Anthropogenic activities introduce heavy metals (HMs) into soils which can be absorbed by plants. We, in the present study, determined the concentration of four priority HMs (Cu, Pb, Cd and Zn) in orchard soils and edible fruits (sweet oranges and mangoes) grown along the arterial Mbale-Soroti Highway of Uganda. A total of 78 fruit samples were systematically obtained from the fruit trees at distances of 10 m, 100 m, 300 m and 5000 m from the Highway, along with 78 soil samples. They were analyzed for the HMs using inductively coupled plasma-optical emission spectrometry. Health risks were assessed using the hazard index and incremental life cancer risk methods, while ecological risks were evaluated based on geoaccumulation and pollution indices. The mean metal total concentrations followed the order Zn > Cu > Pb > Cd, and were all within permissible limits. In the fruit and soil samples, the concentration ranges (mg/kg) were Cu (0.05 ± 0.01 - 1.81 ± 0.37 and 11.42 ± 3.00 - 30.85 ± 5.97), Zn (2.41 ± 2.18 - 8.11 ± 1.20 and 19.00 ± 1.30 - 40.03 ± 7.28), Pb (0.01 ± 0.00 - 0.06 ± 0.03, and 7.72 ± 1.05 - 21.00 ± 3.13) and Cd (<0.001, and <0.001 - 0.44 ± 0.21), respectively. The metal concentrations were higher in soils than fruits, and decreased with distance from the highway, with a strong soil-to-fruit transfer correlation. Health risk assessment revealed that mango pulp and orange juices had hazard indices less than 1 for all the samples, indicating no potential health risks at these proximities.
KeywordsCitrus sinensisMangifera indicaOrchardsAcceptable LimitHazard Index
United Nations Department of Economic and Social Affairs, Population Division (2024) World Population Prospects 2024: Summary of Results (UN DE-SA/POP/2024/TR/NO. 9). United Nations.
van Dijk, M., Morley, T., Rau, M.L. and Saghai, Y. (2021) A Meta-Analysis of Projected Global Food Demand and Population at Risk of Hunger for the Period 2010-2050. Nature Food , 2, 494-501. https://doi.org/10.1038/s43016-021-00322-9
Oncini, F., Hirth, S., Mylan, J., Robinson, C.H. and Johnson, D. (2024) Where the Wild Things Are: How Urban Foraging and Food Forests Can Contribute to Sustainable Cities in the Global North. Urban Forestry & Urban Greening , 93, Article ID: 128216. https://doi.org/10.1016/j.ufug.2024.128216
Crețan, R., Chasciar, D. and Dragan, A. (2024) Forests and Their Related Ecosystem Services: Visitors’ Perceptions in the Urban and Peri-Urban Spaces of Timișoara, Romania. Forests , 15, Article 2177. https://doi.org/10.3390/f15122177
Khan, M.M., Akram, M.T., Janke, R., Qadri, R.W.K., Al-Sadi, A.M. and Farooque, A.A. (2020) Urban Horticulture for Food Secure Cities through and Beyond Covid-19. Sustainability , 12, Article 9592. https://doi.org/10.3390/su12229592
Rutehenda, D.R., Adaku, C., Omara, T., Angiro, C. and Ntambi, E. (2024) Enrichment, Bioaccumulation and Health Risks of Trace Metals in Soils and Leafy Vegetables Grown on the Banks of the Ugandan Lifeline River, River Rwizi. World , 5, 136-154. https://doi.org/10.3390/world5010008
Chatzistathis, T., Kavvadias, V., Sotiropoulos, T. and Papadakis, I.E. (2021) Organic Fertilization and Tree Orchards. Agriculture , 11, Article 692. https://doi.org/10.3390/agriculture11080692
Ritika,, Bora, B., Ismail, B.B., Garba, U., Mishra, S., Jha, A.K., et al. (2024) Himalayan Fruit and Circular Economy: Nutraceutical Potential, Traditional Uses, Challenges and Opportunities. Food Production , Processing and Nutrition , 6, Article No. 71. https://doi.org/10.1186/s43014-023-00220-6
