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Manure application is the primary input route for antibiotic resistance genes (ARGs) in farmland soil. This study investigated the effects of varying the rates of five chicken manure applications on the accumulation and distribution of ARGs across different soil depths (0–20, 20–40, and 40–60 cm) using metagenomic sequencing. The results revealed that the distribution of ARGs in farmland soil was closely linked to soil depth and influenced to some extent by the fertilizer quantity after 30 days of fertilization. ARGs were predominantly concentrated in the surface soil and exhibited a significant decrease in type and abundance with an increased soil depth. Compared with soil treated with chemical fertilizers alone, chicken manure-treated surface soil presented a higher diversity and abundance of ARGs. However, the diversity and abundance of ARGs did not increase proportionally with the increasing ratios of chicken manure application (0, 25, 50, 75, and 100%). ARGs in soil primarily conferred resistance to host bacteria through antibiotic efflux pumps (~33%), antibiotic target alteration (~31%), antibiotic inactivation (~20%), and antibiotic target protection (~8%). Correlation analysis involving ARGs and soil microorganisms revealed widespread multidrug resistance among soil microorganisms. Furthermore, two genera of human pathogenic bacteria (Pseudomonas sp. and Listeria sp.) were identified as potential microbial hosts of ARGs in all treatments. Correlation analysis involving ARGs and environmental factors indicated that soil ARGs are predominantly influenced by heavy metals and microorganisms. This paper offers valuable insights for environmental risk assessments regarding the utilization of livestock manure resources. Additionally, it furnishes a scientific foundation for farmland application strategies pertaining to livestock manure. [ABSTRACT FROM AUTHOR]

The spatial characteristics, pollution sources, and risks of soil heavy metals were analyzed on Hainan Island. The results showed that the heavily polluted points accounted for 0.56%, and the number of mildly and above polluted points accounted for 15.27%, respectively, which were mainly distributed in the northern part of the study area. The principal component analysis–absolute principal component score–multiple linear regression (APCS-MLR) and the positive matrix factorization (PMF) revealed four sources of heavy metals: agricultural pollution sources for cadmium, (Cd), industrial and mining pollution sources for arsenic, (As), transportation pollution sources for zinc and lead (Zn and Pb), and natural pollution sources for chromium, nickel, and copper (Cr, Ni, and Cu). The human health risk assessment indicated that the average non-carcinogenic risk (HI) for both adults and children was within the safe threshold (<1), whereas Cr and Ni posed a carcinogenic risk (CR) to human health. In addition, the total non-carcinogenic risk (THI) indicated that heavy metals posed a potential non-carcinogenic risk to children, while the total carcinogenic risk (TCR) remained relatively high, mainly in the northern part of the study area. The results of the Monte Carlo simulation showed that the non-carcinogenic risk (HI) for all heavy metals was <1, but the total non-carcinogenic risk index (THI) for children was >1, indicating a potential health risk above the safe threshold. Meanwhile, nearly 100% and 99.94% of the TCR values exceeded 1 × 10−4 for children and adults, indicating that Cr and Ni are priority heavy metals for control. The research results provide the necessary scientific basis for the prevention and control of heavy metals in agricultural soils. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board 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.)

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board 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.)

【Objective】The research was conducted to explore the remediation effect of water regulation and biochar on farmland soil near mining areas and improve the safe use of farmland.【Method】Taking farmland soil near a lead-zinc mine in Yunnan as the research object, three water conditions: dry-wet alternation (G), flooding (Y) and natural moisture content (Z), and four biochar addition amounts of 0% (BC0, CK), 2.5% (BC1), 5.0% (BC2), and 7.5% (BC3) were set up. Through soil culture experiments, the effects of applying chicken manure biochar under different water regulation measures on the forms of Pb and Zn in heavy metal contaminated soil were studied.【Result】Under the three water conditions, the application of biochar could increase soil pH. The concentrations of water-soluble and exchangeable Pb and Zn in soil treated with biochar were significantly lower than that of CK, reducing the bioavailability of Pb and Zn. The mass fractions of oxidizable and residual Pb in soil treated with biochar increased, with ZBC2 treatment having the highest mass fractions of oxidizable and residual Pb, which were 64.58% and 25.06%, respectively. The mass fractions of residual Zn in soils under various treatments ranked as: dry-wet alternation > flooding > natural moisture content. Under different water conditions, the application of biochar significantly reduced the mass concentrations of TCLP-extracted Pb and Zn, both of which were far below the international limitation standards. Among them, the soil treated with GBC3 had the lowest concentration of TCLP-extracted Zn, which was 3.45 mg/L. The average mass fraction of Pb and Zn bioavailability by SGET method was lower than that by PBET method and SBET method, while the ZBC3 treatment by SGET method had the lowest mass fractions of Pb and Zn bioavailability, which were 0.43% and 0.27%.【Conclusion】The application of different amounts of biochar under three types of water regulation effectively passivated soil heavy metals Pb and Zn, reducing their harm to the soil environment. Under natural moisture content conditions, the application of high amounts of biochar (5.0%, 7.5%) had the best passivation effect on heavy metal Pb in soil; the optimal passivation effect of 7.5% biochar on heavy metal Zn in soil was observed under dry-wet alternation conditions.

【Objective】The research was conducted to explore the remediation effect of water regulation and biochar on farmland soil near mining areas and improve the safe use of farmland.【Method】Taking farmland soil near a lead-zinc mine in Yunnan as the research object, three water conditions: dry-wet alternation (G), flooding (Y) and natural moisture content (Z), and four biochar addition amounts of 0% (BC0, CK), 2.5% (BC1), 5.0% (BC2 ), and 7.5% (BC3 ) were set up. Through soil culture experiments, the effects of applying chicken manure biochar under different water regulation measures on the forms of Pb and Zn in heavy metal contaminated soil were studied.【Result】Under the three water conditions, the application of biochar could increase soil pH. The concentrations of water-soluble and exchangeable Pb and Zn in soil treated with biochar were significantly lower than that of CK, reducing the bioavailability of Pb and Zn. The mass fractions of oxidizable and residual Pb in soil treated with biochar increased, with ZBC2 treatment having the highest mass fractions of oxidizable and residual Pb, which were 64.58% and 25.06%, respectively. The mass fractions of residual Zn in soils under various treatments ranked as: dry-wet alternation > flooding > natural moisture content. Under different water conditions, the application of biochar significantly reduced the mass concentrations of TCLP-extracted Pb and Zn, both of which were far below the international limitation standards. Among them, the soil treated with GBC3 had the lowest concentration of TCLP-extracted Zn, which was 3.45 mg/L. The average mass fraction of Pb and Zn bioavailability by SGET method was lower than that by PBET method and SBET method, while the ZBC3 treatment by SGET method had the lowest mass fractions of Pb and Zn bioavailability, which were 0.43% and 0.27%.【Conclusion】The application of different amounts of biochar under three types of water regulation effectively passivated soil heavy metals Pb and Zn, reducing their harm to the soil environment. Under natural moisture content conditions, the application of high amounts of biochar (5.0%, 7.5%) had the best passivation effect on heavy metal Pb in soil; the optimal passivation effect of 7.5% biochar on heavy metal Zn in soil was observed under dry-wet alternation conditions. [ABSTRACT FROM AUTHOR]

