• • Groundwater in Guyuan is Class IV per GB/T 14848—2017, with TDS averaging 1350.9 mg·L−1, rendering it unsuitable for direct drinking but usable for irrigation after treatment; As requires special attention.
• • Nemerow index classifies overall pollution as moderate, with Cr, As, and Mn as key contributors; HPI averages 10.56 but reaches 36.15 at sample PS1-51-下, indicating severe local contamination.
• • Carcinogenic risk from Cr and As is 8.037×10−6 a−1 for adults and 3.863×10−6 a−1 for children, below US EPA limits but above stricter international guidelines, emphasizing the need for risk management, especially for children.
• • Isotopic and statistical analyses indicate atmospheric precipitation as the primary recharge source; Cr, As, and Mn derive from copper mining, coal extraction, and agricultural activities, highlighting anthropogenic impacts in populated loess areas.