Mng'ong'o Marco, Munishi Linus K, Ndakidemi Patrick A, Blake William, Comber Sean, Hutchinson Thomas H
School of Life Sciences and Bioengineering (LiSBE), Nelson Mandela African Institution of Science and Technology, P.O.Box 447, Arusha, Tanzania.
School of Geography, Earth and Environmental Science, University of Plymouth, Drake Circus, PL4 8AA, UK.
Heliyon. 2021 Jul 7;7(7):e07514. doi: 10.1016/j.heliyon.2021.e07514. eCollection 2021 Jul.
The build-up of heavy metals (HM) in agricultural soils accelerates the HM uptake by plants, which could potentially affect food quality and food safety. Here we studied the status and bioaccumulation of HM from soils to plant parts (roots, stem, and grains) in Usangu agro-ecosystem-Tanzania. In total 68 soil samples and 42 rice plant samples from six irrigation schemes were studied. The concentrations of cadmium-Cd, chromium-Cr, copper-Cu, lead-Pb, zinc-Zn, nickel-Ni, and iron-Fe were determined to estimate accumulation, distribution, bioconcentration. Total soil HM concentration in soil and plant samples was determined by acid digestion. The concentration of HM in soils samples (in mg/kg) were Cr (4.58-42.76), Co (1.486-6.12), Fe (3513.56-12593.99), Zn (7.89-29.17), Cd (0.008-0.073), Cu (0.84-9.25), Ni (0.92-7.98), and Pb (1.82-18.86). The total HM concentration in plant samples were (in mg/kg) were Cu (5.18-33.56), Zn (57.03-120.88), Fe (963.51-27918.95), Mn (613.15-2280.98), Cd (4.3-17.46), Pb (0.01-28.25), Cr (12.88-57.34) and Ni (9.65-103.33). The concentration of HM in soil and plant parts was observed to vary among locations where high concentrations of HM were detected in stems and roots compared to grains. The ratio HM in plants and soil samples (bioconcentration) was higher than one for some sites indicating higher HM uptakes by plants leading to possible health risk to soil invertebrates, animals, and humans. The bioconcentration factor varied among schemes, with the highest values at Igalako and Mahongole, which could be caused by artisanal gold mining and mining quarry existed in the area. Therefore, steps are needed to reverse the situation to balance the HM in agricultural soils and plant tissues to be within acceptable limits.
农业土壤中重金属（HM）的积累加速了植物对重金属的吸收，这可能会影响食品质量和食品安全。在此，我们研究了坦桑尼亚乌桑古农业生态系统中土壤重金属的现状及其在植物各部位（根、茎和谷粒）中的生物累积情况。共研究了来自六个灌溉区的68个土壤样本和42个水稻植株样本。测定了镉（Cd）、铬（Cr）、铜（Cu）、铅（Pb）、锌（Zn）、镍（Ni）和铁（Fe）的浓度，以评估其积累、分布和生物富集情况。通过酸消解测定土壤和植物样本中的总土壤重金属浓度。土壤样本中重金属的浓度（mg/kg）分别为：Cr（4.58 - 42.76）、Co（1.486 - 6.12）、Fe（3513.56 - 12593.99）、Zn（7.89 - 29.17）、Cd（0.008 - 0.073）、Cu（0.84 - 9.25）、Ni（0.92 - 7.98）和Pb（1.82 - 18.86）。植物样本中的总重金属浓度（mg/kg）分别为：Cu（5.18 - 33.56）、Zn（57.03 - 120.88）、Fe（963.51 - 27918.95）、Mn（613.15 - 2280.98）、Cd（4.3 - 17.46）、Pb（0.01 - 28.25）、Cr（12.88 - 57.34）和Ni（9.65 - 103.33）。观察到土壤和植物各部位的重金属浓度在不同地点存在差异，与谷粒相比，茎和根中检测到的重金属浓度较高。在某些地点，植物与土壤样本中重金属的比值（生物富集）高于1，这表明植物对重金属的吸收较高，可能会对土壤无脊椎动物、动物和人类造成健康风险。生物富集系数在不同灌溉区有所不同，伊加拉科和马洪戈勒的系数最高，这可能是由于该地区存在手工金矿开采和采石场所致。因此，需要采取措施扭转这种局面，使农业土壤和植物组织中的重金属含量平衡在可接受的范围内。
