Application of the FAO quantitative and SINDI methods to assess the quality of different soils in Castilla-La Mancha (Spain)

In the region of Castilla-La Mancha (Spain), over half of the soils are under cropping. This vast agricultural activity, combined with other anthropological uses, has led to a deterioration of the soil quality and virtual degradation. Therefore, it was deemed to assess the quality of these soils, which was achieved by applying two different methods. Three soils, representative of typical conditions in this community, were sampled and diverse properties were analysed in order to apply two different approaches. The first soil evaluation was carried out by a traditional method developed by FAO using a productivity index, whereas the second method consisted of the application of a new method called SINDI, developed in New Zealand. Both approaches make an evaluation based on a number of indicators that differs in each case. These differences explain why each method ranked the soils studied in different order reaching diverse conclusions on their quality.     

Environmental evaluation of elemental cesium and strontium contents and their isotopic activity concentrations in different soils of La Mancha (Central Spain)

Cesium and Strontium concentrations were analyzed in eight pedogenetic soil profiles developed on different rocks from a semiarid mediterranean region: La Mancha (Central Spain). Concentration activities of ¹³⁷Cs and ⁹⁰Sr, as for some soil properties, were also measured. The results are presented in this document: Cs concentrations range between 0.4 and 18.3 mg kg⁻¹ and Sr varies widely between 11.0 and 3,384 mg kg⁻¹. Therefore, it is clear that there is a broad range of concentrations and there are also values significantly higher than the average values stated by several authors. Concentrations of long-life artificial radionuclides (¹³⁷Cs, ⁹⁰Sr) were determined in some of the same soils. The activity concentration mean values (Bq kg⁻¹) were ranging between 0.82 and 21.76 for ¹³⁷Cs and ⁹⁰Sr variations range between 6.73 and 0.35. There were no significant correlations between radionuclides and stable trace elements. The data indicate that the soils do not show significant radioactivity of these elements and therefore they do not pose a danger. By the same token, no risk of contamination by this activity was detected. Finally, spatial patterns seem to be affected by the soil type and some soil properties.     

Changes in soil quality indicators under long-term sewage irrigation in a sub-tropical environment

Though irrigation with sewage water has potential benefits of meeting the water requirements, the sewage irrigation may mess up to harm the soil health. To assess the potential impacts of long-term sewage irrigation on soil health and to identify sensitive soil indicators, soil samples were collected from crop fields that have been irrigated with sewage water for more than 20 years. An adjacent rain-fed Leucaena leucocephala plantation system was used as a reference to compare the impact of sewage irrigation on soil qualities. Soils were analyzed for different physical, chemical, biological and biochemical parameters. Results have shown that use of sewage for irrigation improved the clay content to 18–22.7%, organic carbon to 0.51–0.86% and fertility status of soils. Build up in total N was up to 2,713 kg ha⁻¹, available N (397 kg ha⁻¹), available P (128 kg ha⁻¹), available K (524 kg ha⁻¹) and available S (65.5 kg ha⁻¹) in the surface (0.15 m) soil. Long-term sewage irrigation has also resulted a significant build-up of DTPA extractable Zn (314%), Cu (102%), Fe (715%), Mn (197.2), Cd (203%), Ni (1358%) and Pb (15.2%) when compared with the adjacent rain-fed reference soil. Soils irrigated with sewage exhibited a significant decrease in microbial biomass carbon (−78.2%), soil respiration (−82.3%), phosphatase activity (−59.12%) and dehydrogenase activity (−59.4%). An attempt was also made to identify the sensitive soil indicators under sewage irrigation, where microbial biomass carbon was singled out as the most sensitive indicator.     

Spatial variability of mercury emissions from soils in a southeastern US urban environment

We quantified gaseous mercury (Hg⁰) fluxes over soil surfaces in an urban setting during the winters of 2003 and 2004 across the metropolitan area of Tuscaloosa, AL. The objective was to provide a first inspection of the local spatial variability of mercury flux in an urban area. Flux sampling took place on bare, undisturbed, soil surfaces within four evenly spaced landuse areas of Tuscaloosa: industrial, commercial, residential, and mixed landuse. Median total gaseous mercury fluxes (ng/m² h) from each site were as follows: 4.45 (residential site), 1.40 (industrial site), 2.14 (commercial site), and 0.87 (mixed landuse site). Using non-parametric statistical analyses, the residential and mixed landuse sites were found to be statistically different from the overall median flux. Landuse and soil type are the suspected factors primarily controlling the observed spatially variable fluxes. The presence of statistically different fluxes over soil surfaces on a local scale in this preliminary study warrants additional investigation, particularly during the spring and summer seasons when terrestrial mercury emission is the highest. Providing such information will help develop better estimates of mercury emission from urban areas and, ultimately, lead to more accurate and useful spatially relevant inventories.     

