Madsen Eric R, Stern Hal S
Great Lakes Indian Fish and Wildlife Commission, P.O. Box 9, Odanah, Wisconsin 54861, USA.
Environ Sci Technol. 2007 Jul 1;41(13):4568-73. doi: 10.1021/es0700294.
Methylmercury data from walleye fillets collected by multiple agencies from northern Wisconsin lakes from 1982 to 2005 were examined for regional time trends. Hierarchical Bayesian methods were used to model dependencies and provide probability statements for parameters pertaining to individual lakes and the region as a whole. A missing data mechanism allowed the sex of the fish to be included as a predictor since the sexes grow at different rates. A slight regional decrease in methylmercury of 0.60% annually was found, consistent with declining atmospheric mercury deposition. Methylmercury was estimated to have decreased in 77% of the 420 lakes from which walleye were sampled, although uncertainty regarding time trends was greater for most individual lakes than for the region as a whole. Methylmercury in walleye varied widely from lake to lake, but generally accumulated in the fish at similar rates by length after accounting for differences in sex. Slower-growing male walleye had higher methylmercury concentrations than females for a given length, and skin-on fillets were 16% lower in methylmercury than skin-off fillets.
对1982年至2005年期间多个机构从威斯康星州北部湖泊采集的大眼狮鲈鱼片甲基汞数据进行了区域时间趋势研究。采用分层贝叶斯方法对相关性进行建模，并为与各个湖泊及整个区域相关的参数提供概率陈述。一种缺失数据机制使得鱼的性别能够作为预测因子纳入，因为不同性别的鱼生长速度不同。研究发现甲基汞在区域内每年略有下降，降幅为0.60%，这与大气汞沉降的下降趋势一致。在采样的420个湖泊中，估计有77%的湖泊甲基汞含量有所下降，不过大多数单个湖泊时间趋势的不确定性要高于整个区域。不同湖泊的大眼狮鲈甲基汞含量差异很大，但在考虑性别差异后，甲基汞在鱼体内通常按长度以相似的速率积累。对于给定长度，生长较慢的雄性大眼狮鲈甲基汞浓度高于雌性，带皮鱼片的甲基汞含量比去皮鱼片低16%。
