This paper reviews the literature on analytical applications of quantitative liquid phase chemiluminescence (CL) from 1991 to mid-1995. Other relevant reviews in this general area are also cited to provide an historical perspective. The focus is on the two major analytical techniques used in conjunction with flow-through CL detection, namely flow injection (FI) and liquid chromatography (LC). Entries have been tabulated under these two headings and are categorized in terms of the analyte, CL reaction, sample matrix and limits of detection.

To investigate the biogeochemistry of iron in the waters of the European continental margin, we determined the dissolved iron distribution and redox speciation in filtered (,0.2 mm) open-ocean and shelf waters. Depth profiles were sampled over the shelf slope southeast of the Chapelle Bank area (47.61uN, 4.24uW to 46.00uN, 8.01uW) and a horizontal surface-water transect over the shelf and through the English Channel (la Manche) and the southern North Sea (46uN, 8uW to 52uN, 4uE). An abrupt trace-metal front was found near the shelf slope, indicated by a horizontal gradient of dissolved iron (DFe) and aluminium (DAl), which correlated with changing salinities (r 2 5 0.572 and 0.528, respectively, n 5 92). Labile Fe(II) concentrations varied from ,12 pmol L 21 in North Atlantic surface waters to .200 pmol L 21 in the near bottom waters of the shelf break. Labile Fe(II) accounted for ,5% of the dissolved iron species in surface shelf waters (mean 5.0 6 2.7%), whereas higher Fe(II) fractions (i.e., .8%) were observed near the sea bottom on the shelf break and during a midday solar maximum in surface waters in the vicinity of the Scheldt river plume. Benthic processes (resuspension and diagenesis) constituted important sources of Fe(II) and DFe in this region, and photoreduction of Fe(III) species in shelf waters caused enhanced labile Fe(II) concentrations. These processes increased the lability of iron and its potential availability to marine organisms in the shelf ecosystem.

A lab-and ship-based analytical intercomparison of two flow injection methods for the determination of iron in seawater was conducted, using three different sets of seawater samples collected from the Southern Ocean and South Atlantic. In one exercise, iron was determined in three different size-fractions (<0.03 µm, <0.4 µm, and unfiltered) in an effort to better characterize the operational nature of each analytical technique with respect to filter size. Measured Fe concentrations were in the range 0.19 to 1.19 nM using flow injection with luminol chemiluminescence detection (FI-CL), and 0.07 to 1.54 nM using flow injection with catalytic spectrophotometric detection with N,N-dimethyl-p-phenylenediamine dihydrochloride (FI-DPD). The arithmetic mean for the FI-CL method was higher (by 0.09 nM) than the FI-DPD method for dissolved (<0.4 µm) Fe, a difference that is comparable to the analytical blanks, which were as high as 0.13 nM (CL) and 0.09 nM (DPD). There was generally good agreement between the FI-CL determinations for the <0.03 µm size fraction and the FI-DPD determinations for the <0.4 µm size fraction in freshly collected samples. Differences in total-dissolvable (unfiltered) Fe concentrations determined by the two FI methods were more variable, reflecting the added complexity associated with the analysis of partially digested particulate material in these samples. Overall, however, the FI-CL determinations were significantly (P = 0.05) lower than the FI-DPD determinations for the unfiltered samples. Our results suggest that the observed, systematic inter-method differences reflect measurement of different physicochemical fractions of Fe present in seawater, such that colloidal and/or organic iron species are better determined by the FI-CL method than the FI-DPD method. This idea is supported by our observation that inter-method differences were largest for freshly collected acidified seawater, which suggests extended storage (>6 months) of acidified samples as a possible protocol for the determination of dissolved iron in seawater.

This paper describes the results of an export coefficient modeling approach to predict total phosphorus (TP) loading in the Frome catchment, Dorset, UK from point and diffuse sources on a seasonal (monthly) basis in 1998 and on an annual basis for 1990-1998. The model predicted an annual TP load of 25 605 kg yr(-1), compared with an observed (measured) value of 23400 kg yr(-1). Monthly loads calculated using the export coefficient model agreed well with monthly observed values except in months of variable discharge, when observed values were low, probably due to infrequent, and therefore unrepresentative, sampling. Comparison between filterable reactive phosphorus (FRP) and TP concentrations observed in the period 1990-1997 showed that trends in FRP could be estimated from trends in TP. A sensitivity analysis (varying individual export coefficients by +/-10%) showed that sewage treatment works (STWs) (3.5%), tilled land (2.7%), meadow-verge-seminatural (1.0%), and mown and grazed turf (0.6%) had the most significant effect (percent difference from base contribution) on model prediction. The model was also used to estimate the effect of phosphorus stripping at STWs in order to comply with a pending change in the European Union wastewater directive. Theoretical reduction of TP from the largest STW in the catchment gave a predicted reduction in TP loading of 2174 kg yr(-1). This illustrates the value of this seasonal export coefficient model as a practical management tool.

Little is known about the biological production of reactive oxygen species (ROS) ). An initial examination of the effect of changing light intensity showed that a rapid light-induced production of both O 2 -and H 2 O 2 by T. weissflogii cells could be readily detected. Moreover, this production was proportional to the biomass present on the flushed filter. These methods enable the monitoring of real-time fluctuations of biological ROS production in response to changing environmental conditions, and therefore facilitate analysis of the biotic component of ROS production and the subsequent impacts on chemical speciation of nutrients and trace metals in aquatic ecosystems.