The most common lead (Pb) and zinc (Zn) ore minerals are galena (PbS) and sphalerite (ZnS). Milling and mining operations of these ores produce huge amounts of waste known as chat and tailings. Chat is composed of gravel, sand, and silt-sized rock materials, whereas tailings are often fine-grained and silt-sized particles with higher toxic element concentrations. Upon oxidation, tailings with high pyritic materials release Pb, Zn, Cadmium (Cd), and other elements associated with ores affecting plant productivity, the ecosystem, and human health. This article is an overview on utilizing the subsurface submergence technique for mitigating environmental impacts from abandoned mine waste materials. In the past, researchers have studied the influence of submergence on these elements; however, an emphasis on gathering a detailed understanding of such redox-based remediation processes is not that common. We reviewed literature that evaluated water chemistry, solid phases, and association of trace elements, and addressed utilization of surface amendments of mine tailings for predicting their interactions within sediments and overlying waters. Case studies specifically focused on mining of Pb and Zn, including a recent study conducted in the Tri-State mining district (Kansas, Missouri, and Oklahoma), are presented to add a more comprehensive understanding of biogeochemical transformations of trace elements present in mine waste materials under a long-term submergence. The purpose of this article is to present evidence on the viability of subsurface disposal of mine waste materials, in order to design effective remediation and mitigation strategies to protect human and environmental health in the global dimension.

The distribution characteristics, sources and ecological risk of antimony (Sb) in the surface sediments of Changjiang Estuary and the adjacent sea were studied. Sb concentrations ranged from 0.320 to 0.968 μg g−1 with mean value of 0.577 μg g−1. Sb concentrations were relatively high in sediments of the south Yellow Sea, the Hangzhou Bay mouth and the inner Changjiang Estuary. The variation trend of Sb concentrations was controlled by hydrodynamics, Al/Fe/Mn oxides. Sb also showed strong chalcophile property. Correlation analysis and enrichment factor showed Sb came mainly from natural sources. Total Sb sediment flux in the study area was 446.3 t/yr. The Changjiang River, the Yellow River and atmospheric inputs accounted for 85.7%, 13.9%, and 0.4% of the total sediment Sb flux, respectively. The result of potential ecological index indicated the very low Sb concentrations could hardly threat the ecological environment of the study area.

The North Yellow Sea is a major aquaculture production area for the scallop Patinopecten yessoensis. In this study, the temporal and spatial variation of phycotoxins in scallops, phytoplankton, and their cysts were analyzed during a survey conducted from June 2011 to April 2012 around Zhangzi Island. The study area is a semi-enclosed epicontinental sea surrounded by the Shandong Peninsula, the Liaodong Peninsula and the Korean Peninsula. The three main results of the study were as follows: (1) The saxitoxin-group toxins, okadaic acid and analogues, and pectenotoxins were the major phycotoxin residues found in scallops; (2) Six kinds of toxic microalgae were identified, Protoperidinium spp., Gonyaulax spp., and Alexandrium spp. were the dominant taxa; Seven types of potential marine toxin-producing dinoflagellates, A. tamarense, A. catenella, Dinophysis fortii, G. catenatum, Gambierdiscus toxicus, Azadinium poporum, and Pseudo-nitzschia pungen were identified as the primary source of phycotoxins and were present at relatively high density from June to October; and (3) azaspiracids and domoic acid might be new potential sources of toxin pollution. This study represents the first assessment to phycotoxins around Zhangzi Island in the North Yellow Sea.

The present study has evaluated temporal and spatial mercury trends based on surficial sediment samples and 210Pb-dated sediment profiles. The obtained results show that there are areas close to the main bay's tributary rivers where the Hg content has doubled during the last 15 years and regions where it has decreased by a factor of 2, mainly the area close to the navigation channel, which is submitted to periodic dredging. In the inner part of the bay, the most contaminated region, mercury shows a strong association with sulfide. In the same region, based on the 210Pb results, it was possible to calculate the yearly increment on the Hg concentration in the surface sediment, 0.62 μg kg−1 y−1 to 0.29 μg kg−1 y−1, according to the distance to the bay's main tributary rivers.

