Heavy Metal Concentrations in Urban And Peri-Urban Gardens of Dzerzhinsk and Nizhny Novgorod, Russia
O. S. Savoskul1 and P. Drechsel2
1 Institute of Geography, Moscow, Russia
2International Water Management Institute (IWMI)
International Water Management Institute (IWMI)
West Africa Office
c/o CSIR, Accra, Ghana
The objective of this study was the assessment of the heavy metal status of selected urban and peri-urban gardens in two Russian cities known for their industrial production. Topsoil samples (0-10 cm) were taken at various locations in Nizhny Novgorod and Dzerzhinsk and analysed for Cd, Co, Cr, Cu, Ni, Pb, and Zn. In both cities metallurgical industry seems to contribute substantially to the heavy metal burden of the soils. It is possible to refer most peak concentrations to distinct emitters. Thus better emission control could significantly reduce health risks related to urban food production. The general heavy metal concentrations in the study area, however, was significantly lower than e.g. in Berlin, Hamburg, Moscow or London, which was attributed to less traffic and potential leaching due to sandy soil texture.
Keywords: Heavy metals, urban agriculture, Russia.
Environmental problems of large cities and urban-industrial agglomerations are subject of vital discussions since the end of the 70s. The heavy metal pollution of urban soils has been investigated in many cities of Western Europe such as London (Thornton, 1991), Berlin (Blume, 1993) or Hamburg (Lux, 1986) indicating high amounts of anthropogenic inputs. This can have serious health implications especially with regard to crops grown in the city (Birley and Lock, 1999). Environmental data of the territory of the former Soviet Union were not made available to the press or public for a long period (Chertov and Kuznetsov, 1993). However, the situation has changed. Data as well as maps showing different levels and patterns of pollution have been increasingly published (Obukhov and Lepneva, 1990; Agarkova et al., 1994; Kalenikin, 1993, Chertov et al., 1996). However, there is still only a few data available from certain industrial centres in Russia, although it is well documented that the industrial and traffic pollution of air in cities affects considerably the population health in Russia (Feshbach, 1995). Some of these "closed" areas were Dzerzhinsk (300.000 inhabitants) close to Nizhny Novgorod (the former Gorki, with 1.4 million inhabitants), both about 400 km east of Moscow.
Dzerzhinsk is hosting several chemical industries and has been described as one of the most polluted in Russia. There is, however, little information on health issues of the city’s residents, although elevated levels of dioxins and PCBs have been recorded (Lutz, 1997), and there is anecdotal evidence of birth defects and generally shortened life spans among local residents (Blacksmith Institute, 2001). The principal industrial branches in Nizhny Novgorod are car and ship-building and metal-working industry with its typical pollution problems. This study was part of a larger survey of heavy metals in different Russian cities (Drechsel and Wilcke, 1999). The results of this sub-study aimed at (i) providing data on the heavy metal concentrations at various urban agricultural sites, (ii) to get hints on sources of single metals, and (iii) to compare the data with corresponding studies from other European cities.
MATERIALS AND METHODS
Study sites and soils
In Dzerjinsk, known for its organo-chemical industry, samples were taken along two transects crossing the city and its industrial complex from West to East, as well as from North to South, from the pine forest belt to the southern Dacha villages. In Nizhny Novgorod, with one of the largest automobile plants in Russia and other steel-making industry, samples were taken in backyard gardens and all larger recreation parks (e.g. Park Im. Kulibina, Park 1. May, Dubky park) and for comparison along streets and places of different traffic intensity (e.g. Prospect Lenina, Belinskogo uliza, Moscow railway station). Further outside both cities samples were taken for background concentrations.
All analysed soil samples (parks and gardens) are composite samples out of 4-6 representative samplings (0-10 cm) per site. Street samples consist out of 2 or 3 parallel samplings on green strips 2 m beside the roads.
Recently disturbed or deposed material without initial A horizon were not sampled. Auger drillings were used to secure representative sample. Natural upland soils in the whole area belong to the Podzoluvisol belt. Around Dzerzhinsk they were derived from sandy parent material of 20-50 m thickness over karstic limestone. In this region, Histosols and Gleysols are dominant soil types of depressions.
Extraction and Analysis
All results are related to air dry soil < 2 mm. The metal concentrations (except for Cd) were determined with 3 parts concentrated HCl and 1 part concentrated HNO3 for 2 hours at 120oC. Cd was extracted with 3 parts concentrated HNO3 and 1 part concentrated HClO4 on the sand bath until dryness. Afterwards the sample was dissolved in 5 M HNO3 for analysis with graphite tube atomic absorption spectrometry (Varian SpectrAA 400 Z). Hg was determined with the cold vapour technique, all other metals were determined by normal flame technique (AAS 30).
"Mobile" metal fractions were extracted for some of the elements with 1 M NH4NO3 (shaking for 24 hours) and determined as described above.
Texture was estimated with standard procedures. The soil reaction (pH) was measured with 0.01 M CaCl2 (1:2.5), total carbon with the C/N-Analyzer (Elementar vario EL).
Multivariate statistical analysis was performed with SPSS for Windows.
RESULTS AND DISCUSSION
Typical for soils of the podzoluvisol belt, texture is predominantly sandy to loamy. Soil reaction in the cities is dominated by the carbonate buffer system whereas in the outskirts of Dzerzhinsk soils are more acid (Al oxide buffer system). The high pH in the cities, untypical for natural soils of the Podzoluvisol belt, is mainly due to the buffering effect of carbonate-containing materials such as cement or bricks and due to the application of thawing salt (Blume, 1993; Bykov and Lysikov, 1991). The soil organic C concentrations in the sampled topsoils vary broadly but are comparable to naturally developed soils in the study area (Table 1).
