Assessment of environmental impacts of shipping on the marine coastal environment of New South Wales (NSW), Australia

Australia is surrounded by a number of sea ports, many of which are in or near environmentally sensitive areas and engaged with extensive commercial and recreational activities. All these ports and shipping activities often a release variety of pollutants (trace elements, nutrients and microplastics), demanding attention to understand their probable impacts on the surrounding ecosystems. In the present study a broad spectrum of contaminants, including trace elements and inorganic nutrients in water, sediment, oysters and seaweed, and microplastics in sediment and oysters of six sea ports, namely Port Jackson, Port Botany, Port Kembla, Port Newcastle, Port Yamba and Port Eden of New South Wales (NSW), were investigated and compared with their background areas which were selected from the non-port areas of the same hydrogeological area. Extensive review on trace elements and microplastics contamination in the sea port environment in Australia was carried out to identify the gaps which helped us to further design this study. Seawater samples at 30 stations from six ports in NSW, Australia were investigated to determine the Water Quality Index (WQI), Heavy metal Evaluation Index (HEI), Contamination Index (Cd) and newly developed Environmental Water Quality Index (EWQI). The study revealed medium water quality index, high and medium heavy metal evaluation index and high contamination index in almost all of the studied ports. Low level dissolved oxygen (DO) and higher dissolved solids, turbidity, faecal coliform, Cu, Fe, Pb, Zn, Mn, Cd and Co are mainly responsible for the poor water qualities of the port areas. Good water quality at the background samples indicated that port activities are the likely cause for poor water quality inside the port area. Likewise, sediment samples from the study ports were collected and analysed for trace element distribution. The study results revealed significant concentrations of As, Cu, Fe, Pb, Ni, Co and Zn in the surface sediments of the port areas which were much higher than the background values and the standards given by Australian and New Zealand Environment and Conservation Council (ANZECC/ARMCANZ, 2000) and other international guidelines including USA-ERM and CSQG-China. The maximum concentrations of Al, Bo, Co, Mo, Ba, Sn, Sr and Ti were also much higher than the background surface sediments, indicating enrichment of these metals at the study ports, although currently no guidelines exist for the concentration of these elements in sediments. However, geoaccumulation index (Igeo), enrichment factor (EF), pollution load index (PLI), potential ecological risk (PER) and sediment pollution index (SPI) also demonstrate sedimentary metal pollution (Pb, Cu, Zn, Fe and Ni) in almost all the studied ports with significant pollution at Port Kembla and Port Eden. Sydney rock oysters (S. glomerata) and seaweeds (Ecklonia radiata) from six major sea ports of NSW, Australia were further used as bioindicators to assess the distribution and concentrations of trace element accumulation in the sea ports. Substantial enrichment of Cu, Pb and Zn in the oysters at the sea ports were detected when compared to their background samples and the United States Environmental Protection Agency (USEPA) provisional tolerable intake standard. Enrichment of As, Al, Fe, Mn, Br, Sr were also found in the oysters at the port areas. The bioconcentration ratios (BCRs) of the trace elements illustrated significant Fe, Cu, Zn, As, Mn, Al, Pb and Cr accumulation in S. glomerate. The biota sediment accumulation factor (BSAFs) also suggested Cu, Mn and Zn accumulation at Port Yamba and Port Botany, indicating availability of these metals in the oysters as strong metal accumulators which is further supported by integrated metal contamination. However, significant levels of Zn, Fe, As, Al, Pb, B, Br, Si and Sn were also found in the seaweed of the studied ports most of which were higher compared to their background ecosystem. The BCRs results illustrated enrichment of Al, Fe, Mn, Zn, Pb, Cu, As and Ba in E. radiata whereas the BSAFs portrayed B enrichment in all sea ports along with bioaccumulation of As in Port Jackson and Pb in Port Botany. Furthermore, the interrelationship of microplastics contamination in the sediments and oysters at the studied sea ports of NSW, Australia were investigated. The study results revealed a significant abundance of microplastic particles both in sediments and oysters of the sea ports with the higher abundance in oysters. The abundance of microplastics was 83–350 particles/kg dry weight in the sediments and 0.15–0.83 particles/g wet weight in the oyster at the studied seaports which were higher than their background areas in most ports, with exceptions to the background sediments of Port Botany, Port Kembla and Port Yamba and the background oyster of Port Kembla. Spherules, fibres and fragments were the three dominant categories of microplastics which were mostly white and transparent in colour and small in sizes (<1 mm) both in sediments and oysters. Fourier Transform Infrared Spectroscopy (FTIR) analysis results of the identified microplastics, in both sediments and oysters, demonstrated that polyethylene terephthalate (23% and 35% respectively) and nylon (20% and 29% respectively) were the two dominant polymer types of the study ports. The distribution, shapes and polymer types of the examined microplastics suggest that anthropogenic activities, industrial effluents, port activities and fishing inside and around the port areas were the likely major reasons for the microplastic pollution in the studied sea ports of Australia. Overall, the obtained findings exposed uneven distribution of contaminants throughout the sea ports. Therefore, for effective management efforts, it is essential to adequately monitor the source, degree and impact of contaminants.