Fig. 1

Geographical location of the study sites. Aquifer samples consist of uncontaminated wells (UC) FW300, FW301, and FW303; low-contaminated wells (LC) GW199, GW715, and GW928; mid-contaminated wells (MC) FW215, FW602, and DP16D; high-contaminated wells (HC) FW104, FW106, and FW021