Agricultural Pollution Control Research Articles

Quantitative prediction of soil chromium content using laboratory-based visible and near-infrared spectroscopy with different ensemble learning models

Soil heavy metal chromium pollution poses significant threats to human health and ecosystems, necessitating accurate quantitative prediction methods for effective monitoring and management. This study aims to develop robust predictive models for soil chromium content in farmland soils of Mojiang Hani Autonomous County, Pu’er City, Yunnan Province, China. These models utilize ensemble learning techniques based on visible and near-infrared spectroscopy. Operations before model building involved partitioning datasets with the Kennard-Stone algorithm to ensure representative training and testing sets. Visible and near-infrared spectroscopy-data preprocessing was performed using Savitzky-Golay smoothing and first-order derivative transformations to enhance signal quality. Bands selection was achieved through the Successive Projections Algorithm (SPA), effectively reducing data dimensionality and collinearity. Six ensemble learning models were constructed and assessed for their predictive performance: Bagging-DTR, Random Forest (RF), Adaboost-DTR, XGBoost-DTR, Stacking-1, and Stacking-2. These models utilized Decision Trees (DTR) and Linear Regression (LR) as base learners. Results demonstrated that ensemble models significantly outperformed individual base learners. Notably, the Stacking-2 model achieved the highest accuracy with an R^2 of 0.954, RMSE of 125.967 mg/kg, and RPD of 4.667. To validate the model’s practical applicability, spatial interpolation of soil Cr content was conducted using the Kriging method based on Stacking-2 model predictions. The spatial distribution maps of measured and predicted values exhibited high congruence, underscoring the model’s effectiveness in accurately mapping Cr distribution across the study area. This study underscores the efficacy of integrating ensemble learning with visible and near-infrared spectroscopy-data preprocessing and SPA for precise soil heavy metal prediction. The findings offer valuable insights and a scientific basis for enhanced soil quality monitoring, environmental risk assessment, and informed agricultural land management and pollution control.

MOF-Enhanced Aluminosilicate Ceramic Membranes Using Non-Firing Processes for Pesticide Filtration and Phytochrome Removal.

Aluminosilicates, abundant and crucial in both natural environments and industry, often involve uncontrollable chemical components when derived from minerals, making further chemical purification and reaction more complicated. This study utilizes pure alumina and fumed silica powders as more controllable sources, enhancing aluminosilicate reactivity through room temperature (non-firing) processing and providing a robust framework that resists mechanical stress and high temperature. By embedding iron-based metal-organic frameworks (Fe-MOF/non-firing aluminosilicate membranes) within the above matrix, these ceramic membranes not only preserve their mechanical robustness but also gain significant chemical functionality, enhancing their capacity to removing phytochromes from the vegetables. Sodium hydroxide and sodium silicate were selected as activators to successfully prepare high-strength, non-firing aluminosilicate membranes. These membranes demonstrated a flexural strength of 8.7 MPa under wet-culture conditions with a molar ratio of Al2O3:SiO2:NaOH:Na2SiO3 at 1:1:0.49:0.16. The chlorophyll adsorption of spinach conducted on these membranes showed a removal rate exceeding 90% at room temperature and pH = 9, highlighting its potential for the selective adsorption of chlorophyll. This study underscores the potential of MOF-enhanced aluminosilicate ceramic membranes in environmental applications, particularly for agricultural pollution control.

