The Legacy of Mercury Contamination from a Past Leather Manufacturer and Health Risk Assessment in an Urban Area (Pisa Municipality, Italy)

Abstract

An abandoned open green space in the urban setting of the Municipality of Pisa (Tuscany, Italy) has been designed for renewal to foster the development of recreational activities and improve the lives of the surrounding communities. However, the geochemical site characterization revealed Pb, Cu, Zn and Hg concentrations in the soil exceeding the thresholds imposed by Italian regulations for residential use. Pb, Cu and Zn contents likely reflect the effects of urban vehicle traffic, while Hg contamination represents the legacy of a past artisanal tannery that used Hg(II)-chloride in leather processing in the mid-1900s. Mercury is widely distributed in the area, with the highest concentration in the uppermost soil layer, and reaching about 170 mg/kg in the common dandelion rhizosphere. Chemical extractions and thermal desorption experiments have indicated that most Hg is in the elemental free and matrix-bound fraction, with a possible minor amount (less than 4 wt%) of HgS and negligible methylated forms (0.1 wt%). The data suggest that soil processes could reduce Hg2+ to volatile Hg0. Mercury in groundwater, hosted in a shallow aquitard in the area, was below 0.2 µg/L. However, the presence of chloride in groundwater might result in the formation of Hg stable aqueous complexes, increasing Hg release from solids. Future water quality monitoring is hence recommended. The risk assessment highlighted that mercury in soil carries a risk of non-cancerous effects, in particular for children, posing the basis for management planning.

Trace Elements in Soil and Urban Groundwater in an Area Impacted by Metallurgical Activity: Health Risk Assessment in the Historical Barga Municipality (Tuscany, Italy)

“…Human receptors have been identified with both adults and children. The Hazard Quotient (HQ) for non-carcinogenic chronic (long term) effects in humans was calculated for each exposure pathway [ 26 ]. In case of direct ingestion and dermal contact, HQ (i.e HQ ingestion and HQ derma l) was calculated by dividing the chronic daily intake (CDI, mg/kg/day) by the corresponding reference dose (RfD, mg/kg/day) [ 27 , 28 ], defined as the maximum daily exposure to a toxic agent that would not produce any appreciable deleterious effects on human health: where CDI represents the exposure to a toxic agent, averaged over a long period of time, through ingestion (CDI ing ) or dermal contact (CDI derm ), given by: where C POE is the exposure point concentration of contaminant in soil (mg/kg), equal to the concentration at the source (Cs) for direct exposure pathways.…”

Groundwater Quality Variations in Multiple Aquifers: A Comprehensive Evaluation for Public Health and Agricultural Use

“…The Hg can transform into methylmercury, a highly toxic form that can accumulate in fish and contaminate water bodies [83]. Consuming Hg-contaminated water or fish can cause neurological damage, impaired cognitive function, and developmental issues in children [82,84]. To reduce Hg below standard limits [41], the use of synthetic chelating ligands such as K 2 BDET could reduce mercury concentrations [85].…”

“…Industrial activities like leather manufacturing, mining, and chemical manufacturing can release mercury (Hg) into the environment [11,82]. The Hg can transform into methylmercury, a highly toxic form that can accumulate in fish and contaminate water bodies The manufacturing can also introduce manganese (Mn) and iron (Fe) into the environment through wastewater discharges [89].…”

Arsenic Contamination in Groundwater, Soil and the Food-Chain: Risk Management in a Densely Populated Area (Versilia Plain, Italy)

“…Here, ET represents the exposure time (24 h/day, suitable for a residential area), AT is given by ED × 365 day/yr × 24 h/day and C POE is the concentration in air at the exposure point (mg/m 3 ), calculated by means of the transport model related to the dust inhalation pathway as defined by the ASTM standard [46,55].…”