An assessment of an oil spill in Gladstone, Australia - impacts on intertidal areas at one month post-spill

Assessing diatom distribution in Cambay Basin, Western Arabian Sea: impacts of oil spillage and chemical variables

Freshwater and marine diatoms produce the majority of the oxygen in aquatic systems. Estimates range from 12,000 to 30,000 species, and spatial distribution varies globally. There is significant variation in diatom diversity based on geographical and environmental conditions as well as the physicochemical characteristics of the habitat. Therefore, understanding the underlying factors that contribute to changes in diatom community structures requires a comprehensive understanding of taxons. A study of diatom assemblages from the Cambay Basin, Western Arabian Sea, was conducted, particularly on oil fields. A total of 37 samples were collected; nine were from oil fields. We evaluated micro-oil spills using Fourier transform infrared (FTIR) analysis and microscopic techniques. Correlations were established through the ordination analysis of pernicious physical and chemical water variables (BOD, COD, TDS, pH, temperature, and DO), including principal component analysis (PCA). The oil field sites showed more total dissolved solids (TDS) and chemical oxygen demand (COD) than the respective marine control sites. The study does not display a cause-and-effect relationship, but we observed a positive correlation between increasing silica concentrations and diatom growth in oil fields. In contrast, high aluminium concentrations in oil fields negatively impacted the growth of diatom assemblage and abundance. When surveyed in nine oil fields, we found that Gomphonella pseudosphaerophorum and Nitzschia palea are well adapted to oil concentrations up to 40 ppm.

Environmental disaster in the northeast coast of Brazil: Forensic geochemistry in the identification of the source of the oily material

The characterization of petroleum or its products spilled in the environment in relation to its source rocks is an important tool to assist in the resolution of issues of environmental impact and legal responsibility since it clarifies the possible region or the producing country of that type of petroleum. This article analyzes the application of analytical techniques for petroleum geochemistry to identify the type and origin of oily material collected from beaches in Northeast Brazil in 2019. Samples of the oily material collected on the beaches in the states of Bahia and Sergipe were analyzed and for comparison purposes, samples of crude oils produced in Brazil, Middle East, Nigeria and Venezuela were also analyzed. The analytical results showed that the oily material that reached the beaches has geochemical characteristics compatible with those of the Venezuelan oil, indicating it was severely weathered or a product made with heavy oil produced.

Sources, presence and potential effects of contaminants of emerging concern in the marine environments of the Great Barrier Reef and Torres Strait, Australia

Current policy and management for marine water quality in the Great Barrier Reef (GBR) in north-eastern Australia primarily focusses on sediment, nutrients and pesticides derived from diffuse source pollution related to agricultural land uses. In addition, contaminants of emerging concern (CECs) are known to be present in the marine environments of the GBR and the adjacent Torres Strait (TS). Current and projected agricultural, urban and industrial developments are likely to increase the sources and diversity of CECs being released into these marine ecosystems. In this review, we evaluate the sources, presence and potential effects of six different categories of CECs known to be present, or likely to be present, in the GBR and TS marine ecosystems. Specifically, we summarize available monitoring, source and effect information for antifouling paints; coal dust and particles; heavy/trace metals and metalloids; marine debris and microplastics; pharmaceuticals and personal care products (PPCPs); and petroleum hydrocarbons. Our study highlights the lack of (available) monitoring data for most of these CECs, and recommends: (i) the inclusion of all relevant environmental data into integrated databases for building marine baselines for the GBR and TS regions, and (ii) the implementation of local, targeted monitoring programs informed by predictive methods for risk prioritization. Further, our spatial representation of the known and likely sources of these CECs will contribute to future ecological risk assessments of CECs to the GBR and TS marine environments, including risks relative to those identified for sediment, nutrients and pesticides.

