Flow injection analysis as a tool for enhancing oceanographic nutrient measurements--a review

Abstract

Macronutrient elements (C, N and P) and micronutrient elements (Fe, Co, Cu, Zn and Mn) are widely measured in their various physico-chemical forms in open ocean, shelf sea, coastal and estuarine waters. These measurements help to elucidate the biogeochemical cycling of these elements in marine waters and highlight the ecological and socio-economic importance of the oceans. Due to the dynamic nature of marine waters in terms of chemical, biological and physical processes, it is advantageous to make these measurements in situ and in this regard flow injection analysis (FIA) provides a suitable shipboard platform. This review, therefore, discusses the role of FIA in the determination of macro- and micro-nutrient elements, with an emphasis on manifold design and detection strategies for the reliable shipboard determination of specific nutrient species. The application of various FIA manifolds to oceanographic nutrient determinations is discussed, with an emphasis on sensitivity, selectivity, high throughput analysis and suitability for underway analysis and depth profiles. Strategies for enhancing sensitivity and minimizing matrix effects, e.g. refractive index (schlieren) effects and the important role of uncertainty budgets in underpinning method validation and data quality are discussed in some detail.

Keywords: 7,7,8,8-tetracyanoquinodimethane; 8-quinolinol immobilised on silica gel, metal alkoxide fluoride glass; 8HQ-MAF; C4 D; CL; CRM; CTAB; DDAB; DIC; DOC; DOP; DRP; Data quality; Estuarine waters; FIA; Flow injection analysis; GD; GF-AAS; GUM; HNLC; HTCO; ICP-SFMS; ID; IDA; LOC; LOD; LWCC; Lab-on-Chip; MRFC; Macronutrients; Marine waters; Micronutrients; NOx; NTA; OPA; PON; PSII; Photosystem II; REU; RI; RM; ROV; RSD; S; SAFe; SCFA; SOD; SP; TA; TC; TCNQ; TDN; TDP; TIC; TN; TOC; TP; TPN; certified reference material; cetyltrimethylammonium bromide; chemiluminescence; contactless capacitively coupled conductivity detector; didodecyldimethylammonium bromide; dissolved inorganic carbon; dissolved inorganic carbon (also called “total carbonate”); dissolved organic carbon; dissolved organic phosphorus; dissolved reactive phosphorus; flow injection analysis; gas diffusion; graphite furnace atomic absorption spectrophotometry; guide to the expression of uncertainty in measurements; high temperature catalytic oxidation; high-nutrient, low-chlorophyll regions; id; iminodiacetate resin; inductively coupled plasmas-sector field mass spectrometry; inside diameter; isotope dilution; limit of detection; liquid waveguide capillary cell; multi-reflection flow cell; nitrate + nitrite; nitriloacetic acid; od; orthophthaldialdehyde; outside diameter; partial pressure of carbon dioxide; particulate organic nitrogen; reference material; refractive index; relative expanded uncertainty; relative standard deviation; remotely operated vehicle; salinity; sampling and analysis of iron program; segmented continuous flow analysis; spectrophotometry; superoxide dismutase; total alkalinity; total carbon; total dissolved nitrogen; total dissolved phosphorus; total inorganic carbon; total nitrogen; total organic carbon; total particulate nitrogen; total phosphorus; ∑CO(2).