Investigation of heavy metals in soil samples before rice planting and after rice harvesting in Mazandaran province; Study of ecological risk potential and integrated pollution indexes

Document Type : Research Paper


1 Department of Environmental Science, Faculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran

2 Department of Environment, Faculty of Natural Resources and Marine Science, Tarbiat Modares University, Tehran, Iran

3 Department of Marine Science, Faculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran


Soil contamination with heavy metals is a serious issue in all the world, and these heavy metals are released from both natural and human resources, especially agricultural activities in the environment. Therefore, in this study, the amount of heavy metals and the indicators of ecological risk potential and integrated pollution in soil samples before rice planting and after rice harvesting in Mazandaran province have been investigated. A mixture of nitric acid, hydrofluoric acid and perchloric acid was used for chemical digestion of soil samples and ICP-MS was used to measure the amount of heavy metals in soil samples. The results of comparing the levels of chromium, zinc, nickel and lead in the soil before rice planting and after rice harvesting with the national and international soil standard show that the levels of these metals in most stations are higher than Domestic and international standard limits were measured. Based on the results, the amount of ecological risk potential index in soil samples showed that in all studied stations ana sampling stages, the amount of this index was calculated in the range of low ecological risk (below 150). Also, the results of PI pollution index and integrated pollution index (IPI) for each studied station in soil samples before rice planting and after rice harvesting show the PI index for arsenic, chromium, cadmium, copper, nickel, zinc and mercury. In all stations in soil samples before rice planting and after rice harvesting in the range of low contamination was calculated, only the amount of this index for lead in all stations and sampling stages, in the range of moderate contamination was obtained. Also, the results of IPI for all studied stations in all stations and sampling stages, show that the level of this index was determined in the low pollution range. In general, the presence of heavy metals in the soil environment, followed by the accumulation of heavy metals in food, has detrimental and irreversible effects on human societies and food security, so more precautions are needed to reduce such effects.


