The potentiation of zinc toxicity by soil moisture in a boreal forest ecosystem

Abstract

Northern boreal forests often experience forest dieback as a result of metal ore mining and smelting. The common solution is to lime the soil, which increases pH, reducing metal toxicity and encouraging recovery. In certain situations, however, such as in Flin Flon, Manitoba, Canada, liming has yielded only moderate benefits, with some locations responding well to liming and other locations not at all. In an effort to increase the effectiveness of the ecorestoration strategy, the authors investigated if these differences in liming responsiveness were linked to differences in toxicity. Toxicity of metal-impacted Flin Flon soils on the oribatid mite Oppia nitens and the collembolan Folsomia candida was assessed, with a view toward identifying the metal of concern in the area. The effects of moisture content on metal sorption, uptake, and toxicity to the invertebrates were also investigated. Toxicity tests with the invertebrates were conducted using either Flin Flon soils or artificial soils with moisture content adjusted to 30%, 45%, 60%, or 75% of the maximum water-holding capacity of the soil samples. The Relative to Cd Toxicity Model identified Zn as the metal of concern in the area, and this was confirmed using validation tests with field contaminated soils. Furthermore, increasing the moisture content in soils increased the amount of mobile Zn available for uptake with the ion exchange resin. Survival and reproduction of both invertebrates were reduced under Zn exposure as moisture level increased. Thus, moisture-collecting landforms, which are often also associated with high Zn concentrations at Flin Flon, have, as a result, higher Zn toxicity to the soil ecosystem because of increases in soil moisture.

Invertebrate biodiversity in apple orchards: agrichemical sprays as explanatory variables for inter‐orchard community differences

“…() noted a potential relationship between magnesium applications and detritivore communities in kiwifruit orchards, suggesting that the relationships between this element and invertebrates involved in decomposition in orchards could profitably be studied in more detail. Toxic effects of boron and zinc in contaminated soils have been shown for invertebrates such as Folsomia candida (Cesar et al ., ; Owojori & Siciliano et al , ; Princz et al ., ) and zinc fertilizer has been shown to alter the physiology of aphids, increasing their production of digestive proteases and lipases (Mardani‐Talaee et al ., ). Clarifying the impacts of fungicides and fertilizers on interactions among plants, microbes and invertebrates involved in decomposition could be a very complex task, especially because recent evidence suggests that relationships between plant quality and insect herbivores may be governed more by variability in nutrients than by their absolute concentrations (Wetzel et al ., ).…”

Toxicity and accumulation of lead and cadmium in the land snail, Archachatina papyracea, in a tropical Alfisol from Southwestern Nigeria

“…Cadmium (Cd) was more toxic than Pb in this study. In many ecotoxicological studies, Cd is usually the most toxic metal to soil organisms (Zhiyou et al 2016;Owojori and Siciliano 2015). The comparatively lower Pb toxicity may be due to its low ability to cross membranes of exposed organisms.…”

Vermibiochar: A Novel Approach for Reducing the Environmental Impact of Heavy Metals Contamination in Agricultural Land

“…Cr harms the alkaline phosphatase, urease, and protease activity. A higher concentration of Zn (>25 ppm in soil) shows a noxious effect on microbial biomass and several types of flora [74]. The schematic description of heavy metals' impact on the soil microbes and enzymes is shown in Figure 2.…”