Chinese Soil Research Articles

Human activities contributing to the accumulation of high-risk trace metal(loid)s in soils of China's five major urban agglomerations

Rapid urbanization has accelerated the accumulation of trace metal(loid)s (TMs) in soils, but the relationship between this accumulation and human activities remains largely unknown. Therefore, based on 775 published literatures (2001–2020), this study aimed to identify the influence of human activities on TM accumulation. Results showed that all soil TM concentrations were higher than their corresponding Chinese soil background values. The pollution risk assessment indicated that the soil TMs in the study area were at moderate levels, and the value of Pollution load index was 2.10. According to the assessment of health risks, the non-carcinogenic risks for adults were at the “Negligible risk” level; while the carcinogenic risk was not negligible for all populations, with children being more susceptible than adults. Meanwhile, six high-risk TMs were identified based on the grading of Contaminating factors (CF ≥ 3) and contribution to health risk (≥ 75%), including four high pollution risk TMs (Cd, Hg, Cu, and Pb) and two high health risk TMs (Cr and As) . In addition, in accordance with the results of the Random forest model, the accumulation of soil high-risk TMs was closely related to influencing factors associated with human activities. The accumulation of Hg and Cr among five major urban agglomerations had the same influencing factors (the number of industrial companies and the amount of industrial wastewater discharge for Hg; the amount of pesticide application and highway mileage for Cr). However, there were significant differences in the factors influencing the accumulation of the other four high-risk TMs (including Cd, As, Cu and Pb), due to the different characteristics of each urban agglomeration. Our results provide new insights into the relationship between human activities and soil TM accumulation.

Diabetes: A Transcultural History of a Disease Concept in the Late Qing and Republican China

In the past few years, the medical knowledge transfer in a West-East direction has attracted increased scholarly attention from European and American historians, whereas studies on such “knowledge travels” conducted in the East Asian context focus mainly on political and socio-cultural concepts. To provide an alternative perspective on the travel of Western medicine to Chinese soil, a case study on “diabetes” is conducted, under the theoretical framework of “transcultural conceptual history.” This article systematically analyzes the standardization, popularization, politicization, and derivatization of “diabetes,” calling for further attention to transcultural histories of medical concepts in modern China.

The inverse texture effect of soil on vegetation in temperate grasslands of China: Benchmarking soil texture effect

The inverse texture effect of soil on vegetation has been reported in a few arid regions, but no information is available on the vast Chinese temperate grassland. In addition, no consistent criteria and approaches have been used to classify soil texture groups, determine the precipitation threshold (Pθ) below which the inverse texture effect occurs, and quantify the effect size (Z), which has limited the generalization of the rules of the soil texture effect in different ecosystems. We analyzed the soil texture effect on vegetation using the remotely sensed vegetation data (MODIS/NDVI) and the Chinese soil profile texture data at 6851 sites in temperate grasslands of China. We found, first, a strong inverse texture effect, i.e., a higher NDVI on coarse- (>50 % sand) than fine-textured soil in low precipitation areas, and Pθ was variable with annual precipitation and averaged 260 mm in the region. Second, we proposed a novel method to use the loam soil as a benchmark against which to quantify the effect of various textured soils, and determine Pθ as the point on precipitation gradient where the soil texture effect shift from positive to negative or vice versa. As such, Pθ decreased with soil coarseness, and increased with precipitation; and the texture effect decreased from positive to negative for sandy soils, whereas it increased from negative to positive for silt or clay soils, on the gradient of precipitation increase. Our results provide new insights into the relations of vegetation pattern and dynamics with precipitation and soil texture, and a method for quantifying and comparing soil texture effect across ecosystem types.

Ecological risk evaluation and sensitivity analysis of heavy metals on soil organisms under human activities in the Tibet Plateau, China.

