Pollutant accumulation in ecosystem components within the zone of influence of cement production in the Ararat valley

Abstract

Atmospheric dust pollution is a primary manifestation of technogenic pressure of cement plants on adjacent ecosystems. Despite a substantial body of research on individual environmental components in areas affected by cement production, comprehensive studies simultaneously covering abiotic and biotic ecosystem components in the zone of influence of specific plants in the South Caucasus remain scarce. The aim of this study was to assess the spatial patterns of distribution and accumulation of technogenic pollutants in abiotic and biotic ecosystem components within the zone of influence of the Araratcement cement plant (Ararat Valley, Armenia). A comprehensive analysis of pollutant concentrations was carried out in atmospheric deposition, topsoil (0–10 cm), leaves of woody plants (Prunus armeniaca L., Morus alba L.), and surface water and groundwater. Sampling was conducted along radial transects from the industrial site, taking into account the prevailing wind directions. A pronounced aerosol load gradient was identified: the median dust deposition rate at 0.3 km from the source was 168 mg/(m2*day), decreasing to 84 mg/(m2*day) at 3 km (p = 0.008). Pb and Cr concentrations in 
dust from the near zone exceeded control-site values by a factor of 2.1 (p = 0.008). PM10 (52 µg/m3) and PM2.5 (21 µg/m3) concentrations at the impact site (0.7 km) exceeded WHO recommended daily levels by factors of 1.16 and 1.4, respectively, whereas SO2 and NO2 concentrations remained below WHO guidelines, indicating a predominantly particulate nature of contamination. In the impact zone soils (0.5 km), Pb (18.2 mg/kg) and Cd (0.42 mg/kg) concentrations exceeded local control-site values (2 km) by factors of 1.86 and 2.0, respectively (p = 0.008), while remaining below the approximate permissible concentrations. A statistically significant alkaline shift of soil pH by 0.40 units (p = 0.008) was recorded, attributed to the deposition of calcium carbonate and hydroxide with cement dust. Local contrast coefficients were 1.86 for Pb and 2.00 for Cd; the integral PLIcontrol index was 1.93, characterizing a moderately expressed multielement contrast. Pb content in leaves of P. armeniaca (4.2 mg/kg) and M. alba (3.4 mg/kg) was in the upper part of the comparison range used; Ca content exceeded 11 g/kg, which is considered a characteristic marker of cement pollution. The leaf-to-soil ratio BCFleaf was 0.231 for P. armeniaca and 0.187 for M. alba, quantitatively characterizing the integrated leaf Pb load. Surface water exhibited higher Pb concentrations (6.2 µg/L) compared to groundwater (4.1 µg/L, p = 0.016), elevated TDS (512 mg/L) and pH (7.50), though all parameters remained below WHO guideline values. The consistency of spatial pollution 
gradients in all studied media proves the expediency of applying a comprehensive approach to the bioindicative assessment of territories adjacent to cement industry enterprises.