Effect of Industrial Effluents of Zob-Ahan on Soil, Water and Vegetable Plants
Hamid Reza Rahmani
Monitoring harmful chemicals especially heavy metals in industrial effluent for prevention and degradation of natural resources are required. The Effluent Water (EW) of Zob-Ahan (steel industrial complex), were seasonally collected, three times during 48 h period. The soils, well-water and vegetable plant samples were collected in land irrigated with EW and soil in adjacent virgin lands. The EW EC, TDS, BOD, COD, sulfate, chloride, bicarbonate, N-NO3 and Cd, Co and Cr were above permissible limit, for wells water in the down side of evaporation ponds EC, TDS, N-NO3, sulfate, chloride, bicarbonate and concentration of Cu, Co, Fe and Cr were above permissible limit and the soils treated with EW Zn, Mn and Cd concentration were in critical range. Soils irrigated with EW had higher OC content and available concentration of Cd, Fe, Cu, Mn, Zn and Pb compared to control sample (adjacent virgin land). In vegetable plants, all measured heavy metals concentration (except Cu content in Taree Irani that was in critical rang) was in normal range. The heavy metals concentration in unwashed plant samples were higher than washed ones. The results showed that Zob-Ahan EW has limitation for application as irrigation water, discharge into surface and subsurface water. Therefore, the EW, should properly be treated before discharging into environment. The heavy metals in soil and well-water affected by EW and irrigated plants with EW should regularly and closely be monitored.
The contamination of water resources in arid region is a serious problem. In such region the irrigation water resources are limited and should be prevented from contamination. In arid and semi-arid area, industrial effluent water utilize as a source of irrigation water. Eventhought, the land application of irrigation water is an easy and least expensive method of disposal however, long-term land application of EW may cause excessive accumulation of heavy metals such as Cr, Ni, Cd, in soil and toxicity in plants (Torabian and Baghuri, 1996).
The accumulation of heavy metals in environmental samples such as plants, sediments, soils, sewage sludges, solid residues, etc. is a potential risk to human health due to their transformation and their uptake by plants and their subsequent introduction into the food chain (Cid et al., 2002).
Cadmium (Cd) and Lead (Pb) accumulation in soil are among the main environmental concerns. Cd is highly toxic to animals and plants (Di Toppi and Gabrielli, 1999). In plants exposure to Cd causes reductions in photosynthesis, water and nutrient uptake (Di Toppi and Gabrielli, 1999). When Cd concentration exceeds 100 mg kg‾1 the plant growth rate decreases (Malakoti et al., 2000). The soil permissible Cd concentration is about 0.5 mg kg‾1 (Malakoti et al., 2000). The permissible concentration of Cd in soil which does not adversely affect plant growth and quality and EW application to agricultural land is 3 mg kg‾1 (Malakoti et al., 2000).
The application of wastewater and sludge in agricultural lands generates numerous sanitary problems (Abedi and Najafi, 2001). In Taiwan more than 800 ha of land has been contaminated with industrial EW. The mean brown rice concentration of Cd, Cr, Cu, Pb and Zn were 0.07, 0.16, 2.48, 0.43 and 39.2 mg kg‾1, respectively (Chen, 2000). Study of the 5 regions in Taiwan show that the soils are containing high level of Pb, Cd and other heavy metals. The Cd, Pb and Zn concentrations were ranging from 175 to 378, 252 to 3145 and 100 mg kg‾1, respectively (Chen, 2000).
Esfahan Province is located in a semi-arid to-arid region in central part of
Iran, where the water resources are scare and water quality should be preserved.
Due to, establishment and rapid expansion of various industries, the environmental
contamination of region by heavy metals are among main environmental concern.
The objectives of this study were to study the properties of Zob-Ahan steel
industrial complex EW and effect of application EW on heavy metals concentration
on soil, water, vegetable plants.
