Fig 1.
Map of sampling locations in the Windmill Islands around Casey Station.
Upper inset shows location of Casey in east Antarctica. Lower inset shows Brown Bay as outlined in box on main Figure. HON = Honkala Island; STE = Stephenson Cove; WIL = Wilkes; NEW = Newcomb Island; MCG = McGrady Cove; Wh = Casey Wharf; SHB = Shannon Bay; OB1 to 5 = O’Brien Bay 1 to 5; BI = Beall Island; SP1 = Sparkes Bay 1; OLD = Old Casey; BBI = Brown Bay Inner; BBM = Brown Bay Middle; BBO = Brown Bay Outer.
Table 1.
Years of marine sediment sampling at locations around Casey station and the Windmill Islands, East Antarctica, between 1996 and 2015.
Fig 2.
Spatial and temporal variation in sediment grain size.
PCA ordination of % composition of grain size classes in sediments. PC1 and PC2 explain over 93% of total variation in grain size. Red to pink symbols represent potentially impacted locations and green, blue and grey represent control locations. A vector plot shows samples dominated by the <63 μm fraction on the left of the ordination with a gradient of increasing sand content correlated with PC1, but also a separation of samples with a gradient of medium and coarse sands to fine sands aligned with PC2.
Fig 3.
Spatial and temporal variation in marine sediments at Casey.
Box and whisker plots showing: A) the percentage of <63 μm fraction and B) % of total organic matter in marine sediments at Casey station in the Windmill Islands, East Antarctica sampled between 1998 and 2014.
Table 2.
Four factor PERMANOVA analysis of all grain sizes, <63 μm and total organic matter (TOM) in sediments.
Table 3.
Spatial variation in grain size classes of marine sediments at Casey, by year of sampling.
Table 4.
Results of PERMANOVA planned comparisons of grain size and TOM in 2014/15 versus pre 2000.
Table 5.
Four factor PERMANOVA analysis of metals in sediments.
Table 6.
Spatial variation in metal concentrations in sediments, by year, at Casey.
Fig 4.
Spatial and temporal variation in metals in sediments at Casey.
PCA ordination of metal concentrations in marine sediments at Casey station (normalised data). PC1 and PC2 explain 68% of variation in metals. Vector plot of correlations of individual metals with PC axes overlaid on ordination. BBI = Brown Bay Inner; BBM = Brown Bay Middle; BBO = Brown Bay Outer; CW = Casey Wharf; HKI–Honkala Island; MGC = McGrady Cove; OB1-3 = O’Brien Bay-1 to -3; OLDCAS = Old Casey; SB = Sparkes Bay; SHB = Shannon Bay; STC = Stevenson Cove; WK = Wilkes.
Fig 5.
A and B: Spatial and temporal variation in metal and element concentrations in sediments at Casey. Box and whisker plots of metal concentrations: Each bar represents all samples in a particular year at a location. Dashed lines show various sediment quality guideline values: SQGV = ANZECC guideline trigger values; TEL = Threshold Effects Level; PEL = Probable Effects Level. Note log scale in some Figures. A) Lead, zinc, tin, iron, copper, cadmium; B) Arsenic, chromium, silver, nickel, sulfur, antimony, barium, manganese.
Fig 6.
Normalized enrichment factors of metals in sediments at disturbed locations.
Note that x-axis crosses y-axis at 1 and values below this are below the average of the control locations, while above 1 are enriched relative to controls.
Table 7.
Impact versus controls: Ratio of metal concentration at each impacted site compared to controls in 2014/15.
Table 8.
Impact versus control: Enrichment factors (EF) in different years for metals at impacted sites at Casey station.
Table 9.
Change over time in metal concentrations.
Ratios of metal concentrations between 2014/15 and pre-2000 at each location.
Fig 7.
Spatial and temporal variation in hydrocarbon concentrations in sediments at Casey.
Box and whisker plots of hydrocarbon concentrations: Each bar represents all samples in a particular year at a location. Dashed lines show various sediment quality guideline values: SQGV = ANZECC guideline trigger values; TEL = Threshold Effects Level PEL = Probable Effects Level.
Table 10.
Spatial variation in hydrocarbons in sediments at Casey station.
Table 11.
Comparison of TPH concentrations between impacted and control locations in 1998 and 2014.
Table 12.
Spatial variation in persistent organic pollutants in sediments at Casey.
Fig 8.
Spatial and temporal variation in persistent organic pollutants in marine sediments at Casey.
Box and whisker plots of POP concentration for: A) PCBs and B) PBDEs (note log scale on Y axes), where each bar represents all samples in a particular year at a location. Dashed lines show various sediment quality guideline values: SQGV = ANZECC guideline trigger values; TEL = Threshold Effects Level PEL = Probable Effects Level; C) Average PBDE congener composition at each time at each location.
Fig 9.
Spatial and temporal variation in nutrients in marine sediments at Casey.
A) Box and whisker plots of nutrient concentrations in marine sediments at Casey station in 2014/15, w here each bar represents all samples; B) PCA ordination of nutrient concentrations (normalized data). PC1 And PC2 explain approx. 82% of variation in nutrients.
Table 13.
Spatial variation in nutrients in sediments at Casey.
Table 14.
Magnitude of anthropogenic change (MAC) and ecological risk posed by sedimentary contaminants.
Table 15.
Comparison of PBDE concentrations in marine sediments in Antarctica and other global regions.