In order to realize the rapid and quantitative monitoring of soil organic carbon content in farmland, nine conventional pretreatment analysis methods were used to optimize the original spectral information and analyze the relationship between each pretreatment spectrum and wheat soil organic carbon content, and the continuous projection algorithm (SPA) was used to extract the spectral characteristics of soil organic carbon, and two types of soil organic carbon spectral monitoring models based on full spectrum and spectral characteristic bands were established. The results showed that the correlation between the pretreatment spectrum and soil organic carbon in wheat could be significantly improved compared with the original spectrum. In the meantime, the SPA method was used to extract and confirm the important information of soil organic carbon content in the spectral regions of 400-450 nm, 510-620 nm, 1010-1 060 nm and 2 000-2 400 nm. Comparing the performance of the two types of models, it can be seen that the continuous projection algorithm-multiple linear regression (SPA-MLR) model is better than the partial least squares regression (PLSR) model under the same pretreatment spectra, and the overall performance of the soil organic carbon content estimation model based on multivariate scattering correction (MSC) pretreatment spectra is the best (Rv2=0.726, RMSEv=0.109, RPDv=1.956), and it has practical application potential. This study confirms that spectral pretreatment can improve the correlation between spectral reflectance and soil organic carbon content in wheat to a certain extent, and affect the performance of the monitoring model, and the model construction method may have a more positive effect on the accuracy of model estimation. The results of this study can provide a theoretical basis and practical exploration for the detection of soil organic carbon content in farmland. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agriculturae Zhejiangensis is the property of Acta Agriculturae Zhejiangensis Editorial Office 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.)

In order to better understand the migration characteristics of ciprofloxacin (CIP) in specific types of soils, two soil samples with significant organic matter composition and physical and chemical properties potentially influenced by different geological and environmental backgrounds were selected from the groundwater irrigated farmland area of the North China Plain, and the adsorption-desorption mechanism of CIP in soil was studied kinetically and thermodynamically. The findings show that the kinetic experimental data are more in line with the quasi-second-order kinetic equation and the isothermal models are nonlinear, of which the Langmuir model turns out the best fitting. The parameters of adsorption kinetics constant (K2, 8 772.64 vs 2 846.37 g/(mg·h)), adsorption equilibrium rate constant (K1, 0.113 vs 0.094 L/mol) and maximum adsorption capacity (Qm, 5 033 vs 3 167 mg/kg) altogether exhibited higher values for Xianxian samples than those for the Zhengding, indicating faster adsorption rate and greater adsorption capacity of Xianxian soil. Correspondingly, the desorption rate (5.98% vs 8.07%), the maximum desorption amount (6 592 vs 7 564 mg/kg) and the adsorption free energy ΔG (-25.08 vs -23.00 kJ/mol) obtained from the desorption experiment consistently reflected that the soil in Xianxian County had better adsorption performance for CIP than the soil in Zhengding County. Based on the results of comprehensive experimental research and the analysis of spectral characteristics and physicochemical parameters, it is concluded that the high molecular weight, high aromaticity and multi-functional humus components of Xianxian soil and higher clay content are important factors for its overall better adsorption effect. The physical adsorption mechanism such as hydrophobic effect and electrostatic effect of humus molecules may play more active role in the adsorption of CIP antibiotics in Xianxian soil. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment Editorial Office 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.)

Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment Editorial Office 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.)

[Objective) Based on the main input source of soil heavy metals pollution idenfitication and screening the most efficient immobilizing agent and low accumulation varieties of vegetable and rice for Cd contaminated soil, the study aimed to provide a reference for farmland soil heavy mtal pollution preventing and control. (Method) The expreriment was conducted to monitor heavy metals concentrations in atmospheric deposition, fertilizer, irrigation water and sediment and further calculated soil heavy metals input flux by these different pathways to find out the pollution source of soil heavy metals in some towns in Junlian county of Yibin, which was in the south of Sichuan province. Further field experiments were conducted to screen vegetables and rice varieties with lowest accumulation of Cd and the most efficient immobilizing agents in JL town. [Result] Hg, As, Pb and Zn in soil mainly came from atmospheric deposition, accounting for 99.99%, 75.88%, 90.57% and 84.82%, respectively. While Cd, Cr and Ni mainly came from fertilizer use, all accounting for 100%. Cu was mainly from irrigation water in the study area during 2019 to 2020, accounting for 93.66%. The application of iron manganese fertilizer (FeSO4 750 kg/ hm² + MnSO4 75 kg/hm²) had the best effect on reducing the Cd content in rice grains, mainly attributed to the improvement of soil microelement supplement on fertility, while the passivation material compounding (3000 kg/hm²) had the highest Cd content in rice grains. The screening results of low Cd accumulation of vegetables and rice varieties showed that Jiujing radish and Chuankangyou 6276 were the most suitable vegetable and rice varieties for planting in the Cd polluted soil in JL. town with the Cd content in edible parts after harvest met the national food safety standard. Conclusion] To ensure the quality and safety of crops, selecting fertilizers that meet national standards and con- trolling atmospheric decomposition are primary step. Besides the iron manganese fertilizer, humic acid and phosphorus fertilizer passivation agents are suggested to be used, and Jiujing radish and Chuankangyou 6276 varieties are recommended to be planted in the study area. [ABSTRACT FROM AUTHOR]

Heavy metal(loid)s (HMs) contamination in farmland soils, an environmental issue of global concern, has undergone extensive research across local and regional scales in the Yellow River Basin (YRB), China, but comprehensive studies at the basin scale remain scarce. This study, utilizing published data from 2000 to 2023, analyzed the concentrations, distribution patterns, potential sources, probabilistic ecological risks, and source-specific health risks of eight HMs (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in farmland soils across the YRB. Results indicated that while most agricultural soils are safe, 21.7% of samples for Cd, 5.6% for As, and 1.2% for Zn exceed China’s risk screening levels for agricultural soil pollution, with Hg and Cd showing the highest pollution levels. Ecological risks were generally high, with Cd and Hg identified as primary risk factors. Correlation analysis and the positive matrix factorization model identified four potential origins, contributing in descending order: traffic-industrial atmospheric deposition (37.0%), mixed agricultural-natural sources (26.7%), industrial-natural sources (14.6%), and mixed agricultural-industrial sources (14.6%). The probabilistic health risk assessment identified negligible noncarcinogenic threats to the population; however, carcinogenic hazards were concerning, particularly due to industrial activities and As. Children are more vulnerable to hazards than adults. These findings enhance our insight into soil HM pollution risks in the YRB and offer a scientific foundation for targeted pollution management and control strategies at the basin scale.

The rise of microplastics (MPs) is a global concern jeopardizing environmental safety. Initial studies have extensively concentrated on aquatic ecosystems, leaving their presence in terrestrial environments unknown. Thus, this study was carried out to investigate the vertical distribution of MPs in farmland soils of Mabibo Bonde la Mchicha Farm (MBMF), Dar es Salaam. 39 soil samples collected from MBMF were investigated using a Stereomicroscope and QATR-S FTIR. Results herein showed that MPs were found in all soil samples in different depths up to 15 cm deep, ranging from 4.8 to 82.2 items g-1 dry weight (DW). There was a statistically significant difference in MP abundance in depths between 0–5, 5–10 and 10–15 cm layers (P = 0.033) at ὰ = 0.05. The observations were revealed by the observed colors, in which white (36.5 %) was the most frequently observed, followed by blue (21.4 %), brown (20.2 %), black (12.8 %) and red (9 %). Fibers (49.7 %), fragments (32.9 %) and films (17.3 %) were the dominant shapes. Polyethylene (PE) and polypropylene (PP) were the dominant polymers observed constituting 33 % each, polyethylene terephthalate (PET) 11 %, high-density polyethylene (HDPE) 8 %, polyester (PES) 7 %, polyamide (PA) 7 % and polyvinyl chloride (PVC) 1 %. It can be inferred that PE and PP exhibited greater vertical mobility. However, PA and PVC were only observed in the topsoil layer. This study reveals MPs' occurrence and vertical transfer in urban farmland soils of MBMF in Dar es Salaam.

