Browsing by Author "Mmochi, Aviti J."

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    Increasing Trends of Legacy and Emerging Organic Contaminants in a Dated Sediment Core From East-Africa
    (Frontiers in environmental science, 2022) Nipen, Maja; Vogt, Rolf D.; Bohlin-Nizzetto, Pernilla; Borgå, Katrine; Mwakalapa, Eliezer B.; Borgen, Anders R.; Schlabach, Martin; Christensen, Guttorm; Mmochi, Aviti J.; Breivik, Knut
    Temporal trends of industrial organic contaminants can show how environmental burdens respond to changes in production, regulation, and other anthropogenic and environmental factors. Numerous studies have documented such trends from the Northern Hemisphere, while there is very limited data in the literature from sub-Saharan Africa. We hypothesized that the temporal trends of legacy and contemporary industrial contaminants in sub- Saharan Africa could greatly differ from the regions in which many of these chemicals were initially produced and more extensively used. For this purpose, a dated sediment core covering six decades from a floodplain system in urban Dar es Salaam, Tanzania, was analysed. The samples were analysed for selected legacy persistent organic pollutants (POPs) [polychlorinated biphenyls (PCBs) and polybrominated biphenyl ethers (PBDEs)] and chemicals of emerging concern (CECs) [alternative brominated flame retardants (aBFRs), chlorinated paraffins (CPs), and dechloranes]. All groups of chemicals showed a steep increase in concentrations towards the uppermost sediment layers reflecting the more recent years. Concentrations of the individual compound groups in surface sediment were found in the order CPs >> aBFRs ∼ ∑25PBDEs > dechloranes ∼ ∑32PCBs. Time trends for the individual compounds and compound groups differed, with ∑32PCBs showing presence in sediments since at least the early 1960s, while some CECs first occurred in sediments corresponding to the last decade. Investigations into potential drivers for the observed trends showed that socioeconomic factors related to growth in population, economy, and waste generation have contributed to increasing concentrations of PBDEs, aBFRs, CPs, and Dechlorane Plus. Further monitoring of temporal trends of industrial organic contaminants in urban areas in the Global South is recommended.
  • Thumbnail Image
    Item
    Mercury in Air and Soil on an Urban-Rural Transect in East Africa
    (Royal Society of Chemistry, 2022) Nipen, Maja; Jørgensen, Susanne J.; Bohlin-Nizzetto, P.; Borg˚a, Katrine; Breivik, Knut; Mmochi, Aviti J.; Mwakalapa, Eliezer B.; Quant, M. I.; Schlabach, Martin; Vogt, Rolf D.; Wania, Frank
    There are large knowledge gaps concerning concentrations, sources, emissions, and spatial trends of mercury (Hg) in the atmosphere in developing regions of the Southern Hemisphere, particularly in urban areas. Filling these gaps is a prerequisite for assessing the effectiveness of international regulation and for enabling a better understanding of the global transport of Hg in the environment. Here we use a passive sampling technique to study the spatial distribution of gaseous elemental Hg (Hg(0), GEM) and assess emission sources in and around Dar es Salaam, Tanzania's largest city. Included in the study were the city's main municipal waste dumpsite and an e-waste processing facility as potential sources of GEM. To complement the GEM data and for a better overview of the Hg contamination status of Dar es Salaam, soil samples were collected from the same locations where passive air samplers were deployed and analysed for total Hg. Overall, GEM concentrations ranged between <0.86 and 5.34 ng m 3 , indicating significant local sources within the urban area. The municipal waste dumpsite and e-waste site had GEM concentrations elevated above the background, at 2.41 and 1.77 ng m 3 , respectively. Hg concentrations in soil in the region (range 0.0067 to 0.098 mg kg 1 ) were low compared to those of other urban areas and were not correlated with atmospheric GEM concentrations. This study demonstrates that GEM is a significant environmental issue in the urban region of Dar es Salaam. Further studies from urban areas in the Global South are needed to better identify sources of GEM.