Self-powered system based on triboelectric nanogenerator in agricultural groundwater pollution monitoring and control

Self-powered system based on triboelectric nanogenerator in agricultural groundwater pollution monitoring and control

Monetization of Ecosystem Services from Nature-Based Solutions for Agricultural Diffuse Pollution Control: Simplified Value Transfer Method at European Scale

When nature-based solutions (NBS) are developed with a primary scope, they also provide simultaneous additional economic, social, and environmental benefits, i.e., Ecosystem Services. A monetary assessment that accounts for these additional benefits is provided by this work, with a focus on Europe. Specifically, this is intended to evaluate nine identified benefits of those wetlands and buffer strips designed to primarily address agricultural diffuse pollution, which must surely be listed among the negative externalities of economic activities that NBS can help resolve. The aim of developing a simplified value transfer methodology for a rapid evaluation of NBS benefits with the adjusted unit Value Transfer method is to create an accessible solution when time, funding, or other constraints prevent the use of highly technical primary monetization approaches. The developed exercise allows us to gather insights from several primary valuation studies and to appropriately transfer the monetary valuation outcomes to new policy sites. In order to reduce the distance from the expected and required concrete achievements of the economic valuations, the study has been integrated with an case study located in the Venice lagoon catchment in Northwestern Italy. The results obtained are to be considered sound, with existing evidence showing that the most valuable benefits of the considered NBS are both water quality and recreation and tourism, to which is added, in the case of wetlands, water supply.

Experimental study on photodegradation and leaching of typical pesticides in greenhouse soil from Shouguang, Shandong Province, East China

BackgroundPesticide use contributes to national food security. The dissipation pathways and degradation mechanisms of pesticides have been widely studied and pesticide residues have remained a focus of public concern. However, studies on the migration and transformation behaviors of pesticide residues in real-world greenhouse soils are insufficient. Therefore, in this study, we collected greenhouse soil from Shouguang, Shandong Province, and investigated the photodegradation and leaching of 17 common pesticides, which leave residues in the soil and are the most frequently used pesticides in Shouguang. The environmental behavior of pesticides in greenhouse soils will provide new information on pesticide residues in the real environment and provide a scientific basis for the prevention and control of pesticide pollution in greenhouse soils.ResultsThe photodegradation of trifloxystrobin followed a first-order kinetic equation, whereas those of emamectin benzoate, chlorantraniliprole, buprofezin, difenoconazole, pyraclostrobin, boscalid, tebuconazole, isoprothiolane, metalaxyl, and oxadixyl followed second-order kinetics. The half-lives of 17 pesticides under light and dark conditions ranged from 2.5–104 (mean: 36.2) and 2.6–110 (mean: 31.4) days, respectively. The half-lives of emamectin benzoate, pyraclostrobin, and metalaxyl in the light were 86.6%, 68.5%, and 94.5% of their half-lives in the dark, respectively. Chlorantraniliprole, metalaxyl, nitenpyram, diethofencarb, acetamiprid, carbendazim, and oxadixyl were leached to ≥ 90% in aqueous solution. Six pesticides, avermectin B1A, emamectin benzoate, trifloxystrobin, difenoconazole, pyraclostrobin, and buprofezin, were difficult to leach from aqueous solutions.ConclusionsThe degradation rate of some pesticides was higher in the light environment than in the dark. The leaching potential of the leachable pesticides was nitenpyram ≫ metalaxyl > acetamiprid > carbendazim > diethofencarb ≈ chlorantraniliprole > isoprothiolane > oxadixyl > boscalid ≈ tebuconazole > hexaconazole. Pesticides that are easy to leach but not easily degraded, such as chlorantraniliprole and metalaxyl, have a high potential risk of groundwater pollution, and additional degradation technologies should be used to reduce their pollution risk. The study of the photodegradation and vertical migration behavior of various pesticides is conducive to providing references for the agricultural use and pollution control of pesticides.