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board 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.)

The form and available state of elements are important indexes to evaluate the activity of elements. Research on the relationship between the available state and form of selenium (Se) and zinc (Zn) in farmland soil is an important basis for accurate land quality evaluation. In this paper, the available states and different forms of Se and Zn in the soil of high Se background area in Luoyang farmland were studied. The results show that the available Se in wheat soil can be replaced by the sum of water-soluble state, ion state and carbonate state. The available Se in the soil of corn, millet, sesame, peanut and sweet potato can be replaced by the sum of water-soluble state and ion state. Available Zn can be represented by the sum of water-soluble, ionic and carbonate states. The active Zn in the farmland soil developed in the basalt area was low and similar to the water-soluble Zn. The available state and forms of Se and Zn in farmland soil were mainly affected by total amount, but also by cultivated crops, pH and organic matter. It is necessary to consider agricultural planting, pH and organic matter to evaluate the availability of Se and Zn by using the form instead of the available state in farmland soil. [ABSTRACT FROM AUTHOR]

Farmland soil quality is a crucial determinant for agricultural productivity, food safety, and human well-being. Among the various contaminants, heavy metals have emerged as pervasive factors significantly impacting farmland quality, attracting widespread societal concern. In this study, we systematically applied multivariate statistical analysis, geostatistical methods, and the positive matrix factorization (PMF) source apportionment technique to elucidate the sources and contributions of eight heavy metals (Cd, Hg, As, Pb, Cr, Cu, Zn, Ni) in farmland soils within an industrialized town. Our findings reveal that Cd, Hg, Pb, and Zn exhibit pollution or enrichment in farmland soils compared to natural background levels, with Hg and Cd surpassing 164.3% and 50.2%, respectively. Notably, Zn demonstrates discernible point-source pollution. Source apportionment results highlight industrial point sources, coal combustion, and agriculture as the primary anthropogenic contributors to heavy metal contamination, with zinc-plating enterprises being the predominant industrial point sources. Addressing the specific issue of point-source pollution from Zn in industrial activities, further analysis establishes a correlation between soil Zn content and the distance from zinc-plating enterprises. Utilizing an atmospheric transport model, we observe that the impact of industrial activities on soil Zn is limited when the distance exceeds 1.5 km, emphasizing the importance of monitoring Zn pollution within areas less than 1.5 km. This study pioneers a progressive source apportionment approach, considering the origins of different heavy metals, pollution levels, distance factors, and the cost-effectiveness of environmental measures. The insights gained provide scientifically sound strategies for future decision making in environmental protection. [ABSTRACT FROM AUTHOR]

Copyright of Journal of South China Agricultural University is the property of Gai Kan Bian Wei Hui 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.)

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board 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.)

The depth of shallow groundwater significantly influences crop growth and yield by altering the physicochemical properties of farmland soil profiles. Concurrently, shallow groundwater is subject to various changes, and it remains unclear how alterations in shallow groundwater depth within field soil impact soil physicochemical properties, crop yields, and the overall dynamics of groundwater transformations. To address these uncertainties, this study utilized a sample plot equipped with a volume lysimeter and implemented four distinct groundwater depths as treatment conditions: G0 (no groundwater depth), G1 (a groundwater depth of 40 cm), G2 (a groundwater depth of 70 cm), G3 (a groundwater depth of 110 cm), and G4 (a groundwater depth of 150 cm). This study was carried out on a weekly basis to monitor fluctuations in ion content in shallow groundwater and soil moisture after the summer maize harvest, and special attention was afforded to non-irrigation conditions. This study also scrutinized the distribution of salt and nutrients in soil profiles and assessed changes in summer maize yield. Very interesting findings were obtained by conducting the study. Firstly, the shallower the groundwater depth, the higher the water and salt content of the soil surface. Small, frequent rainfall events (precipitation ≤ 25 mm) facilitated the effective removal of salt from the soil surface. Despite increased rainfall contributing to salt ion dilution in groundwater, the risk of soil surface salinization increased at the surface level. Secondly, a linear relationship existed between groundwater depth and surface soil moisture and salt content. With every 10 cm increase in groundwater depth, the surface soil moisture and salt content decreased by 0.56% and 0.06 g/kg, respectively. Soil nutrients tended to accumulate in the surface layer, with nutrient content increasing with depth. However, C/N was not notably affected by groundwater depth. Thirdly, Na+ and K+ consistently dominated the soil surface. As soil salinity increased, the prevalence of Cl− and SO42− increased, with the rate of SO42− increase surpassing that of chlorine. HCO3− altered by rainfall served as an indicator of soil alkalization characteristics, while Na+ and K+ in soil, along with Cl− and SO42− derived from groundwater, represented soil salt composition and salinization trends. Ultimately, under the conditions of this study, the most favorable groundwater depth for the growth of summer maize was determined to be 1.1 m. Analyzing the impact of different shallow groundwater depths on the physicochemical properties of farmland soil enhances our understanding of the mechanisms of interaction between groundwater and soil in agricultural ecosystems. This knowledge is instrumental in significantly improving the soil environment, thereby ensuring optimal crop yields. [ABSTRACT FROM AUTHOR]

The impacts of heavy metal pollution in arable soil on agricultural production, environmental health, and the wellbeing of urban and rural residents cannot be overlooked. It has become a significant bottleneck in achieving comprehensive rural revitalization. To accurately grasp the characteristics of heavy metal pollution in suburban cultivated soil, Tangwang Village (a suburb of Huainan City) was subjected to scrutiny. The contents of heavy metals (Hg, Cu, Hg, As, Pb, Cr, Cd, and Zn) in the topsoil of cultivated land in this area were detected, and their spatial distribution characteristics were analyzed using inverse distance spatial interpolation. (1) After conducting a comprehensive analysis and thorough examination of the PMF model sources, it was determined that Cu, Cd, and Zn exhibit a direct correlation with agricultural practices, collectively contributing to a cumulative percentage of 21.10%. Meanwhile, Cr is derived from a combination of sources, including both natural parent materials and human activities, accounting for a total proportion of 24.45%. Notably, lead emissions from automobile exhausts constitute a significant source, while arsenic is primarily associated with dispersed factories and their respective operations, contributing to respective proportions of 36.38% and 18.07%. It is evident that agricultural practices, transportation, and industrial activities are the main reasons for heavy metal pollution in arable soil. (2) The evaluation of geological accumulation indicators reveals that the level of soil arsenic accumulation pollution is mild to moderate (1.199). On the other hand, the cumulative pollution level of Cd, Hg, Cr, and Cu was relatively low (0.462→0.186), whereas the levels of Pb and Zn were below the threshold. (3) The assessment of the ecological risk index revealed that the predominant elements posing potential ecological risks in the investigated region were Hg, As, and Cd, with average Ei values of E(Hg) = 86.81, E(As) = 80.67, and E(Cd) = 67.83, respectively. (4) The human health risk assessment revealed significant differences in the single non-carcinogenic risk values of heavy metals generated by different exposure pathways, with oral ingestion > dermal contact > oral nasal inhalation. Children were more susceptible to the toxic effects of heavy metals compared to adults. Both As and Cr caused an increased risk of cancer in both children and adults, which is a matter of great concern. The results of this study contribute to a more accurate description of the sources of heavy metals in farmland soil. This study indicates that the application of PMF for soil source analysis yields clear results that can be further applied. This research also has potential policy significance as it can help to improve the sustainability of ecosystems by coordinating both environmental and human activities. [ABSTRACT FROM AUTHOR]

