Abstract:Microcystins (MCs) released from cyanobacterial blooms may be transferred to agricultural soil via irrigation water and cyanobacterial compost. Concentration distribution and risk evaluation of three commonly found MCs (including MC-LR, MC-RR, and MC-YR) in 35 soil samples from vegetable fields around heavy eutrophic Dianchi Lake were studied using solid phase extraction and liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Results indicated that MCs were detected in 85.7% of the samples and the total concentrations of MCs ranged from n.d. (below LOQ) to 7.8μg/kg with the average concentration of 1.6μg/kg. MC-RR appeared the highest detection rate (82.9%) and concentration (n.d.~5.3μg/kg), followed by MC-LR and MC-YR. Both the health and ecological risks of the three MCs were acceptable. MC-YR displayed the highest health ecological risk, while MC-LR showed the highest ecological risk. Oral intake and dermal contact were primary exposure pathway of MCs to children and adults, respectively. Children suffered higher health risk than adults.