20 Years of Air-Water Gas Exchange Observations for Pesticides in the Western Arctic Ocean.

The Arctic has been contaminated by legacy organochlorine pesticides (OCPs) and currently used pesticides (CUPs) through atmospheric transport and oceanic currents. Here we report the time trends and air-water exchange of OCPs and CUPs from research expeditions conducted between 1993 and 2013. Compounds determined in both air and water were trans- and cis-chlordanes (TC, CC), trans- and cis-nonachlors (TN, CN), heptachlor exo-epoxide (HEPX), dieldrin (DIEL), chlorobornanes (ΣCHBs and toxaphene), dacthal (DAC), endosulfans and metabolite endosulfan sulfate (ENDO-I, ENDO-II, and ENDO SUL), chlorothalonil (CHT), chlorpyrifos (CPF), and trifluralin (TFN). Pentachloronitrobenzene (PCNB and quintozene) and its soil metabolite pentachlorothianisole (PCTA) were also found in air. Concentrations of most OCPs declined in surface water, whereas some CUPs increased (ENDO-I, CHT, and TFN) or showed no significant change (CPF and DAC), and most compounds declined in air. Chlordane compound fractions TC/(TC + CC) and TC/(TC + CC + TN) decreased in water and air, while CC/(TC + CC + TN) increased. TN/(TC + CC + TN) also increased in air and slightly, but not significantly, in water. These changes suggest selective removal of more labile TC and/or a shift in chlordane sources. Water-air fugacity ratios indicated net volatilization (FR > 1.0) or near equilibrium (FR not significantly different from 1.0) for most OCPs but net deposition (FR < 1.0) for ΣCHBs. Net deposition was shown for ENDO-I on all expeditions, while the net exchange direction of other CUPs varied. Understanding the processes and current state of air-surface exchange helps to interpret environmental exposure and evaluate the effectiveness of international protocols and provides insights for the environmental fate of new and emerging chemicals.

Hydration state of the moss Hylocomium splendens and the lichen Cladina stellaris governs uptake and revolatilization of airborne α- and γ-hexachlorocyclohexane.

The partitioning of α- and γ-hexachlorocyclohexane between air and the moss Hylocomium splendens and the lichen Cladina stellaris were studied under laboratory conditions. After cultivation of the sample material to obtain a common starting point free from outside influence, the material was divided into four different treatment categories with different hydration/desiccation regimes. The concentrations of the analytes were 3-5 times higher in the hydrated moss or lichen than in the desiccated material. The results are in contrast to how these compounds are taken up by pine needles in which there is a continuous accumulation, more rapid during periods with high temperatures and dry weather. In general, the different adaptations to water economy is a more important explanatory factor for the concentration of airborne hydrophobic pollutants in mosses, lichens, and vascular plants than their designation as "plants" in a broad sense. It is, therefore, not advisible to mix data from different organism groups for monitoring or modeling purposes.

Aerosol-mediated transport and deposition of brominated diphenyl ethers to Antarctica.

Brominated diphenyl ethers (BDE47, 99, 100, and 209) were measured in air, snow and sea ice throughout western Antarctica between 2001 and 2007. BDEs in Antarctic air were predominantly associated with aerosols and were low compared to those in remote regions of the northern hemisphere, except in Marguerite Bay following the fire at Rothera research station in Sept 2001, indicating that this event was a local source of BDE209 to the Antarctic environment. Aerosol BDE47/100 reflects a mixture of commercial pentaBDE products; however, BDE99/100 is suggestive of photodegradation of BDE99 during long-range atmospheric transport (LRAT) in the austral summer. BDEs in snow were lower than predicted based on snow scavenging of aerosols indicating that atmospheric deposition events may be episodic. BDE47, -99, and -100 significantly declined in Antarctic sea ice between 2001 and 2007; however, BDE209 did not decline in Antarctic sea ice over the same time period. Significant losses of BDE99 and -100 from sea ice were recorded over a 19 day period in spring 2001 demonstrating that seasonal ice processes result in the preferential loss of some BDEs. BDE47/100 and BDE99/100 in sea ice samples reflect commercial pentaBDE products, suggesting that photodegradation of BDE99 is minimal during LRAT in the austral winter.

Manufacturing origin of perfluorooctanoate (PFOA) in Atlantic and Canadian Arctic seawater.

