Accumulation of Heavy Metals in Vegetable Food under Wastewater Irrigation

Abstract

Sewage water contains toxic heavy metals which can be translocated and accumulated in plants and subsequently transferred to human body through the food chain, yet it has become the most commonly used water source for irrigating vegetable crops in peri-urban or urban areas of several countries including in Pakistan. Karachi, the metropolitan city of Pakistan, is the largest industrial and financial hub of the country with an estimated 16 Million population of multilingual, multi-cultural and multi-religious peoples. The current study was conducted to examine the accumulation of six heavy metals (Cr, Ni, Cd, Pb, As and Hg) in cabbage, radish, turnip, cauliflower, and carrot crops, irrigated with sewage water (SW) of peri-urban area of the Karachi. Four treatments were designed, the fresh water (FW) was used as the control (T 0 ), whereas T 1 , T 2 T 3 and T 4 contained 25, 50, 75 and 100% of SW respectively. The samples analyzed through atomic absorption spectrophotometer using flame atomic absorption techniques revealed that among the five treatments, accumulation of the six metals was found higher with 100% SW, which was decreased with decrease in SW concentration up to 25% SW. The minimum accumulation of the metal was noted with 100% FW (control). Among the five types of vegetables, cabbage and cauliflower revealed a high tendency of accumulating the metals. Hence, in order to avoid exposure of excess heavy metals to human health through vegetables, the cabbage and cauliflower crops may not be grown in the vicinity of Karachi city where the source of irrigation water is only sewage water.

Hydrogeochemical investigation of irrigation water in the vicinity of metallic ore deposits in Kiraz‐İzmir, Turkey: Understanding the crucial nexus between “geology and food safety”

“…[30,52,53] The transfer of these metals from soil to food products varies depending on the tillage system and is quantified using the bioaccumulation factor. [13,14,29] Leafy greens tend to accumulate higher levels of PTMs compared to root crops due to their exposure to polluted atmospheric sediments and root uptake. [29] The nonbiodegradable nature of PTMs allows them to accumulate in the environment, contaminating the food chain and causing various health issues in humans, including carcinogenic, teratogenic, endocrine-disrupting, neurological, and behavioral effects.…”

“…Environmental pollutants are notable PTM that exert toxic effects on plants. [12,13,14,51,52] This situation leads to a decline in productivity and presents perilous risks to agroecosystems, as PTM impose stress on plants and disrupt plant physiology. [12] The presence of PTM, including nickel, antimony, copper, lead, cadmium, mercury, and chromium, in the atmospheric, terrestrial, and aquatic environments can lead to bioaccumulation, which exerts wide-ranging impacts on the entire ecosystem and poses potentially adverse health consequences for all living organisms.…”

“…PTMs such as lead, nickel, cadmium, copper, cobalt, chromium and mercury are important environmental pollutants that cause toxic effects on plants. [10][11][12][13][14] Bioaccumulation of metal(loid) from soil to crops varies between tillage systems.…”

“…The anthropogenic impact has generally been investigated as "polluted water." [14,22,31] In addition, the effect of the use of not only anthropogenically polluted water but also geogenically PTM-containing water in irrigation, on human health, primarily as a plant and then as a product and food, should be emphasized.…”

“…The impact of the use of contaminated water in the food supply system on food safety and human health has been poorly studied. The anthropogenic impact has generally been investigated as “polluted water.” [ 14,22,31 ] In addition, the effect of the use of not only anthropogenically polluted water but also geogenically PTM‐containing water in irrigation, on human health, primarily as a plant and then as a product and food, should be emphasized. When all these mentioned issues are taken into consideration, it is seen that this study covers five topics that the United Nations has set targets until 2023 (SDG 2, SDG 3, SDG 6, SDG 13, and SDG 15).…”