Assessment of temporal and spatial variability of soil salinity in a coastal saline field

Many coastal tideland areas in southern Hangzhou Gulf in Zhejiang Province of China have been successively enclosed and reclaimed for agricultural land uses under a series of reclamation projects over the past 30 years. The variability of soil salinity was considerably great and an understanding of the temporal and spatial components of soil salinity variability is essential before decisions can be made about the feasibility of site-specific management. In this paper, a 5.35-ha field reclaimed in 1996 was selected as the study site and 112 bulk electrical conductivity (EC_b) measurements were performed in situ by a hand held device in the topsoil (0–20 cm) at regular 20-m intervals across the field over a two-year period. Conventional statistics and geostatistical techinques were used to assess the spatial variability and temporal stability of soil-salinity distribution. The results indicated high coefficients of variation in topsoil salinity over the three samplings. Simple mean EC_b comparison revealed that soil salinity increased from winter to spring. Kriged contour maps showed the spatial trend of salinity distribution and revealed the consistently high and low salinity areas of the field. In percentage terms, the proportions of the moderately saline class, strongly saline class, and extremely saline class were 37, 39, and 24%, respectively. Temporal stability map indicated that more than 60% of the study field was determined as the stable class. Based on the spatial and temporal characteristics, a similarity assessment map was created, which presented 5 homogenous sub-zones, each with different characteristics that can have an impact on the way the field is managed. It was concluded that saline soil land might be managed in a site-specific way based on the clearly defined management sub-regions within the field.     

Spatial variability of soil water erosion: Comparing empirical and intelligent techniques

Soil water erosion (SWE) is an important global hazard that affects food availability through soil degradation, a reduction in crop yield, and agricultural land abandonment. A map of soil erosion susceptibility is a first and vital step in land management and soil conservation. Several machine learning (ML) algorithms optimized using the Grey Wolf Optimizer (GWO) metaheuristic algorithm can be used to accurately map SWE susceptibility. These optimized algorithms include Convolutional Neural Networks (CNN and CNN-GWO), Support Vector Machine (SVM and SVM-GWO), and Group Method of Data Handling (GMDH and GMDH-GWO). Results obtained using these algorithms can be compared with the well-known Revised Universal Soil Loss Equation (RUSLE) empirical model and Extreme Gradient Boosting (XGBoost) ML tree-based models. We apply these methods together with the frequency ratio (FR) model and the Information Gain Ratio (IGR) to determine the relationship between historical SWE data and controlling geo-environmental factors at 116 sites in the Noor-Rood watershed in northern Iran. Fourteen SWE geo-environmental factors are classified in topographical, hydro-climatic, land cover, and geological groups. We next divided the SWE sites into two datasets, one for model training (70% of the samples = 81 locations) and the other for model validation (30% of the samples = 35 locations). Finally the model-generated maps were evaluated using the Area under the Receiver Operating Characteristic (AU-ROC) curve. Our results show that elevation and rainfall erosivity have the greatest influence on SWE, while soil texture and hydrology are less important. The CNN-GWO model (AU-ROC = 0.85) outperformed other models, specifically, and in order, SVR-GWO = GMDH-GWO (AUC = 0.82), CNN = GMDH (AUC = 0.81), SVR = XGBoost (AUC = 0.80), and RULSE. Based on the RUSLE model, soil loss in the Noor-Rood watershed ranges from 0 to 2644 t ha^–1yr^?1.     

