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Removing nitrate from surface water is a constant challenge due to its high stability. While electrochemical treatment, a clean and renewable energy source, is promising, most strategies focus solely on energy conversion without considering treatment efficiency and practical application prospects. In this study, a Fe-based MOF derived material MC was synthesized by combining the process of hydrothermal and pyrolysis using Fe-MOF as the raw material to investigate the viability of nitrate reduction. The MC electrode exhibits 91.3 % NO 3 - removal and 44.9 % current efficiency in 180 min. The selectivity of ammonia is 90.6 % without Cl- and the selectivity of N 2 is 89.9 % with Cl-. The excellent behavior of MC is attributed to the layered structure of dispersed Fe-based nanocluster and interconversion of Fe three valence states, which are conducive to mass transfer and electron transfer, respectively. The Layered Fe-based electrode material MC is a cost-effective, high-efficiency and stabilized electrode catalyst capable of treating water in a wide pH range and broad hardness. It maintained excellent stability over ten cycles and was used to remove nitrate, TN, and COD from polluted surface water, proving to be an environmentally friendly option for the deep purification of polluted surface water. [Display omitted] • MC showed efficiency and stability for reduction under wide pH and broad hardness. • Enhanced electron transfer was induced by nanocluster and three valence states. • MC has a removal of NO 3 -, TN and COD in polluted surface water simultaneously. [ABSTRACT FROM AUTHOR]

• Yellow River PAH input & sea currents determined PAH spatial distribution in the sea. • Yellow River alluvial loess solid dilution effect led to lower PAH levels in the sediment. • Yellow River & Yellow Sea water dilution effect led to lower PAH levels in the water. • PAH properties decided its partitions in surface/bottom water & bottom water/sediment. • PAH ecological risks in both water and sediment were negligible or acceptable. The marginal Bohai Sea, connected to the northwestern Pacific Ocean, is threatened by human activity. The Yellow River, the second largest river in China, drains large amounts of water, silts, and polycyclic aromatic hydrocarbons (PAHs) into the southern Bohai Sea; however, to what extent the Yellow River inputs influence the spatial distributions and partitions of PAHs in the southern Bohai Sea is not well known. Therefore, this study collected surface water, bottom water, and sediment samples from the southern Bohai Sea and analyzed them to examine the spatial distributions and partitions of 15 priority PAHs. The results showed that PAH concentrations ranged from 26.9 to 50.1 ng L–1 in surface water, 18.8 to 44.1 ng L–1 in bottom water, and 7.4 to 143.9 ng g–1 in sediment, with higher proportions of four-, five-, and six-ring PAHs in sediment than in water. PAH inputs from the Yellow River and sea coastal currents determined the spatial distribution of PAH concentrations in water and sediment, with an overall decrease from the estuary to the southeast. However, the solid dilution effect of input silts from the Yellow River and the liquid dilution effect of water from the Yellow River and Yellow Sea led to lower PAH concentrations in the water and sediment of the southern Bohai Sea than those in other areas of the Bohai Sea. PAH exchange between the atmosphere and seawater led to significantly higher individual PAH concentrations (except for acenaphthylene) in the surface water than in the bottom water, with ratios significantly related to the PAH n-octanol-water partition coefficient, organic carbon-water partition coefficient, and Henry's law constants. These parameters also determined PAH partitioning between the bottom water and sediment. Individual and total PAH concentrations in the sediment were significantly correlated with organic matter, clay, and silt contents. Therefore, the partitions and spatial distributions of PAHs in the southern Bohai Sea comprehensively depend on PAH properties, PAH inputs from the Yellow River and the atmosphere, sea currents, and seawater and sediment properties. The ecological risks posed by individual PAHs in both water and sediment were negligible or acceptable. [Display omitted] [ABSTRACT FROM AUTHOR]