Ahmadi Doabi, S., Karami, M., Afyuni, M., 2016. Regional-scale fluxes of zinc, copper, and nickel into and out of the agricultural soils of the Kermanshah province in western Iran. Environmental Monitoring and Assessment 188(4), 1-18.
Adriano, D.C., 2001. Trace elements in terrestrial environments: biogeochemistry, bioavailability, and risks of metals. New York, Springer, 867 p.
Brevik, E.C., Slaughter, L., Singh, B.R., Stephen, J.J., Collier, D., Barnhart, P., Pereira, P., 2020. Soil and Human Health: Current Status and Future Needs. Air, Soil and Water Research 13, 1-23.
Chen, Y., Jiang, X., Wang, Y., Zhuang, D., 2018. Spatial characteristics of heavy metal pollution and the potential ecological risk of a typical mining area: A case study in China. Process Safety and Environmental Protection 113, 204-219.
Chen, T.B., Zheng, Y.M., Lei, M., Huang, Z.C., Wu, H.T., Chen, H., Fan, K.K., Yu, K., Wu, X., Tian, Q.Z., 2005. Assessment of heavy metal pollution in surface soils of urban parks in Beijing, China. Chemosphere 60(4), 542–551.
Cheng, W., Zhang, G., Yao, H., Dominy, P., Wu, W., Wang, R., 2004.  Possibility of predicting heavy-metal contents in rice grains based on DTPA-extracted levels in soil. Communications in Soil Science and Plant Analysis 35(19-20), 2731-2745.
Çolak, F., Atar, N., Yazıcıoğlu, D., Olgun A., 2011. Biosorption of lead from aqueous solutions by Bacillus strains possessing heavy-metal resistance. Chemical Engineering Journal 173(2), 422-428.
Colombani, N., Gervasio, M.P., Castaldelli, G., Mastrocicco, M., 2020. Soil conditioners effects on hydraulic properties, leaching processes and denitrification on a silty-clay soil. Science of the Total Environment 733, 139342.
ASTM D4698-92, 2007. Standard Practice for Total Digestion of Sediment Samples for Chemical Analysis of Various Metals.
Elbehiry, F., Elbasiouny, H., Ali, R., Brevik, E.C., 2020. Enhanced immobilization and phytoremediation of heavy metals in landfill contaminated soils. Water, Air and Soil Pollution 231(5), 1-20.
Fu, Y., Liu, F., Zhao, C., Zhao, Y., Liu, Y., Zhu, G., 2015. Distribution of chlorpyrifos in rice paddy environment and its potential dietary risk. Journal of Environmental Sciences 35, 101-107.
Gimeno-García, E., Andreu, V., Boluda, R., 1996. Heavy metals incidence in the application of inorganic fertilizers and pesticides to rice farming soils. Environmental Pollution 92(1), 19-25.
Hakanson, L., 1980. An ecological risk index for aquatic pollution control. A sedimentological approach. Water Research 14(8), 975-1001.
Ihedioha, J.N., Abugu, H.O., Ujam, O.T., Ekere, N.R., 2021. Ecological and human health risk evaluation of potential toxic metals in paddy soil, rice plants, and rice grains (Oryza sativa) of Omor Rice Field, Nigeria. Environmental Monitoring and Assessment 193(9), 1-17.
Kalantari, M.R., Shokrzadeh, M., Ebadi, A.G., Mohammadizadeh, C., Choudhary, M.I., Rahman, A., 2006. Soil pollution by heavy metals and remediation (Mazandaran-Iran). Applied Sciences 6, 2110-2116.
Keshavarzi, A., Kumar, V., 2019. Ecological risk assessment and source apportionment of heavy metal contamination in agricultural soils of Northeastern Iran. International Journal of Environmental Health Research 29(5), 544560.
Keshavarzi, A., Kumar, V., Ertunç, G., Brevik, E.C., 2021. Ecological risk assessment and source apportionment of heavy metals contamination: an appraisal based on the Tellus soil survey. Environmental Geochemistry and Health 43(5), 2121-2142.
Kotoky, P., Bora, B.J., Baruah, N.K., Baruah, P., Baruah, J., Borah, G,C., 2003. Chemical fractionation of heavy metals in soils around oil installations, Assam. Chemical Speciation and Bioavailability 15, 115-126.
Li, W., Xu, B., Song, Q., Liu, X., Xu, J., Brookes, P.C., 2014. The identification of ‘hotspots’ of heavy metal pollution in soil–rice systems at a regional scale in eastern China. Science of the Total Environment 472, 407-420.
Li, T., Yuan, X., Song, Y., Chen, H., Liu, Q., Hu, S., 2016. Influence of heavy metals and nutrient concentrations on selenium geochemical behavior in soil-rice system. Polish Journal of Environmental Studies 25, 185-193.
Lin, J., Sun, D., Zhang, Z., Duan, Z., Dong, J., 2021. Heavy metals and health risk of rice sampled in Yangtze River Delta, China. Food Additives and Contaminants Part B 14(2), 133-140.
Lu, S., Teng, Y., Wang, Y., Wu, J., Wang, J., 2015. Research on the ecological risk of heavy metals in the soil around a Pb–Zn mine in the Huize County, China. Chinese Journal of Geochemistry 34(4), 540-549.
Mirzaei, R., Ghorbani, H., Moghaddas, N.H., Martín, J.A.R., 2014. Ecological risk of heavy metal hotspots in topsoils in the Province of Golestan, Iran. Journal of Geochemical Exploration 147, 268-276.
Qin, G., Niu, Z., Yu, J., Li, Z., Ma, J., Xiang, P., 2021. Soil heavy metal pollution and food safety in China: Effects, sources and removing technology. Chemosphere 267, 129205.
Ravankhah, N., Mirzaei, R., Masoum, S., 2016. Spatial eco-risk assessment of heavy metals in the surface soils of industrial city of Aran-o-Bidgol, Iran. Bulletin of Environmental Contamination and Toxicology 96(4), 516-523.
Ren, Y., Lin, M., Liu, Q., Zhang, Z., Fei, X., Xiao, R., Xiaonan, L.V., 2021. Contamination assessment, health risk evaluation, and source identification of heavy metals in the soil-rice system of typical agricultural regions on the southeast coast of China. Environmental Science and Pollution Research 28(10), 12870-12880.
Rezapour, S., Golmohammad, H., Ramezanpour, H., 2014. Impact of parent rock and topography aspect on the distribution of soil trace metals in natural ecosystems. International Journal of Environmental Science and Technology 11(7), 2075-2086.
Rostami, S., Kamani, H., Shahsavani, S., Hoseini, M., 2021. Environmental monitoring and ecological risk assessment of heavy metals in farmland soils. Human and Ecological Risk Assessment: An International Journal 27(2), 392-404.
Sharafati Chaleshtori, F., Rafieian Kopaei, M., Sharafati Chaleshtori, R., 2017. A review of heavy metals in rice (Oryza sativa) of Iran. Toxin Reviews 36(2), 147-153.
Shokrzadeh, M., Rokni, M.A., 2013. Lead, cadmium, and chromium concentrations in irrigation supply of/and tarom rice in central cities of Mazandaran Province-Iran. Journal of Mazandaran University of Medical Sciences 23(98), 234-242.
Steffan, J.J., Brevik, E.C., Burgess, L.C., Cerdà, A., 2018. The effect of soil on human health: an overview. European Journal of Soil Science 69(1), 159-171.
Sun, Y., Zhou, Q., Xie, X., Liu, R., 2010. Spatial, sources and risk assessment of heavy metal contamination of urban soils in typical regions of Shenyang, China. Journal of Hazardous Materials 174(1-3), 455-462.
 Trinh, H.T., Duong, H.T., Le, G.T., Marcussen, H., Strobel, B.W., 2018. Pesticide and element release from a paddy soil in central Vietnam: Role of DOC and oxidation state during flooding. Geoderma 310, 209-217.      
Wuana, R.A., Okieimen, F.E., 2011. Heavy metals in contaminated soils: a review of sources, chemistry, risks and best available strategies for remediation. International Scholarly Research Network. 2011. 
Zarcinas, B.A., Ishak, C.F., McLaughlin, M.J., Cozens, G., 2004. Heavy metals in soils and crops in Southeast Asia. 1. Peninsular Malaysia. Environmental Geochemistry and Health 26, 343-357.
Zeng, F., Mao, Y., Cheng, W., Wu, F., Zhang, G., 2008. Genotypic and environmental variation in chromium, cadmium and lead concentrations in rice. Environmental Pollution. 153(2), 309-314.
Zhao, K., Liu, X., Xu, J., Selim, H.M., 2010. Heavy metal contaminations in a soil–rice system: identification of spatial dependence in relation to soil properties of paddy fields. Journal of Hazardous Materials 181(1-3), 778-787.