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Coastal areas are regions of active interaction between the sea and land and are highly sensitive to changes in heavy metal contamination caused by natural and anthropogenic activities. The contents of heavy metals in 80 surface sediments in the Qizhou Island sea area in the northeast of Hainan Island were determined to assess the contamination status, spatial distribution, sources, and ecological risks. The results indicate that the main factors influencing the distribution patterns and contents of heavy metals are hydrodynamic conditions and sources of materials. The accumulation of Cd and Pb in the sediments is attributed to the combined effects of natural sources and anthropogenic input. In addition to widespread anthropogenic influence, the enrichment of Cd in the southeastern outer shelf area of the study region may be controlled by biogenic carbonate rocks or enhanced input of near-source materials during the late Pleistocene low sea level period., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The Bering Sea and the Chukchi Sea are important regions for marine ecosystems and climate change. However, the historical deposition and sources of metals in these regions are poorly understood. In this study, we utilized Pb isotopes and multi-element concentrations (Ni, Cu, Fe, Mn, Zn, Cd, Pb) coupled with Pb-210 dating to investigate the historical deposition and source identification of metals in sediment cores collected from the Bering Sea and the Chukchi Sea. Our findings reveal that the transport of organic matter was mainly transported by marine and terrestrial sources in the Bering and Chukchi Sea, respectively. Historical variations of metals were similar in both seas, showing an increasing trend of metals (excluding Mn) from the 1960s to the 1990s, followed by a gradual decrease after the 1990s, which can be attributed to the development of industrial and gasoline emission. The results of the geo-accumulation index indicated that sediment in both seas was relatively unpolluted with metals. Additionally, Pb isotopic ratios suggested that natural weathering was the primary source of Pb in the area, but the use and phase-out of gasoline were also well-reconstructed. This study provides valuable information for assessing environmental changes and human activities over the past century in the Arctic and subarctic Ocean., Competing Interests: Declaration of competing interest ☑ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

We analyzed total organic carbon (TOC), total nitrogen (TN), and heavy metals in 58 sediment samples from the Laoshan Bay, China. TOC and TN results identified marine primary production as the dominant source for organic matter, and the weak correlations between TOC, TN, and heavy metals indicated the terrestrial origin of heavy metals. Cd showed insignificant correlations with other metals, which suggests that agriculture production is the main anthropogenic activity affecting the distribution of Cd. Pb contamination in past 50 years was likely to have occurred because of fossil fuel combustion. Despite 210 Pb dating, it was still difficult to trace the contamination condition over interannual variations. Nonetheless, these results provide data for monitoring Pb contamination. As Laoshan Bay is an important economic area, it would be beneficial to conduct further studies to determine the sources and degree of contamination for each heavy metal., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Riverine sediment samples from Hainan Island were collected in 2013 to assess the heavy metal pollution levels, sources, and associated environmental risks. The concentrations of Cr, Ni, Cu, Zn, As, Cd, and Pb measured in this study were 31.6-128.8 mg kg -1 , 9.8-70.3 mg kg -1 , 18.3-210.8 mg kg -1 , 49.3-314.2 mg kg -1 , 2.3-69.2 mg kg -1 , 0.3-1.5 mg kg -1 , and 23.2-113.4 mg kg -1 , respectively. The results indicate that the sediment quality of Hainan Island has been obviously influenced by heavy metals. Based on the effect range classification, the heavy metals in Hainan riverine sediments likely have adverse biological effects on local ecosystems. The enrichment factor (EF), geoaccumulation index (I geo ), contamination factor (CF), and pollution load index (PLI) clearly reflect significant metal pollution in this region. The most significant pollution was observed in the northern and eastern parts of Hainan Island. The pollution levels of the three largest rivers on Hainan Island (i.e., the Nandu, Changhua, and Wanquan Rivers) were notably high. The results of this research will be useful in assessing and managing environmental pollution in this region. In the future, greater attention and further investigation should focus on the metal sources linked to further economic development on Hainan Island.

