Microplastics in groundwater of two rural communities in Mexico

Groundwater is used by almost two billion people worldwide. Microplastic (MP) pollution is found in every environment; however, studies on groundwater MP pollution are scarce. Therefore, the present study evaluated the amount and types of microplastics in ten rural wells where drinking water is extracted for two rural Mexican communities. In each well two samples were taken per month for 10 months; one to evaluate MP air deposition, of surface water (first 5 cm of depth) and another of water without contact with air (3 to 5 m depth). There were no differences between the communities in the average number of microplastics in both types of samples. MP measured 2,100 to 4,400 μm in length. 100% of the MP found were fragments. In both communities, color abundance coincided: black > white > blue > green > gray. The polymers identified were nylon, HDPE, PP, PS, PVC, and PET. There were no differences in the abundance of MP by air deposition, between dry and rainy seasons; however, there was a highest abundance (p<0.05) in the dry season (0.41 MP/L) in deep water, which indicates that rainwater dilutes this type of pollution (0.25 MP/L). Ixtacuixtla and Xocoyucan, Mexico, do not adequately manage their urban solid wastes and wastewater, generating plastic pollution in the region's groundwater, which represents a risk to human health.