Chamberlain, L.K., Scott, H., Beddoe, N. and Rintoul-Hynes, N.L.J. (2024) Heavy Metal Contamination (Cu, Pb, and Cd) of Washed and Unwashed Roadside Blackberries ( Rubus fruticose L.). Integrated Environmental Assessment and Management , 20, 2107-2115. https://doi.org/10.1002/ieam.4981
Warczyk, A., Gruba, P., Józefowska, A., Wanic, T., Warczyk, A., Świątek, B., et al. (2024) Accumulation of Heavy Metals in Blueberry ( Vaccinium myrtillus L.) and Dominant Mosses ( Pleurozium schreberi (Willd. Ex Brid.) Mitt.) as Bioindicators of the Expressway Influence on Forest Ecosystems. Atmosphere , 15, Article 971. https://doi.org/10.3390/atmos15080971
Demirhan Aydın, Ş. and Pakyürek, M. (2020) Heavy Metal Accumulation Potential in Pomegranate Fruits and Leaves Grown in Roadside Orchards. PeerJ , 8, e8990. https://doi.org/10.7717/peerj.8990
Singh, N.B. and Susan, A.B.H. (2018) Polymer Nanocomposites for Water Treatments. In: Jawaid, M. and Khan, M.M., Eds., Polymer-Based Nanocomposites for Energy and Environmental Applications , Elsevier, 569-595. https://doi.org/10.1016/b978-0-08-102262-7.00021-0
Tchounwou, P.B., Yedjou, C.G., Patlolla, A.K. and Sutton, D.J. (2012) Heavy Metal Toxicity and the Environment. In: Luch, A., Ed., Molecular , Clinical and Environmental Toxicology , Springer, 133-164. https://doi.org/10.1007/978-3-7643-8340-4_6
Way, M., Willingham, J. and Goodall, R. (2019) Brazing Filler Metals. International Materials Reviews , 65, 257-285. https://doi.org/10.1080/09506608.2019.1613311
Nuwamanya, E., Byamugisha, D., Nakiguli, C.K., Angiro, C., Khanakwa, A.V., Omara, T., et al. (2024) Exposure and Health Risks Posed by Potentially Toxic Elements in Soils of Metal Fabrication Workshops in Mbarara City, Uganda. Journal of Xenobiotics , 14, 176-192. https://doi.org/10.3390/jox14010011
Li, J., Cao, D., Huang, Y., Chen, B., Chen, Z., Wang, R., et al. (2022) Zinc Intakes and Health Outcomes: An Umbrella Review. Frontiers in Nutrition , 9, Article 798078. https://doi.org/10.3389/fnut.2022.798078
Frugier, C. and Bégin, P. (2024) Food Toxins. In: Sicherer, S.H., Ed., Encyclopedia of Food Allergy , Elsevier, 814-827. https://doi.org/10.1016/b978-0-323-96018-2.00011-0
WHO (2022) Lead in Drinking-Water: Health Risks, Monitoring and Corrective Actions. https://apps.who.int/iris/rest/bitstreams/1460455/retrieve
WHO (2021) Exposure to Lead: A Major Public Health Concern, 2nd Edition. World Health Organization. https://www.who.int/publications/i/item/9789240037656
Kim, H., Jang, T., Chae, H., Choi, W., Ha, M., Ye, B., et al. (2015) Evaluation and Management of Lead Exposure. Annals of Occupational and Environmental Medicine , 27, Article No. 30. https://doi.org/10.1186/s40557-015-0085-9
Eid, R., Arab, N.T.T. and Greenwood, M.T. (2017) Iron Mediated Toxicity and Programmed Cell Death: A Review and a Re-Examination of Existing Paradigms. Biochimica et Bioph ysica Acta ( BBA )— Molecular Cell Research , 1864, 399-430. https://doi.org/10.1016/j.bbamcr.2016.12.002
Balali-Mood, M., Naseri, K., Tahergorabi, Z., Khazdair, M.R. and Sadeghi, M. (2021) Toxic Mechanisms of Five Heavy Metals: Mercury, Lead, Chromium, Cadmium, and Arsenic. Frontiers in Pharmacology , 12, Article 643972. https://doi.org/10.3389/fphar.2021.643972
Vodyanitskii, Y.N. (2010) Equations for Assessing the Total Contamination of Soils with Heavy Metals and Metalloids. Eurasian Soil Science , 43, 1184-1188. https://doi.org/10.1134/s106422931010011x
Herlocker, D. (2024) Africa’s Great North Road. https://storiesofeastafrica.com/2020/09/24/africas-great-north-road/