Early warning of heavy metals contamination in agricultural soils: Spatio-temporal distribution and future trends in the Hexi Corridor

Conducting risk and early warning assessments of heavy metals (HMs) pollution in agricultural soils holds significant importance for pollution prevention and sustainable agricultural development. Early warning studies on heavy metal contamination of agricultural soils in oases in arid zones are rare in previous studies, therefore, this study carried out spatial and temporal simulation and early warning studies on the environmental capacity of agricultural soils in the Hexi Corridor based on field monitoring data and remote sensing technology and other methods. The results revealed that agricultural soils have been affected by human activities, leaving HMs at a moderate pollution level. The mean environmental capacity indices for Cr, Ni, Cu, Zn, As and Pb showed that they all belonged to the medium-capacity state, and 7.01 % of the sampling points being overloaded and in the low capacity for As. Cr, Ni, Zn and As were found in the moderate and high capacity zones located in the study area's western part, and the spatial distribution was basically the same. HMs in the middle parts area were dominated by low to medium capacity status, which may be related to agricultural activities such as application of fertilizers and pesticides and sewage irrigation. Based on the soil dynamic capacity model, it was found that in the next 20 years, HMs showed a decrease of 70–80 %, and the soil environment dynamic capacity was smaller than both the static and existing capacity, and it showed a decreasing trend with the change of time, which indicated that the soil's capacity for pollutants in the study area would be reduced if no pollution control measures were taken. Risk warning results showed that the overall spatial distribution pattern of the probability of pollution in the study area during the next 10 and 20 years was lower in the west and the northern part of Wuwei City, and higher in the middle part. This study suggests constructing a management system of “pollution evaluation - source treatment - risk early warning” for heavy metal contaminated sites, formulating corresponding policies and early warning measures, strengthening the research and development of monitoring, remediation, and treatment technologies, and realizing the prevention and control of agricultural soil pollution and sustainable development in the study area.

Research on the Performance Evaluation of Agricultural Non-point Source Pollution Prevention and Control in Anhui Province

Agricultural and rural pollution control is a key and difficult issue in the revitalization of rural ecology in China, and agricultural non-point source pollution, as the main source of pollution, is of the utmost importance. Building a performance audit system for agricultural non-point source pollution prevention and control is beneficial for measuring the degree of agricultural non-point source pollution prevention and control, identifying constraints, and is of great significance for agricultural non-point source pollution prevention and control. This article selects Anhui Province as the research object, and based on the PSR model of environmental resource management, constructs an agricultural non-point source pollution performance evaluation system. On the basis of this evaluation system, the entropy weight TOPSIS method is used to empirically investigate the agricultural non-point source pollution prevention and control data in Anhui Province from 2017 to 2021, and corresponding suggestions are proposed based on the specific analysis results.

Iron-Nitrogen Amendment Reduced Perfluoroalkyl Acids' Phyto-Uptake in the Wheat-Soil Ecosystem: Contributions of Dissolved Organic Matters in Soil Solution and Root Extracellular Polymeric Substances.

Understanding the mechanisms underlying perfluoroalkyl acids (PFAAs) translocation, distribution, and accumulation in wheat-soil ecosystems is essential for agricultural soil pollution control and crop ecological risk assessment. This study systematically investigated the translocation of 13 PFAAs under different iron and nitrogen fertilization conditions in a wheat-soil ecosystem. Short-chain PFAAs including PFBA, PFPeA, PFHxA, and PFBS mostly accumulated in soil solution (10.43-55.33%) and soluble extracellular polymeric substances (S-EPS) (11.39-14.77%) by the adsorption to amino- (-NH2) and hydroxyl (-OH) groups in dissolved organic matter (DOM). Other PFAAs with longer carbon chain lengths were mostly distributed on the soil particle surface by hydrophobic actions (74.63-94.24%). Iron-nitrogen amendments triggered (p < 0.05) soil iron-nitrogen cycling, rhizospheric reactive oxygen species fluctuations, and the concentration increases of -NH2 and -OH in the DOM structure. Thus, the accumulation capacity of PFAAs in soil solution and root EPS was increased. In sum, PFAAs' translocation from soil particles to wheat root was synergistically reduced by iron and nitrogen fertilization through increased adsorption of soil particles (p < 0.05) and the retention of soil solution and root EPSs. This study highlights the potential of iron-nitrogen amendments in decreasing the crop ecological risks to PFAAs' pollution.