The Tibetan Plateau (TP), once considered a pristine environment, is now facing increased heavy metal pollution due to human activities, causing unprecedented ecological risks to soil organisms. However, little is known about the sensitivity and tolerance of different soil organisms to heavy metal toxicity in the high-altitude areas of the TP under the background of human activity intensity and future risk control priorities. In this study, we conducted an ecological risk assessment and threshold calculation for 10 heavy metals in soil for typical soil organisms, including Cd, Co, Cr, Cu, Ni, Pb, Zn, Mn, Sb, and Sn, using the species sensitivity distribution (SSD) method in the zone between Ranwu town and Renlongba glacier on the TP. The results revealed that most sampling sites had average levels of Cd, Sb and Ni exceeding their regional soil environmental background values and were the major contaminants. Impressively, the hitherto undeveloped Renlungba Glacier showed relatively high contamination levels of Sb and Ni. From the view of sensitivity differences, the toxicity risks of Cd, Cr, Cu, Ni and Pb were higher for terrestrial plants than for soil invertebrates based on the fitted heavy metal SSD curve trends. In terms of the ecological risk level, the average potentially affected fraction values of Zn and Ni reached 18.5% and 17.0%, respectively, with significant ecological risk at a few sampling sites. In terms of ecological risk thresholds, the Cd concentration at the 5% hazard concentration (HC5) control level was 0.05 mg/kg, which was the heavy metal with the highest risk in this study. Comparing the HC5 values of each heavy metal with the limit values in the current Chinese soil environmental quality standards, the existing administrative policies as a whole lack a powerful prevention of the potential ecological risk posed by heavy metals to soil organisms.

Legal System of Soil Pollution Remediation in China and Its Regulation and Guidance to Soil Pollution Remediation

Faced with increasingly serious soil pollution problems, China has passed the Chinese Soil Pollution Prevention and Control Law (hereinafter referred to as the Law on the Prevention and Control of Soil Pollution) and established a series of soil pollution remediation systems. However, there are still some shortcomings in the current legal system for soil pollution remediation, which cannot fully solve the problems faced in soil remediation activities. The research focuses on the legal system for soil pollution remediation. This study analyzes the development process of relevant systems, focusing on the analysis of the Soil Pollution Prevention and Control Law, including the basic content and process of soil pollution prevention and control work. On this basis, this study summarizes the legal structure and practice of soil pollution control in China and analyzes the problems existing in the implementation of China’s soil pollution remediation legal system, such as imperfect remediation standards and insufficient public participation. Then, the relevant policies of EU countries are summarized and analyzed. Combined with the actual situation of China, suggestions are put forward to improve the legal system of soil pollution remediation in China and strengthen soil remediation.

Prediction of the cadmium content in grains of low-accumulating wheat cultivars and soil cadmium threshold for safe production

Wheat cultivars with low cadmium (Cd) accumulation (WCCA-Cd) are widely used on Cd-contaminated farmland and can effectively reduce the grains Cd content to achieve the clean production in agriculture. However, there is a lack of soil Cd content thresholds specifically for the WCCA-Cd. To achieve safer production of wheat grains, a prediction model for WCCA-Cd was developed based on total Cd content in wheat grains (Grain-Cd) and soil factors using 379 soil‒wheat datasets from 10 field experiments in this research. The adaptability of the prediction model was tested using 312 pairs of data. Descriptive statistics (N = 379) showed that soil pH ranged from 4.28 to 8.76, the total Cd content in soil (Soil-Cd) ranged from 0.09 to 10.25 mg kg−1, and Grain-Cd ranged from 0.002 to 1.35 mg kg−1. Correlation analysis showed that Grain-Cd had a highly significant negative correlation with soil organic matter (SOM), soil pH, and soil conductivity (EC) and a highly significant positive correlation with Soil-Cd and Cd content in the diethylenetriaminepentaacetic acid extraction state (DTPA-Cd) (P < 0.001). The bioconcentration factor (BCF) decreased with increaseing soil pH. Both random forest and stepwise regression equations indicated that the most important factors affecting Cd bioeffectiveness were Soil-Cd and soil pH, explaining 80% of the variation in Grain-Cd. The prediction model indicated a soil Cd threshold (0.23–1.25 mg kg−1) for the safe production of WCCA-Cd at soil pH (4–9), which has a wider range of applicability compared with the Chinese Soil Safety Standards. Therefore, these results can quantify the grain Cd content of WCCA-Cd and guide the safe and clean production of WCCA-Cd on different Cd contaminated farmlands.

