Toxicology Centre, University of Saskatchewan, Saskatoon, SK, Canada, S7N 5B3.
Toxicology Centre, University of Saskatchewan, Saskatoon, SK, Canada, S7N 5B3.
Chemosphere. 2019 Jul;227:444-454. doi: 10.1016/j.chemosphere.2019.04.090. Epub 2019 Apr 13.
Soil habitat quality is thought to influence metal toxicity via changes in speciation and thereby toxicokinetics. Here, we assessed the toxicokinetic and toxicodynamic effects of habitat quality on mite, Oppia nitens when exposed to zinc (Zn) contaminated soils. Forty-seven soils were ranked into three habitat qualities; high, medium, and low based on biological reproduction of Folsomia candida, Enchytraeus crypticus, and Elymus lanceolatus. From the 47 soils, eighteen soils (comprising of six soils from each habitat quality) were randomly selected and dosed with field relevant concentrations of Zn. Mite survival and reproduction were assessed after 28 days. Total Zn, bioaccessible Zn, Zn bioavailability, Zn body burden, lactate dehydrogenase activity (LDH) and glucose-6-phosphate dehydrogenase (G6PDH) activities of the mites were determined. Zinc toxicity and potency were much less in the high compared to low quality soils and the mites in the high habitat quality soils tolerated higher zinc body burdens (2040 ± 130 μg/g b.w) than the lower habitat quality (1180 ± 310 μg/g b.w). Lower LDH activity (20 ± 2 μU mg) in the high quality soils compared to lower quality soils (50 ± 8 μU mg) suggested that there was less stress in the high habitat quality mites. Despite changes in speciation across habitat qualities, bioavailability of zinc was similar (∼20%) irrespective of habitat quality. Our results suggest that the influence of soil properties on survival is modulated by toxicodynamics rather than toxicokinetics. Restoring habitat quality may be more important for soil invertebrate protection than metal concentration at contaminated sites.
土壤生境质量被认为通过形态变化进而影响金属毒性和毒动学。在这里，我们评估了生境质量对接触锌污染土壤的恙螨 O. nitens 的毒动学和毒效动力学的影响。根据 Folsomia candida、Enchytraeus crypticus 和 Elymus lanceolatus 的生物繁殖能力，将 47 种土壤分为高、中、低三种生境质量。在这 47 种土壤中，随机选择 18 种土壤（每种生境质量各 6 种土壤），并用野外相关浓度的锌处理。28 天后评估螨的存活率和繁殖情况。测定螨的总锌、生物可利用锌、锌生物有效性、锌体负荷、乳酸脱氢酶（LDH）和葡萄糖-6-磷酸脱氢酶（G6PDH）活性。与低质量土壤相比，高质量土壤中的锌毒性和毒性强度要低得多，高质量土壤中的螨能够承受更高的锌体负荷（2040±130μg/g b.w），而低质量土壤中的螨只能承受 1180±310μg/g b.w。与低质量土壤（50±8 μU mg）相比，高质量土壤中的 LDH 活性（20±2 μU mg）较低，这表明高质量土壤中的螨压力较小。尽管生境质量发生了变化，但锌的生物可利用性相似（约 20%），与生境质量无关。我们的结果表明，土壤特性对生存的影响是由毒效动力学而不是毒动学调节的。与污染地点的金属浓度相比，恢复生境质量可能对土壤无脊椎动物的保护更为重要。