Spatial variability of soil properties in relation to land use and topography in a typical small watershed of the black soil region,northeastern China

Soil degradation resulted from unreasonable land use and erosion has been a serious problem in the black soil region of northeastern China. This paper seeks to understand the relationships between topsoil properties and topography and land use for land management targeting at improving soil quality in this region. A total of 292 soil samples and 81 volumetric rings were taken from a typical small watershed of the region in June 2005 for examining total carbon (TC), total nitrogen (TN), soil texture (classified into gravel, sand, silt, and clay), and bulk density (ρ _b), respectively. Spatial variability of these soil properties was evaluated with classical statistics and geostatistics methods. The results of classical statistics indicated that TC, TN, sand, silt, clay content, and ρ _b were moderate variables while gravel had great variability. Soil properties were mainly correlated to slope position, elevation and land types. Geostatistical analyses showed that the spatial autocorrelation for TC, TN, and silt was weak, strong for clay and moderate for and ρ _b sand, respectively. The spatial variations of soil properties are affected comprehensively by topographic factors, land use, erosion, and erosion control in this watershed. Past erosion, however, is the most important component to induce change of soil properties. In this small watershed, current soil and water conservation measures play an important role in controlling soil loss. But the restoration of soil properties was unsatisfactory. Comparing with untilled soil of this region, TC, TN, silt content are excessively low; whereas ρ _b, sand and clay content are excessively high; gravel appears at most sampling locations. It is necessary for improving soil properties to protect forest and grassland and change cultivation system of farmlands.     

Environmental impact assessment on water quality deterioration caused by the decreased Ganges outflow and saline water intrusion in south-western Bangladesh

 This paper deals with an environmental impact assessment of low water flow in the river Ganges during a dry period at the Khulna and Mongla port areas in south-western Bangladesh. Large-scale surface water withdrawal in India after commissioning the Farakka Barrage causes a drastic fall in the Ganges low-flow condition within the Bangladesh territory during every dry period. The average lowest discharge in the Ganges is 552 m³/s, which is about 73% less than that in the pre-Farakka time. This has caused the deterioration of both surface and groundwater quality of the study area. Salinity is the principal cause of water quality degradation in the area. Present observation shows that the surface water of the area is sulphate-chloride dominated, which signifies high salinity whereas the groundwater is categorized as of medium to high salinity. To maintain the Rupsa River's maximum salinity below 1000 μS/cm the discharge in the Ganges should be ∼1500 m³/s, whereas that at Garai basin is ∼10 m³/s. If this present situation continues it will be a crippling blow to the environment of the area in the long term. An integrated multidisciplinary approach to hydrogeological research is urgently required to salvage the area from further deterioration. Received: 9 August 1999 · Accepted: 8 March 2000     

上海某厂区土壤和地下水环境质量评估

对上海某地老厂区土壤和地下水采样、检测,表明土壤重金属元素Cd、As,Pb的含量符合国家《土壤环境质量标准（GB15618-1995）》的一级标准要求,Hg、V、Cu的含量明显受到了污染,Mg、Cd、As、Zn、Pb、Be等金属元素含量水平与本地区的土壤环境背景水平相吻合;地下水中pH、NO3^-,-N,Zn属《地下水质量标准》（GBl4848-93）Ⅰ类,Cl^-和NH3^＋-N属V类,地下水对混凝土无腐蚀性,对钢筋有弱腐蚀性。     

Local-scale spatial variability of soil organic carbon and its stock in the hilly area of the Loess Plateau, China

Soil organic carbon (SOC) is one of the key components for assessing soil quality. Meanwhile, the changes in the stocks SOC may have large potential impact on global climate. It is increasingly important to estimate the SOC stock precisely and to investigate its variability. In this study, Yangjuangou watershed was selected to investigate the SOC distribution under different land uses. We found that SOC concentration decreased with increasing soil depth under all land uses and was significantly different across the vertical soil profile (P < 0.01). However, considering effect of land use on SOC, it is only significant (P < 0.01) in the topsoil (0-5 cm) layer. This indicated that land use has a large effect on the stocks of SOC in the surface soil. The stratification ratio of SOC > 1.2 may mean that soil quality is improving. The order of the SOC density (0-30 cm) under different land uses is forestland > orchard land > grassland > immature forestland > terraced cropland. The SOC stock is found to be as large as 2.67 × 10³ t (0-30 cm) in this watershed. Considering time effect of restoration, the slope cropland just abandoned is more efficient for SOC accumulation than trees planted in the semi-arid hilly loess area.     

