Distribution and possible sources of polycyclic aromatic hydrocarbons (PAHs) and metals in marine surface sediments off northern Mozambique

S Boitsov; B K Newman; H F Muiambo; E F C Chaúque; B Serigstad; B S Malauene

doi:10.1016/j.marpolbul.2020.111952

Distribution and possible sources of polycyclic aromatic hydrocarbons (PAHs) and metals in marine surface sediments off northern Mozambique

Mar Pollut Bull. 2021 Feb:163:111952. doi: 10.1016/j.marpolbul.2020.111952. Epub 2021 Jan 16.

Authors

S Boitsov¹, B K Newman², H F Muiambo³, E F C Chaúque³, B Serigstad⁴, B S Malauene⁵

Affiliations

¹ Institute of Marine Research (IMR), P.O. Box 1870 Nordnes, N-5817 Bergen, Norway. Electronic address: stepan.boitsov@hi.no.
² Coastal Systems Research Group, Council for Scientific and Industrial Research (CSIR), P.O. Box 59081, Umbilo 4075, Durban, South Africa; Nelson Mandela University, P.O. Box 77000, Port Elizabeth 6031, South Africa.
³ Chemistry Department, Eduardo Mondlane University, P.O. Box 257, Maputo, Mozambique.
⁴ Institute of Marine Research (IMR), P.O. Box 1870 Nordnes, N-5817 Bergen, Norway.
⁵ Instituto Nacional de Investigacão Pesqueira, Av. Mao Tsé Tung 309, Maputo, Mozambique; Ocean Science and Marine Food Security, Nelson Mandela University, Port Elizabeth 6001, South Africa.

PMID: 33461077
DOI: 10.1016/j.marpolbul.2020.111952

Abstract

Liquid natural gas (LNG) exploration has started off the coast of northern Mozambique, in the Rovuma Basin, East Africa. In advance of gas production, we collected in 2018 over 100 samples of surface sediments from 40 locations in the pristine and exploration areas at water depths of 5-2000 m. We have determined the levels of hydrocarbons (total hydrocarbon contents (THC) and 49 individual PAHs), heavy metals, arsenic, grain size and total organic carbon. While sediment composition varied strongly from coarse sediment to high mud contents (<63 μm), background levels of hydrocarbons and metals were found in most samples. We found anthropogenic contamination at one site in Pemba harbor. We observed no petroleum-related contamination, including the Palma area with numerous exploration wells. Elevated concentrations of barium and THC at some locations in this area are attributed to drilling activities but are not considered to be of environmental concern.

Keywords: LNG; Metals; Northern Mozambique Channel; PAHs; Rovuma Basin; Sediment.

MeSH terms

Africa, Eastern
Environmental Monitoring
Geologic Sediments
Indian Ocean Islands
Mozambique
Polycyclic Aromatic Hydrocarbons* / analysis
Water Pollutants, Chemical* / analysis

Substances

Polycyclic Aromatic Hydrocarbons
Water Pollutants, Chemical