Time Integrated Metal Accumulation on Pellets in an Industrial Harbour “Durban Harbour”

Abstract

Once in the environment, preproduction plastic polymers between 2–5 mm in size, also known as pellets, can cause physical harm to animals that mistake them for food as they have been reported to accumulate toxic substances, including on their surface. However, the rate of metal enrichment on pellets is not well investigated. In October 2018, Durban experienced a storm that resulted in ±2000 tons of polyethylene pellets being spilt into Durban Harbour, which caused environmental pollution concerns. This event provided a unique opportunity to study metal accumulation on pellets. Pellets were collected at one-month intervals for 6 months following the spill from October 2017 to March 2018, and metal concentrations were compared to concentrations found on pellets collected before the spill. The pellets were digested using a mixture of concentrated nitric acid (55%) and sulphuric acid (60%) at a ratio of 3:1 and analysed for numerous trace metals (Al, As, Pb, Cd, Cr, Fe, Cu, Mn, Ni, and Zn) using the Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Pellets collected in Durban Harbour prior to the spill in a related study (unpublished data) showed higher metal accumulation; however, there was no evident linear increase in metal concentration in pellets over time. ANOVA showed no significant difference for all metals (p > 0.05) in metal concentration between months; however, there was a significant difference between aged and newly introduced pellets.

Quantification and Characterisation of Pre-Production Pellet Pollution in the Avon-Heathcote Estuary/Ihutai, Aotearoa-New Zealand

“…Sandy Point has been recorded to have the highest concentration of metals across estuary sites and both Southshore Spit and Sandy Point have presented with copper concentrations above the recommended guidelines [79]. Metals such as copper have been documented to be absorbed by plastic [20,80] and pellets made from LDPE and HDPE, which are most prevalent in the estuary, have shown a higher potential to absorb hazardous chemicals than other plastics such as PVC and PET [81]. This also suggests that the pellets may present a direct chemical hazard to biota due to the associated chemicals.…”