Integrated method of RS and GPR for monitoring the changes in the soil moisture and groundwater environment due to underground coal mining

Mining affects the environment in different ways depending on the physical context in which the mining occurs. In mining areas with an arid environment, mining affects plants’ growth by changing the amount of available water. This paper discusses the effects of mining on two important determinants of plant growth—soil moisture and groundwater table (GWT)—which were investigated using an integrated approach involving a field sampling investigation with remote sensing (RS) and ground-penetrating radar (GPR). To calculate and map the distribution of soil moisture for a target area, we initially analyzed four models for regression analysis between soil moisture and apparent thermal inertia and finally selected a linear model for modeling the soil moisture at a depth 10 cm; the relative error of the modeled soil moisture was about 6.3% and correlation coefficient 0.7794. A comparison of mined and unmined areas based on the results of limited field sampling tests or RS monitoring of Landsat 5-thermatic mapping (TM) data indicated that soil moisture did not undergo remarkable changes following mining. This result indicates that mining does not have an effect on soil moisture in the Shendong coal mining area. The coverage of vegetation in 2005 was compared with that in 1995 by means of the normalized difference vegetation index (NDVI) deduced from TM data, and the results showed that the coverage of vegetation in Shendong coal mining area has improved greatly since 1995 because of policy input RMB￥0.4 per ton coal production by Shendong Coal Mining Company. The factor most affected by coal mining was GWT, which dropped from a depth of 35.41 m before mining to a depth of 43.38 m after mining at the Bulianta Coal Mine based on water well measurements. Ground-penetrating radar at frequencies of 25 and 50 MHz revealed that the deepest GWT was at about 43.4 m. There was a weak water linkage between the unsaturated zone and groundwater, and the decline of water table primarily resulted from the well pumping for mining safety rather than the movement of cracking strata. This result is in agreement with the measurements of the water wells. The roots of nine typical plants in the study area were investigated. Populus was found to have the deepest root system with a depth of about 26 m. Based on an assessment of plant growth demands and the effect of mining on environmental factors, we concluded that mining will have less of an effect on plant growth at those sites where the primary GWT depth before mining was deep enough to be unavailable to plants. If the primary GWT was available for plant growth before mining, especially to those plants with deeper roots, mining will have a significant effect on the growth of plants and the mechanism of this effect will include the loss of water to roots and damage to the root system.     

Hydrothermal pattern of frozen soil in Nam Co lake basin,the Tibetan Plateau

Hydrothermal processes and the regimes of frozen soil formed in alpine regions with glaciers and lake area are complex and important for ecological environment but have not been studied in Tibet. Based on soil temperature and moisture data from October 2005 to September 2006 collected in the Nam Co lake basin, Tibetan Plateau (TP), those questions were discussed. The mean annual air temperature was −3.4°C with 8 months below 0°C. Air and soil temperature varied between −25.3~13.1°C and −10.3~8.8°C, respectively. Soil moisture variations in the active layer were small with the minimum value of 1.4%, but were influenced greatly by snowmelt, rainfall and evaporation, varying up to 53.8%. The active layer froze later, thawed earlier and was thinner, however, the lower altitude limit of permafrost is higher than that in most areas of TP. The effects of soil moisture (unfrozen water content) on soil temperature, which were estimated through proposed models, were more significant near ground surface than the other layers. The surface soil temperature decreased with snowcover, the effect of cold snow meltwater infiltration on soil thermal conditions was negligible, however, the effect of rainfall infiltration was evident causing thermal disruptions.     

黄土高原区域尺度土壤水分空间变异性

土壤水分是黄土高原植物生长发育和生态环境重建的主要限制因子。为揭示黄土高原区域尺度深层土壤水分的空间变异性,在黄土高原共布点234个,采集深剖面土壤水分样品12198个。采用经典统计和地统计学相结合的方法系统分析了土壤水分的分布规律、变异特征及影响因素。结果表明:①黄土高原地区土壤水分在水平方向上表现出由东南向西北递减,在垂直方向上(0~500cm)表现出先减小后增加的分布特征;②土地利用对区域尺度土壤水分的数量及垂直分布规律具有显著影响;③土壤水分在不同土层深度(0~500cm)的变异系数、空间异质比等参数的垂直分布均呈先减小后增加趋势,这些参数在表达土壤水分变异的效果上具有一致性。相关结果对黄土高原区域尺度水土过程调控、生态水文过程研究具有一定参考价值。     

