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Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Soil pollution is becoming increasingly serious due to resource exploitation in mining areas, which directly affects the stability of the surrounding soil and water environment, and the accurate prediction of heavy metal pollution source analysis has an important guiding role in scientific mine remediation and treatment. On the basis of the previous study, in order to improve the interpretation of the soil media model, positive matrix factorization (PMF) and absolute factor analysis-multiple linear regression (APCS-MLR) models, which have a high degree of maturity and accuracy in the evaluation of heavy metal source analysis in soils, were further selected to enrich the UNMIX model in the previous study. The results of the multiple receptor models analyzing the sources of heavy metal contamination and the contribution of the sources were combined with the ecological risk assessment method to determine the most suitable model in study area under quantitative conditions. The results showed that: 1) the ecological high-risk areas were mainly concentrated in the south and east part of the study area, and Cd was the main risk element of the mine; the mean value of igeoaccumulation index was 3.75, which was highly consistant with the mean value of 731.22 for the potential ecological risk index though latter provided a more comprehensive evaluation of ecological hazards. 2) Comparing the results of the three models, the PMF model resolved four pollution sources: coal combustion source, natural-traffic integrated source, natural source and atmospheric deposition source, and the source contribution rates are 38.15%, 20.62%, 24.28% and 16.95%, respectively. 3) The fitted variables R2 in the PMF model reached to 0.96, which showed the best fitting effect. The PMF model refines source apportionment by accounting for sampling point errors and accurately ascertaining pollution sources and their contributions, making it highly suitable for complex mine-contaminated soils in realistic research settings. The findings of this study can provide a reference for tracing the origins of contaminants, which is essential for the remediation efforts of polluted soils following mining activities in the area. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Bacillus subtilis has great effects on soil water and salt movement. In this paper, 5 different contents of Bacillus subtilis (0, 1, 3, 5 and 7 g/kg) were set, aiming to study the soil water cumulative infiltration, infiltration rate, wetting front, soil water contents and salt contents in each profile, as well as water-stable aggregate contents. The results showed that with the applying of Bacillus subtilis, the cumulative infiltration and infiltration rate in saline-alkali soil decreased obviously, compared to that in the control of soil columns, due to the water retention properties of Bacillus subtilis, especially after the initial 300 min. Moreover, with the increase of Bacillus subtilis content, the cumulative infiltration and infiltration rate first decreased and then increased. When the Bacillus subtilis content was 3 g/kg, the cumulative infiltration and infiltration rate of soil water tended to be the smallest in a certain time, and the variations between the treatments were significant (P<0.01). At the end of the infiltration, the cumulative infiltration with the Bacillus subtilis content of 1, 3, 5 and 7 g/kg was decreased by 18.49%, 21.85%, 12.18% and 3.78% respectively compared with that without Bacillus subtilis. With the applying of Bacillus subtilis, the wetting front decreased as well. At the initial time, there were no significant differences between different treatments. With the infiltration time increasing, the effect of Bacillus subtilis on wetting front in each treatment was significant (P<0.01). The wetting front took 3 700, 7 260, 7 700, 5 100 and 4 320 min to reached the bottom of the soil column with Bacillus subtilis content of 0, 1, 3, 5 and 7 g/kg, respectively, and the migration rates were 7.84×10-3, 4.00×10-3, 3.77×10-3, 5.69×10-3, and 6.71×10-3 cm/min, accordingly. When the content was 3 g/kg, the migration rate of wetting front was the smallest. Both Philip and Green-Ampt model could fit soil infiltration process well with different Bacillus subtilis contents. For Green-Ampt infiltration model, with the increase of Bacillus subtilis contents, soil water saturated hydraulic conductivity first decreased and then increased, and the wetting front suction showed an