Source-sinks Pattern On Organophosphorus Pesticides Under Different Crop Modes Located At The Downstream Of Minjiang River

Pesticide pollution mainly refers to the pesticide and its degradation products contaminating air, water and soil, and destroying ecosystem, causing animals and plants acute or chronic poisoning. Research on pesticide residues in farmland ecosystems is an important content of non-point source pollution. It has an important practical and theoretical necessary to study the input, output, flux and distribution of organophosphorus pesticides (OPPs) under different crop models. It is necessary to understand the flow and distribution of OPPs in farmland. It is also important to establish a systhesis theory to prevent the input from source, to control the distribution in flow direction, and to rehabilitate the pollution.Here the data was obtained from survey and experiment to estimate the monthly average flux of the pesticides input(including precipitation, fertilization, irrigation) and output (including surface runoff, seepage, and crop harvesting) under different cropping patterns (i.e. M1: Zingiber officinale+Lactucapsativap sativa L.var.aspparagina+Z. officinale, M2:Zen mays +Z. officinale+Brassica rapa chinensis, M3:Z. mays+Ipomoea batatas+B. juncea). Spatial and temporal distribution was also analyzed. The results were summarized as follows: (1)In M1,the annual flux of mevinphos, IBP, parathion-methyl, fenitrothion, bromophos, isocarbophos, phenthoate, and methidathion were 25.6,-682.5,186.7,98.2,-58.8,-79.6,-87.0,-113.4mg/hm2 respectively. Thus, the patterns of input-output of IBP, Isocarbophos, Phenthoate, Bromophos and Methidathion,were more justifiability in this mode; The pollutants won't be accumulation in the system.In M2, the annual flux of mevinphos, IBP, parathion-methyl, fenitrothion, bromophos, isocarbophos, phenthoate, and methidathion were-1.8,-267.2,152.9,83.9,119.4,31.4,82.1, and 25.4mg/hm2 respectively. In this mode, the patterns of source-sink of mevinphos and IBP were justifiability. But in the long term, it may accumulate Parathion-methyl, Isocarbophos and Fenitrothion pollutant and result in serious pollution.In M3, the annual flux of mevinphos, IBP, parathion-methyl, fenitrothion, bromophos, isocarbophos, phenthoate, Methidathion were-13.7,-233.1,80.3,80.3,59.6,80.3,14.2,-99.3, and 36.4mg/hm2 respectively. In this mode, the annual flux of mevinphos IBP phenthoate was less than zero. The patterns of source-sink of Fenitrothion and Phenthoate were more justifiability. The remediation was prominent to Fenitrothion and Phenthoatethe pollutionComparing the three crop mode, we found that three planting modes all have some what effects on remediation to organophosphorus pesticide residues pollution. But M1 can repair five category of organophosphorus pesticide pollution in soil, while M2 can only repair two category of them and repairing effect for IBP pollution is not obvious. The M3 can repair three category of organophosphorus pesticide pollution. In comparison, M1 was better than M2 and M3 for pollution remediation.(2)In different planting modes, the rank of total content of organophosphorus pesticide residues in soil is M1>M3>M2. Detected frequency of IBP and Phenthoate in soil samples is 87% and 91.3%.(3)By research on distribution features of total organophosphorus pesticide residues in plants under different crop modes, we found that the rapa chinensis B. had the highest content of organophosphorus pesticide residues while Zen mays L. had the lowest,. The results also showed that I. batatas had the strongest function of enrichment. The distribution of organophosphorus pesticide residues is:on leafy vegetables> rhizome vegetables>grain crop.