To investigate the heavy metals (HMs) contamination of surface farmland soil along the river in the southeast of a mining area in southwest China and identify the contamination sources, 54 topsoil samples were collected and the concentrations of seven elements (Zn, Ni, Pb, Cu, Hg, Cr, and Co) were determined by inductively coupled plasma optical emission spectrometry (ICP-OES) and atomic fluorescence spectrometry (AFS). The geo-accumulation index ( I geo ) and comprehensive potential ecological risk index ( RI ) were used for analysis to determine the pollution degree of HMs and the risk level of the study area. Meanwhile, the Positive Matrix Factorization (PMF) model was combined with a variety of statistical methods to determine the sources of HMs. To explore the influence of the river flowing through the mining area on the concentrations of HMs in the farmland soil, 15 water samples were collected and the concentrations of the above seven elements were determined. The results showed that the concentrations of Pb, Cu, and Zn in soil all exceeded the risk screening value, and Pb in soil of some sampling sites exceeded control value of "Agricultural Land Soil Pollution Risk Control Standard". I geo showed that Pb was heavily contaminated, while Cu and Zn were moderately contaminated. RI showed that the study area was at moderate risk. PMF and various statistical methods showed that the main source of HMs was the industrial source. In the short term, the river flowing through the mine has no significant influence on the concentration of HMs in the soil. The results provide a reference for the local government to control contamination and identify the sources of HMs. [ABSTRACT FROM AUTHOR]

Heavy metals (HMs) in agricultural land have caused serious environmental problems, resulting in severe contamination of the food chain and posing potential health threats. This study aims to investigate the pollution levels and potential ecological risks of HMs in farmland soils in central China, taking into account atmospheric deposition. Several indices were used to assess the status of HMs and compare surface soil with deeper soil. Descriptive statistics, Pearson correlation, and UMAP clustering methods were utilized to identify the characteristics of HMs. Additionally, stepwise linear regression models were employed to quantify the contributions of different variables to the potential ecological risks of HMs. The results showed that the average content of Zn in surface soil (289.41 ± 87.72 mg/kg) was higher than in the deeper soil (207.62 ± 37.81 mg/kg), and similar differences were observed in the mean values of related Igeo (1.622 ± 0.453 in surface soil and 1.183 ± 0.259 in deeper soil) and PEI (0.965 ± 0.292 in surface soil and 0.692 ± 0.126 in deeper soil) indices. This indicates that surface soil is more heavily polluted. The UMAP results confirmed the high variability of HMs in the surface soil, while PCA results suggested the importance of pollution and ecological risk indices. The stepwise linear model revealed that different variable structures contribute differently to the risk. In conclusion, Cr and Zn were found to be the major contaminants in the local farmland soil, with higher concentrations in the surface soil. The geoaccumulation and total potential ecological risk were classified as low risk. High variability of HMs was observed in the surface soil. Therefore, HM-related pollution indices and ecological risk indices are important for assessing the contamination status of local HMs. The local potential ecological risk can be attributed to specific heavy metals, each of which can have different effects on the local ecological risk. [ABSTRACT FROM AUTHOR]

Microplastics are an emerging and persistent form of environmental contaminants, and they have been detected in a variety of environments. Most researchers have focused on microplastics in marine environments, but there are relatively fewer studies on farmland soil ecosystems. Therefore, the aim of this study was to investigate feasible and effective methods for the identification and quantification of microplastics in farmland soil using pyrolysis-gas chromatography mass spectrometry (Pyr-GC-MS). In this work, we report on the application of density flotation, filter membranes, and digestion for effective separation and preconcentration of microplastics in soil samples. Subsequently, we optimised the density separation approach according to the number of flotations and the density of the flotation solution. The results showed that flotation twice with NaCl solution and once with ZnCl2 solution achieved a high recovery rate of microplastics at the lowest cost. A recovery percentage of 77.30–94.87% was achieved. The precision of the recovery expressed as the relative standard deviation (RSD) of the peak area was 5.05% for polyethylene (PE) microplastics, 1.71% for polypropylene (PP) microplastics, and 0.78% for polystyrene (PS) microplastics. The above data indicated that the proposed method showed excellent reproducibility and high sensitivity. Among the samples, the main component was PE (60%), followed by PP (20%) and PS (20%). The average concentrations of PE, PP, and PS microplastics in the soil were 685.55, 1069.98, and 864.23 μg/g, respectively. Based on these results, we conclude that our method has the potential for application in routine analyses. [ABSTRACT FROM AUTHOR]

[Objective] The aims of this study are to evaluate the effects of fallow on soil nutrients in farmland, clarify the suitability of fallow patterns, and provide a scientific basis for developing appropriate land management measures and improving the quality of soils in this area. [Methods] Based on the fallow trial data of three consecutive years from 2017 to 2019, seven soil nutrient indexes, including soil organic matter（SOM）, total nitrogen（TN）, available phosphorus（AP）, available potassium（AK）, pH value, exchangeable calcium and exchangeable magnesium, were selected to compare the changes in soil nutrients before and after the implementation of the fallow mode of green manure cultivation and the differences in soil nutrients between fallow and non-fallow controls（potato-corn-potato rotation） by using farmland in the dryland farming area of central Gansu as the research object. [Results]（1） Compared with the basic nutrients before fallow, the contents of SOM, TN and AK showed the increasing trend after three years of fallow, increasing by 19.5%, 23.0% and 9.2%, respectively, in which there were significant differences（p＜0.05） in the contents of SOM and TN before and after fallow, except for AK; AP, pH value, and exchangeable calcium and magnesium significantly decreased by 21.8%, 1.0%, 36.5% and 39.6%, respectively（p＜0.05）.（2） Compared with the non-fallow control, the contents of SOM, TN and AK were 3.5%, 11.0% and 8.5% higher than those in the control area, respectively. AP and exchangeable calcium were lower than those in the control area. However, there were significant differences only in the contents of TN and exchangeable calcium（p＜0.05）.（3） There was a significant logarithmic relationship between the rate of change of AP and its basic content（p＜0.001）, and a significant negative linear function between the rate of change of SOM, TN, AK and pH value and their basic content（p＜0.01）. In other words, the effect of fallow on change of soil nutrients decreased with the increase of its basic nutrients, but this relationship was not significant for exchangeable calcium and exchangeable magnesium.（4） After three years of fallowing, there were remarkable positive correlations among SOM, TN, AK and AP（r＞0.38, p＜0.05）. The pH value was significantly negatively correlated with other soil nutrient indexes except exchangeable magnesium（p＜0.01）. The correlation of soil nutrient indexes in the fallow area was higher than that in the control area. [Conclusion] The fallow mode of green manure planting can improve the quality of cultivated land in the dryland farming area of central Gansu to some extent, and it is more effective for soils with low basic nutrients. However, the three-year fallow is less effective than the potato-maize crop-potato rotations, indicating that the improvement effect of fallow on soil is still limited in a relatively short time scale. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences 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.)

