Browsing by Author "Kishimba, Michael A."
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Item Biota uptake of pesticides by selected plant species; the case study of Kilombero sugarcane plantations in Morogoro Region, Tanzania(2010-01) Zacharia, James T.; Kishimba, Michael A.; Masahiko, HayashiThis paper reports on biota uptake of pesticides by selected plant species from soil in which they are grown. The study was conducted at Kilombero sugarcane plantations and environs, Morogoro Region, Tanzania. Three species of the plant materials were collected namely sugarcane (Saccharum officinarum), guinea grass (Panicum maximum) and mango leaves (Mangifera indica). The sugarcane and guinea grass were used to reveal the plant uptake in the plantations whereas mango leaves were used to represent the environs. GPC cleaned sample extracts were analysed by GC–ECD and GC–NPD and the results confirmed using GC–MS. A total of 16 different pesticide residues were detected in soil samples and only 11 pesticide residues were detected in flora samples. o,p′-DDT had the highest concentration of all detected pesticides in soil samples with a mean concentration of 21.04 μg/kg d.w. whereas the highest concentrations of 17.16 μg/kg d.w. was recorded for p,p′-DDD in flora samples. The other DDT metabolites detected in soil samples were p,p′-DDT, p,p′-DDE, o,p′-DDE, p,p′-DDD and o,p′-DDD with concentration ranging from 2.00 to 18.30 μg/kg d.w. whereas the other pesticides detected in flora samples were p,p′-DDT α-endosulfan and γ-HCH with a mean concentration range of 3.21 to 13.54 μg/kg d.w. The paired sample t-test showed no significant difference between the concentrations of pesticides in flora and those found in soil.Item Concentrations of pesticide residues in grasses and sedges due to point source contamination and the indications for public health risks, Vikuge, Tanzania(Elsevier, 2005) Mahugija, John A.M.; Kishimba, Michael A.The concentrations of organochlorine pesticide residues were determined in roots and leaves of giant sedges (Cyperus exaltatus), fresh leaves and dry hay of guinea grasses (Panicum maximum), and in stems and leaves of elephant grasses (Pennisetum purpureum) in the vicinity of a point source of contamination, an old storage site at Vikuge farm in Tanzania. The GPC-cleaned extracts were analyzed by GC-ECD and GC/MS. The concentrations of total DDT ranged from 83 – 18274 ng/g, 166 – 7922 ng/g, and 68 – 405 ng/g, on fresh weight bases, in C. exaltatus, P. maximum and P. purpureum, respectively. The concentrations of total HCH were up to 74 ng/g fw in leaves of C. exaltatus, 43 ng/g dw in dry hay of P. maximum, and 10 ng/g fw in stems of P. purpureum. Aldrin and dieldrin were only detected in C. exaltatus and their concentrations were up to 11 and 8 ng/g fw, respectively. The strong positive correlations between the concentrations of the detected compounds suggest a common source. The concentrations of total DDT were far above the Australian extraneous maximum residue limit in primary animal feedstuffs. These findings indicate potential risks and concerns for livestock and public health. The concentrations of aldrin, dieldrin and lindane were lower than the Australian limits. 2005 Elsevier Ltd. All rights reserved.Item Concentrations of polar pesticide residues in the surface waters of selected areas of Coast region, Tanzania(Makerere University, Kampala-Uganda, 2005-01-20) Mahugija, John A.M.; Kishimba, Michael A.The concentrations of 60 polar pesticide residues were investigated in surface waters from eleven sites in two rivers, a pond and four drinking water wells in Coast region, Tanzania. The extracts were analyzed by Gas Chromatography-Nitrogen Phosphorus Detection (GC-NPD) and confirmed by high-performance liquid chromatography-tandem mass spectrometry (HPLC/MS/MS). Quantification of analytes was done by using the peak heights with two different m/z for each analyte. The compounds detected were atrazine, isoproturon and diuron. The highest concentrations of atrazine were 13 ng/l in drinking water, 16 ng/l in pond water and 172 ng/l in river water. The highest concentrations