Ecological Risk Assessment and Source Identification of Heavy Metals in Soils from Shiyang River Watershed in Northwest China.

Shiyang River Watershed is an important ecological barrier and agricultural production area in Northwest China, and the study of soil heavy metal content, distribution, and sources is important for agricultural product safety, pollution control, and ecosystem health. In this paper, 140 soil samples were collected from 28 stations to assess the level of heavy metal (Arsenic (As), Copper (Cu), Lead (Pb), Cadmium (Cd), Chromium (Cr), Mercury (Hg), Nickel (Ni), Zinc (Zn)) contamination, pollutant sources and influencing factors of soil in Shiyang River Watershed through determination of the metal contents and statistical analysis. The results indicated that the soils in the study area are typical saline soils in arid zones. The enrichment factors (EF) of As, Cr, Cu, Ni, Zn, and Pb indicate no contamination, and the EFs of Cd and Hg suggested minor contamination. Although the concentrations of Cd and Hg in soil are lower than others, they are more biotoxic and exhibit a moderate-high ecological risk. The index of geoaccumulation (Igeo) values reflect that most of the stations, especially the three groups of samples from depths of 10-20 cm, 20-40 cm, and 40-80 cm, are below the contamination threshold for all heavy metals. The chemical speciation of heavy metals, principal component analysis, and correlation analysis showed that Cr, Cu, Pb, Cd, Ni, and Zn mainly come from the natural accumulation upon weathering of soil-forming matrices. Hg and As mainly come from anthropogenic contributions. The effect of agricultural crop cultivation on soil heavy metal contamination is mainly through farm irrigation and crop-soil interactions, which accelerate the release of heavy metals through the weathering of soil-forming parent material and irrigation, which transports the heavy metals below the surface. The results of this study can provide a scientific basis for the involved authorities to formulate reasonable policies on environmental protection and pollution control.

Evaluation of agricultural and rural pollution under environmental measures in the Yangtze River Economic Belt, China

In this study, material flow and spatial analysis methods were used to evaluate and predict the spatial–temporal pattern evolution of agricultural and rural nitrogen (N) flow in the Yangtze River Economic Belt in China from 1949 to 2050 and to analyze agricultural and rural pollution control by environmental measures. The results showed that since the founding of the People’s Republic of China, the crop harvest in the Yangtze River Economic Belt has shown an overall upward trend, and the increase in the period from 1979 to 1997 was the fastest, with an average annual increase rate of 3.8%. Since the reform and opening up, N loss (storage) increased from 50.97 × 108 kgN in 1978 to 140.15 × 108 kgN in 2014, a 2.75-fold increase. In 2015, China began to implement measures to prevent and control agricultural and rural pollution, and N loss (storage) decreased yearly. In 2019, the N loss (storage) decreased by 18.22% compared with that in 2015, but it was still high. Each year, 113.44 × 108 kgN was still lost to the atmosphere, water and soil, which was 1.53 times the amount of N harvested with crops. The N loss rate was as high as 60%. Before 2014, N discharge into surface water from agricultural and rural areas in the Yangtze River Economic Belt increased annually, especially after 1978, with an average growth rate of 4.76%, leading to severe nonpoint source pollution. With the implementation of the pollution control policy, the N lost to surface water began to show a downward trend in 2015, but it was still 2.17 times higher than the environmental risk threshold in 2019. According to the prediction, under the scenarios of the business-as-usual, fertilizer reduction, engineering and rural improvement patterns, the N emissions from the system to surface water in 2050 are expected to be reduced by 25.76%, 45.5%, 30% and 30%, respectively, compared with those in 2019, but will still be higher than the environmental risk threshold. Under the integrated pattern, the N emissions to surface water are reduced to 4.32 × 108 kgN in 2050, which is lower than the environmental risk threshold and can achieve the goal of nonpoint source pollution control. A single environmental measure cannot effectively control nonpoint source pollution. It is necessary to promote an integrated pattern to achieve green and sustainable development of agriculture in the Yangtze River Economic Belt.