Spatial variability of heavy metals in soils across a valley plain in Southeastern China

An investigation was carried out to survey the magnitude and spatial distribution of heavy metals, as well as their relation with soil series, in a valley plain in Southeastern China. Soil was sampled at 159 sites by combining a squared grid and nested sampling strategies along the transect perpendicular to the Qujiang River in Zhejiang Province, China. Total concentrations of six metals, namely Cu, Fe, Mn, Ni, Pb and Zn, were measured. Classical statistics and geostatistics were used to quantify their spatial characteristics. There was a considerable variation in many of these parameters. The total concentrations ranged from 6.8 to 29.3 mg kg⁻¹ for Cu, 6,784 to 18,678 mg kg⁻¹ for Fe, 94 to 385 mg kg⁻¹ for Mn, 6.1 to 20.3 mg kg⁻¹ for Ni, 25.0 to 49.5 mg kg⁻¹ for Pb, and 12 to 160 mg kg⁻¹ for Zn. Pearson correlation coefficients among total metal concentrations and selected soil properties showed a number of strong associations. By virtue of analysis of variance, a predominant influence of soil series on the spatial variability of metal concentrations was observed. All metals were spatially correlated. The semivariograms of Cu, Fe, Mn, Ni and Zn were dominated by short range correlation (600 or 700 m), and that of Pb by long range (1200 m). Block kriging maps of total metal concentrations and soil properties showed strip distributions, perpendicular to the river, in the manner similar to the soil series. Principal component analysis was run to identify common distribution patterns of heavy metals and soil properties. These results illustrate that soil series information of valley plain may be useful for developing management zones for site-specific agriculture.     

Spatial variability assessment of soil nutrients in an intense agricultural area,a case study of Rugao County in Yangtze River Delta Region,China

Topsoil samples (0–20 cm) (n = 237) were collected from Rugao County, China. Geostatistical variogram analysis, sequential Gaussian simulation (SGS), and principal component (PC) analysis were applied to assess spatial variability of soil nutrients, identify the possible areas of nutrient deficiency, and explore spatial scale of variability of soil nutrients in the county. High variability of soil nutrient such as soil organic matter (SOM), total nitrogen (TN), available P, K, Fe, Mn, Cu, Zn, and B concentrations were observed. Soil nutrient properties displayed significant differences in their spatial structures, with available Cu having strong spatial dependence, SOM and available P having weak spatial dependence, and other nutrient properties having moderate spatial dependence. The soil nutrient deficiency, defined here as measured nutrient concentrations which do not meet the advisory threshold values specific to the county for dominant crops, namely rice, wheat, and rape seeds, was observed in available K and Zn, and the deficient areas covered 38 and 11%, respectively. The first three PCs of the nine soil nutrient properties explained 62.40% of the total variance. TN and SOM with higher loadings on PC1 are closely related to soil texture derived from different parent materials. The PC2 combined intermediate response variables such as available Zn and P that are likely to be controlled by land use and soil pH. Available B has the highest loading on PC3 and its variability of concentrations may be primarily ascribed to localized anthropogenic influence. The amelioration of soil physical properties (i.e. soil texture) and soil pH may improve the availability of soil nutrients and the sustainability of the agricultural system of Rugao County.     

Soil quality changes in land degradation as indicated by soil chemical, biochemical and microbiological properties in a karst area of southwest Guizhou, China

Not only the nutritional status and biological activity but also the soil ecological functioning or soil health has been impacted profoundly by land degradation in the karst area of southwest China where the karst ecosystems are generally considered as extremely vulnerable to land degradation under intensified land-use changes. The objectives of this study are to elucidate the changes in overall soil quality by a holistic approach of soil nutritional, biological activity, and soil health indicators in the karst area as impacted by intense cultivation and vegetation degradation. Topsoil samples were collected on selected eco-tesserae in a sequence of land degradation in a karst area of southwest Guizhou in 2004. The soil nutrient pools of organic carbon (C_org), extractable extracellular carbon (C_ext), total soil nitrogen (N_t), alkali-hydrolyzable nitrogen (N_ah), total phosphorus (P_t), available phosphorus (P_a) were analyzed by wet soil chemistry. The soil biological properties were studied by means of measurements of microbial biomass carbon (both by fumigation–extraction, FE-C_mic, and by calculation from substrate-incubation respiration, SIR-C_mic) of respiration [respiration without addition of substrates, basal respiration (BR), and potential respiration (PR) with substrate-incubation] and of soil enzyme activities (invertase, urease, and alkaline phosphatase). Soil health status was assessed by simple indices of C_mic/C_org and BR/C_mic in conjunction with bacterial community structures determined by polymerase chain reaction and denaturing gradient gel electrophoresis. While the nutritional pool parameters, such as C_org and C_ext, described basically the changes in soil life-supporting capacity with cultivation interference and vegetation declined, those parameters of biological activity such as FE-C_mic, SIR, and SIR-C_mic as well as bacterial community structures measured by molecular method evidenced well the changes in soil functioning for ecosystem health with the land degradation.     

