Heavy metal and metalloid mobilisation and rates of contamination of water, soil and bottom sediments in the Chiprovtsi mining district, Northwestern Bulgaria

Abstract

Geochemical studies of seasonally collected mine, stream and drinking waters, bottom sediments (mine and stream) and soil samples from all mining sections were carried out in order to assess the rates of pollution in the immediate proximity to underground mining facilities and related waste rock dumps. The determined concentrations of studied elements in water (As, Pb, Cu, Zn and Sb) show spatial distribution corresponding to ore mineralisation in different sections. Arsenic concentrations show gradual decrease in west-east direction, whereas Pb concentrations peak in the central and eastern sections. Arsenic and, to a lesser extent, Pb proved to be major pollutants in mine and surface waters, as well as in bottom sediments and soils. Detailed geochemical study of soils revealed strong spatial relation with host rocks and ore mineralogy. Comparisons with state guidelines for harmful elements revealed that alluvial and meadow soils in close proximity to waste dumps contain As, Pb, Cu, Zn and Cd above maximum permissible levels. It was also found that, compared to other Bulgarian and world alluvial (fluvisol) soils and the upper continental crust, the soils in Chiprovtsi mining district are enriched in Te, Re, W, Pd, Au, Ag, Mo, Ti, Mn, Co, Se, Sb, Bi and Cs. Since the processes of weathering and oxidation of mine waste remaining in the area continue naturally, the pollution with As and Pb will presumably carry on with decreasing effect.

Multivariate Exploratory Analysis of the Bulgarian Soil Quality Monitoring Network

“…The PC3 map presents a spatial distribution of elevated factor scores regions coinciding with the ore deposits in Bulgaria, mainly copper, lead–zinc and polymetallic ores ( Figure 4 ). Dimitrova et al [ 40 ] reported higher concentrations of Cu, Zn, As and Pb in northwestern Bulgarian soils caused by mining activities in the region. It has already been mentioned that the largest mining areas are in the central Rhodope zone, the western part of the Balkan zone and the eastern part of the Srednogorie zone, but unexploited ore deposits are also located in the southern central part of the Moesian platform [ 41 ].…”

Ecología microbiana de minas de cobre de seis diferentes regiones geográficas

“…Además, se realizaron análisis estadísticos multivariados como el análisis de componentes principales (ACP), haciendo uso de la librería FactoMineR (Lê et al 2008) y el análisis de correspondencia canónica (ACC) utilizando la librería Vegan (Oksanen et al 2019). Los datos físicos y químicos de las minas fueron recolectados de los estudios individuales de cada mina y recomendamos revisarlos a profundidad para conocer sus detalles metodológicos (Aguinaga et al 2018, Dimitrova et al 2016, Pakostova et al 2020, Ettamimi et al 2019, Rodrigues et al 2014, Li et al 2019.…”