Appraisal of Soil Taxonomy and the World Reference Base for Soil Resources Applied to Classify Purple Soils from the Eastern Sichuan Basin, China

Purple soil is a type of global soil that is referred to by various names in different countries, which makes it difficult to understand, utilize, and ameliorate purple soil internationally. Soil Taxonomy (ST) and the World Reference Base for Soil Resources (WRB) are the most widely used soil classification systems in the world. The aim of this study was to clarify the classification of purple soil in ST and the WRB and to establish a reference between different classification systems of purple soil. Therefore, based on the current principles and methods of the ST and WRB systems, 18 typical purple soil profiles in the eastern Sichuan Basin were identified, retrieved, and classified. Then, the soil units of the WRB were compared with those of ST and the Chinese Soil Taxonomy (CST). The results revealed that the 18 typical purple soil profiles could be classified into three soil orders, four soil group orders, and seven soil subgroups in ST and four reference soil groups (RSGs) in the WRB; each profile had its own unique principal and supplementary qualifier combinations within the soil units. It was found that when compared with the ST system, the WRB and CST systems had stronger abilities to distinguish purple soil. In addition, the WRB system was able to more comprehensively consider soil characteristics such as soil layer thickness, ferric horizon, soil color, texture mutations, and carbonate through qualifiers. However, the CST system added diagnostic characteristics, such as the lithologic characteristics of purplish sandstones and shales and the ferric properties and alic properties at the soil group and subgroup levels, which enhanced the differentiation ability of the purple soil at the subgroup level.

Chinese Soil Moisture Observation Network and Time Series Data Set for High Resolution Satellite Applications

High-quality ground observation networks are an important basis for scientific research. Here, an automatic soil observation network for high-resolution satellite applications in China (SONTE-China) was established to measure both pixel- and multilayer-based soil moisture and temperature. SONTE-China is distributed across 17 field observation stations with a variety of ecosystems, covering both dry and wet zones. In this paper, the average root mean squared error (RMSE) of station-based soil moisture for well-characterized SONTE-China sites is 0.027 m3/m3 (0.014~0.057 m3/m3) following calibration for specific soil properties. The temporal and spatial characteristics of the observed soil moisture and temperature in SONTE-China conform to the geographical location, seasonality and rainfall of each station. The time series Sentinel-1 C-band radar signal and soil moisture show strong correlations, and the RMSE of the estimated soil moisture from radar data was lower than 0.05 m3/m3 for the Guyuan and Minqin stations. SONTE-China is a soil moisture retrieval algorithm that can validate soil moisture products and provide basic data for weather forecasting, flood forecasting, agricultural drought monitoring and water resource management.

Soil Stoichiometry Characterization in the Oasis-desert Transition Zone of Linze, Zhangye

To investigate the changes in C, N, P, and K contents and ecological stoichiometry of desert oasis soils and to elucidate their ecological responses to environmental factors, 10 sample plots were selected in the Zhangye Linze desert oasis in the middle part of the Hexi Corridor, and surface soil samples were collected to determine the C, N, P and K contents of soils and to reveal the distribution characteristics of soil nutrient contents and stoichiometric ratios in different habitats and the correlation with other environmental factors. The results showed that:① the distribution of soil carbon was uneven and heterogeneous across sites (R=0.761, P=0.06). The highest mean value was 12.85 g·kg-1 in the oasis, followed by 8.65 g·kg-1 in the transition zone and 4.1 g·kg-1 in the desert. ② The content of total soil potassium did not vary significantly and was high among deserts, transition zones, and oases and low in saline areas. ③ The mean soil C:N value was 12.92, the mean C:P value was 11.69, and the mean N:P value was 0.9, all of which were lower than the global average soil content (13.33, 72.0, and 5.9) and the Chinese soil average (12, 52.7, and 3.9). ④ Soil water content was the most influential factor affecting C, N, P, K, and ecological stoichiometry characteristics of desert oasis soils, with a contribution of 86.9%, followed by soil pH and soil porosity, with contributions of 9.2% and 3.9%, respectively. The results of this study provide basic information for the restoration and conservation of desert and oasis ecosystems and establish a basis for future study of the biodiversity maintenance mechanism in the region and its correlation with the environment.