We collected seven cores from five coastal ponds in St Thomas, USVI, dated them via 210Pb, and measured their Hg profiles. Levels ranged from 20 to 100ngg−1 and always increased upward to the surface or a shallow mixed zone. Taking into account differences in sediment accumulation rates and the presence or absence of a mixed zone, all sites revealed similar deposition histories. Mercury levels were at low, possibly pristine, values until the early to mid-20th century. Then they then doubled or quadrupled steadily until about 1990, after which Hg became relatively constant. We conclude that Hg in the sediments of these ponds came from long range deposition directly to the ponds and to their watersheds. Constant levels in recent years may be caused by transfer from watersheds, a pathway that is delayed compared to direct deposition from the atmosphere.

Variations and trends in water quality parameters (total suspended matter and coloured dissolved organic matter) were examined in five harbours in the eastern Baltic Sea using satellite imagery collected from 2002 to 2011 by the Medium Resolution Imaging Spectrometer (MERIS) at full spatial resolution (300×300m). In the eastern Gulf of Finland harbours (Sillamäe, Kunda) the TSM monthly variations were related to monthly mean wind speed. In Tallinn harbour, which operates >6000 vessels annually, evidence of anthropogenic impacts was identified through inter-annual TSM variations. The vessel traffic footprint was ascertained from the significant correlation (R=0.66; p=0.035) between the number of annual vessel visits and mean annual TSM concentration. In the harbour of Pärnu, located close to the river mouth, inter-annual water quality variations in terms of the CDOM concentrations were affected by the mean annual river discharge levels of the Pärnu River.

Concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), lead (Pb), and zinc (Zn), grain sizes, and concentrations of organic carbon (Corg) were measured in 323 river sediment samples from the Pearl River Delta (PRD). Results showed that the heavy metal concentrations in the sediments ranged from 1.6–93 mg/kg for As, 0.04–9.3 mg/kg for Cd, 2–315 mg/kg for Cr, 1.1–352 mg/kg for Cu, 0.01–0.67 mg/kg for Hg, 11–221 mg/kg for Pb, and 11–1234 mg/kg for Zn. The highest values of As, Cr, Cu, Hg, Pb, and Zn appeared in the Beijiang River, whereas Cd was high in the Xijiang River. The overall sediment quality in the area with respect to metal concentrations generally met the primary standard criteria of China (Marine Sediment Quality), except for Cd and Cu. The spatial distributions of the heavy metals were influenced by both grain sizes and Corg concentrations. The Igeo geo-accumulation index indicated that there was no significant Cr, Cu, Hg, or Zn pollution, slight to moderate pollution by As and Pb, and moderate Cd pollution in the study area. Spatial distributions of an eco-toxicological index based on probable effect levels indicated that there was a 21% probability that the combination of the seven metals was exerting a toxic stress in the PRD river sediments.

This is the first study on the distribution and characteristics of plastic debris found in the sediments of Rameswaram Island, Gulf of Mannar, India. Studies on the distribution of plastics and microplastic content in highly populated coral islands and their impact on the coral ecosystem are very scarce. For this purpose, marine sediment samples were collected from 20 locations along the coastal areas of the study region. The distribution and characterization study was carried out by visual examination followed by FTIR spectroscopy. The results showed abundance of white-colored and irregular-shaped plastic debris in this study area. Polypropylene was identified as a dominant polymer variety, followed by polyethylene, polystyrene, nylon, and polyvinyl chloride. Tourist activities and fishing practices were found to be the possible sources of the microplastic debris. Additionally, the distribution of the plastics was found to be dominantly controlled by the aeolian process and the nature of the coast.

Direct mortality of wildlife is generally used to quantify the damage caused by pollution events. However, free-ranging wildlife that survive initial exposure to pollutants may also experience long-term consequences. Individuals that are rehabilitated following oil exposure have a known history of oiling and provide a useful study population for understanding behavior following pollution events. We GPS-tracked 12 rehabilitated brown pelicans and compared their movements to those of eight non-oiled, non-rehabilitated controls over 87–707 (mean = 271) days. Rehabilitated pelicans traveled farther, spent more time in long-distance movements, and occupied more productive waters than controls. These differences were more apparent among females than males. Rehabilitated pelicans also visited breeding colonies and nest sites at lower rates than controls. Our results indicate that, although rehabilitated pelicans undertake long-distance movements, they may display increased dispersion and reduced breeding investment, particularly among females. Such behavioral changes could have long-term effects on populations.