of isoproturon and diuron in river water were 18 ng/l and 12 ng/l, respectively. Atrazine was the most predominant pollutant in water. The results indicate that the source of contamination is due to the agricultural use of these pesticides in the nearby areas. The concentrations of atrazine, isoproturon and diuron in drinking water were far below the WHO guidelines for drinking-water quality.Item Contamination of Surface Waters by Obsolete Pesticides Emanating from a Point Source in Coast Region, Tanzania(University of Nairobi, 2007) Mahugija, John A.M.; Kishimba, Michael A.This paper reports on the concentrations of organochlorine pesticide residues in water samples collected from 1 – 25 km away from a highly obsolete pesticides contaminated site at Vikuge farm in Coast region -Tanzania. GPC-cleaned extracts analyzed by GC-ECD and confirmed by GC-MS showed the presence of twelve compounds namely p,p’-DDT, o,p’-DDT, p,p’-DDE, o,p’-DDE, p,p’-DDD, o,p’-DDD, pentachloroanisole, a-HCH, b-HCH, g-HCH, aldrin and dieldrin. The concentrations of total DDT ranged from 819 – 1764 ng/l in pond water, below detection limit (bdl) – 1076 ng/l in river water, and bdl – 572 ng/l in drinking water. The concentrations of total HCHs were up to 23 ng/l in pond water, 1167 ng/l in river water, and 12 ng/l in drinking water. The highest concentrations for other compounds were 29.2 +/- 0.1 ng/l for pentachloroanisole, 8+/- 0.7 ng/l for aldrin and 6+/- 0.6 ng/l for dieldrin. There are strong positive correlations in the concentrations of most of the detected compounds suggesting a common source. Some concentrations were higher than the respective maximum residue limits and guidelines for aquatic ecosystems indicating potential risks and concerns for public health and the environment at large.Item Distribution of Pesticide Residues in Soil and Sediments from Areas of Coast Region Near a Heavily Contaminated Site in Tanzania(University of Nairobi, 2007-12) Mahugija, John A.M.; Kishimba, Michael A.Soil and sediment samples collected from 0.1 to 25 km away from a heavily contaminated site at Vikuge farm in Coast region were extracted, cleaned by GPC and analyzed using GC-ECD and GC-MS. Ten compounds namely p,p’-DDT, o,p’-DDT, p,p’-DDE, o,p’-DDE, p,p’-DDD, o,p’-DDD, pentachloroanisole, a-HCH, b-HCH and g-HCH were detected in the samples. In general, contaminants during this round of sampling were widespread. The compounds o,p’- and p,p’-DDT, DDD and DDE were detected in 64.3% - 100% of the samples. Pentachloroanisole was detected in 95.5% of the soil and 50% of the sediment samples, while for the HCH isomers, the highest frequency was for b-HCH (57.1%) in sediments. The concentrations of total DDT were up to 534 ng/g dry weight (dw) in soil and 1945 ng/g dw in sediments. The highest concentrations for total HCH were 3.8 ng/g dw in soil and 24.6 ng/g dw in sediments. The very strong positive correlations in the concentrations of the detected compounds suggest a common source. The low DDE/DDT ratios (0.01 - 0.83) in all but one sample indicate input of significantly non-degraded DDT from the source. The high DDE/DDT ratio (1.35) in one soil sample indicates significant degradation. The low a-HCH/g- HCH ratios in the samples indicate inputs of lindane. There is an urgent need for remedial actions to solve the problem at the source.Item Distribution of Pesticide Residues in Soil and Sediments from Areas of Coast Region Near a Heavily Contaminated Site in Tanzania(University of Nairobi, 2007) Mahugija, John A.M.; Kishimba, Michael A.Soil and sediment samples collected from 0.1 to 25 km away from a heavily contaminated site at Vikuge farm in Coast region were extracted, cleaned by GPC and analyzed using GC-ECD and GC-MS. Ten compounds namely p,p’-DDT, o,p’-DDT, p,p’-DDE, o,p’-DDE, p,p’-DDD, o,p’-DDD, pentachloroanisole, a-HCH, b-HCH and g-HCH were detected in the samples. In general, contaminants during this round of sampling were widespread. The compounds o,p’- and p,p’-DDT, DDD and DDE were detected in 64.3% - 100% of the samples. Pentachloroanisole was detected in 95.5% of the soil and 50% of the sediment