Assessment of arsenic status and distribution in Usangu agro-ecosystem-Tanzania.

The research article published by Elsevier Ltd., 2021This study was conducted to assess arsenic (As) status and distribution in Usangu agroecosystem-Tanzania, including three land use. About 198 soil samples were collected in ten irrigation schemes in three land uses. Total and bioavailable As were determined by acid digestion (Aqua regia (AQ)) and Mehlich 3 method (M3) to estimate status, distribution and bioavailability. Arsenic concentration were variable among land use and irrigation schemes where total arsenic ranged 567.74-2909.84 μg/kg and bioavailable As ranged 26.17-712.37 μg/kg. About 12-16% of total arsenic were available for plant uptake. Approximately 86.53% of studied agricultural soils had total As concentration above Tanzania maximum allowable limit. Bioavailable As were lower compared to total As and were within the acceptable threshold. Total arsenic concentration were variable among schemes and higher values were observed in schemes which are highly intensified and mechanized. Thus, this study provides essential site specific preliminary baseline information for As status and distribution in agricultural soils to initiate monitoring and management strategies for increased land productivity and environmental safety

Effects of cadmium uptake on growth and productivity of Chinese cabbage (Brassica rapa subsp. pekinensis) and pumpkin (Cucurbita moschata Duchesne) vegetables

Cadmium (Cd) is recognized as one of the most toxic elements to plants and humans when available in higher concentrations. In the present study, a pot experiment was carried out to investigate the effect of different Cd levels (0, 10, 20, 30, and 40 mg/kg) on the growth, production, and uptake of Cd using Chinese cabbage (Brassica rapa subsp. pekinensis) and pumpkin leaves (Cucurbita moschata Duchesne) vegetables. The study found significant differences (P < 0.05) in all growth parameters in the studied vegetables. The Cd treatments resulted in decreasing number of leaves, shoot fresh weight, shoot dry weight, and total dry weight in both vegetables compared to the control. The total dry weight of Chinese cabbage was decreased by 6.79%, 48.42%, 5.88%, and 5.43%, at 10, 20, 30, and 40 mg/kg respectively compared to the control. In pumpkin leaves total dry weight was decreased by 28.95%, 28.95%, 18.42%, and 14.47% at 10, 20, 30, and 40 mg/kg respectively compared to the control. Increase and decrease effects on root length were observed for all the vegetables. Pumpkin leaves showed increased root length at 10 mg/kg (61.39%), 20 mg/kg (17.87%), and 30 mg/kg (70.03%) while at 40 mg/kg, there was a decrease in root length by 20.13% as compared to the control. The root length of Chinese cabbage decreased by 25.05%, 8.4%, and 7.26% at 20 mg/kg, 30 mg/kg, and 40 mg/kg compared to the control except at 10 mg/kg which was found to be higher by 0.6% compared to the control.The Cd treatment in soil resulted in the increase of shoot Cd concentration in all the vegetables with maximum concentration observed at 20 mg/kg. Therefore, agricultural soil with elevated Cd levels will affect pumpkin and Chinese cabbage cultivation but also the consumption of such vegetables may result to toxic effects on human health

Accumulation and distribution of mercury in agricultural soils, food crops and associated health risks: A case study of Shenda gold mine-Geita Tanzania

Contamination of the environment and foodstuff by potentially harmful elements (PHEs) has become a serious concern due to the associated health risks to the population. In the present study total mercury (Hg) levels in soil and food crops from farms around Shenda gold mine in Geita Tanzania was determined by Cold Vapor Atomic Fluorescence Spectrometry (CVAFS). Generally, it was found that there was significant different of Hg content in soil and food crops (P 1, indicating a potential non-carcinogenic risk to adult population from the consumption of rice grain from the study area. Therefore, people living near Shenda goldmine might be potential victim of Hg accumulation in soil and food crops, thus necessary management options have to be in place