湖泊水质遥感研究进展

详述了湖泊遥感水质最新发展动态,如遥感水质模型的数学方法、与水质指标最敏感的波段以及TM、SPOT、MODIS、MERIS、AVHRR、CASI等传感器的适用情况,并分析了可能导致湖泊水质遥感模型误差的原因和解决办法。湖泊各项水质组分与光谱之间相互影响可认为是一种非常复杂的非线性关系,最适合用神经网络这样的黑箱模型来模拟。应当研究和选取敏感波段,用高光谱逐段分析与各种水质指标相关最密切的波段。湖泊水质遥感最终走向实用化必将其与水生态问题结合起来,作为一种监测手段,在水中藻类的时空分布、流域营养物质输送模型和湖泊水域水质模型等问题中得到广泛应用。我国学者使用超光谱数据源获得更为精确的监测成果还比较少,由于我国卫星可以用来进行水质遥感的波段比较宽,应当在新一代的资源环境卫星上加入更适合水质遥感的波段。     

Origin of water salinity in a lake and coastal aquifer system

The studied area is in the Algerian Northeast. A number of interacting factors at the site are able to modify salinity. The main influences are: (1) The lithology, (2) Fedzara Lake, (3) marine waters, and (4) a prolonged drought. (1) The lithology is very clearly delineated by the outcrop of metamorphic formations (gneiss, marbles, micaschists, and quartzites) and sedimentary formations (limestones, clay, sandstones, and sands). All these formations can influence the chemical composition of waters. (2) Fedzara Lake evacuates its salted waters via the Wadi Meboudja, which connects with the Wadi Seybouse and the phreatic surface. These lake waters might induce changes in salinity. (3) The marine waters represent the third source of salinity change. Over-pumping of water from wells and drillings can cause an imbalance to the fresh–salted water interface. (4) The effects of a local prolonged drought of more than 10 years may increase water salinity. Over-pumping to augment water supply generates a fall in water levels and the drier atmosphere increases evapotranspiration. Both may contribute to increased salinity. Results of water analysis were used to observe the evolution of these various factors.     

Assessing variability of water quality in a groundwater-fed perennial lake of Kashmir Himalayas using linear geostatistics

This paper presents a study on Manasbal lake, which is one of the high altitude lakes in the Kashmir Valley, India. Eighteen water samples were analysed for major ions and trace elements to assess the variability of water quality of the lake for various purposes. Geostatistics, the theory of regionalized variables, was then used to enhance the dataset and estimate some missing spatial values. Results indicated that the concentration of major ions in the water samples in winter was higher than in summer. The scatter diagrams suggested the dominance of alkaline earths over the alkali elements. Three types of water were identified in the lake that are referred to as Ca–HCO₃, Mg–HCO₃ and hybrid types. The lake water was found to be controlled by rock–water interaction with carbonate lithology as a dominant source of the solutes. The major (Ca^2 +, Mg^2 +, Na⁺, K⁺, NO₃ and HCO₃^-{\rm{HCO}}_{3}^{-}, CO₃ and Cl) and trace elements of the lake water were within the World Health Organization standards, therefore the lake water was considered chemically safe for drinking purposes. Although NO₃ concentration (ranging from 1.72 to 2 mg/L), is within the permissible limit and not very alarming, the gradually increasing trend is not acceptable. It is however, important to guard its spatio-temporal variability as the water is used for domestic as well as agricultural purposes. This study is significant as hydrogeological information on such high altitude lakes in India is scanty.