Copyright of Journal of Shenyang Agricultural University is the property of Journal of Shenyang Agricultural University Editorial Department 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.)

Manure application is the primary input route for antibiotic resistance genes (ARGs) in farmland soil. This study investigated the effects of varying the rates of five chicken manure applications on the accumulation and distribution of ARGs across different soil depths (0–20, 20–40, and 40–60 cm) using metagenomic sequencing. The results revealed that the distribution of ARGs in farmland soil was closely linked to soil depth and influenced to some extent by the fertilizer quantity after 30 days of fertilization. ARGs were predominantly concentrated in the surface soil and exhibited a significant decrease in type and abundance with an increased soil depth. Compared with soil treated with chemical fertilizers alone, chicken manure-treated surface soil presented a higher diversity and abundance of ARGs. However, the diversity and abundance of ARGs did not increase proportionally with the increasing ratios of chicken manure application (0, 25, 50, 75, and 100%). ARGs in soil primarily conferred resistance to host bacteria through antibiotic efflux pumps (~33%), antibiotic target alteration (~31%), antibiotic inactivation (~20%), and antibiotic target protection (~8%). Correlation analysis involving ARGs and soil microorganisms revealed widespread multidrug resistance among soil microorganisms. Furthermore, two genera of human pathogenic bacteria (Pseudomonas sp. and Listeria sp.) were identified as potential microbial hosts of ARGs in all treatments. Correlation analysis involving ARGs and environmental factors indicated that soil ARGs are predominantly influenced by heavy metals and microorganisms. This paper offers valuable insights for environmental risk assessments regarding the utilization of livestock manure resources. Additionally, it furnishes a scientific foundation for farmland application strategies pertaining to livestock manure.

The spatial characteristics, pollution sources, and risks of soil heavy metals were analyzed on Hainan Island. The results showed that the heavily polluted points accounted for 0.56%, and the number of mildly and above polluted points accounted for 15.27%, respectively, which were mainly distributed in the northern part of the study area. The principal component analysis–absolute principal component score–multiple linear regression (APCS-MLR) and the positive matrix factorization (PMF) revealed four sources of heavy metals: agricultural pollution sources for cadmium, (Cd), industrial and mining pollution sources for arsenic, (As), transportation pollution sources for zinc and lead (Zn and Pb), and natural pollution sources for chromium, nickel, and copper (Cr, Ni, and Cu). The human health risk assessment indicated that the average non-carcinogenic risk (HI) for both adults and children was within the safe threshold (1, indicating a potential health risk above the safe threshold. Meanwhile, nearly 100% and 99.94% of the TCR values exceeded 1 × 10−4 for children and adults, indicating that Cr and Ni are priority heavy metals for control. The research results provide the necessary scientific basis for the prevention and control of heavy metals in agricultural soils.

Introduction: Lead (Pb) pollution in agricultural soil has been accelerated by industrial development and human activities, and poses a major threat to agricultural ecosystems. Both biochar and arbuscular mycorrhiza (AM) fungi are considered to play an important role in remediation of Pb contaminated soil. Methods: The combined remediation effects of introduced AM fungi and biochar on soil properties, Pb availability, microbial community and functional profiles were systematically investigated in unsterilized Pb-polluted agricultural soil. Results: Results indicated that soil nutrients were significantly improved through the combined application of biochar and introduced AM fungi. The introduced AM fungi combined with biochar prepared at 400°C and 500°C promoted the transformation of Pb to a more stable state with low bioavailability. Moreover, the addition of AM fungi and biochar affected the relative abundances of dominant bacteria and fungi at the phylum and genus levels. Biochar mainly affected soil bacterial community and obviously increased the relative abundance of Actinobacteria and Blastococcus. The interactions between biochar and introduced AM fungi mainly affected fungal community, and increased the abundance of Ascomycota and Botryotrichum. Further, PICRUSt analysis indicated biochar amendment supported stronger bacterial metabolic functional potentials. Discussion: Therefore, the combined application of biochar and Therefore, the combined application of biochar and introduced AM fungi could improve soil nutrients, reduce Pb introduced AM fungi could improve soil nutrients, reduce Pb availability, availability, and show and show a positive effect on a positive effect on indigenous microbial communities and indigenous microbial communities and metabolic functions in metabolic functions in farmland soil. [ABSTRACT FROM AUTHOR]

[Objective] To understand the heavy metal pollution of typical farmland soil in a certain area of Yunnan Province. [Method]The contents of heavy metals such as Cd, As, Pb, Cu, Zn, Cr and Hg in typical heavy metal contaminated farmland soils in a certain area of Yunnan Province were investigated; the principal component analysis, correlation analysis, individual pollution index, Nemerow comprehensive pollution index and potential ecological hazard index were used in combination with GIS interpolation to evaluate the status, sources and potential risks of heavy metal pollution in soils. [Result] The contents of Cd, As, Cu, Zn and Hg in the farmland soil of the study area were higher than the soil background values of Yunnan Province, and the contents of Cd, As and Cu at different depths were higher than the risk screening values in the Agricultural Land Pollution Risk Control Standard for Soil Environmental Quality (Trial Implementation) (GB 15618-2018). The contents of Cd, As, Cu and Zn in some surface soil samples exceeded the national standard, and the exceeding rate of heavy metals was in the order of Cu >Cd>As>Zn>Pb =Cr =Hg. The spatial distributions of Cd, Pb and Cr in the surface soil of the study area were similar, and their content distributions showed that the contents of these metals gradually decreased from east to west in the study area. The high values of As and Zn were mainly distributed in the southwest of the study area, the spatial distribution of Cu content was high in the northwest and low in the southeast, while Hg was unevenly distributed in the soil. The results of single pollution index and Nemerow comprehensive pollution index showed that farmland soil was polluted by Cd, As and Cu, Cu pollution was the most serious and the overall level of heavy metals in the study area was in the moderate degree. Potential ecological risk assessment indicated that Cd was the main ecological risk factor, with medium ecological risk as the main hazard, and the heavy metal pollution in local soil was at a mild potential ecological hazard degree. The principal component analysis and correlation analysis showed that Pb and Cr were mainly from parent materials. Cd and some Pb and Cr might come from sewage irrigation, As and Zn might be related to industrial waste gas emission, Cu might come from organic fertilizer, and Hg might be caused by atmospheric deposition of heavy metal dust. [Conclusion] There existed heavy metal pollution in typical farmland soils in a certain area of Yunnan Province, where Cu was the most seriously polluted, but Cd was the most harmful. [ABSTRACT FROM AUTHOR]

