Assessment of heavy metal concentrations in roadside soils and plants around the Dexing copper mine: implications for environmental management and remediation.

While land transportation is crucial for social development, it also introduces various pollutants, including heavy metals, which pose risks to both the environment and human health. This issue is particularly acute in mining areas, yet research focusing on heavy metal accumulation in soils and plants along transportation routes in these areas has been limited. Addressing this gap, this study investigates soil contamination levels and heavy metal concentrations in dominant plants along a highway and railway in the vicinity of the Dexing Copper Mine, the largest open-pit copper mine in China, located in Jiangxi Province. These transportation routes are heavily utilized for ore transportation, making them critical areas for environmental monitoring. Results reveal that the primary heavy metal contaminants in the soil were Cu (84.9 to 2554.3 mg/kg), Pb (38.3 to 2013.4 mg/kg), Cd (0.1 to 46.6 mg/kg), Zn (81.3 to 875.8 mg/kg), and As (11.8 to 2985.2 mg/kg), with significantly higher concentrations found in soils adjacent to the railway compared to the highway. Specifically, for plants along the highway, Cyperus rotundus showed a significant enrichment in Cd and demonstrated a notable capacity to translocate heavy metals from its roots to aerial parts. This is evidenced by the elevated concentration of Cd in the plant's aboveground tissues (0.87 mg/kg). Notably, both the bioconcentration factor (BCF) and translocation factor (TF) values exceeded 1, ranging from 1.07 to 3.62. Contrastingly, despite the elevated heavy metal concentrations in soils adjacent to the railway, plants in these areas did not exhibit hyperaccumulation characteristics. The unique behavior of Cyperus rotundus in accumulating and translocating Cd underscores its potential role in phytoremediation, particularly in the context of environmental management for areas impacted by mining activities, such as those surrounding China's largest copper mine.

Linking human activity to spatial accumulation of microplastics along mangrove coasts.

Microplastics (MP) in mangrove coasts are threating ecological health and seafood safety. However, quantitative evidence on the effects of different coastal human activities on microplastic accumulation in mangrove sediments is lacking, thereby impeding the policy development of evidence-based waste management. In this study, continuous geographical sampling (N = 50) was applied to collect sediments from the largest mangrove coast, namely the Leizhou Peninsula in China. Similar worldwide research data (16 mangrove coasts) were collected from the Science Citation Index Expanded (SCIE) database of the Web of Science. The connections between human drivers and microplastic accumulation were evaluated by spatial comparison, multi-correspondence analysis, and multiple differences analysis. The microplastic abundance fluctuated widely along the mangrove coasts (average value was 51.24, ranged from 6.40 to 255.57 items·kg-1 dry weight; coefficient of variation = 97%) with a globally lower-middle concentration in sediments of the Leizhou Peninsula. Densely populated urban residents and the floating population of tourists largely contributed to the high abundance of microplastics in mangrove sediments, of which large-sized (1-5 mm) white foams were the dominant type. Although suburbs had less crowds, both onshore and offshore fishery production could cause high accumulation of microplastics in neighboring mangrove coasts, which were characterized by small-sized (<1 mm) fragments with fresh color. Small microplastics (80%) with fresh color (44%) were dominant. Weathering may break down more toxic particles in urban areas neighboring mangrove coasts. Larger mangrove patches could partly block ocean-based microplastics; however, coasts surrounded by more geographical barriers had intensified pollutant accumulation. It was suggested that foam packaging of commodities for urban residents and tourists in popular tourism areas should be reduced and restrictions of fishery waste plastics are needed along shores with mangroves, especially in coasts surrounded by more geographic barriers.