Assessment and analysis of agricultural non-point source pollution loads in China: 1978-2017.

Eutrophication of natural water is a universal problem. Nitrogen (N) and phosphorus (P) from agricultural runoff are the main sources of nutrient input, provided that emissions from industrial point sources (IPS) are under control. Therefore, it is of great environmental importance to reduce pollution associated with agricultural runoff as a means of regulating eutrophication levels in natural water. Numerous methods proposed for treating agricultural runoff can be classified into three categories: source control, process control, and end treatment. In this review, major technologies for N and P control from agricultural runoff are summarized along with discussion of newly proposed technologies such as biochar biomimetics and microbial catalyst. Because agricultural runoff (from farmlands to receiving waters) is a complicated pollution process, it is difficult to regulate the nutrients discharged via such process. This review will thus offer a comprehensive understanding on the overall process of agricultural runoff and eutrophication to help establish control strategies against highly complicated agricultural non-point sources.

https://link.springer.com/content/pdf/10.1186/s13765-020-0493-6.pdf

Recent advances in control technologies for non-point source pollution with nitrogen and phosphorous from agricultural runoff: current practices and future prospects

Cleaner agricultural production in drinking-water source areas for the control of non-point source pollution in China.

Impact-oriented water footprint assessment of wheat production in China.

Spatiotemporal variation in nitrogen loads and their impacts on river water quality in the upper Yangtze River basin

It is the key point to reveal the effect of irrigation water and fertilization conditions on the agriculture non-point pollution in the paddy field. In this study, the estimation model of agricultural non-point source pollution loads at field scale was established on the basis of agricultural drainage irrigation model and combined with pollutant concentration predication model. Based on the estimation model of agricultural non-point source pollution in the field and experimental data, the load of agricultural non-point source pollution in different irrigate amount and fertilization schedule in paddy field was calculated. The results showed that the variation of field drainage varies greatly under different irrigation conditions, and there is an “inflection point” between the irrigation water amount and field drainage amount. The non-point pollution load increased with the increase of irrigation water and showed a significant power correlation. Under the different irrigation condition, the increase amplitude of non-point pollution load with the increase of irrigation water was different. When the irrigation water is smaller, the non-point pollution load increase relatively less, and when the irrigation water increased to inflection point, the non-point pollution load will increase considerably. In addition, there was a positive correlation between the fertilization and non-point pollution load. The non-point pollution load had obvious difference in different fertilization schedule even with same fertilization level, in which the fertilizer pollution load increased the most in the period of turning green to tillering. The results provide some basis for the field control and management of agricultural non-point source pollution.

Effect of irrigation amount and fertilization on agriculture non-point source pollution in the paddy field

This paper is devoted to determining the inelastic responses of geological materials by the binary-medium-based constitutive model. The geomaterials are conceptualized as two-phase composites that are composed of the bonded medium of elastic–brittle nature and the frictional medium of elastoplastic nature. The evolution of meso-structure upon loading is considered by the progressive transformation of the bonded medium into the frictional medium. By introducing the statistical meso-breakage concept, the breakage ratio indicating the degree of such transformation is determined by statistical approaches. The interactions among inclusions (the bonded medium) and matrix (the frictional medium) and the influence of the varying breakage ratio are considered with the help of the double-inclusion model within the framework of the mean-field homogenization scheme. An application is presented for the structured/bonding geomaterials based on the proposed model. The comparisons between computed results and experimental data of three kinds of structured soils show that the proposed model can reproduce the typical behaviors of cemented/structured geomaterials. 

A binary-medium-based constitutive model for geological materials based on the statistical meso-breakage concept and mean-field homogenization

The seasonal variation and spatial distribution of pharmaceuticals in typical drinking water sources in the middle reaches of the Yangtze River were analyzed using the solid-phase extraction and high-performance liquid chromatography-tandem mass spectrometry methods. Combined with the risk entropy method, the corresponding ecological risks for aquatic organisms were evaluated. The results showed that 80% of the target pharmaceuticals were detected in the drinking water sources, with average concentrations of 0.07-13.00 ng·L-1. The concentrations of the target pharmaceuticals were lower than or comparable with those in other drinking water sources reported in China. The spatiotemporal distribution of different pharmaceuticals varied. Generally, the detection level in winter was higher than that in summer, and there was no significant difference between that upstream and that downstream. This might be mainly attributed to seasonal/regional use and emissions of the pharmaceuticals, the impact of flow rate on dilution, and the impact of temperature on biodegradation. Compared with those before the COVID-19 epidemic, the detection concentrations of the target pharmaceuticals were relatively low. The reason for this might be that the prevention and control of the epidemic reduced the use and emission of the pharmaceuticals to a certain extent, and the high rainfall and runoff strengthened the dilution of water flow. The target pharmaceuticals, especially antibiotics, posed medium or low risks to aquatic organisms (especially algae). Considering the ecological risks and genotoxicity of pharmaceuticals and the potential risks of antibiotic-resistant genes, it is suggested to strengthen the investigation, evaluation, treatment, and control of pharmaceuticals in the water environment.

[Spatiotemporal Distribution and Risk Assessment of Pharmaceuticals in Typical Drinking Water Sources in the Middle Reaches of the Yangtze River].

Microbes play an important role in aquatic carbon cycling but we have a limited understanding of their functional responses to changes in temperature across large geographic areas. Here, we explored how microbial communities utilized different carbon substrates and the underlying ecological mechanisms along a space-for-time substitution temperature gradient of future climate change. The gradient included 47 lakes from five major lake regions in China spanning a difference of nearly 15°C in mean annual temperatures (MAT). Our results indicated that lakes from warmer regions generally had lower values of variables related to carbon concentrations and greater carbon utilization than those from colder regions. The greater utilization of carbon substrates under higher temperatures could be attributed to changes in bacterial community composition, with a greater abundance of Cyanobacteria and Actinobacteriota and less Proteobacteria in warmer lake regions. We also found that the core species in microbial networks changed with increasing temperature, from Hydrogenophaga and Rhodobacteraceae, which inhibited the utilization of amino acids and carbohydrates, to the CL500-29-marine-group, which promoted the utilization of all almost carbon substrates. Overall, our findings suggest that temperature can mediate aquatic carbon utilization by changing the interactions between bacteria and individual carbon substrates, and the discovery of core species that affect carbon utilization provides insight into potential carbon sequestration within inland water bodies under future climate warming.

Peng He

Papers

Effect of irrigation amount and fertilization on agriculture non-point source pollution in the paddy field

A binary-medium-based constitutive model for geological materials based on the statistical meso-breakage concept and mean-field homogenization

[Spatiotemporal Distribution and Risk Assessment of Pharmaceuticals in Typical Drinking Water Sources in the Middle Reaches of the Yangtze River].

Temperature-mediated microbial carbon utilization in China's lakes.