MATERIALS AND METHODS
Zob-Ahan steel industrial complex is located 22 km East of Esfahan City which
has gone through several expansion phases. It daily consumes about 86400 m3
water and produces 14400 m3 EW. The EW of Zob-Ahan after partial
treatment use for irrigation of agricultural land and woody plants. This research
did in agricultural lands (around of Zub-Ahan) in 2003. During a one-year period,
the EW was seasonally sampled for 48 h (any sample removed in 8 h periods and
samples in 48 h mixed and made one complex sample). In 15 locations soil from
0 to 20 cm in agricultural land irrigated with EW and in the virgin land, were
sampled in three replicates. Water from four irrigation-wells, adjacent to land
irrigated with EW; in the down side of industrial waste evaporation ponds were
sampled. The EW and well-water: pH, EC, TDS, TSS, NO3-N, cations,
anions, BOD, COD and the concentration of heavy metals including Cu, Zn, Mn,
Ni, Co, Cd, Fe, Pb, Cr were measured by standard methods (APHA, 1995). The soil
samples pH, EC, texture, organic matter, cations, anions and concentration of
heavy metals including Cu, Cd, Zn, Fe, Mn, Pb were measured by standard methods
(Page, 1991). The plant samples Basil (Ocymum basilicum) and Allium ampeloprasum
ssp.persicum (Taree IIrani) the concentration of heavy metals, including Cu,
Cd, Zn, Fe, Mn and Pb were measured by standard methods (Robert, 1990). The
results were compared with the standard permissible concentration levels (IEPO,
1994; EPA/ROC, 1989; Allaway, 1990; Pendias and Pendias, 1992).
RESULTS AND DISCUSSION
Comparison of the results of analysis of EW (Table 1) with
the permissible levels (IEPO, 1994; Ayers and Westcot, 1985), show that for
discharge EW into surface and absorption wells, the COD, BOD, TSS, TDS, EC,
NO3-N, Cl‾ and SO42‾ and for utilization
of EW for irrigation water, the TDS, EC, SAR, HCO3‾, NO3-N,
Cl‾, Na+ and SO42‾ are the limiting
factors. The chemical properties of EW from this study are similar to Yazd City
textile and industrial EW (Rahmani, 1998). None of the measured concentration
of heavy metals exceeded the threshold levels for discharge into surface water
and absorption well (IEPO, 1994). Cobalt (Co) concentration is higher than permissible
level for utilization of EW for irrigation water. Comparing the results with
the United State Environmental Protection Agency (EPA) standards shows concentration
of Cr, Co and Cd exceed the permissible level for irrigation water (EPA/ROC,
|| The chemical properties and range of concentration of heavy
metals in EW and Well water compare to permissible limit
|| Mean available concentration of heavy metals in polluted
soil compare with non polluted soil (virgin land)
|| Mean total concentration of heavy metals in soil samples
compare with normal and critical range (Allaway, 1990; Pendias and Pendias,
||Mean concentration of heavy metals in washed and unwashed
plant samples compare to normal and critical range (Allaway, 1990; Pendias
and Pendias, 1992)
|*: Less than detection level
Heavy metals may accumulate in soil as the result of long-time application
of industrial EW within the range of permissible concentration level. Therefore,
for EW discharging into surface water, absorbtion well, or land irrigation monitoring
the heavy metals concentrations in soil are required.
The results of well-water properties in the down side of evaporation ponds
(Table 1) shows that the well-water limiting chemical properties
are: salinity, bicarbonate, TDS, NO3-N, Cl‾, SO42‾
and SAR. The utilization of well water for direct human and animal consumption
have serious limitation and requires special treatments for irrigation of agricultural
land. The comparison of the result of concentration of heavy metals with the
permissible level (IEPO, 1994) shows that Iron concentration is the limiting
factor for discharge into surface water or into absorption wells. Investigation
of underground water (well-water) in the EW irrigated land in the Yazd City
shows that concentration of non of the Cr, Cu, Zn, Cd and Pb exceed permissible
level (Rahmani, 2001) while others report contamination of soil, surface and
ground water, due to discharge of EW into environment and utilization as irrigation
water. The well-water and associated irrigated land should be monitor closely,
due to high concentration level of heavy metals. The well-water concentration
of Co and Fe for irrigation are higher than permissible levels (IEPO, 1994).
The well-water concentration of Fe, Cu, Cr and Co are higher than permissible
level for crop lands irrigation (EPA/ROC, 1998).
The available concentration of heavy metals in well-water treated soil is considerably
higher than control (Table 2 ), which shows the gradual accumulation
of heavy metals with time due to application of well-water. The comparison of
the average total concentration of heavy metal in soil irrigated (Table
3) with EW with the permissible level (Allaway, 1990; Pendias and Pendias,
1992) shows that the Pb concentration is in the permissible, the concentration
of Zn and Cd is in critical and Zn and Mn is higher than permissible range,
Considering the results of analysis of heavy metals in soil irrigated with
EW and control (the virgin land) and the high concentration level of various
heavy metals in land, irrigated with EW, it is concluded that the heavy metal
concentration of EW is the limiting factor and significantly (p<0.05) increased
heavy metals concentration in soil compare with control. Also, the total content
of heavy metal in soil have increased more than permissible levels therefore,
has caused soil contamination. Many reports shows that application of untreated
EW may increase the concentration of heavy metals more than permissible level
(Elliott and Stevenson, 1986). In Taiwan, 800 ha of agricultural land irrigated
with industrial EW, the concentration of Cd, Cr, Pb, Zn, Cu were 10, 16, 120,
80 and 100 mg kg‾1, respectively that are higher than permissible
levels according to US. Environmental Protection Agency (USEPA) standards (Frank
and Martinez, 1981). Others report no environmental, hazard has been associated
with land disposal of industrial EW (Elliott and Stevenson, 1986). In general,
many researchers have reported an increase of heavy metals in soils treated
with industrial EW (Elliott and Stevenson, 1986).