Analytical study on heavy metal output fluxes and source apportionment of a non-ferrous smelter in southwest China

Abandoned Pb/Zn smelters are often accompanied by a large amount of smelting slag, which is a serious environmental problem. Previous studies have demonstrated that slag deposits pose an environmental threat even if the smelters are shut down. Herein, a Pb/Zn smelter and its impacted zone in GeJiu, Yunnan, China were selected as the study area. The risk and source apportionment of heavy metals (HMs) in the soil of the impacted zone were systematically studied. Based on the hydrogeological features, the migration path and output fluxes of the HMs released from smelting slag to the impacted zone were investigated. The HM contents (Cd, As, Zn, Pb, and Cu) in the soil substantially exceeded the screening values of the Chinese soil standard (GB15618-2018). Based on the results of the Pb isotopic and statistical analyses for source apportionment, the contaminated sites and agricultural irrigation water had a large impact on the HMs of soil. The hydrological analysis results showed that runoff, as an HM migration path under rainfall, continued to affect the environment. The water balance calculations using the Hydrologic Evaluation of Landfill Performance model showed that the rainfall was distributed on site as follows: evaporation (57.35%), runoff (32.63%), and infiltration (10.02%). Finally, the output fluxes were calculated in combination with the leaching experiment. As, Zn, Cd, Pb, and Cu runoff had the output fluxes of 6.1 × 10−3, 4.2 × 10−3, 4.1, 1.4 × 10−2, and 7.2 × 10−4 mg/kg/y, and infiltration of 1.9 × 10−3, 1.3 × 10−3, 1.3, 4.0 × 10−4, and 2.2 × 10−4 mg/kg/y, respectively. Therefore, this study offers theoretical and scientific recommendations for effective environmental management and engineering remediation.

A Chinese soil conservation dataset preventing soil water erosion from 1992 to 2019

Soil conservation service (SC) is defined as the ability of terrestrial ecosystems to control soil erosion and protect soil function. A long-term and high-resolution estimation of SC is urgent for ecological assessment and land management on a large scale. Here, a 300-m resolution Chinese soil conservation dataset (CSCD) from 1992 to 2019, for the first time, is established based on the Revised Universal Soil Loss Equation (RUSLE) model. The RUSLE modelling was conducted based on five key parameters, including the rainfall erosivity (interpolation of daily rainfall), land cover management (provincial data), conservation practices (weighted by terrain and crop types), topography (30 m), and soil properties (250 m). The dataset agrees with previous measurements in all basins (R2 > 0.5) and other regional simulations. Compared with current studies, the dataset has long-term, large-scale, and relatively high-resolution characteristics. This dataset will serve as a base to open out the mechanism of SC variations in China and could help assess the ecological effects of land management policies.

From rejection to acceptance: the institutionalization of adopting university ranking outcomes as policy and strategic tools in China since the 1980s

ABSTRACT China is an important player in global university ranking exercise. Nevertheless, existing studies have not adequately explored how the legitimacy of adopting university ranking outcomes has been chronologically established on Chinese soil. This paper attempts to fill this knowledge gap drawing on interviews with 37 stakeholders between 2003-2021 and an analysis of 2086 articles and reports published between 1984–2022 concerning university rankings. It first analyses the process of institutionalization of adopting university ranking outcomes in China, and discusses how the policy initiatives such as the ‘985 Project' in 1998 and the ‘Double First-Class' Project in 2016 intertwined with university rankings over the time and provide opportunities for establishing such legitimacy. Secondly, it analyses the mechanisms through which university ranking outcomes gain legitimacy, and suggests that interactions among the stakeholders are one of the key mechanisms, whereby the central government plays a pivotal role in legitimizing adoption of international university ranking results. Furthermore, we argue that the universities have responded actively to adopting the ranking outcomes and use them as strategic tools to achieve their own goals. As such, this paper sheds a new light on the impact of university rankings in China and beyond.