Soil organic matter (SOM) plays a critical role in terrestrial ecosystem functioning and is closely related to many global issues like soil fertility, soil health and climate regulation. Therefore, obtaining accurate information on the spatial distribution of SOM and its potential controlling factors is of global interest. However, this remains a great challenge since SOM is affected by numerous natural and anthropogenic factors and usually showed strong heterogeneity. In this study, we collected a total of 16,580 surface soil (0–20 cm) samples from the farmland throughout Jiangxi Province. And the Random Forest (RF), Cubist and gradient‐boosted models were compared and used to define the factor which is most associated with SOM. Then the ordinary kriging (OK) and machine learning‐ordinary co‐kriging (ML‐COK) were used to map SOM. We found that on average, 30.86 g kg−1 SOM was present in farmland soil of Jiangxi Province. Anthropogenic activities strongly affected SOM level, with five of the top 10 most important factors are anthropogenic related. The straw return amount was proved to have the largest importance (31.46%) for modelling SOM and a significant (p < 0.001) positive relationship between SOM content and the amount of straw returned to farmland was detected. Additionally, returning straw improved crop production. Soil derived from the Quaternary Subred Sand has the highest SOM content (37.82 g kg−1). Crop rotation also improved SOM content and the rice‐bean rotation system has the highest SOM content (34.27 g kg−1). With the best performance, the RF algorithm (R2 = 0.49, RMSE = 6.77 g kg−1) was selected to identify the primary control of SOM and integrated with COK, which we termed as ML‐COK, to map the SOM in the farmland of Jiangxi Province. ML‐COK outperformed OK method for mapping the SOM in farmland of Jiangxi Province with R2 of 0.351 and Lin's concordance correlation coefficient of 0.549. Farmland distributed in the central part of the province had high SOM content. In contrast, farmland in the north, south and east parts had relatively low SOM. Our study offers new insight for mapping soil properties, identifying potential factors driving variation in SOM, and also provides valuable information for making more reasonable and environmentally friendly farmland management measures. [ABSTRACT FROM AUTHOR]

Plastic pollution in farmland soil has become a significant concern for scientists studying farmland ecosystems. However, the current research focus on the environmental impacts of plastics in soil overlooks crucial factors such as sources, distribution, and persistence. In this study, we examined the distribution of residual film after eight years of film mulching in mid-April 2018. We also assessed changes in spatial distribution from 2018 to 2020. Our findings reveal that eight years of film mulching significantly increased the quantity of agricultural mulch film residues in the soil. The size of residual film fragments varied from 0.25 cm2 to 109 cm2, and the average size, number, and quantity of residues were influenced by soil depth. There was a noticeable downward trend in the quantity of agricultural mulch film residues, decreasing annually by 0.525 kg·ha−1. In contrast, the number of residual films showed an average annual growth rate of 2.13 × 105 p·ha−1. Importantly, we observed a substantial accumulation of residual film fragments below the 10 cm soil layer over time. Fragments ranging from 1–5 cm2 were the most abundant and gradually accumulated in deeper soil layers, enhancing mulching film recovery efficiency. This study provides valuable insights into the influence of mulch cycles on farmland soil profiles, identifying the key locations and size-to-shape ratios of residual films. These findings serve as a theoretical foundation for implementing effective measures to control mulch film pollution in agricultural practices. [ABSTRACT FROM AUTHOR]

Copyright of Asian Journals of Ecotoxicology is the property of Gai Kan Bian Wei Hui 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.)

The environmental risk posed by heavy metals in agricultural soil is primarily influenced by their sources, bioavailability, and geochemical transfer behavior. This study focused on Weining County, a region in Guizhou province, Southwest China, with a high geological background and long-term impact from artisanal Zn smelting. Vertical soil profiles, crop, and rhizospheric soil samples were collected and analyzed for heavy metal concentration (As, Cd, Co, Cr, Cu, Hg, Ni, Pb, V, and Zn) including the total concentration and chemical fraction. The results revealed elevated concentrations of Cd (range: 0.7–6.9 mg·kg−1), Co (range: 19.3–120.0 mg·kg−1), Cu (range: 71.6–386.0 mg·kg−1), Ni (range: 51.0–121.0 mg·kg−1), and V (range: 310.0–721.0 mg·kg−1) in all soil samples compared to the background values of Guizhou Province. Chemical fractionation analysis indicated that Cr, Ni, As, Cu, and Zn were predominantly present in the residual fraction, while Hg and Pb were predominantly found in the potentially bioavailable fraction. Cd exhibited the highest bioavailability, accounting for 58.5% of its total concentration. Enrichment factor analysis suggested that artisanal Zn smelting activities were the main sources of Cd, Pb, and Zn contamination. Furthermore, Cd, Pb, and Zn were found to be highly accumulated in the surface soil layer (0–20 cm). Notably, 90.0% of potato and 9.4% of maize grain samples exceeded the food hygiene standards for Cd concentration, posing potential health risks to consumers. The bioconcentration factor (soil-to-root) and translocation factor (root-to-grain) analyses indicated that maize roots had a higher tendency to accumulate Cd from the soil, while Zn and Cu showed a significant transferability from roots to maize grains. These findings offer valuable insights for devising heavy metal remediation strategies in similar areas. [ABSTRACT FROM AUTHOR]

Heavy metal (HM) contamination of agro-ecosystems has raised great attention across the world due to the rapid development of industrialization and urbanization. Importantly, HMs have been consistently entering the food webs, imposing great risks on public health. However, previous studies have focused more on large-scale areas. Exemplarily, some typical areas (e.g., riverside farmlands) receive insufficient attention, but they may have a higher ecological risk. In this study, we used a series of indices to evaluate risks, including single factor index, Nemerow index, geological accumulation index, potential ecological risk index, risk assessment code, etc. Based on the field investigation, we systematically analyzed the pollution characteristics and ecological risks of five HMs (i.e., Pb, Cu, Zn, Cr, and Ni) in the typical vegetable soil and its irrigation sediment in Xijiang River Basin, Guangdong, China. The results indicate that the pH values of the soil and sediment are mainly neutral or slightly acidic. Moreover, large-scale natural sources may have the effect on the soil and sediment, among which storm runoff and scouring of the river may be main natural factors of HM activation. And importantly, there was a migration cycle (with the in-out trait) for the main non-residual forms of HMs between riverside soil and sediment. According to the principal component analysis (PCA), HMs may be mainly affected by anthropogenic sources. Specifically, PC1 may be related to transportation and agricultural machineries, and PC2 may be related to pesticides and fertilizers. Also, according to risk assessment code and the ration of secondary phase to primary phase, these meant high proportion of the bio-available forms of HMs. Conversely, Pearson correlation coefficient between bioavailable metal index and the sum of toxic unit was not high, which was related to low contents of the bio-available HMs. And though, these indices may show great differences due to different method focuses, an important suggestion is that integrating all the methods can receive more comprehensive results of ecological risks. According to the bioavailable metal index, the bio-availability of HMs decreases in the following order: river sediment (3.69 ± 1.24) > riverside farmland soil (2.28 ± 0.61) > inside-dyke farmland soil (2.26 ± 1.24) > reservoir sediment (1.99 ± 0.18). Besides, comprehensive evaluation indicates that Cu and Zn pose the greater environmental risks as they have the highest effective content, bioavailability, and mobility. Thus, developing high-tech environmental monitoring, properly purifing irrigation water, and improving the drainage systems are a necessity for these HMs. [ABSTRACT FROM AUTHOR]

Farmland soil quality is a crucial determinant for agricultural productivity, food safety, and human well-being. Among the various contaminants, heavy metals have emerged as pervasive factors significantly impacting farmland quality, attracting widespread societal concern. In this study, we systematically applied multivariate statistical analysis, geostatistical methods, and the positive matrix factorization (PMF) source apportionment technique to elucidate the sources and contributions of eight heavy metals (Cd, Hg, As, Pb, Cr, Cu, Zn, Ni) in farmland soils within an industrialized town. Our findings reveal that Cd, Hg, Pb, and Zn exhibit pollution or enrichment in farmland soils compared to natural background levels, with Hg and Cd surpassing 164.3% and 50.2%, respectively. Notably, Zn demonstrates discernible point-source pollution. Source apportionment results highlight industrial point sources, coal combustion, and agriculture as the primary anthropogenic contributors to heavy metal contamination, with zinc-plating enterprises being the predominant industrial point sources. Addressing the specific issue of point-source pollution from Zn in industrial activities, further analysis establishes a correlation between soil Zn content and the distance from zinc-plating enterprises. Utilizing an atmospheric transport model, we observe that the impact of industrial activities on soil Zn is limited when the distance exceeds 1.5 km, emphasizing the importance of monitoring Zn pollution within areas less than 1.5 km. This study pioneers a progressive source apportionment approach, considering the origins of different heavy metals, pollution levels, distance factors, and the cost-effectiveness of environmental measures. The insights gained provide scientifically sound strategies for future decision making in environmental protection.

