含量具有极显著空间自相关性。4种土壤有效态微量元素空间分布格局差异较大,有效铁含量呈现南高北低的趋势,有效锰含量随地面坡度的增加呈现降低趋势,有效铜含量斑块状分布明显,有效锌含量则呈现出从研究区两端向中部递减的分布特征。有效铁含量与有机质、pH显著正相关,有效锌含量则与有机质呈极显著正相关,有效锰含量与坡度之间存在显著相关性,有效铜含量则与各因子均无显著相关性。  【结论】  中锋生态茶园土壤有效铁、有效锰、有效铜和有效锌含量总体上均较丰富,均属中等变异强度。土壤有效铜存在空间孤立现象,有效铁、有效锰和有效锌表现为空间聚集特征。茶园土壤有效铁和有效锌含量主要受土壤有机质含量的影响,有效锰含量则主要受坡度的影响。     

农田土壤速效钾含量的空间变异研究

论文以高产潮土区2007年104个土壤采样点耕层速效钾含量为基础,基于地统计学原理,结合GIS空间分析技术,探讨了土壤速效钾含量的空间变异特征,建立了土壤速效钾含量的空间变异模型,形成了土壤速效钾含量的空间分布图,阐明了影响高产农田土壤速效钾含量分布不均衡的原因。研究结果表明,高产潮土区土壤速效钾含量平均为287．476gkg^-1,最高为483．433gkg^-1,最低为119．435gkg^-1,球状模型是土壤速效钾连续性空间分布的最佳模型,其块金值,基台值为0．399,说明土壤速效钾在变程为57．691米的范围内具有中等强度的空间变异性,含量高低的区域分布比较明显,在地块东南部和中部为其含量较高的区域,含量较低的两个突出区域呈典型的圈层分布,由内向外含量递增,具有较强的渐变性分布规律。总的来看,土壤速效钾约有60．1％的空间变异来自于土壤母质、地形地貌、气候等非人为的结构性因素,39．9％的变异来自于随机性因素如施肥、灌溉、管理水平等因素的影响。     

Impact of environmental factors on the spatiotemporal variability of soil organic matter: a case study in a typical small Mollisol watershed of Northeast China

Journal of Soils and Sediments - Soil organic matter (SOM) content is one critical indicator of agricultural sustainability. Analyzing the spatial distribution and temporal variation of...     

山区典型小流域可持续发展评价——以北京三渡河小流域为例

以三渡河小流域为研究对象,提出适用的、可操作的、简化的小流域综合治理可持续发展指标体系,该指标体系由目标层、类目指标层、项目指标层和指标变量层构成。依照从低到高次序逐层计算各项指标值,最终得出小流域综合治理可持续发展度指标值。并对不同年度三渡河小流域可持续发展进行科学评价。     

Use of scaling to quantify variability of heavy metal sorption isotherms

Sorption isotherms of heavy metals in soil often vary strongly from place to place in the field. Scaling might be useful to quantify the variability of such functional relations. Application of scaling to sorption isotherms requires a rule. In this paper the derivation of a scaling rule for sorption isotherms, based on a hypothesis of 'sorption similarity’, and its application to cadmium sorption isotherms measured in 25 fields on sandy soils are reported. Scale factors are calculated by least squares procedures. Scaling reduced the variation of the Cd isotherms, expressed as sum of squares about an average, by about 86%, preserving the variation through the calculated scale factors. Scaling of sorption isotherms requires no specific equation to fit the sorption data. The aforementioned average should be calculated as scale mean because of the theoretical stringency of this approach.     

