Study on the transport of land-derived solutes in coastal stratified aquifers

To better protect coastal water environment and water ecological functions, it is imperative to explore the transport mechanism of land-derived solutes in coastal stratified aquifers. This study constructed a 2-D numerical model of a coastal stratified aquifer, used groundwater software SUTRA-MS to simulate and analyze the transport characteristics of land-sourced solutes in a tide-influenced coastal stratified aquifer. The results show that: ① Compared to a homogeneous aquifer, the presence of a low-permeability layer would prolong the residence time of solute plume, increase its maximum spreading area, and weaken its degree of horizontal and vertical spreading. ② A low-permeability layer can reduce the maximum discharge rate of land-derived solute plume and increase the discharge duration. ③ The hydraulic conductivity and thickness of low-permeability layer exerts more significant influences than the depth on the spreading area, residual mass within the low-permeability layer, and horizontal and vertical spreading of the solute plume.