Persistent Organic Pollutants at the base of the Antarctic marine food web

Polybrominated diphenyl ethers (PBDE) are, together with PAHs, between the substances being considered for inclusion in the Stockholm Convention other than the so called dirty dozen. Researchers measured brominated diphenyl ethers (BDEs), organic compounds produced for use as flame retardants and exactly BDE-47, -99, and -100, in sea ice algae and water column plankton, collected in the Palmer Long-Term Ecological Research (LTER) region west of the Antarctic Peninsula during late austral winter andmidsummer, 2001-2002. BDEs were 100-1000 times higher in ice algae and 2-10 times higher in phytoplankton than the most abundant organochlorine pesticide, hexachlorobenzene (HCB), reflecting the current production and use of BDEs versus organochlorine pesticides. Moreover, lower vapor pressures of BDEs versus HCB render the former more easily condensed out of the atmosphere and incorporated into sea ice. However, concentration of HCB and BDEs was significantly lower in summer plankton than in ice algae indicating lower atmospheric inputs, removal from the water column, and/or biodilution of persistent organic pollutants at the base of the food web during summer. The level of γ-HCH (<0.06-5.6 ng/glipid), heptachlor epoxide (<0.04-5.5 ng/glipid), p,p'-DDT (<0.04-16.4 ng/glipid), and p,p'- DDE (<0.03 5.2 ng/glipid) in plankton measured in this study was almost 2 orders of magnitude lower than the concentration previously reported for plankton samples taken during 1987 in the Indian Ocean sector of the Antarctica. Similarly, lower concentration of α- HCH, γ-HCH and DDTs was measured in phytoplankton in this study than previously in the Antarctic Peninsula region. The reduced frequency of occurrence and concentration of pesticides in Antarctic plankton can be attributed to decreases in use and to the subsequent decrease of atmospheric concentration over the past few decades. The decline in ΣHCH (α- + γ-HCH) in Antarctic plankton over time yields an estimated environmental half-life of 2 yrfor HCHs in coastal Antarctic surface waters.