Cadmium retention and microbial response in volcanic soils along gradients of soil age and climate on the Galápagos Islands. Issue 5 (30th August 2021)

• Record Type: Journal Article
• Authors: Rechberger, Maria V.; Roberti, Daniela; Phillips, Avion; Zehetner, Franz; Keiblinger, Katharina M.; Kandeler, Ellen; Gerzabek, Martin H.
• Is Part Of: Journal of Environmental Quality. Volume 50:Issue 5(2021)
• Page Start: 1233
• Page End: 1245
• Publication Date: 2021-08-30
• Subjects: Agricultural ecology -- Periodicals; Environmental engineering -- Periodicals; Pollution -- Periodicals; 630
• DOI: 10.1002/jeq2.20275
• Languages: English
• ISSNs: 0047-2425

Abstract

Abstract: The behavior of trace metals may vary strongly in the course of volcanic soil development. Cadmium retention in soils is specifically important for some Galápagos islands where agriculture is leading to anthropogenic Cd contamination. To assess the influence of soil development factors on soil Cd retention and toxicity, we performed Cd sorption–desorption experiments with volcanic topsoils from the Galápagos Islands sampled along gradients of (a) substrate age (chronosequence, 1.5–1, 070 ka) and (b) climate (elevation sequence, 47–866 m asl) ranging from arid lowland areas to humid highland areas. Additionally, the effects of Cd toxicity on the soil microbial community composition were evaluated for two soils of the chronosequence. In young volcanic soils, the sorption capacity was very high but decreased rapidly with soil age and increasing elevation. These trends were coupled with decreases in soil weathering indicators (e.g., electrical conductivity, pH, and effective cation exchange capacity) as well as changes in soil mineralogy. Cadmium addition did not influence total phospholipid fatty acids and basal respiration in most soils. However, with increasing Cd concentration, a pronounced reduction in the Gram‐negative/Gram‐positive bacteria ratio (from 0.32 to 0.12) occurred in an old, highly weathered soil with low Cd retention capacity. Our results show that up to 60% of added Cd was only weakly sorbed in old volcanic soils. As a consequence, the old volcanic soils of Galápagos bear the potential risk that the mobile Cd fraction is taken up by soil microorganisms, transferring this element into the food chain. Core Ideas: High Cd retention was found after 1, 500 yr of soil development. Cd sorption capacity decreased with increasing soil age. Cd sorption capacity correlated with electrical conductivity and Fe (hydr)oxide crystallinity. Total phospholipid fatty acids (PLFAs) and soil respiration were unaffected by Cd addition. PLFA composition changed in response to Cd in an old, less well buffered soil.