Can China reach the win-win goals for food security and pollution control from the perspective of nitrogen flow analysis？

Producing enough food to simultaneously address food shortage and agro-environmental pollution problems attracts attention globally. To quantify the risks of nutrition crisis to food security and the agro-environment under current agricultural policies in China, this study evaluates and predict the spatiotemporal patterns of nitrogen (N) flows during 1949–2050 through material flow analysis (MFA) and spatial analysis methods. The results show that (1) the crop harvest (including grains, fruits and vegetables) in China increased by a factor of 8.12 from 1949 to 2019, accompanied by a large amount of N loss to the environment. Compared to 1949, N runoff increased 1.23 times in 1979 and 3.43 times in 1999 after which time agricultural pollution control policy achieved initial results, and the crop harvest increased steadily. (2) At the national average level, crop production will increase by 58.60% in 2050, which is higher than the food security threshold while N loss to the environment will be lower than the agro-environmental risk threshold. Under the current agricultural policy, the win-win goals of crop production increase and pollution control can be realized in China. (3) China has obvious temporal and spatial differences in N flows, for which four regions has been divided. Region II, mainly located in Yangtze River Economic Belt, is a high-risk area for N loss. By 2050, environmental pollution can be controlled under the current agricultural policies. However, crop production will only increase by 10% compared with its historical high value, lower than food security threshold. It is necessary to implement more targeted management of high-risk areas by adopting methods such as fallowing or construction of pollution buffer zones while improving N fertilizer use efficiency. For region III, the impact of N loss on the environment has always been at a low level, so there is still great room for increasing future crop production in this region. On average, China will be able to achieve green and sustainable development for agriculture nationally, but there are remaining food security risks in high N loss areas. More targeted N management strategies should be applied to achieve better goals in the future.

Environmental regulations, green development of agriculture, and residents' health-empirical analysis of Yangtze River Economic Belt in China.

Environmental pollution and food safety have become key public health issues to be addressed in China. Since they are closely related to the green development of agriculture, it is of great practical significance to elucidate the intrinsic relationships between green development of agriculture, environmental regulation and residents' health. Based on the panel data of the Yangtze River Economic Belt from 2011 to 2020, this study investigates the impacts of environmental regulation and green development of agriculture on residents' health and the influencing mechanism by applying fixed effects method, mediating effectsmethod and the spatial Dubin method. Results show that the use of chemical fertilizers, pesticides and agricultural films is harmful to residents' health; environmental regulation has a negative correlation with the green development of agriculture and affect residents' health through mediating effects; the green development of agriculture has negative spillover effects on residents' health, indicating that purchasing finished products instead of producing locally reduces the input of production factors such as chemical fertilizers and pesticides and transfers health risks associated with agricultural production activities to neighboring areas. Intensifying command-and-control environmental regulation will induce the expansion of hidden economic activities and harm local residents' health, while intensifying market-incentive environmental regulation will lead to the 'Pollution Haven' phenomenon because of the 'race to the bottom', in government and is harmful to the health of residents in neighboring areas. Therefore, it is necessary to formulate reasonable and feasible policies and strengthen the control and prevention of agricultural pollution to enhance green development of agriculture and improve residents' health.

