T.W. Fileman

Pigment signatures of the phytoplankton composition in the northeastern Atlantic during the 1990 spring bloom

Abstract Pigment signatures were used to track the development and composition of a phytoplankton bloom in the northeastern Atlantic during May/June 1990 using reversed-phase high-performance liquid chromatography. Chlorophyll a concentrations at 5 m increased from 1.2 to 3.7 μg 1 −1 during the first half of May, and decreased progressively thereafter in the post-bloom stage. Multiple regression analysis of chlorophyll a and selected accessory pigments indicate that diatoms (fucoxanthin; 23–70%) and prymnesiophytes (19′-hexanoyloxyfucoxanthin; 40-20%) dominated the chlorophyll a biomass in the development phase, with prymnesiophytes dominating the post-bloom stage (45–55%). Dinoflagellates (peridinin; 5–25%) and “green” algae (chlorophyll b ; 5–10%) were secondary components of the microalgal community. Depth distributions revealed that the pigment maxima occurred near the surface at 5–15 m, with concentrations decreasing rapidly below 15 m. At the peak of the bloom, diatoms (fucoxanthin) were dominant throughout the water column down to 300 m, while in the post-bloom phase, prymnesiophytes (19′-hexanoyloxyfucoxanthin) dominated the community in the upper 20 m with diatoms accumulating in deeper water. Concomitant measurements of nutrients and downwelling irradiance suggest that nitrate availability limited the growth of the phytoplankton in the upper 15 m and below this depth limitation was due to low irradiance levels.

Antifouling paint booster biocides in the UK coastal environment and potential risks of biological effects.

In the yachting sector of the UK antifouling market, organic biocides are commonly added to antifouling preparations to boost performance. Few data presently exist for concentrations of these compounds in UK waters. In this study the concentrations of tributyltin (TBT) and eight booster biocides were measured before and during the 1998 yachting season. The Crouch Estuary, Essex, Sutton Harbour, Plymouth and Southampton Water were chosen as representative study sites for comparison with previous surveys of TBT concentrations. Diuron and Irgarol 1051 were the only organic booster biocides found at concentrations above the limits of detection. Diuron was measured at the highest concentrations, whilst detectable concentrations of both Irgarol 1051 and diuron were determined in areas of high yachting activity (e.g. mooring areas and marinas). Maximum measured values were 1,421 and 6,740 ng/l, respectively. Lower concentrations of both compounds were found in open estuarine areas, although non-antifouling contributions of diuron may contribute to the overall inputs to estuarine systems. TBT was found to be below or near the environmental quality standard (EQS) of 2 ng/l for all samples collected from estuarine areas frequented by pleasure craft alone, but with much higher concentrations measured in some marinas, harbours and in areas frequented by large commercial vessels. Using the limited published environmental fate and toxicity data available for antifouling booster biocides, a comparative assessment to evaluate the risk posed by these compounds to the aquatic environment is described. TBT still exceeds risk quotients by the greatest margins, but widespread effects due to Irgarol 1051 and less so diuron cannot be ruled out (particularly if use patterns change) and more information is required to provide a robust risk assessment.

Changes in the sedimentary organic carbon pool of a fertilized tropical estuary, Guanabara Bay, Brazil: an elemental, isotopic and molecular marker approach

Sediments from Guanabara Bay, sampled as short-cores (50–60 cm) from eight stations, were analysed for the elemental (C and N), isotopic (δ13C and δ15N) and molecular composition (steroids) of the organic matter. The objective of this study was to examine whether there are changes in the sources of sedimentary organic matter pool due to increasing N, P and particulate loads to the bay over the last 100 years. On average, we found a 10-fold increase in the flux of organic matter to the sediments with a maximum of 41.7 mol C m−2 year−1. C/N and δ13C time–space distribution and mass balance calculations indicate that the organic material results from a mixture of marine, terrestrial and estuarine sources, with a growing predominance of autochthonous inputs in recent years. Dinosterol was predominant in most samples (>50% of all measured sterols). Concentrations of dinosterol increased significantly in the last two decades and reached values as high as 150 μg g−1 dry sediment. Net increases in concentration were estimated using the first-order decay rate constants derived from experimental data. There are strong indications that an increase in carbon storage occurred in response to growing eutrophic conditions. In spite of the high respiration rates occurring in the water column, fast sedimentation rates result in the transfer of a significant carbon fraction to the anoxic sediments. Further decomposition proceeds only in the first 10 cm of sediment as indicated by the decay rates.