The extent to which different manufacturing sources and long-range transport pathways contribute to perfluorooctanoate (PFOA) in the world's oceans, particularly in remote locations, is widely debated. Here, the relative contribution of historic (i.e., electrochemically fluorinated) and contemporary (i.e., telomer) manufacturing sources was assessed for PFOA in various seawater samples by an established isomer profiling technique. The ratios of individual branched PFOA isomers were indistinguishable from those in authentic historic standards in 93% of the samples examined, indicating that marine processes had little influence on isomer profiles, and that isomer profiling is a valid source apportionment tool for seawater. Eastern Atlantic PFOA was largely (83-98%) of historic origin, but this decreased to only 33% close to the Eastern U.S. seaboard. Similarly, PFOA in the Norwegian Sea was near exclusively historic, but the relative contribution decreased to ∼50% near the Baltic Sea. Such observations of contemporary PFOA in coastal source regions coincided with elevated concentrations, suggesting that the continued production and use of PFOA is currently adding to the marine burden of this contaminant. In the Arctic, a spatial trend was observed whereby PFOA in seawater originating from the Atlantic was predominantly historic (up to 99%), whereas water in the Archipelago (i.e., from the Pacific) was predominantly of contemporary origin (as little as 17% historic). These data help to explain reported temporal and spatial trends from Arctic wildlife biomonitoring, and suggest that the dominant PFOA source(s) to the Pacific and Canadian Arctic Archipelago are either (a) from direct emissions of contemporary PFOA via manufacturing or use in Asia, or (b) from atmospheric transport and oxidation of contemporary PFOA-precursors.

Perfluoroalkyl acids in the Atlantic and Canadian Arctic Oceans.

We report here on the spatial distribution of C(4), C(6), and C(8) perfluoroalkyl sulfonates, C(6)-C(14) perfluoroalkyl carboxylates, and perfluorooctanesulfonamide in the Atlantic and Arctic Oceans, including previously unstudied coastal waters of North and South America, and the Canadian Arctic Archipelago. Perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) were typically the dominant perfluoroalkyl acids (PFAAs) in Atlantic water. In the midnorthwest Atlantic/Gulf Stream, sum PFAA concentrations (∑PFAAs) were low (77-190 pg/L) but increased rapidly upon crossing into U.S. coastal water (up to 5800 pg/L near Rhode Island). ∑PFAAs in the northeast Atlantic were highest north of the Canary Islands (280-980 pg/L) and decreased with latitude. In the South Atlantic, concentrations increased near Rio de la Plata (Argentina/Uruguay; 350-540 pg/L ∑PFAAs), possibly attributable to insecticides containing N-ethyl perfluorooctanesulfonamide, or proximity to Montevideo and Buenos Aires. In all other southern hemisphere locations, ∑PFAAs were <210 pg/L. PFOA/PFOS ratios were typically ≥1 in the northern hemisphere, ∼1 near the equator, and ≤1 in the southern hemisphere. In the Canadian Arctic, ∑PFAAs ranged from 40 to 250 pg/L, with perfluoroheptanoate, PFOA, and PFOS among the PFAAs detected at the highest concentrations. PFOA/PFOS ratios (typically ≫1) decreased from Baffin Bay to the Amundsen Gulf, possibly attributable to increased atmospheric inputs. These data help validate global emissions models and contribute to understanding of long-range transport pathways and sources of PFAAs to remote regions.

First report of chlorinated and brominated hydrocarbon pollutants in marine bird eggs from an oceanic Indian Ocean island.

We report for the first time levels of persistent organic pollutants in marine bird eggs from an oceanic island in the Indian Ocean, the world's third largest ocean. Ten eggs each of the Common Noddy, also known as the Brown Noddy (Anous stolidus), and Sooty Tern (Sterna fuscata) were collected from Ile Cocos off the coast of the island of Rodrigues, located 560 km east of the island of Mauritius. ΣPCBs had the highest levels (2.2 and 2.6n g/g wm, wet mass; 20 and 19 ng/g lm, lipid mass) for common Noddy and Sooty Tern, respectively (and following), then ΣDDT (1.9 and 3.1 ng/g wm; 17 and 23 ng/g lm), and mirex (0.96 and 0.69 ng/g wm; 8.7 and 5.0 ng/gl m). ΣChlordanes (0.094 and 0.15 ng/g wm; 0.48 and 0.73 ng/g lm) and Σtoxaphenes (0.26 and 0.61 ng/g wm; 2.4 and 5.9 ng/g lm) are rare data for these compounds from this ocean. Brominated flame retardants were low (0.08 and 0.07 ng/g wm; 0.7 and 0.7 ng/g lm). Multivariate analyses indicated different contamination patterns in the prey items as Sooty Terns had significantly higher levels of mean Σchlordanes and Σtoxaphenes, as well as CB105, -108 and -157. p,p'-DDE had an association with thinner eggshells in the Sooty Tern. Although the contaminant levels were in all respects low, industrialisation, development on the periphery, commercial exploitation of the marine environment, and pollutants transferred over long distances by marine debris is likely to add to chemical pressure in this region. Monitoring changes in background levels of pollutants in remote regions will indicate such trends, and marine bird eggs from Rodrigues would be an excellent site.

