Taking the coral communities of the Xuwen coral reef in 2020 as the research object, we analyzed the species composition, diversity, and interspecific Spearman correlation of the scleractinian coral communities, investigated the features and spatial distribution of the scleractinian coral community, and discussed the correlation between the community composition and environmental factors to identify the affecting factors and their sources. These results showed that (1) compared with the survey in 2004, the coverage of corals in 2020 had significantly decreased, while the dominant genera were still Goniopora and Porites. The coral morphology was massive, and the diversity of the coral community (Shannon–Wiener index, H’) was 2.87. The distribution of coral was uneven. The competition among some dominant species of coral was intense. (2) The mass coral bleaching event in the NSCS in August 2020 did not cause severe coral death in the short term on the Xuwen coral reef. (3) The growth of the coral community in 2020 might be greatly affected by high suspended solids and nutrient levels, which were related to the current, mariculture, and coastal erosion. (4) Anthropogenic activities such as coastal aquaculture and fishing were the major factors leading to the reduction in coral coverage on Xuwen coral reef in the past 10 years.

The behavior and influence mechanisms of trace elements in Antarctic ecosystems are particularly complex and important. This study aims to assess the ecological risk to the Fildes Peninsula by systematically analyzing the distribution of trace elements, and provides a scientific basis for the protection of the Antarctic ecosystem. Trace element concentrations in the soils of the Fildes Peninsula are highest for Fe, Al, and Mg, with notable differences in distribution due to varying topographies and landscapes. Principal component analysis reveals strong correlations among Zn, Fe, Mn, Co, and Cu, and distinct patterns for Na, Ca, As, and Cr. Moss demonstrates a high enrichment capacity for Cu and Zn, often accumulating them to higher levels than soil, with significant spatial variation observed. The bioaccumulation factors (BAF) for K and Ag exceed 1 at all 12 stations, indicating a high capacity for bioaccumulation. Over half of the stations show BAF values greater than 1 for Na, Ca, and Cd, while the other trace elements have BAF values greater than 1 at only limited stations. The geo-accumulation index (I_geo) shows most trace elements in the Fildes Peninsula soils are unpolluted, with Mg, Mn, Cr, and Ni concentrations varying between unpolluted and moderate pollution, and all potential ecological risk index (PERI) values under 150 indicating low ecological risk.

Inert construction and demolition waste from Hong Kong (HK public fills) has been used for marine trial reclamation in the Guanghai Bay (GHWT) of the Chinese Mainland. However, an environmental assessment of HK public fills is necessary due to higher radioactivity in HK soils than typical global levels. Here, radiation dose rate, gamma radionuclides and gross beta of HK public fills were analyzed. The origin information was explored using natural primordial radionuclides as fingerprints. Our data show that radiation dose rate of HK public fills before disposal was 0.14-0.54 (0.33 ± 0.03) μSv/h (n = 16,722 data with 2787 ships) in 2014, which is less than the GHWT background. Monthly detection of ²³⁸U, ²²⁶Ra, ²¹⁰Pb, ²³²Th, ²²⁸Th, ⁴⁰K, and gross beta in HK public fills was conducted on three random ships. Their specific activities were <6.27-155.5, 58.7-98.7, <7.83-238.2,97.9-168.6, 87.1-136.0, 463.1-1,018, and 1047-1658 Bq/kg_DW, respectively. These results suggest that the radioactivity levels of HK public fills are essentially the same as the GHWT background. The study assessed potential risks using various indices icluding Ra_eq (Radium equivalent activity), H_ex (External radiation hazard index), H_in (Internal radiation hazard index), I_γ (Gamma index), AUI (Activity utilization index), AUI (Activity utilization index), E (Annual effective dose), AGDE (Annual gonadal dose equivalent), RLI (Representative level index), D_in (Indoor air absorbed dose rate), D_out (Outdoor air absorbed dose rate), and ELCR (Excess lifetime cancer risk). The study suggests that HK public fills should be used for the trial reclamation rather than building-house materials. This provides valuable insights for the resource utilization and minimizing environmental pollution of HK public fills. The aim is to offer fundamental technical assistance for future waste resource utilization, ecological protection, and restoration in the Guangdong-Hong Kong-Macao Greater Bay Area.

This study aimed to investigate the acute and chronic toxic effects of two thermodynamic inhibitors (methanol and ethylene glycol) widely used in deep-sea oil and gas operations on two typical marine fish species, the medaka (Oryzias melastigma) and the yellowstripe goby (Mugilogobius chulae), to assess their potential ecological risks in marine environments. The 96-h median lethal concentration (LC₅₀) was determined through acute toxicity tests. A 56-day chronic toxicity test was conducted to evaluate the effects on fish growth (body length) and the antioxidant defense system, specifically the activities of superoxide dismutase (SOD) and catalase (CAT). The results revealed marked species-specific differences. In terms of acute toxicity, medaka exhibited exceptionally high sensitivity to ethylene glycol (LC₅₀ 15.77 g/L), while the yellowstripe goby showed greater tolerance (LC₅₀ 22.17 g/L). Chronic exposure led to concentration-dependent growth inhibition in both species, and medaka showed significantly higher mortality than yellowstripe goby. Under methanol exposure, medaka exhibited significantly higher mortality (30–45%) than yellowstripe goby (5–20%). When exposed to ethylene glycol, medaka showed markedly high mortality (55–85%), while yellowstripe goby mortality remained below 15%. At the molecular level, both chemicals induced oxidative stress, but the response patterns of the antioxidant enzymes (SOD and CAT) were species-specific, indicating differences in toxic mechanisms and detoxification capacities. Methanol and ethylene glycol pose non-negligible ecotoxicological risks to marine fish, and the toxicity intensity is influenced by species specificity, exposure concentration, and the effectiveness of the antioxidant defense system. This study emphasizes that environmental risk assessments for such chemicals must fully account for species differences and sublethal effects, providing critical scientific evidence for formulating precise environmental safety standards for marine hydrocarbon exploitation.