Seasonal distribution of dissolved pesticides and polynuclear aromatic hydrocarbons in the Humber Estuary and Humber coastal zone

The distribution of atrazine, 2-methylthio-4-tert-butyl-amino-6-cyclopropylamino-s-triazine (Irgarol 1051), lindane, malathion, fluoranthene and pyrene dissolved in the water column of the Humber Estuary and adjacent coastal zone was determined. Atrazine concentrations declined from the head (35–53 ng l−1) to the mouth (5–11 ng l−1) of the estuary; the highest concentrations were found in June. Lindane concentrations also declined through the estuary, although elevations were observed near a sewage outfall, especially in June and September. Irgarol concentrations typically peaked in April, then decreased in June before increasing again in September. The patterns of variation of fluoranthene and pyrene were similar to each other, suggesting common sources. Levels were similar throughout the estuary, with an exceptionally large elevation at a sewage outfall in June. Malathion concentrations were generally very low (<1–9 ng l−1). The concentrations of all compounds were lower off-shore than in the estuary, suggesting that the Humber catchment is a major source of organic micropollutants to the Humber coastal zone. Concentrations of atrazine and lindane were also elevated at stations close to the Wash, suggesting a contribution from rivers into the Wash.

Occurrence of the marine antifouling agent irgarol 1051 within the Plymouth Sound locality: Implications for the green macroalga Enteromorpha intestinalis

Abstract Water samples taken from the Plymouth Sound locality were analysed for the presence of the s-triazine herbicide Irgarol 1051, which is an ingredient of antifouling paints used on pleasure boats and ships. Irgarol 1051 was detected at all sampling sites within the Sound; the highest levels were found in close proximity to areas of high boat density, especially where water flow was restricted within marinas. Concentrations within the semi-enclosed Sutton Harbour were less than values predicted from leach rate data. The highest detected concentration of over 120 ng dm−3 significantly inhibited the growth of Enteromorpha intestinalis spores under laboratory conditions; the no effect concentration was 22 ng dm−3. Photosynthetic efficiency in the adult frond of E. intestinalis from Sutton Harbour marina was inhibited by Irgarol 1051 in the laboratory with an EC 50 (72 h) of 2.5 |Gmg dm−3. A small adverse impact on E. intestinalis reproduction within the harbour is therefore likely. More polluted sites identified elsewhere in Europe will suffer proportionally greater impact.

Fluoranthene and pyrene in the suspended particulate matter and surface sediments of the Humber Estuary, UK

Abstract As part of the UK-based Land-Ocean Interaction Study (LOIS) community programme, suspended particulate matter (SPM) and surface sediments have been collected from the Humber estuary, which is a large and complex estuarine system on the east coast of England fed by several rivers including the Trent and Ouse. The samples from four surveys were extracted and analysed to determine the levels of anthropogenic organic contaminants such as fluoranthene and pyrene. Their concentrations in SPM and surface sediments ranged from 44 to 1560 ng g −1 dry weight and 13–1969 ng g −1 dry weight, respectively, and displayed no strong seasonal variation. Mean fluoranthene and pyrene concentrations were higher in the Trent than in the Ouse for both SPM and sediment samples, and were elevated at a sewage outfall, suggesting a multiplicity of inputs for these two compounds. Fluoranthene and pyrene on SPM showed no correlation with salinity, although correlations with suspended solids concentrations (SSC) and particulate organic carbon (POC) have been confirmed.

The partition of fluoranthene and pyrene between suspended particles and dissolved phase in the Humber Estuary: a study of the controlling factors

Abstract Particle–water interactions are one of the most important mechanisms controlling the distribution and movement of hydrophobic organic chemicals such as polycyclic aromatic hydrocarbons (PAHs) in aquatic environments (e.g. estuaries and oceans). To accurately predict the transport and fates of hydrophobic contaminants in estuarine and coastal marine environments, the partition coefficient ( K p ) and organic carbon normalised partition coefficient ( K oc ) are widely used in various biogeochemical models. Such partition coefficients may be calculated from the so-called linear free energy relationships between K p , K oc and more easily measured parameters such as the octanol-water partition coefficient ( K ow ). However K p and K oc values measured for real environmental samples of water and particles obtained from seasonal field surveys in the Humber Estuary, UK deviated from such ideals. For example, K P values showed no correlation with the fraction organic carbon content of particles ( f oc ) and instead of being constant, K oc , values varied with f oc . Both K p and K oc were 1–3 orders of magnitude higher than those predicted from the simple equilibrium–partitioning model, but were in good agreement with several other recently published field studies. To improve our understanding of PAH partitioning, the soot carbon (SC) content of particulate samples was measured so that the simple partition model can be extended to incorporate SC. The partition coefficients derived from the extended partition model are very close to the field K p s. The results suggest that PAHs associated with particles are in fact present in the form of soot and soot-like particles that are not subject to particle–water equilibrations. In other words, the PAHs on soot-like particles are extremely strongly bound and not influenced by further partitioning between the particles and water. However, there are still limitations with the extended partition model as it failed to simulate the field K oc values. No correlation was found between the partition coefficients and salinity, which again we attribute to the non-equilibrium nature of the PAHs. However both K p and K oc generally decreased with increasing suspended solids concentrations (SSC) in the estuary. Such a relationship is probably due to the mixing of soot-like permanently suspended particles with resuspended estuarine sedimentary particles at the higher SSC values, and to the increased concentrations of dissolved organic carbon (DOC) associated with increase in SSC. However, it has been shown that DOC concentrations are not a suitable tool for correcting the SSC effect. There is therefore an urgent need to harmonise the laboratory and field approaches for K p measurements.