Soil nitrogen (N) transformation is vital in determining farmland N availability. Although many studies have investigated the effect of biochar on N retention and loss via leaching and gaseous emissions, few have determined the dynamics of gross N transformation during crop growth in long‐term biochar‐amended soils and compared the effect of the biochar with that of its feedstock. In this study, we conducted a five‐time field measurement of soil gross N turnover rates via 15N isotope pool dilution during maize growth in 2021. Three treatments were employed, including no amendment, biochar and straw applied annually at rates of 2.63 and 7.50 t ha−1, respectively, since 2013. The results showed that biochar did not change the rate of gross N mineralisation when compared with no amendment, but straw increased it by 139% in August, resulting in significantly higher cumulative gross N mineralisation than biochar and no amendment (701 vs 489 and 499 mg kg−1 in 200 d). The inconsistent influence was attributed to the fact that inherent biochar‐N was recalcitrant and could not be mineralized like the straw. The gross nitrification rate was decreased by 72.9% and 77.4% by biochar and straw application, respectively, in June relative to no amendment, but then it increased from July to August in the straw treatment as a result of the elevated gross N mineralisation rate. The decreased nitrification in the biochar treatment was an outcome of the synergetic effect of a low ammonium pool (−59.4%) and a high gross ammonium immobilisation rate (+263%), which was likely due to excessive fertilizer N loss and abiotic adsorption to biochar. Meanwhile, biochar amendment inhibited bacterial 16S and fungal ITS genes, as well as ureC and bacterial and archaea‐amoA gene copies. In conclusion, straw is more effective than biochar at improving soil N transformation and availability in the long term. [ABSTRACT FROM AUTHOR]

Converting biowaste into biochar and incorporating it into soil is recognized as an effective method for carbon (C) sequestration. However, biochar inevitably undergoes an aging process in soil, which influences its stability, and ultimately threatens its carbon sequestration ability. This study selected CaCl2 as an exogenous additive of sewage sludge and bone dreg for producing Ca-rich biochars, and both surface C and bulk C stability in them were investigated under three aging processes (dry–wet aging, freeze–thaw aging, and natural aging in farmland soil). The results showed that the above three aging processes resulted in oxidized surface C in Ca-rich biochar decreasing by 10~23%, 28~41%, and 0~74%, respectively, compared with that in pristine biochar, while oxidized bulk C decreased by 6~10%, 0~1%, and 0~35%, respectively. This was attributed to the "protective effect" of Ca-containing crystals on the biochar surface, including CaO, Ca5(PO4)3Cl, Ca5(PO4)3(OH), Ca8H2(PO4)6·H2O, and Ca10(PO4)6(OH)2, which intervened in the oxidation of C–C/C=C in biochar but also reduced the generation of a fragmented C structure. By comprehensively assessing surface C and bulk C stability under three aging processes, final C sequestration in Ca-rich biochar increased to 27~80%, compared to that in pristine biochar (23~74%). Therefore, Ca-rich biochar is more dominant than pristine biochar, considering C sequestration potential during long-term aging in soil. [ABSTRACT FROM AUTHOR]

Human exposure to ionizing radiation in the environment is mainly due to naturally occurring radionuclides in the soils, building materials and rocks, but the level may vary depending on the anthropogenic activities prevalent in each location. Presently, in Nigeria, there are concerns due to environmental health implications of all sorts of mineral mining and processing spreading across the southwestern states of the country. This work determines the activity concentrations of naturally occurring radionuclide materials (NORMs) in the farmland soil with the aim of evaluating the radiation hazards. A total of 200 composite soil samples were taken from five states in the southwest of Nigeria, close to active mining sites at the root (0.2 m) and at deep planting zones (0.5 m) for analysis by gamma-ray spectrometry using NaI(Tl) detector. The activity concentrations of natural radionuclides in the composite soil samples were determined to vary in the order of 40 K > 232Th > 226Ra/238U for all locations. In contrast to the other locations, Olode and Igbokoda had average radium equivalent activities (Raeq) to be 1.6 and 1.8 times, respectively, higher than the reference limit of 370 Bqkg−1. The estimated excess life cancer risk values were lower than the 0.29 × 10−3 global average value for soil by United Nations on Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and International Commission on Radiological Protection (ICRP). Negative and low skewness values of 0.61 and 1.20 were obtained for 40 K in Itagunmodi, and also 0.47 and 0.66 for 232Th were obtained in Sagamu. The kurtosis analysis of the activity concentrations was low and negative for soil at Itagunmodi for 40 K and 226Ra/238U; Olode for 40 K and 232Th; and Igbokoda for 226Ra/238U and 232Th where mining activities are commonly practiced. The variation in the results has been attributed to different agriculture practices and artisanal mining operations in each location. [ABSTRACT FROM AUTHOR]

