Use of land snails (pulmonata) for monitoring copper pollution in terrestrial ecosystems

Biomonitoring of PAHs and PCBs in industrial, suburban, and rural areas using snails as sentinel organisms

There is a worldwide concern about the presence of persistent organic pollutants (POPs) in the environment because of their toxicity, bioaccumulation, and resistance to degradation. Various conventional monitoring techniques have been used to assess their presence in diverse environmental compartments. Most currently available methods, however, have limitations with regards to long-term monitoring. In the present work, juvenile Cornu aspersum (O. F. Müller, 1774) snails were tested in field microcosms as biomonitors for two major classes of organic pollutants, namely, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). The study assessed their deployment in one suburban, one rural, and two industrial sites over an 18-week period and monitored for temporal variations of 16 PAHs and 22 PCBs. Sampling was conducted once every 3 weeks. Targeted pollutants were extracted from the caged snails using the QuEChERS extraction procedure and subsequently analyzed using gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). The results showed that the bioaccumulation of specific pollutants was site dependent; significantly higher levels of PCBs were observed at the industrial sites as compared to the suburban and rural ones. PAHs were bioaccumulated by the snails via ingestion of air and soil whereas PCBs were mainly bioaccumulated via soil contact and ingestion. The findings of this study indicate that C. aspersum is a reliable model organism for the biomonitoring of organic pollutants in air and soil compartments and can be used as part of an integrated environmental assessment.

Field evaluation of metal bioaccumulation in the gastropod Helix aspersa at agricultural and industrial sites in Lebanon

Juvenile Helix aspersa Müller exposed in field microcosms were used to assess the spatial and temporal bioaccumulation of Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn at two agricultural and two industrial sites in Lebanon. The study was performed over a 12-week period where caged snails were sampled once every 3 weeks and assessed for metal bioaccumulation and partitioning between soft tissue and shells. Results showed that metal bioaccumulation by snails was site dependent, with Fe and Cd being the greatest and least accumulated metals, respectively. Significant differences between bioaccumulation in each of the matrices (soft tissue and shells) were also observed. Time-dependent bioaccumulation results showed an increasing accumulation trend at both agricultural sites, while a slight decline was observed at the end of the sampling campaign for the industrial sites. The study of the bioaccumulation factors (BAF) revealed that tested H. aspersa were macroconcentrators for Zn and Cd (BAF > 2) and deconcentrators for all other analyzed elements (BAF < 1). The high partitioning factor values obtained for Cu and Zn indicate an affinity of these two elements for the soft tissues of the snails. The results of this field study indicate that H. aspersa are well suited for active biomonitoring and could provide reliable information on metal pollution and bioavailability.

Effects of Cadmium Sulfate on the Brown Garden Snail Cornu aspersum: Implications for DNA Methylation

An extensive literature exists regarding the cellular, physiological, and genetic effects of cadmium (Cd)—A highly toxic, but commonly used trace metal in modern industry. However, limited data are available on its epigenetic effects, especially for terrestrial sentinel invertebrates. We determined Cd retention, total DNA methylation, and the methylation status of 5′ end of the Cd-MT gene in the hepatopancreas of the brown garden snail, Cornu aspersum, fed Cd sulfate for four weeks. Bodyweight changes and survival were also measured. Hepatopancreas cadmium increased in a dose-dependent manner from the third-lowest dose onward, with very large amounts being found for the highest treatment group. However, no mortalities occurred, irrespective of dietary Cd dose. We identified significant genome-wide hypermethylation in specimens given the highest dose, which overlapped with a significant bodyweight decrease. The Cd-MT gene showed an unmethylated 5′ end of the Cd-MT gene and this status was not affected by cadmium exposure. Hepatopancreas DNA methylation is as sensitive as bodyweight to non-lethal concentrations of dietary Cd given as cadmium sulfate but less responsive than tissue accumulation. Such an exposure event, by contrast, does not affect the methylation status of the Cd-MT gene 5′ end.