Broeckx, J., Maertens, M., Isabirye, M., Vanmaercke, M., Namazzi, B., Deckers, J., et al. (2018) Landslide Susceptibility and Mobilization Rates in the Mount Elgon Region, Uganda. Landslides , 16, 571-584. https://doi.org/10.1007/s10346-018-1085-y
Opedes, H., Mücher, S., Baartman, J.E.M., Nedala, S. and Mugagga, F. (2022) Land Cover Change Detection and Subsistence Farming Dynamics in the Fringes of Mount Elgon National Park, Uganda from 1978-2020. Remote Sensing , 14, Article 2423. https://doi.org/10.3390/rs14102423
Nugent, P. and Soi, I. (2020) One-Stop Border Posts in East Africa: State Encounters of the Fourth Kind. Journal of Eastern African Studies , 14, 433-454. https://doi.org/10.1080/17531055.2020.1768468
Fitzmaurice, M. and Hartmann, O. (2025) Border Crossing Monitoring along the Northern Corridor. The International Bank for Reconstruction and Development/The World Bank. https://openknowledge.worldbank.org/server/api/core/bitstreams/da67157a-93ab-51a0-a6a3-7677f98dabd4/content
Collins, T. (2020) East African Community Battles Trade Disruption. https://african.business/2020/08/trade-investment/east-african-community-battles-trade-disruption/
Joshua (2022) Places to Visit in Eastern Uganda. https://toptenuganda.com/places-to-visit-in-eastern-uganda/
Hong, S., Hwang, S., Adriko, J., Semalulu, O., Nampamya, D., Lee, J., et al. (2020) Effect of Pseudocercospora Spot Disease Control and Soil Moisture Management on Citrus Production in Teso Region, Uganda. Journal of the Korean Society of International Agricultue , 32, 199-205. https://doi.org/10.12719/ksia.2020.32.3.199
Kongai, H., Mangisoni, J., Elepu, G., Chilembwe, E. and Makoka, D. (2018) Analysis of Citrus Value Chain in Eastern Uganda. African Crop Science Journal , 26, 417-431. https://doi.org/10.4314/acsj.v26i3.7
Achuu, S.P., Nachuha, S., Nakizito, J., Musoke, S.H. and Opedes, H.E. (2022) Citrus Fruit Farmers’ Adaptation Capacities to Climate Variability in Ngora District, Eastern Uganda. Kabale University Interdisciplinary Research Journal , 1, 86-98.
Gumisiriza, M., Tadesse, T., Isubikalu, P., Kabirizi, J. and Zziwa, E. (2016) Perception on Climate Change and Climate Smart Agricultural Technologies among Small Holder Mixed Farmers in East Africa. RUFORUM Working Document Series , No. 14, 225-234.
Office of the Prime Minister, G. O. U. (2016) Ngora District Hazard, Risk and Vulnerability Profile. https://www.necoc.opm.go.ug/HzEastern/Ngora%20District%20HRV%20Profile.pdf
Akbar, K.F., Hale, W.H.G., Headley, A.D. and Athar, M. (2006) Heavy Metal Contamination of Roadside Soils of Northern England. Soil and Water Research , 1, 158-163. https://doi.org/10.17221/6517-swr
Wang, Q., Liu, J. and Cheng, S. (2014) Heavy Metals in Apple Orchard Soils and Fruits and Their Health Risks in Liaodong Peninsula, Northeast China. Environmental Monitoring and Assessment , 187, Article No. 4178. https://doi.org/10.1007/s10661-014-4178-7
Shaheen, N., Irfan, N.M., Khan, I.N., Islam, S., Islam, M.S. and Ahmed, M.K. (2016) Presence of Heavy Metals in Fruits and Vegetables: Health Risk Implications in Bangladesh. Chemosphere , 152, 431-438. https://doi.org/10.1016/j.chemosphere.2016.02.060
Kaggwa, A., Byamugisha, D., Omara, T. and Ntambi, E. (2024) Assessment of Potentially Toxic Elements and Their Risks in Water and Sediments of Kitengure Stream, Buhweju Plateau, Uganda. Earth , 5, 743-760. https://doi.org/10.3390/earth5040039
U.S. Environmental Protection Agency (1994) Method 200.7: Determination of Metals and Trace Elements in Water and Wastes by Inductively Coupled Plasma-Atomic Emission Spectrometry. Revision 4.4.