BACKGROUND As the significant factor of the accumulation of heavy metals in farmland soils, mineral activities such as mining, traffic and mineral processing and smelting allow heavy metals to spread into the surrounding environment by water or atmospheric deposition, and finally collected into the soil, causing heavy metal pollution in the surrounding farmland soil. Heavy metals pollution in soils especially in farmland soils around the mining area thus has received great attention in the field of environmental pollution. Located in the middle reaches of the Yellow River watershed, the gold mining area in western Henan is an extremely important gold deposit area with great prospecting potential in China for the strong late Yanshan acidic magmatic activity and the extremely favorable metallogenic geological conditions, in which more than 40 large, medium or small gold deposits have been discovered. Under the background of ecological protection and high-quality development in the Yellow River watershed, the western Henan gold mining area, with a long history of gold mining development, lacks more attention to the accumulation, spatial distribution and ecological risk of heavy metals in farmland soil around the mining area during the years of mining, beneficiation and processing. It is particularly necessary to study the heavy metal pollution in soil, find out the impact of mining activities on heavy metals in surrounding farmland soil, and provide a scientific basis for prevention and control of heavy metal pollution in farmland soil. OBJECTIVES To clearly understand the impact of mining activities in the western Henan mining area on heavy metals in the surrounding farmland soil, provide necessary basic data for supporting the safe production of key mineral resources, the surrounding agricultural safety, and prevent and control heavy metal pollution in farmland soil. METHODS 375 topsoil samples from the farmland around the western Henan gold mining area at a depth of 0-20cm were systematically investigated and analyzed with reference to Code of Practice for Soil Geochemical Survey (DZ/T 0145—2017). The contents and spatial distribution characteristics of Cd, Cu, Zn, Pb, Hg, As, Cr, Ni were analyzed. The heavy metal pollution and ecological risk were evaluated by the geo-accumulation index method and potential ecological risk index method. RESULTS (1) The contents variation range of Cu, Pb, Zn, Ni, As, Hg, Cd, Cr are 1.00-71.72, 2.00-524.79, 8.00-320.37, 2.00-52.77, 2.29-24.64, 0.0067-0.268, 0.04-1.30, 28.20-107.93, respectively, and the average are 35.33, 74.43, 137.69, 31.60, 12.39, 0.064, 0.43, 76.27, respectively, showing significant differences between the 8 heavy metals. Compared with the soil background value in the middle reaches of the Yellow River, the average contents of Cu, Pb, Zn, Ni, As, Hg, Cd, Cr are 1.47, 3.24, 2.06, 1.05, 1.03, 1.52, 2.77 and 1.07 times of them, respectively, but lower than the value of risk screening values for soil contamination of agricultural land.(2) The characteristics of coefficients of variation show that Pb(90.72%)>Hg(85.25%)>Cd(65.65%)>Zn(44.0%)>Cu(33.66%)>As(31.72%)>Ni(24.23%)>Cr(13.61%), the Pb, Hg, Cd are the primary factors causing the soil pollution as the external input by mineral activities for the high coefficients of variation and special relation with mining. The main ore-forming elements in the gold deposit area are Au and Mo, and the associated elements are Cu, Pb, Zn, Ni, As, Hg, Cd, which may diffuse into the surrounding environment during ore transportation, waste rock and slag piling along the river, and processing. Alongside the Daping River, the two gold mining areas and concentrators are distributed around the farmland, and the gold ore heap leaching site on the east side is located at the top of the hillside and hill. The heavy metals produced by mining activities can diffuse in the downstream agricultural areas through atmospheric deposition, rainwater leaching, river drainage, and can accumulate in the surrounding agricultural soil, causing heavy metal pollution in the agricultural soil around the mining area.(3) The geo-accumulation index of 8 heavy metals is -0.1, 0.74, 0.33, -0.56, -0.60, -0.29, 0.62, -0.49 with the order Pb>Cd>Zn>Cu>Hg>Cr>Ni>As, in which Cu, Hg, Cr, Ni, As show no influence to the quality of soils for the average geo-accumulation index lower than 0, and Pb, Cd, Zn show moderate pollution for the average geo-accumulation index between 0-1. Among them, the proportion of samples with a Cd element of medium or higher impact grade is 20.27%, the proportion of samples with medium to strong impact grade is 7.73%, and the proportion of samples with strong impact grade is 1.07%. The proportion of samples with a Pb element above the moderate impact level is 18.93%, and the proportion of samples with moderate to strong impact level is 10.40%. Hg and Zn also have 7.46% and 13.33% of the samples reaching the moderate impact level, indicating that Hg, Cd and Pb in the soil at local sampling sites have different degrees of impact on farmland soil quality.(4) The average value of the single-factor potential ecological risk index of eight heavy metals is between 2.06 and 83.62, among which the single-factor potential ecological risk index of As, Cr, Ni, Cu and Zn is a slight potential ecological risk. Pb is mainly subject to slight potential ecological risks for 92% of samples, moderate potential ecological risks for 7.47% of samples and strong potential ecological risks for 0.53% of samples. Cd is dominated by moderate potential ecological risks, with 46.14% of samples, and there are 25.33% and 10.93% of samples reaching strong and very strong potential ecological risks respectively. For the ecological risk index of Hg, there are 35.47%, 11.46%, 4.27% and 3.20% of the samples that reach moderate, strong, very strong and very strong degree. The comprehensive potential ecological risk index (RI) ranges from 51.66 to 689.64, with an average of 192.07. The proportion of samples with slight, moderate, strong and very strong impact degree is 46.40%, 41.07%, 11.20% and 1.33%, respectively. The overall comprehensive potential ecological risk index shows moderate potential ecological risks. CONCLUSIONS Compared with the risk screening values for soil contamination of agricultural land, the contents of Cd, Cu, Zn, Pb, Cr, Ni, As, Hg are all lower than the standard, indicating low risk for the soil environment. There were different degrees of accumulation surrounding the intense mining area of Cd, Pb, and Zn by longtime mineral development. Cu, Ni, As, Hg, and Cr were influenced by the natural factor. The farmland area with strong and very strong comprehensive potential ecological risks is 349.4 hectares and 11.71 hectares, respectively. Cd and Hg are the main contributing elements, with higher risk to the soil ecology, which should be monitored and controlled from source to avoid the further accumulation of heavy metal elements in the soil.

To explore the short-term impact of uranium pollution on the microecology of farmland soil, this study investigated the activities of four enzymes involved in key soil processes (β-glucosidase, urease, phosphatase, and arylsulfatase) and analyzed the changes in microbial metabolic activity, carbon utilization capacity, and diversity using Biolog EcoPlate under short-term (3 d, 13 d, and 20 d) uranium treatments (0 mg/kg, 50 mg/kg, 200 mg/kg, and 500 mg/kg). The results showed that the activities of the three soil enzymes, except that of urease, were inhibited by uranium pollution, especially phosphatase activity, which was reduced by 75.9% in the 20-day U500 treatment group. In addition, microbial metabolic activity was inhibited by uranium pollution. However, the inhibition effect showed a downward trend with the extension of the treatment time. The carbon metabolism capacity of microorganisms was inhibited. By contrast, the ability of microorganisms to utilize amino acids, carbohydrates, and polymer carbon sources was positively correlated with time in the U50 treatment group. The results of diversity indices analysis and sho principal component analysis wed little effect on the microbial diversity of uranium contamination. Therefore, uranium pollution inhibited the metabolic activities of farmland soil microorganisms, especially the carbon, phosphorus, and sulfur cycles. This study provides a direction for the ecological restoration of farmland soil uranium pollution.

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board 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.)

Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment Editorial Office 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.)

The dissolved organic matter (DOM) is one of the most sensitive indicators of changes in the soil environment, and it is the most mobile and active soil component that serves as an easily available source of nutrients and energy for microbes and other living organisms. In this paper, DOM structural characteristics and main properties were investigated by three-dimensional fluorescence spectroscopy (EEM) and UV–visible spectrum technology in the farmland soils around Urumqi of China, and its possible sources and pathways were analyzed by spectroscopic indices. The results showed that humic-like substances were the main composition of the soil DOM, and its autogenesis characteristics were not obvious. Main DOM properties such as aromatability, hydrophobicity, molecular weight, molecular size, and humification degree in the southern region of Urumqi were higher than those of the northern region of Urumqi and Fukang in China, and higher on the upper layers of the soil (0–0.1 and 0.2 m) than in the deeper layer (0.2–0.3 m).This may be because the tilled layer is more subjected to fertilization and conducive to microbial activities. The spectroscopic analysis showed that the source of DOM of these regions is mainly from microbial metabolites. These results provide basic scientific data for the further research on the environmental chemical behavior of pollutants and pollution control in this region. [ABSTRACT FROM AUTHOR]

Fomesafen, a long residual diphenyl ether herbicide, is widely used for control of annual and perennial broadleaf weeds in peanut and soybean fields. With the development of agricultural production mechanization in China, the application of fomesafen has been rising. Long-term and large-scale application leads to obvious residues in the soil. As a consequence, the resulting ecological and environmental problems need urgent attention from the agricultural and environmental protection departments. We systematically reviewed the research progress about the residual characteristics, ecotoxicological effects and abatement process of fomesafen in farmland soil, and proposed some prospects from the residual formation mechanisms, safe application limit standard, abatement mechanism and technology, aiming to provide some new insights and ideas for solving the problem of residual injury of fomesafen. [ABSTRACT FROM AUTHOR]