Diagnostic surface horizon vs. conventional surface horizon: The impact of topsoil delineation on the results of topsoil organic carbon density assessment in China

Accurate assessment of the topsoil organic carbon density (TSOCD) is of great importance for the management and conservation of the topsoil organic carbon pools. The conventional surface horizon (CSH) delineation method, which involves specifying a uniform topsoil thickness for all sampling points across a study area, carries the potential risk of inaccurate TSOCD estimation. Chinese soil scientists developed the definition and determination criteria for diagnostic surface horizon (DSH) in Chinese Soil Taxonomy (CST), which were based on the distinctive characteristics of topsoil in China. This study employed a DSH-based topsoil classification method to evaluate the TSOCD of China, based on the findings of the recent national soil survey. Also, TSOCD was calculated for all sample points based on the CSH method, where the thickness of CSH was defined as 5, 10, 15, 20, 30, and 60 cm from the surface. The results showed that DSH-based TSOCD in China ranged from 0.03 to 74.63 kg m−2 with a mean value of 4.34 kg m−2. The standardized topsoil delineation based on the DSH method shows great potential for improving the accuracy of TSOCD assessment and different DSH types exhibited very significant differences in TSOCD (p < 0.01). There was a significant difference between the TSOCD results based on the six CSH delineation thicknesses (p < 0.01). Excessive or insufficient uniform CSH thickness settings may result in over- or underestimation of TSOCD values in comparison to DSH. This study provides evidence that specific uniform thickness delineations are suitable for particular soil types, climatic conditions, and land use patterns, and that the mean TSOCD results derived from these delineations do not significantly differ (p < 0.01) from those based on DSH. The findings of this study have the potential to support the development of more accurate surface horizon delineation methods for managing and making decisions related to topsoil organic carbon pools.

Fidelity to the deep structure of literature: Yu Kwang-chung’s translation of Emily Dickinson

ABSTRACT Yu Kwang-chung embarked on a translational project, Anthology of American Poetry, around 1960. Edited by Stephen Soong, the anthology was published by World Today Press, Hong Kong, in 1961. This research commences with Yu’s plight in selecting what poems of Dickinson’s to translate, a plight associated with Poundian translatology. It follows with textual analyses of Yu’s translations of and introduction to Dickinson’s poetry. I aruge that Yu is far from being an absolutist inasmuch as translational fidelity is concerned. In contrast, what he pursues in poetry translation is an optimal fidelity, one that intends to bring about as profuse poetics as possible in the target language. The translator exerts optimal faithfulness to a variety of traditional literary elements, all of which amount to what I call “fidelity to the deep structure of literature.” It is with such a flexible fidelity that Yu transplants Dickinson’s metaphysical universe onto the Chinese soil.

Changes in soil Cd contents and microbial communities following Cd-containing straw return

Contamination of soil with cadmium (Cd) threatens food safety and human health. In general, crop straws from contaminated soils could accumulate considerable amounts of Cd. The addition of Cd-containing rice straw can have negative effects on soil environment. In this study, straws varying in Cd concentration were added to soil at a rate of 5% (w/w) to investigate the effects of Cd-containing straw on soil Cd dynamics and soil microbial communities. Results showed that large amounts of Cd, especially bioavailable Cd, were released into soil during the decomposition of Cd-containing straws. The addition of straws with 10, 20 and 40 mg kg−1 Cd increased total Cd in soils from 0.31 mg kg−1 to 0.89, 1.39 and 2.09 mg kg−1, respectively, exceeding the screening value of total Cd < 0.4 mg kg−1 for paddy soils of pH 5.5–6.5 according to Chinese Soil Environmental Quality Standards. Moreover, the addition of Cd-containing straw decreased alpha-diversity of bacterial and fungal communities compared to the clean straw. Indeed, changes in soil factors including pH, Eh, dissolved organic C and Cd level jointly reconstructed soil microbial communities. The addition of Cd-containing straw increased the relative abundance of bacterial species Acidobacteria and Proteobacteria but decreased that of Firmicutes. Meanwhile, it increased the relative abundance of fungal species Basidiomycota and Fusarium which were considered Cd-tolerant. This study revealed the potential environmental risk and the variation of microbial communities caused by increasing soil Cd bioavailability after direct application of Cd-containing rice straw to the field.

