Do the soft tissues of Helix aspersa serve as a quantitative sentinel of predicted free lead concentrations in soils?

• Published in: Applied soil ecology : a section of Agriculture, ecosystems & environment ecosystems & environment, 2003-02, Vol.22 (2), p.159-165
• Main Authors: Beeby, Alan, Richmond, Larry
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Animal, plant and microbial ecology; Applied ecology; Bioavailability; Biological and medical sciences; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on protozoa and invertebrates; Fundamental and applied biological sciences. Psychology; Lead; Monitoring; Sentinels; Snails; Soil and water pollution; Soil science
• ISSN: 0929-1393; 1873-0272
• DOI: 10.1016/S0929-1393(02)00130-0

Previous research suggests that free metal concentrations in soils are the best correlate of the proportion available for uptake, especially by plants. The same may be true for animals which ingest soil, such as earthworms and gastropod molluscs. Using predictions from a simple model proposed by Sauvé et al. [Environ. Pollut. (1997) 149] and based on soil pH and total soil concentrations, the relationship between free soil Pb and soft tissue Pb concentrations is evaluated in the garden snail Helix aspersa. Five replicate adults collected from 23 sites in England and Wales were partitioned into two tissue fractions and the relationship between their Pb concentrations and those of their native soil was examined using simple regression analysis. Levels in both fractions rose with free Pb concentrations, but the terms of each relationship and its level of significance were greatly influenced by the most contaminated soils. Neither tissue fraction served as an effective sentinel of free soil Pb and the regression coefficient was a poor summary statistic across sites with a large range of contamination. The same was true of Pb concentrations in the whole soft tissues. It may be that free ion concentrations are not indicative of metal availability to animals with a range of mechanisms to assimilate nutrients, perhaps because of undescribed environmental and physiological factors governing assimilation or limiting soft tissue concentrations.