Geogenic cadmium pollution and potential health risks, with emphasis on black shale

Abstract

Cadmium (Cd) is a non-essential trace element that is toxic to humans. Previous studies of Cd in the environment have primarily focused on pollution resulted from anthropogenic sources, but little is known on naturally occurring sources of Cd. This paper aims to review the geochemical distribution of geogenic Cd and associated environmental risk. The source, accumulation, mobility, transportation, and health risk of Cd are discussed in a geo-environmental perspective, with an emphasis on black shale soils. Cadmium generally occurs in sulfides in black shale, and is easily released when exposed to oxygen and water. Leaching of these rocks tends to elevate Cd concentrations in aquatic systems, and may pose the potential to produce acid rock drainage (ARD) as well. Weathering of Cd-rich rocks also elevates soil Cd concentrations, and influence the geochemical species of Cd. Crops grown in these soils tend to accumulate higher Cd and threaten the food safety. Local inhabitant exposed to high geogenic Cd via food chains may experience Cd-related health risk. High Cd concentrations are observed in urine, and renal damage is also detected in Cd naturally enriched area based on low molecular weight proteins in urine. Overall, the findings in literature have provided with insights for potential health risk of Cd in areas with high Cd geochemical background levels, particular for the black shale exposed areas, more attentions should be paid on the geogenic Cd pollution, and suitable strategies of remediation and geo-environmental management for geogenic Cd pollution need further research.

Spatial Distribution and Pollution Assessment of Potentially Toxic Elements in Urban Forest Soil of Nanjing, China

“…Therefore, zinc and copper pollution were caused not only by traffic and industrial origin, but also by pesticide, fertilizer, and sewage irrigation widely used in greening and daily life waste. Many researchers revealed that fertilizer with high content of Cu and Zn was a source of long-term soil contamination [47][48][49]. Spatial distribution characteristics of metals in the study area suggested that seven elements in urban forest soils of Nanjing were anthropogenic sources: industrial origin, traffic origin, fertilizer and pesticides, which were in total agreement with the PAC and CA results.…”

Molecularly Imprinted Polymers for Removal of Metal Ions: An Alternative Treatment Method

“…Cadmium is a poisonous and cancer-causing metal that can happen as a food contaminant and worldwide pollutant. Long-term occupational exposure to high cadmium concentrations may cause lung cancer, kidney and bone damages and hematuria [34]. Variance exists on the maximum advisable concentration limit of several metal ions in water.…”

Cadmium distribution in Pb-Zn slags from Upper Silesia, Poland: Implications for cadmium mobility from slag phases to the environment

“…The major natural carrier of Cd are sulphides: sphalerite and pyrite (Schwartz, 2000) with sphalerite showing a rather limited range of Cd concentrations from 0.2 to 1 wt % (Cook et al., 2009). Direct weathering of Cd-bearing ore releases Cd to the environment (Liu et al, 2017), where, depending on the conditions, it can precipitate as Cd-bearing carbonates and sulphosalts (Cabala and Teper, 2007) as well as Cd sulphide -greenockite (e.g. Mogessie et al, 2009).…”