Vegetation restoration dominated the attenuated soil loss rate on the Loess Plateau, China over the last 50 years

The Chinese Loess Plateau has experienced large-scale land use changes in the past few decades. Understanding how land use change affects soil erosion is critical in the region's ecological construction and land management. In this study, the Beiluo River Basin in the core area of the Loess Plateau was selected to investigate the effects of land use changes on soil loss rates over the last 50 years. Results show that the land use has changed considerably, mainly reflected in the upper reaches. From 1970 to 2020, cropland in the upper reaches decreased by 54 %, directly leading to a 9.1-fold increase in forested land. Landsat-NDVI shows vegetation coverage increased from 21.1 % to 69.9 % over time. The Chinese Soil Loss Equation (CSLE) was used and confirmed to be satisfactory with a high coefficient of determination (R2, 0.89) and a strong Nash–Sutcliffe efficiency coefficient (0.72), although an underestimation exists. The specific soil loss simulated in the upper reaches maintained a high rate of around 8,000 t·km−2·yr−1 from the 1970s to the 1990s, dramatically dropping to 3,058 t·km−2·yr−1 in the 2000s, then attenuated to 1,321 t·km−2·yr−1 in the 2020s. For the entire basin, soil loss rates dropped from 4,090 to 1,848 and 890 t·km−2·yr−1 from the 1970s to the 2000s and 2020s, respectively. Attribution analysis showed that the dominant factor of the change in soil loss rates in the 1980s and 1990s relative to the 1970s was the change in rainfall erosivity for the entire watershed. However, vegetation restoration rapidly converted to the dominant factor contributing 78.3 % to soil loss decrease in the 2000s. The shift is evident in each reach of the basin except the terrain-plain area with the majority of farmland. The findings are helpful for sustainable land use planning and socio-economic development on the Loess Plateau and in similar areas.

Strategies for predicting soil organic matter in the field using the Chinese Vis-NIR soil spectral library

The large-scale soil spectral library (SSL) can provide abundant information for predicting soil properties at a local scale, especially in places lacking data. However, since all the existing large-scale SSLs only contain dry spectra recorded under laboratory conditions, the challenge remains in using SSL for predicting soil information using in situ soil spectra. Previous studies have focused on the methods of transforming in situ spectra to dry spectra when using SSLs, while few studies have compared which strategies are optimal in predicting soil properties. To determine the optimal strategies for predicting soil organic matter (SOM) from an area not located in the archived Chinese Soil Spectral Library (CSSL), we investigated the prediction accuracy of memory-based learning (MBL) using spectra transformed by external parameter orthogonalization (EPO) on the CSSL (MBL_EPO) and on the CSSL spiked with subset samples selected by the conditioned Latin hypercube (cLH) algorithm (MBL_EPO_spiking) and using the data from CSSL spiked directedly by the subset in situ samples (MBL_wet_spiking). We also evaluated the prediction accuracy of the in situ and dry spectra using the selected subset and the partial least squares regression (PLSR) model directly. The results showed that the mean squared Euclidean distance (msd) calculated from spectra was an optimal indicator for selecting the representative samples for both the laboratory and in situ conditions. When only 20 samples with both in situ and dry spectra are available to predict SOM, MBL_EPO_spiking is suggested; otherwise, MBL_wet_spiking with the spiking of in situ spectra determined by the smallest msd is optimal. Our findings pave the way for efficient SOM prediction in situ by integrating a large-scale SSL.

Environmental geochemical baseline determination and pollution assessment of heavy metals in farmland soil of typical coal-based cities: A case study of Suzhou City in Anhui Province, China