samples, while for the HCH isomers, the highest frequency was for b-HCH (57.1%) in sediments. The concentrations of total DDT were up to 534 ng/g dry weight (dw) in soil and 1945 ng/g dw in sediments. The highest concentrations for total HCH were 3.8 ng/g dw in soil and 24.6 ng/g dw in sediments. The very strong positive correlations in the concentrations of the detected compounds suggest a common source. The low DDE/DDT ratios (0.01 - 0.83) in all but one sample indicate input of significantly non-degraded DDT from the source. The high DDE/DDT ratio (1.35) in one soil sample indicates significant degradation. The low a-HCH/g- HCH ratios in the samples indicate inputs of lindane. There is an urgent need for remedial actions to solve the problem at the source.Item Organochlorine pesticides and metabolites in young leaves of Mangifera indica from sites near a point source in Coast Region, Tanzania(Elsevier, 2007) Mahugija, John A.M.; Kishimba, Michael A.Young leaves of Mangifera indica (mango tree) from nine sites were used as bioindicators of local atmospheric contamination by organochlorine pesticides and metabolites from a point source, an old storage site at Vikuge farm in Tanzania. Sample extracts were analyzed by GC-ECD and GC-MS. The concentrations ranged 2.7–649 ng g-1 p,p’-DDT, below detection limit (bdl)–290 ng g-1 o,p’-DDT, 0.4–13 ng g-1 p,p’-DDE, bdl to 4 ng g-1 o,p’-DDE, 1–231 ng g-1 p,p’-DDD and 0.5–55 ng g-1 o,p’-DDD. The concentrations of other compounds were up to 3.9 ng g-1 pentachloroanisole, 1.3 ng g-1 a-HCH, 12 ng g-1 b-HCH and 2 ng g-1 g-HCH, on fresh weight basis. The compounds p,p’-DDT, p,p’-DDE, p,p’-DDD and o,p’-DDD were found in 100% of the samples, while pentachloroanisole, o,p’-DDT and o,p’-DDE were detected in 78%, 56% and 67% of the samples, respectively. The low DDE/DDT ratios (0.01–0.20) in all samples indicate recent input of significantly non-degraded DDT from the point source. The low a-/g-HCH ratios (<0.3–0.7) in most samples indicate recent input of lindane (99% g-HCH). The slightly high a-/g-HCH ratios in some samples might be due to photochemical or bacterial transformation of g-HCH to a-HCH, or could reflect input of technical HCH. The very strong positive correlations in the concentrations of p,p’-DDT, p,p’-DDE, p,p’-DDD, o,p’-DDT, o,p’-DDE and o,p’-DDD (r = 0.91–0.98, n = 18, p < 0.01) indicate that they have a common source. The results suggest that young mango leaves are suitable bioindicators of recent inputs of organochlorine contaminants from a point source.Item Pesticides and metabolites in cassava, eucalyptus, plum and cashew leaves and roots in relation to a point source in Kibaha, Tanzania(Elsevier, 2006) Mahugija, John A.M.; Kishimba, Michael A.Leaves of Eucalyptus sp, Prunus domestica (plum), and Anacardium occidentale (cashew), as well as roots and leaves of Manihot esculenta (cassava) were used to study the local distribution of pesticides and metabolites from a point source, an old storage site at Vikuge farm in Tanzania. The GPC-cleaned extracts were analyzed by GC-ECD and GC/MS. Eleven organochlorine pesticide residues namely pentachloroanisole, p,p’-DDT, o,p’-DDT, p,p’-DDE, o,p’-DDE, p,p’-DDD, o,p’-DDD,a-HCH, b-HCH, d-HCH and e-HCH were detected in the samples. The concentrations of total DDT were 818 ng/g fw in Eucalyptus sp, 16 ng/g fw in A. occidentale and 4 ng/g fw in P. domestica. In M. esculenta, total DDT ranged from 191 – 586 ng/g fw in roots and 7 – 425 ng/g fw in leaves. The concentrations of total HCH were up to 15 ng/g fw in Eucalyptus sp, while the concentrations of pentachloroanisole were up to 2 ng/g fw in leaves of M. esculenta. There are very strong positive correlations in the concentrations of the detected compounds, suggesting that they have a common source. The low DDE/DDT ratios (0.02 – 0.07) in all samples indicate input of non-degraded DDT from the source. The high a-HCH/g-HCH ratios in some samples (> 3.1 – 10) indicate input of technical HCH. The concentrations of total DDT in cassava roots were either very close to, or greater than, the FAO/WHO limit, indicating risks and concern to public health.