饲料中Pb和Cd在中华绒螯蟹体内的吸收与释放特性

为获知饲料中重金属与中华绒螫蟹各组织间的富集与释放特性,应用生物富集双箱动力学模型,模拟中华绒螫蟹分别在Pb含量为10.21、22.01、40.81 mg/kg,Cd含量为1.78、2.80、4.48 mg/kg的饲料驯养过程中,其鳃、肝胰腺和肌肉对Pb和Cd的生物富集与释放特性,为Pb与Cd在中华绒螫蟹体内的分布、富集和迁移提供理论依据,为中华绒螫蟹安全生产提供指导。同时通过非线性拟合得到中华绒螫蟹对饲料中Pb和Cd的富集速率常数k_1、排出速率常数k_2、生物富集系数BCF、生物半衰期B_(1/2),富集平衡时生物体内Pb和Cd含量CAmax等动力学参数。结果显示:①中华绒螫蟹对饲料中的Pb和Cd具有明显的富集,蟹鳃、肝胰腺和肌肉中Pb的含量与富集时间和饲料中Pb的添加量表现出了很好的正相关,在富集的第48天,各组织器官中Pb的含量达到最大,在鳃中的含量分别为0.18、1.14、1.27和1.91 mg/kg;肝胰腺中含量分别为1.00、2.17、2.33和3.50 mg/kg;肌肉中含量分别为0.18、0.73、1.00和1.35 mg/kg。鳃和肝胰腺对饲料中Cd的吸收与Pb情况类似,在富集的第48天,4个饲料组蟹鳃中的浓度值均达到最高,分别为0.026、0.073、0.107和0.154mg/kg;肝胰腺除了在C组实验的第24天含量达到最高,为1.90mg/kg外,其他3组实验,在富集的第48天含量达到最高分别为0.33、1.05和1.24 mg/kg,C组在第48天的含量有所降低,为1.76 mg/kg。但是肌肉中Cd含量没有明显的规律。②中华绒螫蟹对Pb和Cd的生物富集和释放都较缓慢。达到平衡状态时,鳃、肝胰腺、肌肉各组织器官中Pb含量分别为1.07~1.69、4.87~4.95、0.79~1.28 mg/kg,鳃、肝胰腺中Cd含量分别为0.06~0.14和1.25~2.66 mg/kg。Pb和Cd在组织器官中的生物富集系数(BCF)范围分别为0.03~0.48和0.03~0.87,中华绒螫蟹对Cd的富集能力明显高于Pb;Pb和Cd在各组织器官的生物学半衰期(B_(1/2))范围分别为9~67 d和8~48 d。中华绒螫蟹对Pb的排除能力明显低于Cd。③Pb和Cd在中华绒螫蟹组织器官中的富集具有选择性,在经不同含量Pb和Cd的饲料驯养后得到统一含量分布规律:肝胰腺鳃肌肉。

In vivo absorption and release characteristics of Pb and Cd in diet in Eriocheir sinensis

To learn more about the enrichment and release characteristics of heavy metals in the feed and the tissues of Eriocheir sinensis, kinetic parameters were gained for biological accumulation and release of two heavy metals Pb and Cd in gill, hepatopancreas and muscle of E. sinensis, by using two-compartment bioconcentration model to carry out the experiment in which the crabs were exposed to the feed with Pb concent of 10.21 mg/kg, 22.01 mg/kg, 40.81 mg/kg, and Cd concent of 1.78 mg/kg, 2.80 mg/kg, 4.48 mg/kg, so as to provide theoretical basis for the distribution, migration and enrichment, and provide guiding significance for safe production eriocheir sinensis for Pb and Cd in E. sinensis. Heavy metal uptake rate constant (k₁), extracting rate constant (k₂), bioconcentration factor (BCF) and biological half-lives (B_1/2), equilibrium concentration of heavy metals in vivo C_Amax were obtained by non-linear curve fitting. The results showed:(1) The concent of Pb in crab gill, hepatopancreas and muscle exhibited an apparently positive correlation to the accumulation time as well as the concent. On the forty-eighth day of enrichment, the content of Pb in each tissue reached the maximum, the content in gill was 0.18 mg/kg, 1.14 mg/kg, 1.27 mg/kg and 1.91 mg/kg respectively; Content in hepatopancreas was 1.00 mg/kg, 2.17 mg/kg, 2.33 mg/kg and 3.50 mg/kg respectively; Content in muscle was 0.18 mg/kg, 0.73 mg/kg, 1.00 mg/kg and 1.35 mg/kg respectively; The accumulation of Cd in gill and hepatopancreas presented the similar results to that of Pb.On the forty-eighth day of enrichment, the content of Cd in gill reached the maximum, the content of was 0.026 mg/kg, 0.073 mg/kg, 0.107 mg/kg and 0.154 mg/kg respectively. In addition to the twenty-fourth day of the group C, the content of the hepatopancreas reached the highest,was 1.90 mg/kg; The other 3 groups of experiments, the highest content was reached in the enrichment of forty-eighth days, it was 0.33 mg/kg, 1.05 mg/kg and 1.24 mg/kg respectively. In group C, the content of forty-eighth days decreased, it wsa 1.76 mg/kg. But there was no obvious rule of Cd in muscle. (2) The accumulation and release of Pb and Cd were both slow in tissues and organs of E. sinensis. At steady state the concentration of Pb in crab gill, hepatopancreas and muscle ranged from 1.07 mg/kg to 1.69 mg/kg, 4.87 mg/kg to 4.95 mg/kg, 0.79 mg/kg to 1.28 mg/kg, the concentration of Cd in crab gill, hepatopancreas ranged from 0.06 mg/kg to 0.14 mg/kg, 1.25 mg/kg to 2.66 mg/kg. The bioconcentration factor (BCF) of Pb and Cd in the tissues and organs ranged from 0.03 to 0.48 and 0.03 to 0.87, respectively, indicating that the absorption of Cd was much more higher than that of Pb in E. sinensis. The biological half-lives of Pb and Cd in the tissues and organs (B_1/2) ranged from 9 to 67 d and 8 to 48 d, which signified that the release of Cd is significantly slower than that of Pb. (3) Pb and Cd were accumulated selectively in the major organs and tissues in E. sinensis. After feeding with the feed, Pb and Cd were distributed in the same way, namely, hepatopancreas > gills > muscle.