Balancing water quality impacts and cost-effectiveness for sustainable watershed management

Balancing clean water and economic growth remains challenge to achieve the Sustainable Development Goals (SDGs) issued by the United Nations. In this study, the water quality impacts and cost-effectiveness analysis of catchment actions were integrated by a new proposed watershed management framework (WAM-SDGs). The source appointment and control practices were incorporated based on physical-based model and heuristic algorithm. The tradeoffs between different targets were balanced using multiple attribute decision-making (MADM) and Pareto score approaches. The method was tested in two paired catchments including typical urban and agricultural catchments in China. The results indicated that 1) the cost-effectiveness and reliability of catchment action was improved by 4% and 3.3% compare to traditional methods. 2) The restriction of urban pollution is mainly attributable to strong spatial heterogeneity, while that of agricultural pollution control is attributed to lack of investment. 3) For water quality improvement, sources and sinks of pollutants are quantified and used as priority areas for catchment action. Due to high pollution intensity and control reliability, urban catchments should be given priority and agricultural catchments are more cost-effectiveness when fund is no longer a limiting factor. The economic-based and water-quality-based protection strategies are suggested for urban and agricultural catchment, respectively. This new framework could be extended to other catchments for global sustainable development.

Experimental study of rock wool on the farmland soil erosion and crop growth of winter wheat and its comprehensive evaluation

Introduction: Droughts and flooding occur frequently due to climate change and human activities, which have significantly affected the ecological environment of farmland and crop production. Rock wool (RW) has some properties like high porosity and water retention capacity, and it is widely used in green roofing and agricultural production to reduce flood and drought disaster.Methods: We set 24 artificial rainfall experiments to analyze the impact of RW on the farmland runoff, soil water storage capacity (SWSC), nitrogen and phosphorus loss and crop growth. Finally, the Critic-Entropy comprehensive evaluation method was used to select the best solution for RW embedding.Results: The result shows that RW could reduce the runoff by 49.6%–93.3%, and it made the SWSC increase by .2%–11% Vol in the 10–70 cm depth. During the runoff process, the concentration of nitrogen and phosphorus decreased with the increase of the RW volume, while the nitrogen and phosphorus loss reduced by 51.9%–96.6% and 72.4%–96.4% respectively when RW was buried in the farmland, so RW could effectively promote soil and water conservation. Finally, RW increased the plant biomass and yield by a maximum of 12.1% and 20.4% respectively due to the large retention of water and nutrients. Therefore, combined with the above experimental result, this study indicates that RW could obtain the best comprehensive benefit in the embedding volume of 536.73 m3/ha.Discussion: When the volume of RW embedding was too large, RW easily caused insufficient water storage in short-duration rainfall or irrigation, which made the RW unable to release water to alleviate the soil water deficit during the critical growth period, which may result in drought events being aggravated and crop yield reduced. Overall, this study is conducive to clarifying the comprehensive application effect of RW in agricultural production, pollution control, and urban landscape, and it provides an important basis for expanding its application field and promoting the stability of farmland ecosystems.

Study on groundwater recharge based on chloride mass balance and hydrochemistry in the irrigated agricultural area, North China Plain

In the North China Plain, water shortage seriously restricts economic development, and agricultural irrigation depends heavily on groundwater extraction. Irrigation water and precipitation may directly recharge groundwater in the irrigated agricultural region. Therefore, calculating the recharge of precipitation and irrigation to groundwater is essential for the sustainable utilization of water resources. Furthermore, determining the transformation relationship of precipitation-soil water-groundwater is helpful to understand the hydrological cycle process better. The average groundwater recharge calculated by the chloride mass balance method is between 66 and 144 mm/year, accounting for only 7–17% of the total precipitation and irrigation water. The hydrogen (2H) and oxygen (18O) isotopes reveal that precipitation only affects soil water in topsoil, and soil water in deep soil is recharged upward by groundwater. The hydrochemical composition of soil water shows high concentrations of salt in unsaturated zones. Infiltration water dissolves salt through the unsaturated zone and carries them into the shallow groundwater, causing the deterioration of shallow groundwater quality. These results contribute to the effective management of groundwater resources and the control of agricultural pollution in groundwater.

