BACKGROUNDThe problem of heavy metal contamination in farmland is more and more serious, and has become one of the main factors that restrict the development of ecological agriculture, which has raised attention.

OBJECTIVESTo study spatial distribution characteristics of heavy metals in small scale farmland and use it as an effective guide for land management.

METHODSSoil, irrigation water, agricultural products and chemical fertilizer from an agricultural park in Xinmadun village, Zhuhai.

RESULTSIt was revealed that the content of Cd in surface soil was relatively high, with the average value 3.7 times higher than the background value in the Pearl River Delta (0.11 mg/kg), classified as moderate pollution scale and serious potential ecological risk. The Cd pollution was related to the long-term cadmium phosphate fertilizer overuse having a mean cadmium phosphate fertilizer content of 20.5 mg/kg. The average contents of Cu, Pb, Zn, Cr, Ni, As, and Hg in surface soil were lower than the soil environmental standard Ⅰ and was classified as low potential ecological risk. The vertical distribution of 8 heavy metals in four soil profiles presented different characteristics, which was influenced by the heterogeneity and discontinuity of the soil. The concentrations of heavy metals in the irrigation water and edible parts of five agricultural products were in compliance with standards. Bok choy and ficus carica had higher potential in enriching heavy metals, while aspartame, jujube and dragon fruit had lower enrichment potential.

CONCLUSIONSIt is suggested to reduce the usage of cadmium phosphate fertilizer in the agricultural park, pay attention to the potential ecological hazard of cadmium, and choose breeds of crop that have weaker heavy metal enrichment capacity.