Application of catchment scale sediment delivery model INCA-Sed to four small study catchments in Finland

The novel catchment scale erosion and sediment delivery model INCA-Sed was applied to four small study catchments in Finland. Three of these, the Mustajoki, Haarajoki and Luhdanjoki, are headwater catchments located in central Finland. The associated rivers have differing morphological characteristics varying from a ditch to a small river. Soil textures in the area are derived from moraine deposits and are largely sand and gravel. The Mustajoki and Haarajoki catchments are forested and only 10% of the area is under cultivation. In the Luhdanjoki catchment agricultural fields cover 40% of the area. The fourth study site, the Savijoki catchment, represents an intensively cultivated area in south-western Finland. Cultivated fields cover 40% of the catchment area, and they are located on clay soils along the river. The INCA-Sed model was able to capture both the correct magnitude and seasonal behaviour of suspended sediment concentrations in the rivers, as well as the correct magnitude of the sediment load derived from different land use classes. Small differences in river morphology and soil textures between the catchments have a significant influence on suspended sediment concentration in the rivers. Correct timing of suspended sediment concentration peaks is not, however, captured by the INCA-Sed model, which may be due to the stochastic nature of erosion and delivery processes at the catchment scale which are not taken into account in the parameter values used in the modelling. Parameter values were estimated from previous researches based on average process loads. The INCA-Sed model was, however, generally found to be a suitable tool for evaluating effects of land use change on erosion and sediment delivery in Finland as it correctly reproduces spatial and seasonal variations in sediment delivery, in addition to annual averages with spatial and temporal variations.     

Response of the sorption behavior of Cu,Cd, and Zn to different soil management

This study investigated the effect of different farming practices over long time periods on the sorption‐desorption behavior of Cu, Cd, and Zn in soils. Various amendments in a long‐term field experiment over 44 y altered the chemical and physical properties of the soil. Adsorption isotherms obtained from batch sorption experiments with Cu, Cd, and Zn were well described by Freundlich equations for adsorption and desorption. The data showed that Cu was adsorbed in high amounts, followed by Zn and Cd. In most treatments, Cd ions were more weakly sorbed than Cu or Zn. Generally, adsorption coefficients K_F increased among the investigated farming practices in the following order: sewage sludge ≤ fallow < inorganic fertilizer without N ≈ green manure < peat < Ca(NO₃)₂ < animal manure ≤ grassland/extensive pasture. The impact of different soil management on the sorption properties of agricultural soils for trace metals was quantified. Results demonstrated that the soil pH was the main factor controlling the behavior of heavy metals in soil altered through management. Furthermore, the constants K_F and n of isotherms obtained from the experiments significantly correlated with the amount of solid and water‐soluble organic carbon (WSOC) in the soils. Higher soil pH and higher contents of soil organic carbon led to higher adsorption. Carboxyl and carbonyl groups as well as WSOC significantly influenced the sorption behavior of heavy metals in soils with similar mineral soil constituents.     

Affinity constants and behavior of Cd sorption in some acid soils

Cadmium sorption was studied in several acidic soils in a pH range from 4.5 to 6.5. The soils had two classes of surfaces with acidity constants (pKa₁ = 4.09 and pKa₂ = 6.39) similar to those for weakly and very weakly cidic carboxyls, and N-containing groups in fulvic acid. Titratable H and acidity constants were used to estimate the number of exchange sites at each pH level. Sorption of Cd was closely related to Cd concentration, pH, and soil type. Although the inclusion of pH and organic C contents in a regression accounted for some variations in the Cd distribution coefficient defined as the ratio of the quantity of Cd sorbed to the solution Cd concentration, the number of sorption sites was a more appropriate factor to explain the variability. Because of a negligible contribution to the number of exchange sites from Fe oxides, the sorption of Cd at pH = 4.5 was considered to be of a one-surface Langmuir type. A two-surface Langmuir equation was considered to model sorption at higher pH values. The average affinity constants (log K) were 3.61 and 4.89 for Cd sorption by the two classes of surfaces.     

