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【Objective】 Nonpoint source pollution poses a significant threat to the surface water environment, particularly in agricultural systems. Reconstructed wetlands are an environmentally friendly method to mitigate nonpoint source pollution. This paper investigates the efficacy of plants and their growing medium in removing pollutants from farmland receding water. 【Method】 The experiment was conducted in a subsurface-flow wetland and an ecology surface flow wetland at Bapaigan region along the bank of Duliujian River. We measured the impact of aquatic plant species, planting density, matrix materials and filling rate, and hydraulic retention time of water in the wetland on purification of the water. 【Result】 Among all treatments we compared, the combination of plant species of Scirpus tabernaemontani+ Iris tectorum and matrix of zeolite+ volcanic rock was most effective to purify the receding water, as they nurtured a microbial community which increased denitrification and dephosphorization. Keeping the hydraulic retention time 3 day and running 10 consecutive cycles can remove ammonia nitrogen, total phosphorus and chemical oxygen demand (COD) contents by 95.74%, 49.94% and 89.03%, respectively. 【Conclusion】 Following the implementation of the Bapaigan constructed wetland, the plants, substrate medium and their associated microbiome were effective to remove the pollutants from the receding water, with the effluent water quality reaching Class V standard for surface water. These findings have important implications for remediating farmland runoff using constructed wetlands in north China.

Plasmin is an important factor affecting the shelf-life quality of milk products, and its hydrolytic activity is regulated by many factors, such as activators, inhibitors, and activator inhibitors. Compared with protease secreted by psychrophilic bacteria, plasmin presents different thermal inactivation parameters and hydrolysis properties; the milk gelation properties induced by the two enzymes, the gelation mechanisms and the methods used to detect the milk hydrolysates are different. Plasmin activity in raw milk is affected by dairy cow breeds, lactation stage, parity, and the number of somatic cells, as well as protease secreted by bacteria. As whey protein, casein and Maillard reaction can affect plasmin structure and substrate recognition by it, heating, membrane filtration, and high pressure processing can affect plasmin activity. In this paper, we summarize the composition and regulatory mechanism of the plasmin system in milk, the mechanism of plasmin-induced age gelation of milk, the factors affecting plasmin activity and the methods used to assay plasmin activity, with the aim to provide a reference for further research on milk plasmin.

BACKGROUND Mircobeam Lu-Hf isotopic analysis on minerals provides an important means to understand the microscopic process of magmatic activity and metamorphic reaction and to trace provenance of sediment, which greatly promotes the development of petrogeochemistry. Many methods were provided to obtain accurate and precise microbeam Lu-Hf isotopic data, and many mineral standards for microbeam Lu-Hf isotopic analysis were developed. OBJECTIVES To review and understand the microbeam methods for Lu-Hf isotopic analysis. METHODS Systematic compilations of published data of standards and discussion on the different methods for microbeam Lu-Hf isotopic analysis. RESULTS The development history of microbeam Lu-Hf isotopic analysis in the past 30 years is reviewed, and the influence of 176Yb and 176Lu isobars, REE oxides, and Ta-rich matrices on the precision and accuracy of Hf isotope measurement is systematically evaluated as well as the different correction strategies and programs provided in previous studies. In addition, a comprehensive compilation of the different Yb and Lu isotopic compositions reported in references and the different methods of microbeam Lu-Hf isotopic analyses on various Hf-rich minerals such as zircon, baddeleyite, zirconolite, zirkelite, calzirtite, eudialyte, rutile, cassiterite, and columbite-group minerals is made. The micro-drill/micro-saw sampling Lu-Hf isotopic analysis of Lu-rich minerals has played an important role in revealing the multi-stage orogenic process and the duration of mineral growth. The advent of laser ablation inductively coupled plasma triple quadrupole mass spectrometry (LA-ICP-Q-MS/MS) has increased the spatial resolution of Lu-Hf single-spot/isochron dating analysis of Lu-rich minerals to the micrometer scale. This method relies on the collision reaction of Hf and NH3 to realize the online separation of Hf from Lu, and achieves the purpose of synchronous measurement of 176Lu/177Hf and 176Hf/177Hf ratios, which is introduced in detail. CONCLUSIONS The new generation of tandem multi-collector sector field mass spectrometer with collision/reaction cell has high stability and sensitivity, which can be used to determine online separation of Hf from REEs, produce high-precision Hf isotope measurements for high Yb/Hf or Ta-rich minerals under high spatial resolution conditions, and significantly improve the precision and accuracy of microbeam Lu-Hf isotopic analysis. This deserves extensive attention in the future.

In recent years, due to the rapid development of China’s nuclear industry, the need for uranium has been expanding, while the environmental pollution of water caused by uranium is also receiving more and more attention. Laminated double hydroxide (LDH) is favored by researchers in water pollution removal due to its special layered structure, good adsorption performance, regeneration and easy recycling. The mechanism of adsorption of uranium by the new LDH is summarized, the preparation process and removal effect are introduced, the removal mechanism and influencing factors are analyzed, and on this basis, the future development and research of adsorbent materials are proposed.