opposite trend compared with control treatment (P<0.05). For the Philip infiltration model, with the increase of Bacillus subtilis contents, the soil sorptivity and stable infiltration rate first decreased and then increased, which were obviously less than that without Bacillus subtilis (P<0.05). When the Bacillus subtilis was 3 g/kg, the minimum values of soil sorptivity, soil water saturated hydraulic conductivity and stable infiltration rate were obtained, and the maximum value of wetting front suction was obtained, which further confirmed that Bacillus subtilis could increase soil water holding capacity. When the Bacillus subtilis contents were 1, 3, 5 and 7 g/kg, the water contents were greater than that in control. At the depth of 27 cm, the water content in the treatments with Bacillus subtilis of 1, 3, 5 and 7 g/kg increased by 17.65%, 31.76%, 11.76% and 7.06% respectively, compared with that in control. Soil salt contents were also significantly decreased with the application of Bacillus subtilis. The salt content in the treatments with Bacillus subtilis of 1, 3, 5 and 7 g/kg decreased by 22.37%, 31.29%, 17.78% and 10.67% respectively, compared to that in control. After applying Bacillus subtilis, soil water-stable aggregate also increased. In the whole soil layer, the water-stable aggregates in the treatment with Bacillus subtilis of 1, 3, 5 and 7 g/kg were greater than those in control, and increased by 13.02%, 17.59%, 9.68% and 5.24%, respectively. This study can provide a theoretical support for the microorganism application in saline-alkali soil amendment. [ABSTRACT FROM AUTHOR]

High weathered soils in arid and semi-arid area are characterized by low soil fertility and high erosion potential. This paper evaluated the influences of nano-carbon on soil erosion and water loss on the sloping land (15°) of the Chinese Loess Plateau. Simulated rainfall experiments were performed on a natural, fallow loessial slope in the Shenmu Erosion and Environment Research Station, Institute of Soil and Water Conservation, Chinese Academy of Sciences, which locates in the Liudaogou watershed, Shenmu County, Shaanxi Province. Five application rates (i.e., 0, 0.1%, 0.5%, 0.7%, and 1.0%) of nano-carbon were selected during the simulated rainfall experiments (rainfall intensity of 60 mm/h); and 4 vegetation species (i.e., caragana, alfafa, bean, and maize) were planted on the slope to evaluate the vegetation effect on soil and water conservation with the bare as the control. A constant-intensity rainfall method was adopted under natural conditions. Field plots were established on the slope that had been fallow for 5 years. The rainfall simulator came from the independent design of Xi'an University of Technology. Under the 60 mm/h rainfall intensity, the simulated rainfall experiments were carried out for 50 times in the 25 different pretreated plots in order to estimate soil erosion and water loss for all the treatments. The main results were as follows: the initial runoff time was delayed with the increase of nano-carbon contents. Compared to the control treatment without nano-carbon application in bare land, the initial runoff time in alfalfa plot was delayed by 287.1%, which was the most obvious. Furthermore, with the increase of nano-carbon contents, the runoff in each treatment decreased obviously. The nano-carbon alfalfa coverage also had the most obvious effect in the reducing runoff, and the runoff was reduced by 66.47%; for other vegetation species, the reduction was between 31.5% and 33.6%. Moreover, the nano-carbon had a significant effect on soil loss controlling. The nano-carbon in alfalfa land showed the best effect for soil loss controlling, which was followed by caragana. Soybean land showed the highest soil loss. For the bare land (control) and alfalfa coverage, when the nano-carbon content was 1%, the lowest sediment yield was obtained; while for caragana, soybean and maize coverage, when the nano-carbon content was 0.5%, the sediment yield was the lowest. Based on the correlation analysis between nano-carbon and runoff and sediment yield, it could be concluded that nano-carbon has a significant impact on the experimental results. In the evaluation of soil and water loss control effect, the 0.5% nano-carbon had the obvious effect, which was similar with the 0.7% and 1.0% nano-carbon content, so considering the price, 0.5% nano-carbon content was appropriate on soil and water loss control in loess area. The results provide a guide for controlling soil water and nutrient loss on the sloping land. [ABSTRACT FROM AUTHOR]