The impact of marginal ice zone processes on the distribution of 21OPb, 21OPo and 234Th and implications for new production in the Bellingshausen Sea, Antarctica

Abstract The vertical distributions of 21OPb, 210Po and 234Th in both dissolved and particulate phases of seawater were measured at five stations along the 85°W meridian in the Bellingshausen Sea, Antarctica. Sea-ice conditions during the expedition ranged from fully ice-covered (fast ice) to open water away from the marginal ice zone. Concurrent primary productivity and algal chlorophyll measurements revealed a band of high productivity at approximately 67°30′S, which remained in a rather static location during ice melt-back. Along the transect a progressive increase in removal (“scavenging”) and sinking of 210Pb, 210Po and 234Th occurred towards the north (open water conditions). Application of a simple, irreversible scavenging model, and particulate organic carbon and organic nitrogen to radionuclide ratios measured on suspended particulate matter, allows the calculation of export production for this region. Under fast ice conditions some removal of phytodetritus from the euphotic zone was observed (1–2 mgC m−2 day−1), representing a low proportion of the primary production (f-ratio of 0.02). Near the Antarctic continental margin upwelling of regenerated dissolved 210Po was found. At the open water site near the algal band, new production had risen to 27–252 mgC m−2 day−1, but a greater proportion of the original primary production was removed by sinking detritus (f-ratio of 0.03–0.33). Comparison of 210Po and 234Th as tracers of of export production indicates considerable differences, with 210Po yielding rather lower rates of export flux compared to 234Th Radionuclide estimates of new production are significantly greater than those obtained by traditional sediment trap methods. This may be due to the dynamic nature (short duration and spatial variability) of algal growth in the Southern Ocean.

Pigment chemotaxonomic distributions of phytoplankton during summer in the western Mediterranean

Pigment distributions were investigated in the western Mediterranean basin during July 1993 to document the trophic status of the summer phytoplankton community. The characteristic deep chlorophyll maximum (DCM) was observed at all oceanic stations, and chlorophyll a concentrations of up to 1700 ng 1−1 were measured in the DCM in the northern regions. High chlorophyll a levels (2000–3000 ng 1−1) were determined in the lower reaches of the Rhone River, accompanied by high fucoxanthin levels. Fucoxanthin was also the dominant accessory pigment at the inshore stations influenced by the Rhone, while hexanoyloxyfucoxanthin was the major carotenoid at all other northern sites. Divinyl chlorophyll a concentrations were very low in the north (<30 ng 1−1) and only accounted for a maximum of 8% of the total chlorophyll a. Chlorophyll a levels were much lower in the southwestern Mediterranean; we estimate that divinyl chlorophyll a contributed 11–40% to the total chlorophyll a. Fucoxanthin was the prominent accessory pigment at Gibraltar, but hexanoyloxyfucoxanthin, chlorophyll b, zeaxanthin and divinyl chlorophyll a were more important at the other southern stations. The pigment data were used to estimate the contributions of prokaryotes (cyanobacteria and prochlorophytes) and eukaryotes to the total chlorophyll a at the surface and in the DCM. Overall, we determined that eukaryotes accounted for most of the chlorophyll a biomass, contributing 53–98%, and the prokaryote proportion was 2–47%. The pigment pattern revealed that the phytoplankton assemblage was not homogeneous and trophic conditions ranged from eutrophic in coastal and frontal regions where fucoxanthin containing diatoms dominated, to oligotrophic throughout most of the basin. Higher chlorophyll a biomass and dominant hexanoyloxyfucoxanthin containing prymnesiophytes were observed in the northern sector, while an increased prominence of prokaryotes in the south suggested that the southern sector was more oligotrophic.

Occurrence of the antifouling herbicide, Irgarol 1051, within coastal-water seagrasses from Queensland, Australia

Abstract The s-triazine herbicide Irgarol 1051 is now widely distributed throughout European coastal waters. In Australia, the compound is not registered for use as a biocide in antifouling paints. To investigate contamination, seagrasses were sampled from the east coast of Queensland and within the Great Barrier Reef Marine Park. A green alga was also sampled from the Outer Barrier Reef. Tissues were analysed for the presence of Irgarol 1051 using solvent extraction followed by quantification with GC-MS and confirmation by GC-MS-MS. Irgarol 1051 was detected at nine of the ten locations sampled. Concentrations of up to 118 ng g−1 wet weight leaf tissue were recorded in samples from the Gold Coast (near Brisbane) which is the highest plant tissue concentration yet reported. Antifouling paint purchased within Australia was analysed by GC-MS (full scan) and found to contain Irgarol 1051. The concentrations of Irgarol 1051 reported within the Australian coastal environment are potentially toxic and the possible consequences for long-lived herbivores (such as the dugong) and for endosymbiotic algae of corals, are discussed.