Cotton lint yield variability in a heterogeneous soil at a landscape scale

Landscape variability associated with topographic features affects the spatial pattern of soil water and N redistribution, and thus N uptake and crop yield. A landscape-scale study was conducted in a center pivot irrigated field on the southern High Plains of Texas in 1999 to assess soil water, soil NO₃-N, cotton (Gossypium hirsutum L.) lint yield, and N uptake variability in the landscape, and to determine the spatial correlation between these landscape variables using a state-space approach. The treatments were irrigation at 50 and 75% cotton potential evapotranspiration (ET). Neutron access tubes were placed at a 15-m interval along a 710 m (50% ET) and 820 m (75% ET) transect across the field. Soil NO₃-N in early spring was autocorrelated at a distance varying between 60 and 80 m. Measured soil volumetric water content (WC), total N uptake, and lint yield were generally higher on lower landscape positions. Cotton lint yield was significantly correlated to soil WC (r=0.76), soil NO₃-N (r=0.35), and site elevation (r=−0.54). Differences of site elevation between local neighboring points explained the soil water, NO₃-N and lint yield variability at the micro-scale level in the landscape. Soil WC, cotton lint yield, N uptake, and clay content were crosscorrelated with site elevation across a lag distance of ±30–40 m. The state-space analysis showed that cotton lint yield was positively weighted on soil WC availability and negatively weighted on site elevation. Cotton lint yield state-space models give insights on the association of soil physical and chemical properties, lint yield, and landscape processes, and have the potential to improve water and N management at the landscape-scale.     

贵州喀斯特人工草地土壤水分空间异质性对放牧强度的响应

采用地统计学方法研究贵州南部人工草地不同放牧强度(零牧、中牧和重牧)下浅层土壤剖面(0—10,10—20,20—30cm)水分的空间异质性及其影响因素。结果表明:喀斯特人工草地土壤水分的平均值与变异系数均呈现出明显的放牧强度变化与剖面变化规律;在不同放牧强度下,0—10cm和10—20cm土壤剖面含水量均表现为NGHGMG,20—30cm土层土壤含水量为NGMGHG,变异系数均呈中等变异(10%CV100%),平均含水量处于中等水平时土壤水分变异性较高;土壤水分的Moran’s I自相关分析表明,不同放牧强度下不同土层草地土壤水分均具有较强的空间自相关性,且空间自相关性主要受放牧影响;土壤水分半方差分析表明,不同放牧强度下不同土层草地土壤水分空间分布特征模型为指数模型、球状模型或高斯模型,表明其均为聚集分布;不同放牧强度C/(C0+C)值在0.500~0.817之间,表明土壤水分表现出中等或很强的空间自相关性;不同放牧强度土壤水分变程在2.77~15.61m范围内变化(零牧,2.53~12.82m;中牧,2.77~15.61m;重牧,14.03~18.79m),说明影响土壤水分的生态过程随放牧强度变化在不同尺度上起作用;Kriging maps直观地反映和验证了草地土壤水分的空间变化规律,与Moran’s I和半方差函数分析的结果相吻合。综合分析发现,在小尺度内,重牧是地势平坦的喀斯特人工草地表层土壤水分空间变异的主要影响因素。     

Evaluation of arsenite sorption in Spanish soils

Abstract

Arsenite sorption was studied at different temperatures (30,40, and 50°C) to investigate processes that remove arsenite from soil solution (adsorption or precipitation), and if adsorption was taking place, how many sites were involved in this process, and their nature. Adsorption was the only reaction reducing levels of soluble arsenite in the two alkaline soils used in this experiment, Jijona and Agost; however, arsenite precipitation occurred in an acidic substrate (pH 4.0), Galicia soil. Iron (Fe) oxides and clay minerals were the soil components controlling arsenite sorption in the Jijona soil (pH 7.9 and high levels of Fe oxides). Calcite and clay minerals were the inorganic constituents involved in arsenite sorption in the Agost soil (pH 8.0 and high levels of CaCO₃). Arsenite sorption was an endothermic and non‐spontaneous process. The fact that the higher the temperature, the higher the arsenite sorption, however, was likely due to an increase in the diffusion rate.     