Trace metals in aquatic environments of a mangrove ecosystem in Nansha, Guangzhou, South China: pollution status, sources, and ecological risk assessment

Mangrove forests are widely located along coastlines. They have been identified to be inimitable and dynamic ecosystems. This study investigated the trace metals in mangrove water and surface sediments of Nansha, Guangzhou, China. Zn (148.42 ± 247.47 μg L^-1) was the most abundant metal in waters, followed by As (82.34 ± 118.95 μg L^-1), Pb (22.96 ± 120.50 μg L^-1), and Ni (19.42 ± 47.84 μg L^-1). In sediments, the most abundant metal was Fe (27.04 ± 1.91 g kg^-1), followed by Mn (1049.04 ± 364.11 mg kg^-1), Zn (566.33 ± 244.37 mg kg^-1), and Cr (106.9 ± 28.51 mg kg^-1). Higher contents of trace metals were detected in vicinity areas of the river mouth. The results of pollution indexes, including contamination factor, enrichment factor, and geo-accumulation index, indicated the pollution of Cd, Cu, Pb, and Zn in sediments. The Spearman correlation and cluster analysis were used to evaluate the metal sources. In water, the significant correlations among Zn and water chemical parameters (Na, Mg, K, Ca, conductivity, pH, and Cl) might indicate the natural source of Zn from the seawater. Water sampling sites in estuaries and coastal areas were clustered separately, which might indicate the influences of upstream water and the seawater, respectively. In sediments, the significant relationships among Cd, Pb, and Zn concentrations were likely to imply the emissions from industries and exploitation of the Pb-Zn mine. The occurrence of Cr and Cu in sediments can be attributed to the spills of lubricants or oil. Cd in sediments could cause serious ecological risk.

Effects of hydrocarbon pollution in the structure of macrobenthic assemblages from two large estuaries in Brazil

Changes in the structure of benthic macrofauna and its relationship with hydrocarbon contamination were determined at different spatial scales in sublittoral sediments of two large estuaries in Brazil. Guanabara Bay (GB) is a heavily polluted estuary due to the presence of a large industrial complex and high demographic density. Laranjeiras Bay (LB) lies in an Environmental Protection Area and can still be considered as preserved from human activities. Despite some spatial differences within each bay, the PAHs concentrations were significantly and consistently higher in GB, with values generally above the threshold effect levels. No signs of hydrocarbon contamination were observed in LB. Macrofauna abundance, diversity and overall assemblage structure were largely different between bays. Canonical analysis of principal coordinates (CAP), used to model the relationship between macrofauna and PAHs levels, indicated that this class of hydrocarbons is the main structuring factor of soft-bottom assemblages in both bays.

Are intertidal soft sediment assemblages affected by repeated oil spill events? A field-based experimental approach

This study investigates the impact of repeated diesel spills on the structure of intertidal macrofaunal assemblages of a subtropical estuary. Three frequencies of exposure events were compared against two dosages of oil in a factorial experiment with asymmetrical controls. Hypotheses were tested to distinguish between (i) the overall effect of oil spills, (ii) the effect of diesel dosage via different exposure regimes, and (iii) the effect of time since last spill. Repeated oil spills dramatically altered the overall structure of assemblages and reduced the total density of macrofauna and densities of dominant taxa. Increasing the frequency of oil spills negatively affected macrofauna. In general, frequent low-dosage oil spills were more deleterious than infrequent high-dosage ones. However, increases in densities of some taxa, mainly the gastropod Heleobia australis, were observed in response to infrequent spills. Our results highlight the importance of repeated exposure events in determining the extent of oil impacts.

Impact of hydrocarbons from a diesel fuel on the germination and early growth of subantarctic plants

Special Antarctic Blend (SAB) is a diesel fuel dominated by aliphatic hydrocarbons that is commonly used in Antarctic and subantarctic regions. The past and present use of SAB fuel at Australia's scientific research stations has resulted in multiple spills, contaminating soils in these pristine areas. Despite this, no soil quality guidelines or remediation targets have been developed for the region, primarily due to the lack of established indigenous test species and subsequent biological effects data. In this study, twelve plant species native to subantarctic regions were collected from Macquarie Island and evaluated to determine their suitably for use in laboratory-based toxicity testing, using germination success and seedling growth (shoot and root length) as endpoints. Two soil types (low and high organic carbon (OC)) were investigated to reflect the variable OC content found in soils on Macquarie Island. These soils were spiked with SAB fuel and aged for 14 days to generate a concentration series of SAB-contaminated soils. Exposure doses were quantified as the concentration of total petroleum hydrocarbons (TPH, nC9-nC18) on a soil dry mass basis. Seven species successfully germinated on control soils under laboratory conditions, and four of these species (Colobanthus muscoides Hook.f., Deschampsia chapmanii Petrie, Epilobium pendunculare A.Cunn. and Luzula crinita Hook.f.) showed a dose-dependent inhibition of germination when exposed to SAB-contaminated soils. Contaminated soils with low OC were generally more toxic to plants than high organic carbon soils. Increasing soil-TPH concentrations significantly inhibited shoot and root growth, and root length was identified as the most sensitive endpoint. Although the test species were tolerant to SAB-contaminated soils in germination assays, development of early life stages (up to 28 days) were generally more sensitive indicator of exposure effects, and may be more useful endpoints for future testing.

Are changes in the structure of nematode assemblages reliable indicators of moderate petroleum contamination?

This study assesses through a multiple before-after-control-impact (MBACI) design the effects of diesel oil on the structure of nematode assemblages in unvegetated tidal flats of a subtropical estuary. Oil-exposed treatments were contrasted with controls for a duration of four successive days before and after an experimental spill in three distinct areas of the Paranaguá Estuarine Complex (Southern Brazil). No significant differences were observed in nematode total density, number of taxa and the overall assemblage structure between the control and impact treatments from before to after the experimental spill. This reinforces the idea that, despite being good indicators of environmental stress, free-living marine nematodes are able to tolerate low concentrations of hydrocarbons and to survive in moderately contaminated areas. We also show that robust experimental designs are useful to avoid confounding expected natural variability with the effects of a mild impact.

Toxicities of oils, dispersants and dispersed oils to algae and aquatic plants: review and database value to resource sustainability

Phytotoxicity results are reviewed for oils, dispersants and dispersed oils. The phytotoxicity database consists largely of results from a patchwork of reactive research conducted after oil spills to marine waters. Toxicity information is available for at least 41 crude oils and 56 dispersants. As many as 107 response parameters have been monitored for 85 species of unicellular and multicellular algae, 28 wetland plants, 13 mangroves and 9 seagrasses. Effect concentrations have varied by as much as six orders of magnitude due to experimental diversity. This diversity restricts phytotoxicity predictions and identification of sensitive species, life stages and response parameters. As a result, evidence-based risk assessments for most aquatic plants and petrochemicals and dispersants are not supported by the current toxicity database. A proactive and experimentally-consistent approach is recommended to provide threshold toxic effect concentrations for sensitive life stages of aquatic plants inhabiting diverse ecosystems.

Reciprocal experimental transplantations to assess effects of organic enrichment on the recolonization of benthic macrofauna in a subtropical estuary

Coastal benthic habitats are usually in a state of continuous recolonization as a consequence of natural disturbances or human activities. Recolonization patterns can be strongly affected by the quality of the sediment. We evaluated herein the macrobenthic recolonization of organically enriched sediments through a manipulative experiment involving reciprocal transplants between contaminated and non-contaminated intertidal areas. Regardless of the experimental treatments, the density of the polychaete Capitella sp. was extremely high in the contaminated area as well as the density of the gastropod Cylichna sp. in the non-contaminated area. We rejected the hypothesis that differences in sediment quality would determine macrofaunal recolonization at least in the considered scales of space in meters and time in weeks. The recolonization process in a subtropical estuarine environment was strongly dependent on the migration of adults present in the sediments adjacent to the experimental units.