Soil is the foundation of agricultural green development and human survival; the study of local environmental geochemical baselines can guide soil management and ensure the safe use of soil. In this study, a total of 100 shallow farmland soil samples were collected in each township of Yongqiao District, Suzhou City, Anhui Province, China. Herein, the contents of 10 heavy metal elements including As, Hg, Cd, Pb, Cr, Cu, Mn, Ni, Zn and Fe were determined. In addition, the geochemical baseline of heavy metals was calculated based on the relative cumulative frequency curve method, and the soil pollution status was evaluated. The results show that the average contents of As, Hg, Cd, Cu, Mn and Zn exceeded the soil background values of Anhui Province by 3.82%–64.74% (1.04–1.65 times), meanwhile, the average contents of Pb and Cr were lower than the soil background values of Anhui Province. The average contents of Cd, Cr, Cu, Mn and Ni exceeded the Chinese soil background values by 1.61%–64.74% (0.98–1.65 times). The geochemical baseline values of As, Hg, Cd, Pb, Cr, Cu, Mn, Ni, Zn and Fe were 9.585 mg/kg, 0.028 mg/kg, 0.112 mg/kg, 21.59 mg/kg, 53.66 mg/kg, 19.31 mg/kg, 543.8 mg/kg, 24.93 mg/kg, 50.57 mg/kg and 2.654%, respectively. The pollution assessment results also showed that most of the farmland soil samples in the study area were non-polluting or slightly polluted based on geochemical baselines. Hg and Cu in a few samples were moderately polluted, and Cd in only one sample was moderately intensely polluted. Combined with the distribution of pollution and field investigation, it is considered that Hg comes from atmospheric deposition and agricultural non-point source pollution of industrial pollution. Cu comes from animal husbandry and agricultural pollution. Meanwhile, Cd is related to natural sources, wood processing and agricultural fertiliser application. The study demonstrated that the calculation of soil geochemical background value should take full account of the differences between the various regions, combined with the current state, particularly the pre-consideration of the distribution of elements or pollutants. Then, reasonably select the evaluation standard value so that the evaluation results can truly reflect the state of soil pollution.

Quantifying anthropogenic soil erosion at a regional scale – The case of Jiangxi Province, China

Soil erosion is a severe global eco-environmental problem threatening human survival and development. It is the combined result of natural factors and human activities. Human activities have played a key role in soil erosion by both promoting and inhibiting it. Only by effectively quantifying anthropogenic soil erosion and analyzing its contribution to actual soil erosion can we alleviate and solve the problem of soil erosion in a targeted manner. In view of this and taking Jiangxi Province as an example, we propose a quantitative assessment model (QAM) based on the Chinese Soil Loss Equation (CSLE) model to quantify anthropogenic soil erosion and construct a contribution rate (CR) to explain the impact degree of human activities on soil erosion. The results were as follows: 1) the annual average anthropogenic soil erosion in 2000, 2010, and 2018 was 309.96, 287.07, and 240.32 t/(km2·a), respectively, with a decrease of 69.63 t/(km2·a) (22.47 %) throughout 2000–2018, indicating that human activities aggravate soil erosion, although this aggravating effect tends to weaken over time; 2) human activities represent the dominant factor inducing soil erosion, and the annual average CR values of human activities were all above 55 % in 2000, 2010, and 2018, larger than the annual average CR values of natural factors in each year. The QAM can provide a methodological reference for the quantification of anthropogenic soil erosion at the regional scale, and the CR can be used to analyze the degree of anthropogenic impact on soil erosion.

Predicting and delineating soil temperature regimes of China using pedotransfer function

Soil temperature regime (STR) is important for soil classification and land use. Generally, STR is delineated by estimating the mean annual soil temperature at a depth of 50 cm (MAST50) according to the Chinese Soil Taxonomy (CST). However, delineating the STR of China remains a challenge due to the difficulties in accurately estimating MAST50. The objectives of this study were to explore environmental factors that influence the spatial variation of MAST50 and generate an STR map for China. Soil temperature measurements at 40 and 80 cm depth were collected from 386 National Meteorological Stations in China during 1971–2000. The MAST50 was calculated as the average mean annual soil temperature (MAST) from 1971–2000 between 40 and 80 cm depths. In addition, 2 048 mean annual air temperature (MAAT) measurements from 1971 to 2000 were collected from the National Meteorological Stations across China. A zonal pedotransfer function (PTF) was developed based on the ensemble linear regression kriging model to predict the MAST50 in three topographic steps of China. The results showed that MAAT was the most important variable related to the variation of MAST50. The zonal PTF was evaluated with a 10% validation dataset with a mean absolute error (MAE) of 0.66°C and root mean square error (RMSE) of 0.78°C, which were smaller than the unified model with MAE of 0.83°C and RMSE of 0.96°C, respectively. This study demonstrated that the zonal PTF helped improve the accuracy of the predicted MAST50 map. Based on the prediction results, an STR map across China was generated to provide a consistent scientific base for the improvement and application of CST and land use support.