Assessment of Heavy Metal Contamination and Health Risks in “Snow Cover–Soil Cover–Vegetation System” of Urban and Rural Gardens of an Industrial City in Kazakhstan

Abstract

This article investigates the extent of heavy metal pollution in both urban and rural gardens in Pavlodar, which cultivate potatoes and tomatoes. As a city of industrialization, Pavlodar is exposed to emissions from industrial enterprises, transport and stove heating. The city also has the highest incidence of environmental diseases among the population. This study examines the accumulation of heavy metals and metalloid in the snow, their migration into the soil and their accumulation in plants, and assesses the non-cancer and cancer health risks of consuming these vegetables. The results show that the concentrations of trace elements in the solid phase of snow decrease in the following order: Fe (26,000) > Mn (592.5) > Cr (371.3) > Zn (338.8) > Pb (161.9) > Cu (142.5) > Ni (30.9) > As (15.1) > Co (12.1) > Cd (2.6). In soils, the concentrations of elements decrease in the following order: Mn (22,125) > Fe (20,375) > Zn (246.9) > Cr (109.5) > Cu (39.3) > Pb (25.6) > Ni (22.4) > As (9) > Co (6.6) > Cd (0.2). In urban gardens, the snow pollution coefficient was the highest. In rural gardens, the contamination index varied from 0.3 (Cr) to 5.3 (Cd). Magnesium in the soil exceeds the maximum allowable concentration (MPC) by 28.6–35.7 times, and zinc by 1.6–10.9 times. Only zinc and copper exceed the MPC for vegetables. Nickel in potatoes exceeds MPC by a factor of 6 and in tomatoes by a factor of 4.4. The cobalt content in tomatoes exceeds the background value by 2.2 times, with a maximum value of 5.3 times. The risk assessment showed that the non-carcinogenic and carcinogenic risks associated with potato and tomato consumption were low. However, these risks are higher in urban areas than in rural areas.