Characteristics and Planting Safety Assessment of As Content in Dryland Soil and Maize in Guizhou Province

In order to understand the distribution characteristics of As content in dryland soils and maize seeds in Guizhou province and to evaluate the safety of maize cultivation, 468 natural soil samples, 1260 dryland surface soil samples, and 980 corresponding maize seed samples were systematically collected to determine their As content and basic physicochemical properties. The degree of contamination of the samples was evaluated by using the single-factor contamination index method. The results showed that: ① the range of ω(As) in dryland soil was 0.35-758.53 mg·kg-1, with a geometric mean of 23.28 mg·kg-1. The independent sample T-test showed that the As content of dryland soil in Guizhou province was significantly higher than that of natural soil ω(As) 21.29 mg·kg-1 (P<0.01), indicating the existence of arsenic accumulation effects in dryland soil; compared with the screening value of the "Agricultural Land Soil Pollution Risk Management and Control Standard" (GB 15618-2018), the excess rate of soil samples was 33.81%. ② Corn seed ω(As) ranged from 0.001 to 0.868 mg·kg-1, with a mean value of 0.064 mg·kg-1, and 0.61% of the corn seed samples exceeded the limit value of "Limits of Contaminants in Foods" (GB 2762-2017), with the exceeding points distributed in Bijie City, Qianxinan Prefecture, and Tongren City. ③ When corn seeds were used as feed and grain, maize could be safely grown in dryland soils in Guizhou province. This study showed that the soil As pollution in the dryland of Guizhou province was relatively serious, and overall safe maize cultivation can be achieved; however, the cultivation of maize around the As-related non-ferrous metal mining areas is still of concern.

Occurrence, spatiotemporal dynamics, and ecological risk of fungicides in a reservoir-regulated basin

As an indispensable type of pesticide, fungicides have been somewhat neglected compared to insecticides and herbicides. Heavy fungicide application in agricultural regions may generate downstream ecological concerns via in-stream transport, and the reservoir complicates the process. Monitoring fungicide exposure and exploring reservoir effect on fungicide transport is the key to develop the downstream strategies of agricultural diffusion pollution control. Here, we investigated the exposure, spatiotemporal dynamics, and ecological risk of fungicides in a reservoir-regulated agricultural basin, located in the middle of the Yangtze River Basin, China. Seven fungicides were preliminarily identified and exhibited high detection frequencies (>85 %) in subsequent quantification of water samples from three sampling activities. The total concentration of fungicides ranged from 2.47 to 560.29 ng/L, 28.35 to 274.69 ng/L, and 13.61 to 146.968 ng/L in April, September, and November, respectively. Overall, the contamination levels of fungicides were in the ascending order of April < November < September. The spatial distribution of fungicides was closely associated with the dense of cultivated land, supporting its agricultural source. Furthermore, the reservoir plays a retention role in fungicides, alleviating ecological pressure downstream during the water storage period. Yet, due to the alternation of “source” and “sink” function of the reservoir, the contribution of Zijiang River to the fungicide load in the Yangtze River Basin still needs further attention. Although there is no acute risk posed by fungicides, even in the high-exposure scenario, the chronic ecological risk could not be ignored. Agricultural intensive regions, coupled with the reservoir, provide rather substantial chronic ecological concerns. Carbendazim has been designated as a priority pollutant that contributes significantly to cumulative chronic risk. Thus, we emphasize strengthening the supervision of fungicides in surface water and rationally restricting the use of carbendazim in agricultural operations.