The result of heavy metals in Taree Irani (Table 4) shows
that the concentration of Cu in Taree Irani (Allaway, 1990; Pendias and Pendias,
1992) is in critical range and other heavy metals are not limiting. The comparison
of the of heavy metals concentration in Basil (Table 4) with
the permissible and critical levels (Allaway, 1990; Pendias and Pendias, 1992)
shows that heavy metals concentration are in the normal range and are not limiting.
The heavy metals concentration in unwashed plant samples were higher than washed
samples that shows aerosol deposition of heavy metals by industrial pollutant
The EW has not been treated sufficiently and contain higher than permissible concentrations of many hazardous chemicals for discharge into surface water or absorbtion wells. The soil and water resources and plant treated with EW has been contaminated with and the concentration of heavy metals are higher than permissible levels. The increasing trend of hazardous chemical concentrations of soil, water and plant in EW treated area shows the contamination of environment by EW.
1: Abedi, M. and P. Najafi, 2001. Use of Treated Wastewater for Irrigation. Iranian National Committee on Irrigation and Drainage Press, Iran, pp: 248.
2: Allaway, B.J., 1990. Heavy Metals in Soils. Blackie and Son Ltd., Glasgow, London, pp: 177-196.
3: APHA., 1995. Standard Methods for the Examination of Water and Wastewater. 19th Edn., APHA., AWWA. and WEF., USA.
4: Ayers, R.S. and D.W. Westcot, 1985. Water quality for agriculture. FAO Paper. No. 29.
5: Chen, Z.S., 2000. Relationship Between Heavy Metal Concentrations in Soils of Taiwan and Uptake by Crops. ROC, Taiwan.
6: Di-Toppi, L.S. and R. Gabrielli, 1999. Response to Cd in higher plants. Environ. Exp. Bot., 41: 105-130.
7: Elliott, L.F. and F.J. Stevenson, 1986. Soils for Management of Organic Waste and Waste-Water. ASA, Madison, WI., USA., pp: 650.
8: EPA/ROC, 1989. Final Reports of Heavy Metals Contents in Taiwan Agricultural Soils. Vol. 4, ROC, Taiwan.
9: EPA/ROC, 1998. Environmental information of Taiwan. ROC, Environmental Protection Agency (EPA), Taipei, Taiwan.
10: Frank, M.D. and J.A. Martinez, 1981. Municipal Waste-Water Irrigation Agriculture. Academic Press, New York, pp: 358-362.
11: IEPO (Iranian Environmental Protection Organization), 1994. The standards for discharging effluent water. The Research Deputy of Iranian Environmental Protection Organization.
12: Malakoti, M.J., M. Torabi and H. Tabatabaei, 2000. The hazardous effect of Cd and the methods of reducing Cd concentrations in agricultural products. 1st Part the Technical Bulletin 87. Ministry of Agriculture. Soil and Water Research Institute.
13: Page, A.L., 1991. Methods of Soil Analysis. 2nd Edn., ASA and SSA, Madison, WI., USA.
14: Kabata-Pendias, A. and H. Pendias, 1992. Trace Elements in Soils and Plants. 2nd Edn., CRC Press, Boca Raton, Florida, Pages: 365.
15: Rahmani, H.R., 1998. The chemical characteristics and the concentration of Pb, Cd, Ni heavy metals in the effluent water of industrial factories of Yazd City. J. Environ. Stud. Iran, pp: 31-36.
16: Rahmani, H.R., 2001. The pollutant sources of soil, water and plant in Yazd Province. The Final Report of Approved National Scientific Board. Yazd University, Iran.
17: Robert, I.A., 1990. Methods of Plant Analysis. AOAC, USA.
18: Torabian, A. and A. Baghuri, 1996. Investigation of contamination by application of Industrial and municipal. Effluent water in agricultural land in the southern part of Tehran. J. Environ. Stud. Iran, pp: 31-36.