Department of Biology, McMaster University, Hamilton, ON, L8S 4K1, Canada.
Comp Biochem Physiol C Toxicol Pharmacol. 2013 Jun;158(1):10-21. doi: 10.1016/j.cbpc.2013.03.008. Epub 2013 Apr 6.
We investigated the bioaccumulation and acute toxicity (48 h or 96 h) of Ni in four freshwater invertebrate species in two waters with hardness of 40 (soft water) and 140 mg L(-1) as CaCO(3) (hard water). Sensitivity order (most to least) was Lymnaea stagnalis > Daphnia pulex > Lumbriculus variegatus > Chironomus riparius. In all cases water hardness was protective against acute Ni toxicity with LC(50) values 3-3.5× higher in the hard water vs. soft water. In addition, higher water hardness significantly reduced Ni bioaccumulation in these organisms suggesting that competition by Ca and Mg for uptake at the biotic ligand may contribute to higher metal resistance. CBR50 values (Critical Body Residues) were less dependent on water chemistry (i.e. more consistent) than LC(50) values within and across species by ~2 fold. These data support one of the main advantages of the Tissue Residue Approach (TRA) where tissue concentrations are generally less variable than exposure concentrations with respect to toxicity. Whole body Ni bioaccumulation followed Michaelis-Menten kinetics in all organisms, with greater hardness tending to decrease B(max) with no consistent effect on K(d). Across species, acute Ni LC(50) values tended to increase with both K(d) and B(max) values - i.e. more sensitive species exhibited higher binding affinity and lower binding capacity for Ni, but there was no correlation with body size. With respect to biotic ligand modeling, log K(NiBL) values derived from Ni bioaccumulation correlated well with log K(NiBL) values derived from toxicity testing. Both whole body Na and Mg levels were disturbed, suggesting that disruption of ionoregulatory homeostasis is a mechanism of acute Ni toxicity. In L. stagnalis, Na depletion was a more sensitive endpoint than mortality, however, the opposite was true for the other organisms. This is the first study to show the relationship between Na and Ni.
我们研究了在硬度为 40（软水）和 140 mg L(-1) 作为 CaCO(3)（硬水）的两种水中，四种淡水无脊椎动物物种对 Ni 的生物积累和急性毒性（48 小时或 96 小时）。敏感性顺序（从最敏感到最不敏感）为：Lymnaea stagnalis > Daphnia pulex > Lumbriculus variegatus > Chironomus riparius。在所有情况下，水硬度对急性 Ni 毒性都有保护作用，硬水中的 LC(50) 值比软水中高 3-3.5 倍。此外，较高的水硬度显著降低了这些生物体内的 Ni 生物积累，这表明 Ca 和 Mg 对生物配体摄取的竞争可能有助于提高金属抗性。CBR50 值（临界身体残留）比 LC(50) 值更不依赖于水化学（即更一致），在物种内和跨物种之间相差约 2 倍。这些数据支持组织残留法（TRA）的主要优势之一，即组织浓度通常比暴露浓度对毒性的变化更小。所有生物体的 Ni 全身生物积累均遵循米氏动力学，硬度越高，B(max) 越低，但对 K(d) 没有一致的影响。在所有物种中，急性 Ni LC(50) 值随着 K(d) 和 B(max) 值的增加而增加，即更敏感的物种对 Ni 表现出更高的结合亲和力和更低的结合能力，但与体型无关。关于生物配体模型，从 Ni 生物积累中得出的 log K(NiBL) 值与从毒性测试中得出的 log K(NiBL) 值很好地相关。全身的 Na 和 Mg 水平都受到干扰，这表明离子调节稳态的破坏是急性 Ni 毒性的一种机制。在 L. stagnalis 中，Na 耗竭比死亡率更敏感，但对其他生物则相反。这是第一项表明 Na 和 Ni 之间关系的研究。