Current-use and organochlorine pesticides and polychlorinated biphenyls in the biodegradable fraction of source separated household waste, compost, and anaerobic digest.

Several current-use (≤ 80 ng g⁻¹ dry weight) and organochlorine pesticides (≤ 15 ng g⁻¹ dry weight) and polychlorinated biphenyls (≤ 18 ng g⁻¹ dry weight) were found in the biodegradable fraction of source separated household waste, compost, and/or anaerobic digestate. The degradation rates of individual compounds differ depending on the treatment. Dieldrin and pentachloroaniline, e.g., degrade more rapidly than the waste is mineralized and accumulates in the products after all treatments. Many organochlorines degrade at the same rate as the waste and have the same concentrations in the waste and products. Chlorpyrifos degrades slower than the waste and accumulates in all products and ethion during anaerobic digestion. The polychlorinated biphenyls and some pesticides show different degradations rates relative the waste during different processes. Understanding the degradation of the contaminants under different conditions is necessary to develop quality criteria for the use of compost and digest.

The Wasp as a Terrestrial Indicator of Environmental Metal Composition: Evidence from Zimbabwe.

We explored metal concentrations in wasps from 4 sites near Harare, Zimbabwe, on a 106 km west-east transect. We found elevated concentrations at 2 presumed-polluted sites (a platinum [Pt] mine and a known polluted lake) located near a metal-enriched geological feature (the Great Dyke). A site in urban Harare and a nature reserve served as reference. Only wasps from the 2 presumed-polluted sites had quantifiable Pt. For Cr, Ni, Mg, Se, Fe, Mn, and V, we report the highest concentrations in wasps yet published. Wasps from the presumed-polluted sites had significantly higher concentrations of most metals when compared with wasps from the reference sites, suggesting pollution as a source. Geology, however, differs between the sites. It is probable, therefore, that both geology and pollution contributed to the differences in metal concentrations. Because of its long and narrow dimensions (550 km long and 4-11 km wide), the Great Dyke offers opportunities for comparative studies. Because wasps form a complex part of the food web and ecology, studies on the transfer of metals to wasps' predators are needed, especially given that some birds specialize in feeding on hymenopterans. The rich diversity of wasps (>145 000 species worldwide) occupying multiple different trophic levels is a good indicator, and wasps have a rich potential to join other invertebrates as terrestrial indicators. Environ Toxicol Chem 2021;40:1726-1739. © 2021 SETAC.

Chlorine cycling and the fate of Cl in terrestrial environments.

Chlorine (Cl) in the terrestrial environment is of interest from multiple perspectives, including the use of chloride as a tracer for water flow and contaminant transport, organochlorine pollutants, Cl cycling, radioactive waste (radioecology; 36Cl is of large concern) and plant science (Cl as essential element for living plants). During the past decades, there has been a rapid development towards improved understanding of the terrestrial Cl cycle. There is a ubiquitous and extensive natural chlorination of organic matter in terrestrial ecosystems where naturally formed chlorinated organic compounds (Clorg) in soil frequently exceed the abundance of chloride. Chloride dominates import and export from terrestrial ecosystems while soil Clorg and biomass Cl can dominate the standing stock Cl. This has important implications for Cl transport, as chloride will enter the Cl pools resulting in prolonged residence times. Clearly, these pools must be considered separately in future monitoring programs addressing Cl cycling. Moreover, there are indications that (1) large amounts of Cl can accumulate in biomass, in some cases representing the main Cl pool; (2) emissions of volatile organic chlorines could be a significant export pathway of Cl and (3) that there is a production of Clorg in tissues of, e.g. plants and animals and that Cl can accumulate as, e.g. chlorinated fatty acids in organisms. Yet, data focusing on ecosystem perspectives and combined spatiotemporal variability regarding various Cl pools are still scarce, and the processes and ecological roles of the extensive biological Cl cycling are still poorly understood.

Temporal dynamics and ecotoxicological risk assessment of personal care products, phthalate ester plasticizers, and organophosphorus flame retardants in water from Lake Victoria, Uganda.

