Factors Affecting Bioavailability and Toxicity of Lead, Mercury, Organochlorides, Antibiotics, and Micro- and Nanoplastics in Marine and Oceanic Sediments

This chapter deals with the aspects responsible for changing the bioavailability and toxicity of organochlorine pesticides, antibiotics, mercury, and lead in marine and oceanic sediments. In this context, integrated discussions, which contemplated the effects of global warming, dissolved O2 and organic matter levels in marine and oceanic water, organic matter contents in marine and oceanic sediment, and the amount of micro- and nanoplastics in these compartments, established a comprehensive overview of how the abovementioned pollutants migrate from sediment to water and vice versa. After analyzing this chapter, the reader will understand why the same environmental condition can generate opposite responses depending on the pollutant. This situation occurs in mangroves where the salinity decreases the solubility of organochlorines and antibiotics while increasing the desorption of cations such as Hg2+ and Pb2+. Elucidating the complex interrelationships in seas and oceans will also allow an understanding, among other aspects, of why antibiotics in sediments can both promote or inhibit the formation of methylated mercury. In short, knowing the interconnectivity of the different marine and oceanic compartments is necessary to identify, mitigate, and ideally correct the aggressions imposed by the constant and growing anthropic pressure resulting from unsustainable population and economic growth.