Oceanic Sink and Biogeochemical Controls on the Accumulation of Polychlorinated Dibenzo-p-dioxins, Dibenzofurans, and Biphenyls in Plankton

Abstract

Polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) were measured in plankton samples from the Atlantic, Pacific, and Indian Oceans collected during the Malaspina circumnavigation cruise. The concentrations of PCDD/Fs and dl-PCBs in plankton averaged 14 and 240 pg gdw(-1), respectively, but concentrations were highly variable. The global distribution of PCDD/Fs and dl-PCBs was not driven by proximity to continents but significantly correlated with plankton biomass, with higher plankton phase PCDD/F and dl-PCB concentrations at lower biomass. These trends are consistent with the interactions between atmospheric deposition, biomass dilution, and settling fluxes of organic matter in the water column (biological pump), as key processes driving POPs plankton phase concentrations in the global oceans. The application of a model of the air-water-plankton diffusive exchange reproduces in part the influence of biomass on plankton phase concentrations and suggests future modeling priorities. The estimated oceanic sink (Atlantic, Pacific, and Indian Oceans) due to settling fluxes of organic matter bound PCDD/Fs and dl-PCBs is of 400 and 10,500 kg y(-1), respectively. The atmospheric inputs due to gross diffusive absorption and dry deposition are nearly 3 and 10 times larger for PCDD/Fs and dl-PCBs, respectively, than the oceanic sink. These observations suggest that the coupling of atmospheric deposition with water column cycling supports and drives the accumulation of dl-PCBs and PCDD/Fs in plankton from the global oligotrophic oceans.

Impact of Phytoplankton Blooms on Concentrations of Antibiotics in Sediment and Snails in a Subtropical River, China

“…This may be ascribed to greater sorption of the more hydrophobic pollutants onto sinking organic carbon. 47,49 A previous study also reported that concentrations of hydrophobic antibiotics in phytoplankton collected from the monitoring sites with higher biomass were lower than those with less biomass due to the biomass dilution effect. 46 Among different antibiotics investigated in this study, the slope of ETM was larger than that of the other antibiotics, suggesting that the effects of phytoplankton biomass on this antibiotic was more prominent.…”

Trends of Diverse POPs in Air and Water Across the Western Atlantic Ocean: Strong Gradients in the Ocean but Not in the Air

“…This region is influenced by the Brazil Current, moving water masses originating from off Africa, as part of the South Equatorial Current, southwards along the continent. These water masses only possessed trace amount of POPs, as can be explained by a long residence time enabling biogeochemical processes to deplete compounds either via photoloysis, microbial degradation, or settling as part of the biological pump; , (iii) there was a spike in contaminant concentrations at around 2–5°N, which could represent the northern part of the South Equatorial Current, where some North Atlantic water is already entrained from the North Equatorial Counter Current; (iv) the region between 6 and 11°N, where there was a fairly stable signature of PCBs and HCBs but a lack of PBDEs. Samples taken between 9.7 and 11°N represented water masses that were affected by the Amazon and Orinoco river discharges (given the decrease in salinity).…”

“…For several samples, GFFs were analyzed individually, with no compounds detected above MDLs. Prior to extraction, the samples were spiked with 13 C BDEs (28, 47, 100, 99, 154, 153, 183, and 209) for PBDE analysis, PCB 30 and 185 for PCB and OCP analysis, and deuterated PAHs (d 8 -naphthalene, d 10 -phenathrene, d 12 -perylene) for PAH analysis. The concentrated extracts were split into 2 portions: one part of the extract was used for PAHs analysis; another part of the extract was analyzed for PBDEs, indicator PCBs, and OCPs.…”

“…Pioneering work by Iwata et al (1993) started the first global assessment of POPs in the Oceans though it is unclear if any of the results were affected by ship-based contamination . Since their landmark publication, there has been only one other study addressing POPs in oceans on a global scale, the Malaspina cruise (2010–2011). − For several ocean basins, there has been repeated coverage of air–water exchange and spatial gradients of POPs: initially, with a focus on North Atlantic/Arctic Ocean and eastern part of the Atlantic Ocean where ships of opportunity (often polar research vessels) transited. − More lately, some more coverage of POPs in the Pacific Ocean has been published with increasing use of the Chinese Snow Dragon. , Little to no work remains published on POPs in the Indian Ocean, Southern Ocean, , and western part of The Atlantic Ocean, along South America.…”

Understanding the Role of Organic Matter Cycling for the Spatio-Temporal Structure of PCBs in the North Sea

“…This pool is subsequently converted to detritus by phytoplankton aging and zooplankton grazing and digestion, and it is exported to deeper waters by the settling of detritus. It has been shown that the "biological pump" can deplete the concentration of dissolved hydrophobic, persistent chemicals in the surface water and, thus enhance net gaseous deposition from the atmosphere, thus acting as a major sink for both airborne and waterborne POPs [11,14,19]. Experimental evidence has confirmed this aspect [12].…”