Seasonal changes of mercury speciation in the coastal sediments

Abstract

Purpose Mercury speciation in sediments is linked to environmental conditions and processes. Domination of particular mercury species depends on its source, displays considerable seasonal behavior, and may be further modified due to oxygen levels, icing conditions, or the input of fresh organic matter. The purpose of this study was to examine the coastal area of the Gulf of Gdańsk in terms of mercury contamination and the influence of seasonal environmental changes on its speciation. Materials and methods In three highly dynamic coastal sites, mercury speciation in sediments was studied in relation to other environmental parameters (redox conditions, organic matter concentration, bacteria abundance, etc.). Sediment and water samples were collected monthly during a 3-year study. Sequential extraction of sediments was used for identification of four inorganic mercury species: dissolved, bound with fulvic and humic acids, mercury sulfide, and residual fraction. Cold vapor atomic fluorescence spectrometry (CV-AFS) was used for extracts and liquid sample analysis. Total mercury in sediments was measured with atomic absorption spectrometry (AAS). Changes in salinity were analyzed by measurements of chloride and sulfate ion concentrations using ion chromatography. Bacteria number and biomass were measured by direct counting using epifluorescence microscopy. Results and discussion Seasonal changes in mercury speciation were observed at all sites and attributed to different processes. Labile mercury fraction contribution varied from 0 to 80%. The speciation patterns varied locally as the stations selected for the study are diversified in terms of anthropogenic impact, water dynamics, and output from land. Mercury concentrations at all stations fluctuated during phytoplankton blooms, icing of marine waters, precipitation, or increased surface runoff from the land. In this local scale, the global climate changes are visible already as environmental conditions in studied area changed in comparison to elder research. Conclusions Obtained results suggest that although mercury emissions to the environment have decreased in recent years, local weather conditions, which may be intensified by climate change, seriously affect the bioavailability of past mercury deposits in coastal sediments.

Assessment of mercury pollution sources in beach sand and coastal soil by speciation analysis

“…However, its potential to explore the sources of contamination on a beach surrounded by mines and industries is a new issue. The identification of mercury species in similar samples was already been carried out by using other methods of analysis [2,8,50], and in all cases the results were of great relevance from the environmental and social point of view. However, the HgTPD method entails some advantages when compared with X-ray absorption spectroscopy (EXAFS) and classic extraction methods, such as its low detection limit and high selectivity.…”

“…1 INDUROT, Campus de Mieres, Universidad de Oviedo, 33600 Mieres, Spain. 2 Instituto Nacional del Carbón (CSIC), Francisco Pintado Fe, 26, 33011 Oviedo, Spain.…”

Exposure of Mercury from Gold Ming Area: A Case Study in Tendo and Aby Lagoon in Côte d’Ivoire

“…The distribution pattern of Hg in the bottom sediment demonstrates that an expansion of the area occurs in relation to the area of distribution of Hg in the dry season [39]. Bełdowski et al [48] suggested that despite the decrease in mercury emissions to the environment in recent years, local weather conditions intensified by climate change seriously affect the bioavailability of past mercury deposits in coastal sediments. Indeed, global mineralization of the waters of the Aby lagoon caused by significant evaporation due to high temperatures during the dry season [22] [49] could explain this accumulation of mercury.…”

Preface: Proceedings of the 14th IASWS international conference

“…The theme of BSediment-water linkages in estuarine and marine environments: evaluating change in freshwater and saline habitats^is addressed by two papers. The contribution by Bełdowski et al (2018) explored the seasonal changes of mercury speciation in sediments in the coastal area of the Gulf of Gdańsk (Poland). The overall results suggested that although mercury emissions to the environment have decreased in recent years, local weather conditions, which may be intensified by climate change, seriously affect the bioavailability of past mercury deposits in coastal sediments.…”