Effects of beach wrack on the fate of mercury at the land-sea interface – A preliminary study. (15th December 2022)

• Record Type: Journal Article
• Authors: Graca, Bożena; Jędruch, Agnieszka; Bełdowska, Magdalena; Bełdowski, Jacek; Kotwicki, Lech; Siedlewicz, Grzegorz; Korejwo, Ewa; Popińska, Wioletta; Łukawska-Matuszewska, Katarzyna
• Is Part Of: Environmental pollution. Volume 315(2022)
• Publication Date: 2022-12-15
• Subjects: Seaweed -- Decay -- Mercury -- Fractions -- Shoreline; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2022.120394
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Since the 1970s, the amount of aquatic plants and algae debris, called beach wrack (BW), has increased along the shores of industrialised regions. The strong ability of primary producers to accumulate pollutants can potentially result in their deposition on the beach along with the BW. Despite that, the fate and impact of such pollutants on sandy beach ecosystems have not been investigated so far. This study examines the fate of neurotoxic mercury and its labile and stable fractions in BW on sandy beaches of the Puck Bay (Baltic Sea). In addition to BW, beach sediments and wrack-associated macrofauna were also analysed. Rough estimations showed that Puck Bay beaches (58.8 km) may be a temporary storage of 0.2–0.5 kg of mercury, deposited on them along with the BW annually. A large proportion of Hg (89 ± 16%) in a BW was labile and potentially bioavailable. The contribution of Hg fractions in the BW was conditioned by the degree of its decomposition (molar C:N:P ratio). With the progressive degradation of BW, a decrease in the contribution of Hg adsorbed on its surface with a simultaneous increase in the proportion of adsorbed (intracellular), mercury was observed. BW accumulation decreased oxygen content and redox potential and increased methylmercury content in underlying sediments, indicating methylation. Hg concentrations in the studied fauna were up to 4 times higher than in the BW. The highest values occurred in a predatory sand bear spider and the lowest in a herbivorous sand hopper. Regardless of trophic position, most of Hg (92–95%) occurred as an absorbed fraction, which indicates about a 30% increase in relation to its share of BW. These findings suggest the significant role of BW as a mercury carrier in a land-sea interface and increased exposure of beach communities to the adverse effects of mercury in coastal ecosystems. Graphical abstract: Image 1 Highlights: Beach wrack is a carrier of Hg for sandy beach ecosystems. Mean share of labile Hg in the beach wrack accounted for 89% of total Hg. Decomposition increases the proportion of absorbed Hg in the beach wrack. Beach wrack accumulation increases methylmercury content in coastal sediments. Hg content in BW-associated macrofauna was up to 4 times higher than in the wrack.