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Rhizosphere is a soil volume of high spatio-temporal heterogeneity and intensive plant-soil-microbial interactions, for which visualization and process quantification is of highest scientific and applied relevance, but still very challenging. A novel methodology for quick assessment of two-dimensional distribution of available phosphorus (P) in rhizosphere was suggested, tested, and development up to the application platform. Available P was firstly trapped by an in-situ diffusive gradients in thin-films (DGT) sampler with precipitated zirconia as the binding gel, and subsequently, the loaded gel was analyzed with an optimized colorimetric imaging densitometry (CID). The imaging platform was established linking: i) DGT, ii) planar optode, and iii) soil zymography techniques to simultaneously determine available P, oxygen, and acid phosphatase in rhizosphere at sub-millimeter spatial scales. The DGT identified available P level in rice rhizosphere were spatially overlapping to the localized redox hotspots and phosphatase activity. The spatial relationship between available P and acid phosphatase activity was dependent on root development. The root radial oxygen loss (ROL) remained active during the experimental observations (2–3 days), while a flux of available P of 10 pg cm−2 s−1 was visualized within 2–3 mm of roots, confirming the correlative response of rice roots to oxygen secretion and P uptake. Summarizing, the established imaging platform is suitable to capture spatial heterogeneity and temporal dynamics of root activities, nutrient bioavailability, ROL and enzyme activities in rhizosphere. [Display omitted] • Quick establishment of the two-dimensional distribution of available P was realized. • A versatile platform was established for imaging multiple analytes in rhizosphere. • Rhizosphere P dynamics were linked to localized redox conditions and root activity. • Relationship between P and acid phosphatase activities varied as root developed. [ABSTRACT FROM AUTHOR]

Evaluating the health risks of the groundwater and surface water in landfill areas is of great significance to the health and safety of local residents. The current practice of health risk assessment is based only on the analysis results of groundwater and surface water samples, which reflect the current situation of water security in landfill areas. However, due to the neglect of risk causes analysis, thus a health risk assessment is insufficient to provide rigorous scientific countermeasures for risk prevention and control. The health risks caused by groundwater and surface water is mainly controlled by the water quality, which is comprehensively controlled by the conditions of its formation and evolution. When a landfill site is located in a hilly area, the environmental characteristics, causes, main controlling factors, and evolution processes of the surface water and groundwater in different parts of the catchment are significantly different. This study used a municipal solid waste landfill area in a hilly area as an example and defined the causes and main controlling factors of regional health risks caused by water based on an analysis of the characteristics of natural and anthropogenic factors affecting the groundwater and surface water. Then, prevention and control countermeasures were proposed for health risks caused by water in different parts of the landfill area. This study provides a method for the causes analysis and prevention and control countermeasures of health risks caused by water in municipal solid waste landfills in hilly areas. [Display omitted] • The health risks of water around landfills in hilly area are significantly different. • The controlling factors of water environmental health risk are different. • Natural and human factors affect the evolution of water around landfill. • Risk prevention and control measures based on causes of health risks are put forward. [ABSTRACT FROM AUTHOR]