Search of environmental descriptors to explain the variability of the bacterial diversity from maize rhizospheres across a regional scale

The regional scale variability of the bacterial community inhabiting the rhizosphere was studied with soil collected from maize fields located in the Santo Domingo Valley (SDV; Baja California Sur, Mexico), a semi-arid agricultural ecosystem of approximately 200 km². The bacterial community structure was visualized by single-strand conformation polymorphism (SSCP) profiles of PCR-amplified partial 16S rRNA genes of directly extracted rhizosphere soil DNA. SSCP profiles of different SDV sites and an external field site in Germany were evaluated for their similarities and the contributing bacteria were characterized by DNA sequence analyses. SSCP profiles from each site were significantly different from the others, as revealed by permutation of pairwise similarities (P < 0.05). In comparison to the German site, SSCP profiles from SDV were more similar to each other despite contrasting soil salinity levels. Correspondence analysis revealed that among SDV sites, salinity levels, soil organic carbon and calcium (Ca²⁺) were most influential on the bacterial community structure. Depending on the phylogenetic group analyzed (Bacteria, Alphaproteobacteria, Pseudomonas), the importance of these soil variables varied. Interestingly, the East–West direction also revealed an effect, suggesting that future explorations of bacterial diversity patterns should also consider landscape topography in search of explaining patterns of bacterial diversity in soils.     

Evaluation of the sorption process for imidacloprid and diuron in eight agricultural soils from southern Europe using various kinetic models

Kinetic studies are of great concern for understanding the processes and parameters involved in the sorption of pollutants by soils. Sorption kinetics of imidacloprid and diuron in eight soils of different characteristics, with very low organic carbon content were investigated. Pseudosecond-order kinetic reactions closely correlate with the experimental kinetic (R(2) > 0.98) in all soils. The sorbed amount of diuron was higher than that for imidacloprid. The low OC content of these soils correlated neither with the sorbed amount nor with the kinetic parameters for both pesticides. Imidacloprid sorption was correlated with silt and sand content and cation exchange capacity (CEC); meanwhile for diuron, no correlation was found. Thus, sorption kinetics take place throughout different mechanisms related mainly to the chemical character of the pesticides. Sorption kinetic parameters determined using three of the four models selected (pseudosecond-order kinetic reactions, Elovich equation, and Weber-Morris models) have been shown to be worthy to distinguish the process controlling the sorption kinetic of both pesticides.     

土壤水盐空间异质性及尺度效应的多重分形

为了揭示研究区域林地内土壤含水率和电导率的空间分布特征及尺度效应,利用多重分形方法,对杨凌一林地内不同采样时间和不同采样面积下土壤含水率和电导率的空间异质性进行了研究。结果表明：3种采样面积下土壤含水率和电导率的空间异质性都分别随平均含水率和电导率的增大而减弱。随采样面积的增大,平均含水率和电导率较高时,土壤含水率的空间异质性趋于增强,土壤电导率的尺度效应不明显;平均含水率和电导率较低时,土壤含水率和电导率的空间分布都存在明显的斑块结构。不同采样时间和不同采样面积下土壤含水率和电导率的多重分形谱的形态有所差异,表明引起他们空间异质性的信息有所不同。多重分形分析能揭示出较多的采样林地内土壤含水率和电导率分布的局部信息。     

岩溶高原地区小流域土壤厚度的空间变异特征

土壤厚度是制约石漠化地区生态修复的重要因子。在贵州省金沙县乌箐河小流域,通过实地调查土壤厚度,结合地统计学和经典统计学方法,研究岩溶高原地区小流域中3种典型土地利用类型下土壤厚度的空间变异及其分布格局。结果表明：研究区土壤厚度总体呈中等强度空间变异,个别样地属强度变异,具有良好的半方差结构,其变异趋势大致为随着坡位的降低而逐渐减小,而土壤厚度随坡位的降低逐渐变厚。坡耕地土壤厚度空间相关性相对较好,存在一定的连续性;荒山和意大利杨树林地土壤厚度的空间变异程度均较大,斑块状分布明显。除个别样地可以用高斯模型和球状模型拟合外,其余样地均可用指数模型拟合,且拟合效果较好（R^2≈0．8）。研究结果加深了对岩溶高原地区土壤厚度的认识,为石漠化综合治理工程的合理布局和土地资源的有效开发利用提供重要依据。     

Improved cadmium sorption isotherms by the determination of initial contents using the radioisotope 109Cd

