Assessing the impact of natural and anthropogenic activities on groundwater quality in coastal alluvial aquifers of the lower Liaohe River Plain, NE China

The lower Liaohe River Plain (LRP) is an economically and ecologically important area situated on an alluvial plain, where anthropogenic activities are very intensive. Field investigations were conducted in the LRP and 15 water quality parameters surveyed at 216 wells during September and October of 2009 and 2010. These showed significant variation in the hydrochemistry of groundwater throughout the plain. A Piper plot was used to identify the major geochemical processes occurring in the entire plain. Principal components analysis (PCA) was used to identify various underlying natural and anthropogenic processes that created these distinct water types. The Stuyfzand classification was used to subdivide and interpret the complex groundwater hydrochemistry of the Liaohe River delta. Five principal components (PCs) were extracted in terms of PCA, which can be invoked to explain 82% of the total variance in water quality parameters. The PCA results can be categorized by five major factors: (1) Holocene transgression and mixing; (2) surface water infiltration; (3) multi-factor processes; (4) rainfall and agricultural fertilizer contamination; and (5) Geogenic F enrichment. This study demonstrates that the great variation of groundwater hydrochemistry in the LRP should be attributed to both natural and anthropogenic processes.

► We assess the groundwater quality in a region scale alluvial aquifer by 216 samples.
► We analyze a regional groundwater evolution using Stuyfzand classification and Piper plot.
► The major natural and anthropogenic processes occurring in the plain are identified as five PCs.
► The transformation relationships between NH4–N, NO2–N and NO3–N in the river delta are discussed.
► We evaluate the chemical compositions of groundwater affected by different land tillage practices.