Characteristics, source analysis, and health risk assessments of heavy metals for karst water in Shentou spring area, northern China

To identify the contamination characteristics and health risks of heavy metals in karst groundwater systems in northern China, the Shentou Spring area was selected as the study site. A total of 53 karst water samples were collected, and ten heavy metal elements (As, Cr6+, Al, Cu, Pb, Zn, Ni, Mn, Co, and Fe) were analyzed. Multiple statistical analysis, the single-factor pollution index method, the Nemerow comprehensive pollution index method, and a health risk assessment model were comprehensively applied to systematically evaluate the distribution patterns, pollution levels, and associated human health risks of the aforementioned elements. The results showed that the concentrations of Al, Fe, and Mn exceeded the Class III threshold of the Groundwater Quality Standard (GB/T 14848-2017), with the contaminated samples mainly concentrated along the Maguan River. Multivariate statistical analysis revealed that Ni, Mn, and Co primarily originated from natural background and industrial activities; As and Cr6+ were controlled by agricultural pollution; Cu and Pb were dominated by natural factors; Fe was associated with industrial and human activities; Al originated from industrial and agricultural production; and Zn had complex sources. Pollution assessment indicated that Al, Fe, and Mn were at polluted levels, whereas the other elements were at non-polluted levels, suggesting generally good water quality. Health risk assessment showed that the risk values of all heavy metals were below the maximum acceptable risk level (5 × 10−5 a−1). The total health risk through drinking water exposure was higher for children (2.90 × 10−5) than for adults (2.52 × 10−5); through dermal contact, the total health risk was higher for adults (4.88 × 10−7) than for children (3.63 × 10−8). Drinking water was identified as the primary exposure pathway for heavy metal health risks in the study area. In summary, the groundwater quality in the study area generally meets the standard requirements at the regional scale, but certain local areas exhibit potential contamination risks that deserve attention in subsequent water resource management.