Study On Bioaccumulation And Biodegradation Of Or Ganotin In The Undariapinnatifida

Bioaccumulation and biodegradation of organotin in the Undaria pinnutifida were examined in this paper in order to provide scientific evidences for food safety assessment of cultivated U. pinnatifida. New detective methods based on LSE-GC-PFPD techniques were established to determine organotin in the seawater and in the alga. Temporal and spatial distribution of organotin in U. pinnatifida and its influencing factors were clarified using U. pinnatifida cultivated in Jiaozhou Bay. Qingdao. Bioaccumulation and biodegradation of TBT and TPT in U. pinnatifida were also revealed by culture experiment under simulated environmental conditions.1. Establishment of detective methods to determine organotin in the seawater and in the alga Undariapinnatifida.Based on LSE-GC-PFPD technuques, two methods were established respectively to determine fentin chloride (TPT), diphenyltin dichloride (DPT), phenyltin trichloride (MPT), Tetrabutyltin (TeBT), Tri-n-butyltin chloride (TBT), dibutyltin dichloride (DBT), butyltin trichloride (MBT), dimethyltin dichloride (DMT) simultaneously in the seawater and in U. pinnatifida. In seawater, the recovery of eight kinds of organotin under the concentrations of 10,25,50, and 100 u,g/L ranged from 72.94% to 123.14%. The relative standard deviation ranged from 1.23% to 13.2%. These results suggests that this method was a reliable method with high accutacy for determination of organotin in seawater. All compounds showed good linearity on the tested range 5~300 μg/L with correlation coefficient R2>0.991. The limits of detection (LODs), which were calculated as a signal to noise ratio of 3, were 1.53～4.23 μg/L for all organotin compounds. Results showed that the limit of detection was low and suitable for determination of trace amount of organotin in seawater.In U. pinnatifida, the recovery of eight kinds of organotin under three concentrations 25,50,100 μg/L ranged from 72.22% to 116.39%. The relative standard deviation ranged from 0.60% to 11.09%. These results showed that this method was accurate and reliable. All compounds showed good linearity on the tested range 10～300μg/L with correlation coefficient R2> 0.994. The LODs were 0.01-0.033 mg/kg for all organotin compounds. The method had very good repeatability. Within-day precision of this method ranged from 3.41% to 7.99%(which was expressed as relative standard deviation, RSD) and between-day precision ranged from 3.59% to 7.85%.2. Temporal and spatial distribution of organotin in Undaria pinnatifida and its influencing factorsDMT was the only organotin compound found in the seawater. The content of DMT reached the maximum of 1.1μg/L in January, which was significant higher than those in any other months.Temporal and spatial distribution of DMT was found obvious in U. pinnatifida. At the stage of rapid growth from December to January, the maximum content of DMT was observed at the middle and apica) parts of baldes with a value of 478.11-479.17 μg/kg. With the emergence of sporophyll in February, the maximum content of DMT was found at sporophyll with a value of 317.99 μg/kg. Due to improvement of light and nutrient conditions induced by harvest of large algal individuals in March and April, small individuals entered rapid-growth stage, leading to the maximum content of DMT again at the middle and apical parts of blades with a range of 385.19-472.79 μg/kg. In May, the maximum content of DMT moved down and appeared at the part of meristem, with a value of 423.15μg/kg. The temporal and spatial distribution of DMT may be related to resources storage and transport in U. pinnatifida at the growing and maturing stages.Accumulation of TPT occurred mostly in blade, especially in the apical part of blade. TPT accumulated in blade was transported downward as time going on, so the maximum of TPT was found in holdfast in May. In U. pinnatifida, the degradation of TPT mainly occurred in the top of blade and the degradation products were also transported to the bottom position. The occurrence of MPT in April and May and the disappearance of DPT in May indicated that the degradation process of TPT was IPT�'DPT�'MPT.Contents of TPT in sporophyll, stipe and blade were 3.56-17.40μg/kg FW in U. pinnatifida cultured in Jiaozhou Bay in December to May next year. FAO and WHO stipulate that a man weight 60kg can accept organotin 30μg at most. By this way, U. pinnatifida in this sea area conform the food safety standard, moreover stipe of U. pinnatifida is more safe than blade due to its lower TPT.4、Bioaccumulation and biodegradation of organotin by Undaria pinnatifidaThe rule of bioaccumulation of TBT and TPT by U. pinnatifida depended on algae growth phase, the concentration of organotin and organotin supply pattern. Vigorous growth of U. pinnatifida had higher bioaccumulation capacity than maturity, it showed an increase in the amount of enrichment. The higher concentration of the organotin in the culture medium, the enrichment of U. pinnatifida was greater. The enrichment rule of U. pinnatifida was also related to the organotin supply pattern. In the disposable addition experiment group, the maximum of the enrichment was in the third day, then gradually decreased. However, in the continuity addition experiment group, the rule of the enrichment showed gradually increased with the time going by, vigorous growth of algae reached saturation in the ninth day, while, maturity of algae had not reached saturation even in the twelfth day.The rule of biodegradation of TBT and TPT by U. pinnatifida also depended on algae growth phase, the concentration of organotin and organotin supply pattern. Maturity of U. pinnatifida had higher biodegradation capacity than vigorous growth, it showed an increase in the content of degradation products. The higher concentration of the organotin in the culture medium, the content of degradation products by U. pinnatifida was greater. The degradation rule of organotin was different from the organotin supply pattern, it depended on the content of TBT and TPT in the seaweed. TPT was easier to degrade to MPT, but it required a higher concentration when TBT degraded to MBT.Different growing periods, concentrations of organotin and supply pattern of organotin cause differences of concentrations of TBT and TPT in U. pinnatifida According to the two stipulates, one is the acceptable quantity of TBT per kg each day given by IMO and MHW and the other is for TPT published by FAO and WHO, TBT and TPT of algae in both two periods conform to the food safety standards in disposable addition experiment group at the concentration of 0.5 or 1.0 μg/L, but only TBT conforms in the continuity addition experiment group at the concentration of 0.5μg/L.