Cadmium (Cd) sorption isotherms were estimated by two different analytical approaches to assess the influence of initial Cd concentrations of soil matrix on the sorption of added Cd. For the laboratory experiments a heterogeneous set of samples was collected to include a wide range of different initial Cd concentrations. Comparison of both analytical methods (conventional analysis, radioanalysis) resulted in a strong conformity of Cd contents in solution at equilibrium. The calculated Cd concentrations in the soil solid phase differ according to the analytical approach for considering the initial contents. The determination of the initial contents by the proposed radioanalytical method with ¹⁰⁹Cd resulted in long linear Freundlich‐isotherms, even in the low concentration range. Thus, radioanalysis seems to be the most suitable method to recognise the initial contents of Cd in soil. EDTA extractable Cd represent the initial concentrations, which are averaged over solid and liquid phase. However, depending on the sorption characteristics of the soil these rates vary. In the investigated set of soil samples 52.3 to 99.3% of Cd must be added to the solid phase.     

Incorporation of spectral data into multivariate geostatistical models to map soil phosphorus variability in a Florida wetland

Hybrid geostatistical prediction methods incorporate (i) spatially-explicit soil observations and exhaustive grids of ancillary environmental variables (e.g. derived from remote sensing), (ii) spatial autocorrelation, (iii) spatial covariation, and/or (iv) combinations of the above. In numerous studies of terrestrial soils it has been shown that hybrid geostatistical methods outperform univariate spatial and regression (aspatial) methods. However, hybrid methods have rarely been employed to predict soil properties in wetlands. In this study we used spectral data and derived indices from two remote sensors (Landsat ETM+ and ASTER), with different spatial resolutions, from different seasons, but with similar spectral range, ancillary environmental data, as well as floc and soil total phosphorus (TP) observations from 111 sites. The specific objective of our study was to evaluate the performance of aspatial methods (multivariate regressions — REG), univariate spatial (Ordinary Kriging — OK) and hybrid/multivariate geostatistical methods (Regression Kriging — RK and Co-kriging — CK) in predicting the spatial variability and distribution of floc and soil TP in a subtropical wetland, WCA-2A, in the Florida Everglades. Measured floc TP ranged from 194 to 1865 mg kg^− 1 with a median of 751 mg kg^− 1 and standard deviation (SD) of 381 mg kg^− 1. According to cross-validation, predictions for floc TP based on the root mean square prediction error (RMSE) were best in the following order: RK_quadratic (134.9) > RK_multivariate (201.1) > OK (206.1) > CK (212.1) > REG_multivariate (218.3) > REG_quadratic (220.3) > REG_linear (264.4); and based on the mean prediction error (ME) followed the order RK_multivariate (0.9)  RK_quadratic (1.1) > CK (− 6.7) > REG_multivariate (18.2) > REG_linear (25.1) > OK (− 27.3) > REG_quadratic (27.3). The Normalized Difference Vegetation Index (NDVI)-green derived from Landsat ETM+ showed the largest predictive power for floc TP. Measured soil TP ranged from 155 to 1702 mg kg^− 1 with a median of 433 mg kg^− 1 and standard deviation of 316 mg kg^− 1. Predictions for soil TP based on RMSE were best in the following order: RK_ASTER (200.1) > CK_ASTER (238.2)  CK_ETM (239.0) > OK (258.0) > RK_ETM (279.2) > REG_ASTER (281.8) > REG_ETM (356.1); and based on ME followed the order: CK_ASTER (0.1)  CK_ETM (0.2) > RK_ASTER (− 5.2) > RK_ETM (− 31.5) > OK (− 41.8) > REG_ASTER (94.4) > REG_ETM (133.7). The NDVI showed the largest predictive power for soil TP. This comparative study in a subtropical wetland demonstrated the benefits of incorporating remote sensing data into floc and soil TP prediction models. Overall, hybrid geostatistical methods (CK and RK) performed better than regressions and spatial univariate models (OK) in the prediction of floc and soil TP. Depending on the strength of the spatial covariance between primary and secondary variables (CK) and the ability of the regression model in RK to explain the variability of a target variable (e.g., floc or soil TP), either CK or RK performed best. Our findings in this wetland confirmed results from earlier studies on terrestrial soils indicating the superior performance of hybrid geostatistical methods in predicting soil properties.