Estimating the heavy metal contents in farmland soil from hyperspectral images based on Stacked AdaBoost ensemble learning

• Assessment of heavy metal pollution in soil base on hyperspectral image. • Estimating the soil heavy metal content by constructing ensemble learning model. • The estimation accuracy of heavy metal content in soil is improved. • Mapping the distribution trend of heavy metals in farmland soil. • The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Heavy metal pollution poses a huge challenge to the soil environment. With the increasing pollution level, the traditional monitoring methods cannot quickly obtain information on large-area pollution. Therefore, a large-scale mapping method with high precision is urgently needed to effectively control heavy metal pollution. This study explored a method for mapping soil heavy metal concentrations through hyperspectral images. On this basis, a new Stacked AdaBoost ensemble learning algorithm was constructed to construct the inversion model of soil heavy metal contents. The characteristic spectral bands of heavy metals were extracted as model input variables using Pearson’s correlation coefficient and successive projections algorithm. With three sets of heavy metal content data, the prediction accuracy and mapping outcomes of various machine learning methods were compared. Furthermore, the potential sources of heavy metal pollution in the study area were analyzed based on the Moran’s index. The results showed that the Stacked AdaBoost model was relatively stable with higher accuracy than traditional machine learning models. For Cr, Cu, and As, the determination coefficients ( R 2 ) of the verification set were 0.66, 0.61, and 0.74, respectively. Afterward, the results of this model were used to map the heavy metal concentration over the study area. The mapping results suggested that the heavy metal conditions of soils in the Ganhetan area were caused by nature and human activities. The As pollution in agricultural soils was the most serious, with an exceedance rate of 38.66%. Industrial areas were potential sources of soil heavy metal pollution in the study area. In summary, the Stacked AdaBoost ensemble learning model provides detailed and reliable data for agricultural ecological protection and industrial pollution control, allowing the effective management of heavy metal pollution sources.

Spatial Differentiation of Ecological Stoichiometry of Nitrogen and Phosphorus in Mollic Epipedon of China

Nitrogen (N) and phosphorus (P) are essential elements for crop growth. The study on the spatial differentiation characteristics of soil N and P can provide a theoretical basis for regional fertilization as well as prevention and control of agricultural surface pollution. Taking the typical mollic epipedon area in Northeast China as study area, using the geostatistical model and 3S technology (Remote Sensing, RS; Geography information systems, GIS; and Global positioning systems, GPS), the spatial variation and influencing factors of N and P ecological stoichiometry in the surface soil (0-20 cm) were studied with 1,057 samples by five-point soil sampling method. The outcomes of the study showed that the average total nitrogen (TN), total phosphorus (TP), and N/P ratio were 1.88 g/kg, 0.276 g/kg, and 6.81, respectively. The degree of spatial variation is moderate, and structural factors such as topography and soil parent material are the main factors affecting the spatial variation of soil TN, TP content, and N/P ratio. Vegetation primarily affects the soil TN, TP contents, and N/P specific spatial variation. Soil TN and TP contents showed a downward trend from the northeast to the southwest region of the study. Different approaches of balanced fertilization, soil and water conservation, and reasonable spatial allocation are beneficial to improving the balance of soil N and P in the typical mollic epipedon area of Northeast China.

Fertilization strategies to improve crop yields and N use efficiency depending on soil pH

ABSTRACT The efficiency of fertilizer nitrogen (N) use strongly depends on soil pH and affects both agricultural production and environmental pollution control. We selected four treatments (no-fertilization control (CT); combined mineral N, P and K fertilization (CF); 50% CF+50% chicken manure N (CFM); and chicken manure N (M)) to compare crop yield, N uptake, N use efficiency (NUE), and the N surplus in a Chinese cabbage-maize cropping system in a field experiment from 2011 to 2016 along a pH gradient (alkaline (pH 8.32), near-neutral (pH 6.56) and acidic soil (pH 5.91)). Chicken manure treatment was most appropriate in acidic soils because it increased pH by 2.03 units, up to 13% crop yield, and increased N uptake and NUE than that in alkaline and near-neutral soils. Under mineral fertilization, the N surplus in acidic soil was the highest. We conclude that combined organic-mineral fertilization in alkaline, near-neutral, and acidic soils is a promising strategy that not only increases the crop yield, N uptake, and NUE but also decreases the N surplus. Organic manure is especially recommended as an efficient strategy in acidic soils to increase crop yield and NUE.