Potential Ecological and Human Health Risks of Heavy Metals in Soils in Selected Copper Mining Areas-A Case Study: The Bor Area

Surface soil samples were collected near the Open Pit Bor (S1) and Open Pit Cerovo (S2), a grassland along the Borska Reka River (S3) and an unpolluted garden near Slatina village (reference site). Spontaneous plants (dandelion, nettle, coltsfoot, and creeping buttercup) and vegetables (onion, garlic, carrot, parsley, celery, potatoes, dill, and sorrel) were obtained from the former three sites and the reference site, respectively. The samples were analyzed for Zn, Cu, Fe, Mn, and Pb via FAAS. Pollution indices indicated low-to-moderate soil contamination at sites S1, S2, and S3. Cu was the main contaminant of environmental concern, being above the maximum admitted concentration at site S1. Metal levels in spontaneous plants were below phytotoxic levels. Cu content of leafy vegetables and celery roots and Pb content of most vegetables were not safe for human consumption. Metal concentrations tended to be significantly lower in plants than in soils, with only Cu occurring at significantly elevated levels in celery roots and sorrel leaves. Non-carcinogenic risk assessment showed that consumption of carrot roots and especially celery roots grown on unpolluted soils from the Bor area might pose long-term health risks for females and males, with the main contributors being Cu and Fe.

Effect of Copper Sulphate (CuSO4) on Freshwater Snail, Physa acuta Draparnaud, 1805: A Histopathological Evaluation

In this study, freshwater snail (Physa acuta) was investigated to determine histopathological effects of CuSO₄ on digestive gland, foot, mantle and ovotestis under laboratory conditions. The snails were exposed to different sublethal concentrations of CuSO₄ (0.05 mg/L, 0.1 mg/L and 0.2 mg/L) periods of 10, 20 and 30 days. The relationship between CuSO₄ concentration and mortality rate in snails was calculated as Y = 8.8 + 125.14X, R² = 0.9444. The histopathological examinations revealed that CuSO₄ caused significant histopathological changes in all the tissues of the snail. The severity of these lesions in tissues increased with increasing CuSO₄ concentration and duration of exposure. The results showed that freshwater snail, Physa acuta can be considered to be a suitable bioindicator to demonstrate the toxic effect of copper in aquatic environments.

A novel exploratory chemometric approach to environmental monitorring by combining block clustering with Partial Least Square (PLS) analysis

Background

Given the serious threats posed to terrestrial ecosystems by industrial contamination, environmental monitoring is a standard procedure used for assessing the current status of an environment or trends in environmental parameters. Measurement of metal concentrations at different trophic levels followed by their statistical analysis using exploratory multivariate methods can provide meaningful information on the status of environmental quality. In this context, the present paper proposes a novel chemometric approach to standard statistical methods by combining the Block clustering with Partial least square (PLS) analysis to investigate the accumulation patterns of metals in anthropized terrestrial ecosystems. The present study focused on copper, zinc, manganese, iron, cobalt, cadmium, nickel, and lead transfer along a soil-plant-snai food chain, and the hepatopancreas of the Roman snail (Helix pomatia) was used as a biological end-point of metal accumulation.

Results

Block clustering deliniates between the areas exposed to industrial and vehicular contamination. The toxic metals have similar distributions in the nettle leaves and snail hepatopancreas. PLS analysis showed that (1) zinc and copper concentrations at the lower trophic levels are the most important latent factors that contribute to metal accumulation in land snails; (2) cadmium and lead are the main determinants of pollution pattern in areas exposed to industrial contamination; (3) at the sites located near roads lead is the most threatfull metal for terrestrial ecosystems.

Conclusion

There were three major benefits by applying block clustering with PLS for processing the obtained data: firstly, it helped in grouping sites depending on the type of contamination. Secondly, it was valuable for identifying the latent factors that contribute the most to metal accumulation in land snails. Finally, it optimized the number and type of data that are best for monitoring the status of metallic contamination in terrestrial ecosystems exposed to different kinds of anthropic polution.