Persistent organic pollutants (POPs) in coastal wetlands: A review of their occurrences, toxic effects, and biogeochemical cycling

Abstract

Coastal wetlands, such as mangroves, seagrass beds, and salt marshes, are highlythreatened by increasing anthropic pressures, including chemical pollution. Persistentorganic pollutants (POPs) have attracted attention in these particularly vulnerableecosystems, due to their bioaccumulative, pervasive, and ecotoxic behavior. Thisarticle reviews and summarizes available information regarding current levels,biogeochemical cycling, and effects of POPs on coastal wetlands. Sediment POPlevels were compared with international quality guidelines, revealing many areaswhere compounds could cause damage to biota. Despite this, toxicological studies onsome coastal wetland plants and microorganisms showed a high tolerance to thoselevels. These taxonomic groups are likely to play a key role in the cycling of the POPs,with an active role in their accumulation, immobilization, and degradation. Toxicity andbiogeochemical processes varied markedly along three main axes; namely species,environmental conditions, and type of pollutant. While more focused research on newlyand unintentionally produced POPs is needed, mainly in salt marshes and seagrassbeds, with the information available so far, the environmental behavior, spatialdistribution, and toxicity level of the studied POPs showed similar patterns across thethree studied ecosystems.