Abstract
This article is based on extensive biogeochemical research conducted in Moscow’s Eastern Administrative District, where motor-vehicle traffic and heavy industry have resulted in some of the highest levels of pollution in the city. For this study, 26 samples of maple leaves (Acer platanoides) and 49 samples of dandelion leaves (Taraxacum officinale) were collected on a regular grid at 500–700 m intervals. Concentrations of Fe, Mn, Mo, Cd, Pb, Zn, Cu, As and Sb in these plants were measured using atomic absorption spectrometry after washing, drying and HNO3 + H2O2 digestion. Maples accumulated Sb9,7As4,6Mo2,2Fe2,0Zn1,5 Pb1,4Cu1,2, while dandelions accumulated Mo12,7Pb4,9Cd4,4Fe4,3As3,9Sb2,7Cu1,4 — normalized to concentrations in background samples from an unpolluted site west from Moscow. The plants’ geochemical specialization was detected and compared in the following land-use areas: industrial, traffic, recreational, agricultural, and high-, mid-, and low-rise residential development. For maples, the highest concentration factor levels were found in industrial areas, with accumulations of Sb19As2,4Mo1,7Zn1,7Fe1,5Cu1,4Pb1,4. These levels were 2–5 times lower for maples in other land-use areas. Dandelions and maples do not accumulate Mn because of antagonism between Zn, Mo and Mn in soils. Copper is not concentrated by herbaceous species because of antagonism between Mo and Cu. Differences in eochemical specialization were shown using the Sb/Mo ratio: in dandelions this was 5 times lower than in background samples, while in maples it was 4.5 times higher. A Zv ratio was used to evaluate the intensity of biogeochemical transformation in urban plants. The highest Zv ratios were found in plants near industrial zones and large roads.
Highlights
Cities are often sites of concentrated pollution resulting from dense population and industrial production
The present study focuses primarily on biogeochemical characteristics found in washed samples of maple and dandelion leaves, determining the rate of geochemical transformation for plants in comparison with background samples, and identifying spatial differences in the accumulation of Mn, Fe, Pb, Cu, Zn, Cd, Mo, Sb and As
Levels of heavy metals and metalloids (HM) were detected in leaves of woody and herbaceous plants
Summary
Cities are often sites of concentrated pollution resulting from dense population and industrial production. In Russia, as in many countries worldwide, the ecological situation in urban areas is near critical [Bityukova et al, 2011]. Cities consume 75% of the world’s resources while occupying only 2% of the land. More than half the world’s population — 3.6 billion people — live in urban areas, and by 2025 this population is projected to reach 58%, or 4.6 billion people [World Urbanization Prospects, 2011]. In Russia, 73% of the population — 103 million people — live in 1,060 cities and 2,070 townships [Ekologiya..., 2004]. Pollutants accumulate in various parts of the urban landscape, including soil, atmospheric dust, snow cover, water, plants and animals.
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