US EPA (2025) IRIS, Environmental Protection Agency Region I. https://cfpub.epa.gov/ncea/iris2/chemicalLanding.cfm?substance_nmbr=422
Ordóñez, A., Álvarez, R., Charlesworth, S., De Miguel, E. and Loredo, J. (2011) Risk Assessment of Soils Contaminated by Mercury Mining, Northern Spain. Journal of Environmental Monitoring , 13, 128-136. https://doi.org/10.1039/c0em00132e
Omara, T., Karungi, S., Kalukusu, R., Nakabuye, B., Kagoya, S. and Musau, B. (2019) Mercuric Pollution of Surface Water, Superficial Sediments, Nile Tilapia ( Oreochromis nilotica Linnaeus 1758 [Cichlidae]) and Yams ( Dioscorea alata ) in Auriferous Areas of Namukombe Stream, Syanyonja, Busia, Uganda. PeerJ , 7, e7919. https://doi.org/10.7717/peerj.7919
Opolot, M., Omara, T., Adaku, C. and Ntambi, E. (2023) Pollution Status, Source Apportionment, Ecological and Human Health Risks of Potentially (Eco)toxic Element-Laden Dusts from Urban Roads, Highways and Pedestrian Bridges in Uganda. Pollutants , 3, 74-88. https://doi.org/10.3390/pollutants3010007
US EPA (2011) Exposure Factors Handbook. National Centre for Environment Assessment.
USEPA (2010) Risk-Based Concentration Table. United States Environmental Protection Agency, Washington, DC.
Ajeh, E.A., Modi, F.J. and Omoregie, I.P. (2022) Health Risk Estimations and Geospatial Mapping of Trace Metals in Soil Samples around Automobile Mechanic Workshops in Benin City, Nigeria. Toxicology Reports , 9, 575-587. https://doi.org/10.1016/j.toxrep.2022.03.021
Hakanson, L. (1980) An Ecological Risk Index for Aquatic Pollution Control. A Sedimentological Approach. Water Research , 14, 975-1001. https://doi.org/10.1016/0043-1354(80)90143-8
Müller, G. (1981) Die Schwermetallbelastung der Sedimenten des Neckars und Seiner Nebenflüsse. Chemiker - Zeitung , 6, 157-164.
Taylor, S.R. (1964) Abundance of Chemical Elements in the Continental Crust: A New Table. Geochimica et Cosmochimica Acta , 28, 1273-1285. https://doi.org/10.1016/0016-7037(64)90129-2
Chen, C., Kao, C., Chen, C. and Dong, C. (2007) Distribution and Accumulation of Heavy Metals in the Sediments of Kaohsiung Harbor, Taiwan Region. Chemosphere , 66, 1431-1440. https://doi.org/10.1016/j.chemosphere.2006.09.030
Zhang, W., Feng, H., Chang, J., Qu, J., Xie, H. and Yu, L. (2009) Heavy Metal Contamination in Surface Sediments of Yangtze River Intertidal Zone: An Assessment from Different Indexes. Environmental Pollution , 157, 1533-1543. https://doi.org/10.1016/j.envpol.2009.01.007
FAO/WHO (2011) Joint FAO/WHO Food Standards Programme Codex Committee on Contaminants in Foods, Food CF/5 INF/1. Fifth Session. The Hague.
