Heavy metals and As (HMs) pollution in mining areas are a widespread environmental concern. In this study, ground water, surface water, and sediment samples around the Dexing area, one of the largest Cu-polymetallic ore clusters in China, were collected to examine the concentrations and distributions of As, Cd, Cr, Cu, Hg, Pb, and Zn. Pollution indices, geo-accumulation index, and potential ecological risk index were used to estimate the pollution characteristics and ecological risk of HMs. The results show that the major pollutants in the surface water were Cd, Cu, Zn, and Pb, while the dominant ecological risk of HMs in the sediments originated from Cu, As, Hg, and Cd. Moreover, HMs in the surface water and sediments exhibited substantial spatial heterogeneity in the study area, indicating a severely disturbed environment due to mining activities. The proportions of HM pollutions were higher in the Dexing River and its tributaries than in the Le’an River and its tributaries. The surface water pollution was predominant at the tributaries closest to the mine area, while the sediment contamination has been expanded several kilometers downstream of the major rivers. Overall, the ecological risk of HMs was higher in the sediments than in the surface water.

Certified reference materials (CRMs) play a pivotal yet frequently overlooked function in mineral exploration. Effective exploration requires CRMs that closely match the geological background. With the full launch of a new round of prospecting strategic breakthrough actions, large-scale regional geochemical surveys will be conducted around the main metallogenic zones in China. Currently, there is a notable shortage of CRMs specifically designed for the arid desert regions of northern China, which have huge mineralization potential. To address this gap and meet analysis and testing needs for stream sediment samples, five stream sediment CRMs have been developed for these arid desert areas. These CRMs represent diverse geological settings: a regional background area, a Ni-polymetallic mining area, a Cu mining area, a Cu-Pb-Zn polymetallic mining area, and a Cu-Fe mining area. The development process strictly followed the requirements outlined in the ISO series of international standards for CRMs. The candidate materials were prepared in accordance with these standards, involving procedures such as impurity removal, drying, multi-stage milling, and homogenization prior to packaging. Homogeneity and stability were evaluated using 30 randomly selected units per candidate, and the results demonstrated excellent performance in both aspects. For characterization, 13 authoritative laboratories collaborated to determine the concentrations of 73 components using validated measurement techniques. Through statistical measurement and rigorous uncertainty assessment, it was confirmed that these materials meet all requirements for CRMs. These new CRMs are recommended for property value assignment, instrument calibration, quality control, and proficiency testing in regional geochemical surveys and mineral exploration.