The Wenzel SEP showed higher extraction efficiency in potentially mobile tungsten fractions, especially for the tungsten associated with iron hydroxides.

A better understanding of anthropogenic trace metal accumulation in farmland soils is crucial for local food safety and public health, especially for a rapidly industrializing region. In this study, soil samples at two depths were collected from a typical county in East China and analyzed for total concentrations of Fe, Al, Pb, Cd, Cu, Zn, Cr, and Ni. Results showed that trace metals like Pb, Cd, Cu, Zn, Cr, and Ni have accumulated in the regional farmlands, with average topsoil concentrations 1.62–1.77 times higher than their background concentrations in subsoil. However, they were still much lower than the limits of the Chinese Environmental Quality Standard for Soils. By the proper calculation of enrichment factor (EF), it was found that the accumulations of trace metals in the topsoil have been impacted by anthropogenic activities, which could contribute up to 40.83% of total metal concentration. Two principal components were extracted according to the results of principal component analysis (PCA) for EF values, which indicated two important anthropogenic trace metal sources. With the help of spatial distribution maps based on geographical information system (GIS), the anthropogenic sources of Pb, Cr, and Ni were determined to be mostly associated with atmospheric deposition from the central urban area. However, Cd, Cu, and Zn were further confirmed to originate from different agricultural sources. The anthropogenic Cu and Zn inputs were mostly related to pig manure application in the rural northern and southeastern areas, while extensive fertilizer application was identified as the major contributor to anthropogenic Cd accumulation in this region. Overall, the integrated application of EF, PCA, and GIS mapping is an effective approach to achieve the spatial assessment of anthropogenic impact on trace metal accumulation in regional soils.

An economical and effective method is still lacking for cadmium (Cd) toxicity reduction and food product safety improvement in soil–vegetable systems. Therefore, this study aimed to reduce the Cd toxicity to pak choi (Brassica campestris L.) by jointly using passivators and organic fertilizer, highlighting food products’ safety based on pot experiments. The results showed that compared with the control, organic fertilizer decreased the Cd content in edible parts and the soil’s available Cd by 48.4% and 20.9% on average, respectively, due to the 0.15-unit increases in soil pH. Once jointly applied with passivators, the decrements increased by 52.3–72.6% and 32.5–52.6% for the Cd content in edible parts and for the soil’s available Cd, respectively, while the pH increment increased by 0.15–0.46 units. Compared with the control, the transport factor of Cd was reduced by 61.9% and 50.9–55.0% when applying organic fertilizer alone and together with the passivators, respectively. The combination treatment of biochar and organic fertilizer performed the best in decreasing the Cd content in the edible parts and the soil’s available Cd. The combination treatment of fish bone meal and organic fertilizer induced the greatest increases in soil pH. The grey relational analysis results showed that the combination treatment of biochar and organic fertilizer performed the best in reducing the potential Cd pollution risk, thereby highlighting the vegetable food safety. This study provides a potential economical and effective technology for toxicity reduction and food safety in Cd-polluted soil.

Based on the basic statistical data and related parameters of The Yellow River Basin (YRB) from 2000 to 2019, the nitrogen flow model of the YRB was constructed by using the full nitrogen flow analysis model (FNFA) and the emission coefficient method to analyze the characteristics of the nitrogen inputs and outputs in the YRB. The results revealed that over the past 20 years, both the total nitrogen inputs and outputs in the YRB have shown a significant increasing trend. Specifically, the total nitrogen input rose from 12,806.69 Gg to 18,553.42 Gg, while the total output increased from 9,250.93 Gg to 12,955.0 Gg. Among the various subsystems, the industrial and agricultural sectors were the largest contributors to nitrogen balance, accounting for 28.30% and 26.22% of the total nitrogen input, and 26.22% and 40.48% of the total nitrogen output, respectively. The overall nitrogen utilization efficiency (NUE) across the subsystems required improvement, particularly within the cropland subsystem, which had an NUE ranging from 25.67–36.10%. In contrast, the livestock subsystem exhibited only half the NUE of the cropland subsystem. High emissions and inefficient nitrogen utilization led to a continuous increase in environmental nitrogen loads, with atmospheric nitrogen loads being particularly pronounced. Additionally, the life cycle analysis of industrial nitrogen revealed that a substantial amount of nitrogen was enriched in the atmosphere. These findings can serve as scientific basis and support for regulating nitrogen inflow and outflow within watershed areas, and formulating more rational integrated management strategies for nitrogen.