Denneman, C.A.J. and Robberse, J.G. (1990) Ecotoxicological Risk Assessment as a Base for Development of Soil Quality Criteria. In: Arendt, F., Hinsenveld, M. and Van Den Brink, W.J., Eds., Contaminated Soil ‘ 90, Springer Netherlands, 157-164. https://doi.org/10.1007/978-94-011-3270-1_28
Xu, E., Liu, Y., Gu, D., Zhan, X., Li, J., Zhou, K., et al. (2024) Molecular Mechanisms of Plant Responses to Copper: From Deficiency to Excess. International Journal of Molecular Sciences , 25, Article 6993. https://doi.org/10.3390/ijms25136993
Rasheed, N., Maqsood, M.A., Aziz, T., Ashraf, M.I., Saleem, I., Ehsan, S., et al. (2024) Zinc Portioning and Allocation Patterns among Various Tissues Confers Variations in Zn Use Efficiency and Bioavailability in Lentil Genotypes. Frontiers in Plant Science , 14, Article 1325370. https://doi.org/10.3389/fpls.2023.1325370
Ezez, D. and Belew, M. (2023) Analysis of Physicochemical Attributes, Contamination Level of Trace Metals and Assessment of Health Risk in Mango Fruits from Southern Region Ethiopia. Toxicology Reports , 10, 124-132. https://doi.org/10.1016/j.toxrep.2023.01.004
Pant, N., Subedee, A., Gharti, R.B. and Shrestha, S. (2020) Spectrometric Determination of Heavy Metals Present in Mango Fruit of Nepali Origin. Amrit Research Journal , 1, 72-77. https://doi.org/10.3126/arj.v1i1.32457
Mawari, G., Kumar, N., Sarkar, S., Daga, M.K., Singh, M.M., Joshi, T.K., et al. (2022) Heavy Metal Accumulation in Fruits and Vegetables and Human Health Risk Assessment: Findings from Maharashtra, India. Environmental Health Insights , 16, 1-10. https://doi.org/10.1177/11786302221119151
Yildiz, E., Erkek, B., Yilmaz, K.U. and Yaman, M. (2022) Determination of the Effect of Distance to Highway on the Accumulation of Some Heavy Metals in Apple Orchards. Current Trends in Natural Sciences , 11, 145-152. https://doi.org/10.47068/ctns.2022.v11i21.017
Godfrey, M., Johnson, T. and Juliet, K. (2021) Assessment of Heavy Metal Concentrations in Mango Fruits Grown in Kasese District, Uganda. African Journal of Environmental Science and Technology , 15, 451-456. https://doi.org/10.5897/ajest2021.3041
Langunu, S., Imabo, P.M.I., Bibi Fwanda, B., Kilela Mwanasomwe, J., Colinet, G. and Ngoy Shutcha, M. (2023) Accumulation of Trace Metals in Fruits from Mango and Syzygium guineense Growing in Residential Households from a Contaminated District of Lubumbashi (DR Congo): Is Fruit Consumption at Risk? Toxics , 11, Article 620. https://doi.org/10.3390/toxics11070620
Yaman, M., and Dilgin, Y. (2002). AAS Determination of Cadmium in Fruits and Soils. Atomic Spectroscopy , 23, 59-64.
Chata, D., Iliya, A.Y., Chidawa, M.S., Emmanuel, M.B., Juliana, O.O. and Chibuzor, E.K. (2018) Determination of Heavy Metals in Four Mango Fruit Varieties Sold in Minna Modern Market, Niger State, Nigeria. Journal of Biological and Environmental Engineering , 1, 24-29.
P, O.E., F, T. and I, K. (2015) A Physico-Chemical Analysis of Soil and Selected Fruits in One Rehabilitated Mined Out Site in the Sierra Rutile Environs for the Presence of Heavy Metals: Lead, Copper, Zinc, Chromium and Arsenic. African Journal of Pure and Applied Chemistry , 9, 27-32. https://doi.org/10.5897/ajpac2015.0606
Rahimzadeh, M. and Rastegar, S. (2017) Heavy Metals Residue in Cultivated Mango Samples from Iran. Journal of Food Quality and Hazards Control , 4, 29-31.
Širić, I., Eid, E.M., El-Morsy, M.H.E., Osman, H.E.M., Adelodun, B., Abou Fayssal, S., et al. (2022) Health Risk Assessment of Hazardous Heavy Metals in Two Varieties of Mango Fruit ( Mangifera indica L. Var. Dasheri and Langra). Horticulturae , 8, Article 832. https://doi.org/10.3390/horticulturae8090832
Bi, X., Ren, L., Gong, M., He, Y., Wang, L. and Ma, Z. (2010) Transfer of Cadmium and Lead from Soil to Mangoes in an Uncontaminated Area, Hainan Island, China. Geoderma , 155, 115-120. https://doi.org/10.1016/j.geoderma.2009.12.004
Ang, L.H. and Ng, L.T. (2000) Trace Element Concentration in Mango ( Mangifera indica L.), Seedless Guava ( Psidium guajava L.) and Papaya ( Carica papaya L.) Grown on Agricultural and Exmining Lands of Bidor, Perak. Pertanika Journal of Tropical Agricultural Science , 23, 15-22.
