1.16 - Seawater Organic Contaminants

Abstract

This chapter describes the most commonly used sampling approaches for the collection of seawater to determine organic contaminants/pollutants. Recent innovations and future developments are also identified. In the marine environment, sampling and sample preparation methodologies need to take into account the very low contaminant levels or ultratrace concentrations (i.e., concentrations below nanograms per liter in seawater), as well as matrix interference and the potential for sample contamination when working aboard research vessels or ships at sea. This implies working at the limit of quality assurance and quality control schemes. The sample collection and treatment of seawater can be performed by removing samples for onshore analyses within a laboratory, or by pretreatment of the sample in the field (i.e., in situ pretreatment). The latter involves collection and some preliminary steps of sample treatment at sea (i.e., aboard research vessels). Sampling strategies need to be planned for marine environmental studies, in accordance with the duration, type, and location of the sampling survey, and with regard to the collection methods, sample treatments, and subsequently contaminant laboratory analyses in the laboratory. Manual collection using bottles, subsurface sampling vessels, customized samplers, submersible pumps, and large-volume seawater collection with in situ solid-phase extraction, using disks, packed sorbents, commercial cartridges, etc., are described. In addition, laboratory analyses applying subsequent stir-bar solid-phase extraction and solid-phase microextraction are reviewed. A range of novel passive samplers that are used for seawater are also described. The most recent developments in underwater mass spectrometers and robotic vehicles for oceanic exploration and research are reviewed in terms of their application to direct chemical measurements in the marine environment.