  • Thumbnail Image
    Item
    Seasonal Rainfall Affects Occurrence of Organohalogen Contaminants in Tropical Marine Fishes and Prawns from Zanzibar, Tanzania
    (ELSEVIER, 2021) Haarra, Ane; Mwakalapa, Eliezer B.; Mmochi, Aviti J.; Lyche, Jan L; Ruuse, Anders; Othman, Halima; Larsen, Martin M.; Borgå, Katrine
    Seasonal differences in precipitation may affect contaminant dynamics in tropical coastal regions due to terrestrial runoff of contaminants to the marine environment after the rainy seasons. To assess the effect of seasonal rainfall on occurrence of organohalogen contaminants in a coastal ecosystem, marine fishes and prawns were collected off the coast of Zanzibar, Tanzania in January and August 2018, representing pre- and post-rainy season, respectively. Samples were analyzed for organochlorine pesticides (OCPs), polychlorinated biphenyls(PCBs),brominatedflameretardants(BFRs),includingpolybrominateddiphenyl ethers (PBDEs) and emerging BFRs, as well as the dietary descriptors stable isotopes of carbon (δ13C) and nitrogen (δ15N). Across all species and seasons, mean contaminant concentrations ranged frombelowlimitofdetection(LOD)to129ng/glipidweight(lw)ΣPCBs;5.6–336ng/glwΣOCPs;and increaseinlowerhalogenated,moremobilePCBandPBDEcongeners,comparedtohigherhalogenatedcon geners with lower mobility, between January and Augustaligns with a signal and effect of terrestrial runoff followingtherainyseason
  • Thumbnail Image
    Item
    Spatial Trends of Chlorinated Paraffins and Dechloranes in Air and Soil in A Tropical Urban, Suburban, and Rural Environment
    (ELSEVIER, 2021) Nipen, Maja; Vogt, Rolf D.; Bohlin-Nizzetto, Pernilla; Borgå, Katrine; Mwakalapa, Eliezer B.; Borgen, Anders R.; Jørgensen, Susanne J.; Ntapanta, Samwel Moses; Mmochi, Aviti J.; Schlabach, Martin; Breivik, Knut
    There are large knowledge gaps concerning environmental levels and fate of many organic pollutants, particu- larly for chemicals of emerging concern in tropical regions of the Global South. In this study, we investigated the levels of chlorinated paraffins (CPs) and dechloranes in air and soil in rural, suburban, and urban regions in and around Dar es Salaam, Tanzania. Samples were also collected near the city’s main municipal waste dumpsite and an electronic waste (e-waste) handling facility. In passive air samples, short chain CPs (SCCPs) dominated, with an average estimated concentration of 22 ng/m3, while medium chain CPs (MCCPs) had an average estimated concentration of 9 ng/m3. The average estimated air concentration of ∑dechloranes (Dechlorane Plus (DP) + Dechlorane 602 + Dechlorane 603) was three to four orders of magnitudes lower, 2 pg/m3. In soil samples, MCCPs dominated with an average concentration of 640 ng/g dw, followed by SCCPs with an average con- centration of 330 ng/g dw, and ∑dechloranes with an average concentration of 0.9 ng/g dw. In both air and soil, DP was the dominating dechlorane compound. Urban pulses were observed for CPs and dechloranes in air and soil. CPs were in addition found in elevated levels at the municipal waste dumpsite and the e-waste handling facility, while DPs were found in elevated levels at the e-waste handling facility. This suggests that waste handling sites represent important emission sources for these pollutants. Investigations into seasonal trends and environmental fate of CPs and dechloranes showed that monsoonal rain patterns play a major role in governing air concentrations and mobility, particularly for the less volatile MCCPs and dechloranes. This study is the first to report levels of CPs in air from sub-Saharan Africa, and DP, Dechlorane 602, and Dechlorane 603 in soil from sub-Saharan Africa.
  • Thumbnail Image
    Item
    Spatial Variation in Contaminant Occurrence in Marine Fishes and Prawns from Coastal Tanzania
    (Environmental Toxicology and Chemistry, 2022) Haarr, Ane; Mwakalapa, Eliezer B.; Lyche, Jan L.; Mmochi, Aviti J.; Polder, Anuschka; Ruus, Anders; Borgå, Katrine
    There are limited data on organic contaminants in marine biota from coastal Tanzania, especially on the occurrence of industrial‐use contaminants such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). The present study, performed in 2018–2019 in coastal Tanzania and Zanzibar Island, aimed at assessing spatial variation in the occurrence of PCBs; brominated flame retardants (BFRs), including PBDEs; and organochlorine pesticides, including dichlorodiphenyltri- chloroethane (DDT), among three locations that differ in degree of anthropogenic activity. Analyzed samples included edible tissues of marine fishes and prawns representing different trophic levels and habitats. The results indicate a mainland–island difference, with fishes and prawns collected on Zanzibar having significantly lower PCB and DDT concentrations but higher concentrations of hexachlorobenzene compared to the two mainland locations. The highest contaminant concentrations were found in fishes and prawns collected around central Dar es Salaam harbor, with median ΣPCBs ranging from 22.3 to 577 ng/g lipid weight and ΣDDTs from 22.7 to 501 ng/g lipid weight, suggesting local sources. Concentrations of PBDEs were similar among locations, suggesting more diffuse sources. None of the “newer‐type” BFRs, including compounds introduced as replacements for PBDEs, were detected in the present study. Stable isotope values of carbon (δ13C) and nitrogen (δ15N) varied among locations, and the relationship between contaminants and δ15N varied among locations and habitat (pelagic/demersal). Concentrations measured in the present study are below European guidelines for human consumption of fishes and prawns. However, industrial‐use contaminants should be monitored in developing countries because they are contaminants of emerging concern as a result of increasing industrialization and global trade of used products and wastes. Environ Toxicol Chem 2022;41:321–333. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC