In coastal aquifers, seawater intrusion is a significant groundwater issue. The research paper contributes to the understanding of the consequences of seawater intrusion in the Chennai coastal aquifer from Foreshore Estate to Thirunilai along the coastline. 110 groundwater samples were collected and analyzed for physicochemical parameters such as pH, (EC), (TDS), (TH), major anions (Cl⁻, NO₃⁻, HCO₃²⁻, and SO₄²⁻), and cations (Ca²⁺, Mg²⁺, Na⁺, and K⁺) during the pre-monsoon (June 2014) and post-monsoon (January 2015) seasons. Stable isotopic analyses of ¹⁸O were performed on 24 groundwater samples collected from various locations throughout the research region based on EC, TDS, Na, and Cl⁻ concentrations for both seasons. The stable isotopic composition of ¹⁸O and Deuterium in groundwater samples was determined for the study region. According to the Correlation matrix and Factor analysis, the main contributors to groundwater salinity as a result of seawater intrusion into the coastal aquifer are EC, TDS, Na⁺, and Cl⁻. GMWL exhibits a similar pattern, and the samples have been classified into various molar ratio diagrams to identify seawater intrusions for better evaluation. The result revealed that seasonal, geogenic, and anthropogenic factors always make a significant contribution to the heterogeneous chemistry of groundwater.

A multitude of biotic indices that represent environmental status have been developed over the past decades making status comparisons difficult. However, transferring an existing index to a new region can be problematic due to differing stressors, ecosystem components and lack of knowledge on regional species sensitivities. Here we assess whether calculating species sensitivities to specific stressors based on biological traits offers a solution. We use biological traits of macrofaunal species to assess sensitivity to suspended sediment concentrations and calculated the Benthic Quality Index (BQI) at 47 sites across a suspended sediment gradient. This trait-based modification of the BQI was well correlated (0.82) to suspended sediment. Problems previously highlighted, relating to trait plasticity and differential weightings of indifferent and beneficial species, were investigated but did not strongly affect results. A trait-based approach has the additional benefit that the data could be easily converted to evaluate ecosystem function.

This study investigated the sublethal effects of environmentally relevant concentrations of DCOIT on the neotropical oyster Crassostrea brasiliana. Gills and digestive glands of animals exposed to increasing concentrations of DCOIT were analyzed for biochemical, cellular, and histopathological responses. Exposure to DCOIT (0.2 to 151 μg L⁻¹) for 120 h triggered oxidative stress in both tissues (through the modulation of GPX, GST, GSH and GR), which led to damage of membrane lipids (increase of LPO and reduction of the NRRT). DCOIT increased histopathological pathologies in gills, such as necrosis, lymphocyte infiltration and epithelial desquamation. This study showed that short term exposure to environmental concentrations of DCOIT causes negative effects on C. brasiliana at biochemical, physiological, and histological levels. Therefore, the use of DCOIT as a booster biocide in antifouling paints should be further assessed, as it may cause environmental hazards to marine organisms.

Plastic is an omnipresent pollutant in marine ecosystems and is widely documented to be ingested among seabird species. Procellariiformes are particularly vulnerable to plastic ingestion, which can cause internal damage, starvation, and occasionally mortality. In this study, 34 fledgling Fairy Prions (Pachyptila turtur) recovered during a wreck event in south-eastern Tasmania in 2022 were examined for ingested plastics and body condition (e.g., wing chord length). While many of the birds exhibited poor body condition, this was not correlated with the count or mass of ingested plastics. We hypothesise the marine heatwave event, and resulting lack of prey, contributed to bird body condition and subsequent mortality. We provide some of the first data on the size of individual plastic particles ingested by seabirds and make recommendations for future studies to report this important metric in a consistent manner that ensures data are comparable.

We investigated an unexpected microplastic (MP) leakage event that occurred along the coastline of Yantai in January 2021. Sediment samples were collected from three zones on 9 beaches. MPs were identified with an average abundance of 247.6 ± 125.6 items/m² on 7 beaches. The total amount of MPs from the leak accident was estimated to be 1.50 × 10⁷ items (514.67 kg). The MPs were identified as polyethylene (PE), polypropylene (PP), and PP/PE blends using μ-FT-IR analysis. By utilizing a numerical model, the transmission process and potential source of MPs were demonstrated. The modeling results showed that the MPs might originate from the central and western part of the Bohai Sea and be driven to the beaches of Yantai by northwest wind and wind-induced surface current. However, due to the absence of direct evidence, the simulation results might only indicate the range of the leaking source, which was the movement trajectory of MPs.

Brackish areas are where freshwater and seawater meet and possess high geographical and biological importance. However, no unified evaluation method exists for brackish sediments. Therefore, this study applies both the fresh water-sediment quality guidelines (F-SQGs) and the marine-sediment quality guidelines (M-SQGs) to evaluate metal contamination in brackish areas of Korea. The predicted reliability was examined using a receiver operation characteristic (ROC) curve. In the threshold effect level (TEL) evaluation of F-SQGs and M-SQGs, some metals (Cu, Zn, Hg, and Cd) showed significant differences according to guideline characteristics. The ROC curve showed that the predicted reliability of F-SQGs was 97.8 %, which was higher than M-SQGs (91.7 %). From the results of TEL evaluation and ROC curve prediction, F-SQGs are more suitable for the evaluation of brackish sediments in South Korea than M-SQGs.

Oil emulsions can harm marine and coastal environments for extended periods. Timely identification and quantification of oil emulsions are essential for oil spill response. Although SAR is the most commonly used technique in detecting oil presence, it has limits in oil quantification. In contrast, optical remote sensing can fill this gap with more spectral bands. Hyperspectral remote sensing is capable of achieving this purpose. However, it is challenging to use multi-band coarse-resolution imagery due to the fewer bands and mixed pixel effect. Through laboratory measurements, numerical simulation, and Hue-Saturation-Value (HSV) model, we illuminate the multispectral mixed characteristics of oil emulsions and demonstrate Hue's role in characterizing the mixture features and oil concentration trends. Hue-based oil emulsion classification and oil concentration segmentation (OCS) methods are proposed and applied to Landsat-5 images under quantified uncertainties. This approach is expected to expand its application in multispectral remote sensing.

Potassium cyanide (KCN), a highly water soluble and bioaccumulative cyanide salt, is examined to determine the toxic effects by using two green algae (Dunaliella viridis, Nannochloropsis oculata) and genetically different two sea urchin (Paracentrotus lividus, Arbacia lixula) species. To determine the toxic effects on the early developmental stages of sea urchin embryos, 72-hour embryotoxicity studies were conducted. Potassium cyanide toxicity at cellular level was also investigated and 6-hour embryos of both sea urchin species were used to determine genotoxic effects of KCN. Since plutei naturally feed on microalgae, two species of plankton were used to reveal phytotoxic effects of KCN. KCN was found to be embryo- geno- and phytotoxic. EC₅₀'s for P. lividus and A. lixula were found 7.96 and 6.52 μM. IC₅₀'s for N. oculata for 48 h and 72 h were found 23.66 and 80.45 μM. IC₅₀'s for D. viridis for 48 h and 72 h were found 14.31 and 23.36 μM.

In this research, we have developed and validated a modified version of the U.S.EPA method 506 using a liquid-liquid extraction method followed by gas-chromatography mass spectrometry analysis to assess the occurrence and spatial and seasonal variation of six phthalates (di(2-ethylhexyl) phthalate-DEHP, dibutyl phthalate-DBP, butyl benzyl phthalate-BBP, diethyl phthalate-DEP, dimethyl phthalate-DMP, and di-n-octyl phthalate-DOP) in surface and tap waters from South Florida, collected during the wet and dry seasons. The most frequently detected phthalate was DEHP, with concentrations up to 1.56 μg/L in surface water. Higher DEHP concentrations were observed in tap water during the wet season, which aligns with the higher temperature during the summer months facilitating leaching from plastic materials. Preliminary ecological and human health risk assessments suggested low hazard risk based on concentrations observed in tap and surface waters, respectively. PAEs could however still constitute a great concern to sensitive marine species, including early stages organisms and coral reefs.

Tracking the subsea oil plume during the 2010 Deepwater Horizon Oil Spill (DWH) was conducted using in situ fluorescence via vertical profilers (n = 1157) and discrete sample chemical analyses (n = 7665). During monitoring efforts, discrete samples provided a coarse picture of the oil plume footprint, but the majority of the samples were below standard analytical detection limits for petroleum hydrocarbons. In situ fluorescence data improved the spatial and temporal resolution of the subsea oil plume characterization. Here we synthesized millions of continuous fluorescence data points from hundreds of contemporaneously discrete samples collected to demonstrate how fluorescence could serve as a proxy for Benzene-Toluene-Ethylbenzene-Xylene (BTEX) concentration. Data mined from Gulf Science Data repository were well correlated, and geographically and temporally aligned to provide direct comparisons. Described here are the methods used to calibrate the fluorescence data and to spatially approximate the three-dimensional geographic extent of the oil plume.