title: A laboratory study on risk assessment of microcystin-RR in cropland.
abstract: The persistence time and risk of microcystin-RR (MC-RR) in cropland via irrigation were investigated under laboratory conditions. In order to evaluate the efficiency of the potential adsorption and biodegradation of MC-RR in cropland and the persistence time of MC-RR for crop irrigation, high performance liquid chromatography (HPLC) was used to quantify the amount of MC-RR in solutions. Our study indicated that MC-RR could be adsorbed and biodegraded in cropland soils. MC-RR at 6.5mg/L could be completely degraded within 6 days with a lag phase of 1-2 days. In the presence of humic acid, the same amount of MC-RR could be degraded within 4 days without a lag phase. Accordingly, the persistence time of MC-RR in cropland soils should be about 6 days. This result also suggested the beneficial effects of the organic fertilizer utilization for the biodegradation of MC-RR in cropland soils. Our studies also demonstrated that MC-RR at low concentration (<10microg/L) could accelerate the growth of plants, while high concentration of MC-RR (>100microg/L) significantly inhibited the growth of plants. High sensitivity of the sprouting stage plants to MC-RR treatments as well as the strong inhibitory effects resulting from prolonged irrigation further indicated that this MC-RR growth-inhibition may vary with the duration of irrigation and life stage of the plants.
authors.affiliation: Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan, Hubei Province 430072, China.
authors.forename: Liu
authors.initials: L
authors.lastname: Bibo
authors.forename: Gong
authors.initials: G
authors.lastname: Yan
authors.forename: Xiao
authors.initials: X
authors.lastname: Bangding
authors.forename: Liu
authors.initials: L
authors.lastname: Jiantong
authors.forename: Liu
authors.initials: L
authors.lastname: Yongding
mesh_terms: D000327:Adsorption; D000383:Agriculture; D001673:Biodegradation, Environmental; D002273:Carcinogens / Q000032:analysis / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D018556:Crops, Agricultural / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D007700:Kinetics; D008387:Marine Toxins; D052998:Microcystins / Q000009:adverse effects / Q000032:analysis* / Q000737:chemistry; D018570:Risk Assessment; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis*
chemical_list: D002273:Carcinogens; D008387:Marine Toxins; D052998:Microcystins; D012989:Soil Pollutants; C063855:microcystin RR