Dacha gardens at the southern outskirts of Dzerzhinsk (vegetables, potatoes, apples, fallows/meadows) showed total Cu, Zn and Hg values comparable to background levels, while Cd values appeared in part elevated. Co, Ni, Cr values, on the other side, were similar to those analysed in the industrial area of the city (Table 2). Also mobile Ni values (Table 3) in gardens and meadows exceeded background concentrations.
In the industrial area of Dzerzhinsk, where agriculture is not permitted, transects showed that increasing soil levels of copper (up to 110 mg kg-1) and zinc (150 mg kg-1) could be attributed to the local heat and power plant, while high lead concentrations (235 mg kg-1) were analysed near to the Synthez plant, which is producing tetra-ethyl lead (gasoline additives). These data verify similar source indications via water and sediment analyses by a local environmental NGO (Kolpakova et al., 1995).
Garden samples taken in the inner city of Nizhny Novgorod confirm the health risk through distinct emitters. The most affected vegetable backyards were located about 300 meter from the local "Etna" plant where in part significantly higher Cd, Cr, Cu, Hg, Pb and Zn levels were analysed than on roadside soils and in central city parks (Table 2). Also mobile Zn concentration in these gardens reached 4 ppm exceeding significantly values found along roads and other places in town (Table 3). These high levels cannot be explained by traffic alone but indicate a specific metallurgical source.
Urban and peri-urban farmers in the study area use peat from local Histosols to ameliorate their sandy soils. Peat is often found in depressions of the karstic landscape. At a typical peat-mining site in the pine forest belt of Dzerzhinsk, heavy metal analysis showed top layer concentrations exceeding background concentrations fivefold. These concentrations were, however, below international standards for soil inputs (NRC, 1996).
In most cases, the mean heavy metal concentrations in Nizhny Novgorod (with significantly more traffic) were higher than in Dzerzhinsk, but the values of both cities in average lower than values measured in topsoils of London, Berlin, Moscow or Hamburg (Thornton, 1991, Blume, 1993, Drechsel and Wilcke, 1999, Lux, 1986). This might indicate less traffic but also strong leaching from the topsoil, favoured by sandy texture . Groundwater samples taken in the vicinity of the Dzerzhinsk dachas show 0.15-0.46 ppm Cr, 2.1- 2.5 ppm Cu, 0.003-0.005 ppm Pb, 0.03-0.25 ppm Ni, 0.4-0.9 ppm Zn, 1.5. ppm As and less than 0.001 ppm Hg (DRONT, unpublished). Most of the values exceed European drinking water norms and support the argument of heavy metal leaching in the study area. Exemptions are Hg and Pb which are only mobile at very low (<4; Hg, Pb) or high (>7; Pb) pH.
Heavy metal pollution was analysed in two Russian cities and surrounding dachas. Although the cities are certainly non-representative examples of heavy environmental pollution, general traffic density and analysed metal values were lower than in other European cities, except in the direct vicinity of certain emitters. Emission control measures, which target these distinct emitters, could significantly reduce heavy metal contamination in particularly exposed urban and peri-urban gardens. Corresponding programs have been initiated. As soil texture and karstic landscape favours groundwater contamination, special efforts to safeguard drinking water quality, such as the program "Clean water" have been put in place, too (NNA, 2003).
The authors thank Prof. Wolfgang Wilcke, Germany, for his input into the final analysis of the results as well as the municipal authorities of both cities, Harald Lutz and Greenpeace Russia for their support during the field work.
1 Another reason for the difference could be different sampling depths of 0-10 cm in this study and mostly 0-5 cm in the other cities.
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Table 1. Range of properties of the soil samples on agricultural sites
City Texture pH (CaCl2) Corg N [g kg-1] [g kg-1] Nizhny Novgorod loamy sand - loamy clay 5.0 - 6.0 9 - 49 n.d. Dzerzhinsk loamy sand - sandy loam 4.5 - 5.0 15-57 1.1-3.2
Table 3: Heavy metal concentrations (mobile fractions, mg kg-1) in different parts of the two cities (0-10 cm topsoil)
City parks Streets Gardens/Meadows Background n=5 n=13 n=9 n = 3 Cu <200-400 <100-800 <200 <100 Ni 100-800 <100-1200 100-1500 <100 Co <100 <100 <100 <100 Pb <400 300-1800 <400 500-600 Zn <100-1700 <100-2100 200-4000 700-6500
Table 2: Total heavy metal concentrations (mg kg-1) on different sites in both cities (0-10 cm topsoil)
City parks Streets Agriculture/Forestry Background n=5 n=13 n=19 n = 3 Cd 0.14-0.29 0.15-0.42 0.08-0.61 0.07-0.13 Co 1-13 2-11 5-9 1 Cr 10-32 12-42 12-65 7 Cu 12-19 5-31 (110a) 3-77 5-6 Hg 0.04-0.09 0.03-0.20 0.04-0.13 0.03-0.08 Ni 4-24 7-31 5-77 <5 Pb 19-78 15-235b 10-110 8 Zn 37-80 20-150a 11-245 19-40
a: high values near to power plant
b: high values near Synthez plant
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