Effects of an experimental in situ diesel oil spill on the benthic community of unvegetated tidal flats in a subtropical estuary (Paranaguá Bay, Brazil)

The effects of diesel oil on benthic associations from unvegetated tidal flats in a subtropical estuary were experimentally evaluated using a Multivariate Before and After/Control and Impact Model (M-BACI). Impacted treatments were contrasted with controls in 14 successive periods before and after the oil spill. An acute effect was recorded just after the impact, but the recovery to pre-disturbance population levels was extremely fast. The increase in the total density of the benthic community after the disturbance was the result of an increase in the densities of Heleobia australis, oligochaetes, and ostracods, observed in both impacted and control treatments, as a reflection of background variability and not the presence of the contaminant. The experimental spill had little influence on the biological descriptors of the benthic associations, which were resilient or tolerant to oil disturbance at the temporal (147 days) and spatial (cm²) scales used in the experiment.

Impacts of a fuel oil spill on seagrass meadows in a subtropical port, Gladstone, Australia--the value of long-term marine habitat monitoring in high risk areas

We used an established seagrass monitoring programme to examine the short and longer-term impacts of an oil spill event on intertidal seagrass meadows. Results for potentially impacted seagrass areas were compared with existing monitoring data and with control seagrass meadows located outside of the oil spill area. Seagrass meadows were not significantly affected by the oil spill. Declines in seagrass biomass and area 1month post-spill were consistent between control and impact meadows. Eight months post-spill, seagrass density and area increased to be within historical ranges. The declines in seagrass meadows were likely attributable to natural seasonal variation and a combination of climatic and anthropogenic impacts. The lack of impact from the oil spill was due to several mitigating factors rather than a lack of toxic effects to seagrasses. The study demonstrates the value of long-term monitoring of critical habitats in high risk areas to effectively assess impacts.

The Gladstone (Australia) oil spill - impacts on intertidal areas: baseline and six months post-spill

In January 2006, 25 tonnes of heavy fuel oil spilled into the Port of Gladstone in Queensland, Australia, from the breached hull of a bulk carrier ship. While approximately 18 tonnes of the oil was recovered, a certain amount of oil was deposited in the intertidal areas of Port Curtis leaving a highly visible, viscous residue. The objectives of this research were to assess the short-term (one month post-spill) and medium-term (six months post-spill) impacts on the intertidal habitat. Sediment polycyclic aromatic hydrocarbons (PAHs) and metal concentrations, mangrove communities and intertidal macroinvertebrates were assessed at oil impacted sites, adjacent sites which were not visibly impacted and reference sites which were located outside the recorded distribution of the oil spill. At one month post-spill, highest PAH concentrations were found at the impacted sites, with concentrations of some PAHs exceeding Australian and New Zealand sediment quality guidelines (SQG) [ANZECC/ARMCANZ, 2000. Sediment Quality Guidelines. Australia and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand]. However, by six months post-spill PAH concentrations had significantly decreased. PAH concentrations tended to be higher in the back (upper) intertidal zone than at the front of the mangrove stand, and sediment cores indicated that PAH contaminants had remained in the top 4cm of the sediment. These results indicate that the overall decreased PAH concentrations are likely to be due to evaporation, photoxidation and tidal flushing of the residual oil in these impacted sites. During the initial survey, the impact site contained very few or no crabholes in the high intertidal area, indicating a low crab density in comparison to reference sites. However, at six months post-spill mangrove crab communities appeared to be fully recovered with crabhole densities in impact sites similar to reference sites. While little immediate impact was evident on mangrove parameters, significantly higher seedling mortality and defoliation was apparent at six months post-spill, particularly in the upper intertidal zone. Intertidal macrobenthic communities did not appear to be impacted, either immediately or at six months post-spill. Monitoring of these oil impacted intertidal areas will continue to examine the long-term impacts/recovery from the oil spill.