Selected trace elements (As, Cr, Zn, Cu, Cd, Co, Pb and Ni) in 76 surface sediment samples collected from the rivers and the intertidal zone of Jiaozhou Bay (JZB) were evaluated to assess their environmental background values in the JZB catchment. Overall, the sediment quality in the area meets the China Marine Sediment Quality criteria. The background values (ranges) of the elements As, Cr, Zn, Cu, Cd, Co, Pb and Ni were, respectively, 8.28 (4.10-12.46), 67.96 (38.40-97.52), 56.80 (16.42-196.51), 19.13 (5.71-64.06), 0.10 (0.02-0.42), 6.51 (2.08-20.40), 17.97 (12.26-55.84) and 20.69 (10.43-30.95)mg/kg. The background values of most of the trace elements were lower than those in Chinese soil, the upper continental crust, global shales and global preindustrial sediments. The results may assist in defining future coastal and river management measures specifically targeted at monitoring trace element contamination in the JZB catchment., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The concentrations of seven heavy metals (Cr, Ni, Cu, Zn, As, Cd, and Pb) in the surface sediments of the northern portion of the South China Sea (SCS) shelf collected between 2012 and 2014 were measured to assess the potential contamination levels and determine the environmental risks that are associated with heavy metals in the area. The measured concentrations in the sediments were 12.4-72.5 mg kg(-1) for Cr, 4.4-29.2 mg kg(-1) for Ni, 7.1-38.1 mg kg(-1) for Cu, 19.3-92.5 mg kg(-1) for Zn, 1.3-12.1 mg kg(-1) for As, 0.03-0.24 mg kg(-1) for Cd, and 8.5-24.4 mg kg(-1) for Pb. These results indicate that the heavy metal concentrations in the sediments generally meet the China Marine Sediment Quality criteria and suggest that the overall sediment quality of the northern portion of the SCS shelf has not been significantly impacted by heavy metal pollution. However, the enrichment factor (EF) and geoaccumulation index (I geo) clearly show that elevated concentrations of Cd occur in the region. A Pearson's correlation analysis was performed, and the results suggest that Cr, Ni, Cu, and Zn have a natural origin; Cd is primarily sourced from anthropogenic activities, with partial lithogenic components, and As and Pb may be affected by factors such as varying input sources or pathways (i.e., coal burning activities and aerosol precipitation). Heavy metal contamination mostly occurred to the east of Hainan Island, mainly because of the rapid economic and social developments in the Hainan Island. The results of this study will be useful for marine environment managers for the remediation of pollution sources.

The major (Al) and trace metal (Cu, Pb, Zn, Cr, Cd, and As) concentrations in 29 surface sediment samples from the intertidal Jiaozhou Bay (JZB) are evaluated to assess the contamination level. The results show that the overall sediment quality in the area has been obviously impacted by trace metal contamination. The geoaccumulation index and the enrichment factor values indicate that no Cr or Cu contamination has occurred on the whole, only a few stations have been polluted by As, and some areas have been polluted by Cd, Pb, and Zn. Principal component analysis suggests that the Cu, Pb, Zn, and Cd are derived from anthropogenic inputs and that Cr, As, Cu, and Zn are influenced by natural weathering processes. Cu and Zn may originate from both natural and anthropogenic sources. The contamination in the northeastern JZB is higher than that in other areas of the bay., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Major (Al) and trace metal (Cu, Pb, Zn, Cr, Ni, Cd, and As) concentrations in 29 surface sediment samples from the eastern continental shelf of Hainan Island were evaluated to determine the level of contamination. A multivariate analysis indicated that the sources of Cd, As, and Pb were primarily anthropogenic, whereas the sources of Cu, Zn, Cr, and Ni were primarily natural and/or partially anthropogenic. Enrichment factor (EF) and geoaccumulation index (Igeo) values were calculated to assess the anthropogenic contamination in the region. Both the EF and Igeo values indicated relatively elevated Cd and As concentrations. This study provides a useful aid for sustainable marine management in the region., (Copyright © 2015 Elsevier Ltd. All rights reserved.)