Cheng, J., Ding, C., Li, X., Zhang, T. and Wang, X. (2015) Heavy Metals in Navel Orange Orchards of Xinfeng County and Their Transfer from Soils to Navel Oranges. Ecotoxicology and Environmental Safety , 122, 153-158. https://doi.org/10.1016/j.ecoenv.2015.07.022
Li, Q., Wei, C., Huang, Y., Wang, L. and Wang, D. (2010) A Study on the Characteristics of Heavy Metals in Orange Ecosystem. Chinese Journal of Geochemistry , 29, 100-106. https://doi.org/10.1007/s11631-010-0100-3
Ullah, H., Alam, Z., Shah, M., Ali, W., Ahmad, A. and Hadi, F. (2019) Investigation of Cadmium (Cd) and Lead (Pb) Contents in Soil, Orange Fruit and Its Accumulation in Human Blood. International Journal of Agronomy & Agricultural Research , 15, 15-19.
Kabata-Pendias, A. (2011) Trace Elements in Soils and Plants. In: Kabata-Pendias, A. and Pen-dias, H.K., Eds., Trace Elements in Soils and Plants , Taylor and Francis, 548.
Xiao, X., Zhang, J., Wang, H., Han, X., Ma, J., Ma, Y., et al. (2020) Distribution and Health Risk Assessment of Potentially Toxic Elements in Soils around Coal Industrial Areas: A Global Meta-Analysis. Science of the Total Environment , 713, Article ID: 135292. https://doi.org/10.1016/j.scitotenv.2019.135292
Silva, J.P.S.D., Nascimento, C.W.A.D., Biondi, C.M. and Cunha, K.P.V.D. (2012) Heavy Metals in Soils and Plants in Mango Orchards in Petrolina, Pernambuco, Brazil. Revista Brasileira de Ciência do Solo , 36, 1343-1354. https://doi.org/10.1590/s0100-06832012000400028
Kang, T., Yang, H.J., Lee, W., Koo, B. and Park, W. (2023) Accumulation and Origin of Phosphorus and Heavy Metals in Citrus Orchard Soils in Jeju Island, South Korea: Potential Ecological Risks and Bioavailability. Water , 15, Article 3951. https://doi.org/10.3390/w15223951
Shareef, R.S., Mamat, A.S., Al-Shaheen, M.R. and Aslam, M.S. (2015) Study of Heavy Metals in Mango ( Mangifera indica L) in Perlis, Malaysia. Indian Journal of Pharmaceutical Sciences , 7, 299-303.
Nazzal, Y., Ghrefat, H. and A. Rosen, M. (2014) Heavy Metal Contamination of Roadside Dusts: A Case Study for Selected Highways of the Greater Toronto Area, Canada Involving Multivariate Geostatistics. Research Journal of Environmental Sciences , 8, 259-273. https://doi.org/10.3923/rjes.2014.259.273
Ibrahim, M.I.A., Mohamed, L.A., Mahmoud, M.G., Shaban, K.S., Fahmy, M.A. and Ebeid, M.H. (2019) Potential Ecological Hazards Assessment and Prediction of Sediment Heavy Metals Pollution along the Gulf of Suez, Egypt. Egyptian Journal of Aquatic Research , 45, 329-335. https://doi.org/10.1016/j.ejar.2019.12.003
Xiang, Z., Wu, S., Zhu, L., Yang, K. and Lin, D. (2024) Pollution Characteristics and Source Apportionment of Heavy Metal(loid)s in Soil and Groundwater of a Retired Industrial Park. Journal of Environmental Sciences , 143, 23-34. https://doi.org/10.1016/j.jes.2023.07.015
Lei, M., Wang, Y., Guo, G., Zhang, D. and Zhao, X. (2021) The Bio-Availability and Accumulation of the Trace Elements in Rock-Soil-Fruit System in Carbonatite Regions of Different Stratums: Critical Soil Factors and Transfer Models. Science of the Total Environment , 760, Article ID: 143328. https://doi.org/10.1016/j.scitotenv.2020.143328
Xue, J., Jiang, W., Gong, S., Fan, Y. and Li, X. (2013) An Evaluation of Heavy Metals Contamination in Soils from Ganzhou Navel Orange Orchards by Geoaccumulation Indexes and Statistical Analysis. Chemistry and Ecology , 29, 586-594. https://doi.org/10.1080/02757540.2013.831078