For the first time the occurrence of 25 organic micropollutants (OMPs) including; 11 personal care products (PCPs), six phthalate ester plasticizers (PEPs) and eight organophosphorus flame retardants (OPFRs) was investigated in 72 water samples obtained from five bays in the Uganda sector of Lake Victoria. In addition, an assessment of the potential ecotoxic risk of the target OMPs to aquatic organisms was conducted. Water samples were analyzed for the target OMPs using gas chromatography coupled with mass spectrometry (GC/MS). All the target PCPs were found in all the water samples with the exception of musk ketone and 2,6-di-tert-butylphenol. Triclosan (89-1400 ng L-1), benzophenone (36-1300 ng L-1), and 4-methylbenzylidine camphor (21-1500 ng L-1) were the most predominant PCPs. All the six plasticizers were found in all the water samples with dibutyl phthalate (350-16 000 ng L-1), and bis-(2-ethylhexyl) phthalate (210-23 000 ng L-1) detected at the highest concentrations. Five OPFRs out of the eight targeted were found in all the water samples. Tricresyl phosphate (25-8100 ng L-1), tris-(2-chloroethyl) phosphate (24-6500 ng L-1) and triphenyl phosphate (54-4300 ng L-1) were the most dominant OPFRs. The highest concentrations of OMPs were recorded in Murchison and Thurston Bays, presumably due to industrial wastewater effluents from the highly industrialized localities of the two Bays. Ecotoxicological risk assessment showed that PCPs (triclosan, musk ketone, and 4-MBC), plasticizers (dibutyl phthalate, bis-(2-ethylhexyl) adipate and bis-(2-ethylhexyl) phthalate) and OPFRs (tricresyl phosphate, triphenyl phosphate and tris-(2-chloroethyl) phosphate) pose a high ecotoxic risk to lives of aquatic organisms (risk quotients, RQ > 1).

Persistent organic pollutants in sea bird eggs from the Indian Ocean's Mascarene Basin.

We report the concentrations of persistent organic pollutants (POPs) in seabird eggs from St. Brandon's Atoll, a tropical island system in the western Indian Ocean. Ten eggs each of sooty terns (Onychoprion fuscatus), fairy terns (Gygis alba), and common noddies (Anous stolidus) were collected from the atoll. For a terrestrial reference, we analysed three feral chicken (Gallus gallus domesticus) eggs from the same location. Sooty tern eggs contained the highest mean concentrations of three chemical classes: Æ©CHL3 (0.21 ng/g wm; wet mass), Æ©PCB10 (1.5 ng/g wm), and Æ©PBDE6 (1.1 ng/g wm). Fairy tern eggs contained the highest mean concentrations of HCB (0.68 ng/g wm) and Æ©CHB5 (0.83 ng/g wm). The chicken eggs contained the highest mean concentrations of Æ©DDT3 (2.6 ng/g wm), while common noddy eggs contained the highest mean concentrations of Æ©HCH2 (0.5 ng/g wm). We surmise that the differences in chemical composition between species reflect different pollutant compositions in prey from the bird's different foraging ranges. The sooty terns foraging offshore contained higher POPs concentrations than the nearshore-foraging common noddies. Fairy tern eggs contained intermediate concentrations, commensurate with their intermediate foraging. Inter-island differences in contaminant concentrations were seen between eggs of the common noddies from St. Brandon's Atoll and Rodrigues Island, 520 km to the south-east. Concentrations of contaminants found in this study were lower than values quantified by other studies, making St. Brandon's Atoll an ideal reference site to monitor background concentrations of POPs in the tropical Indian Ocean.

Direct and indirect effects of the fungicide azoxystrobin in outdoor brackish water microcosms.

The effects of the strobilurin fungicide azoxystrobin were studied in brackish water microcosms, with natural plankton communities and sediment. Two experiments were conducted: Experiment 1 (nominal conc. 0, 15 and 60 microg/L, 24-L outdoor microcosms for 21 days) and a second, follow-up, Experiment 2 (nominal conc. 0, 3, 7.5, 15 microg/L, 4-L indoor microcosms for 12 days). The microcosms represent a simplified brackish water community found in shallow semi-enclosed coastal areas in agricultural districts in the Baltic Sea region. Measured water concentrations of the fungicide (Experiment 1) were, on average, 83 and 62% of nominal concentrations directly after application, and 25 and 30% after 21 days, for the low and high dose treatments, respectively, corresponding to mean DT50-values of 15.1 and 25.8 days, for low and high dose treatments, respectively. In Experiment 1, direct toxic effects on calanoid copepods at both test concentrations were observed. Similarly, in Experiment 2, the copepod abundance was significantly reduced at all tested concentrations. There were also significant secondary effects on zooplankton and phytoplankton community structure, standing stocks and primary production. Very few ecotoxicological studies have investigated effects of plant protection products on Baltic organisms in general and effects on community structure and function specifically. Our results show that azoxystrobin is toxic to brackish water copepods at considerably lower concentrations than previously reported from single species tests on freshwater crustaceans, and that direct toxic effects on this ecologically important group may lead to cascade effects altering lower food webs and ecosystem functioning.

Screening of antifouling biocides around a pleasure boat marina in the Baltic Sea after legal restrictions.

Copper, zinc, and Irgarol 1051 concentrations were determined around a pleasure boat marina in the Stockholm Archipelago. Copper concentrations in water were twice as high (6.62 µg L⁻¹) in 2004 as 1992-1993, zinc concentrations six times higher (20.0 µg L⁻¹). Concentrations in bladder wrack (Fucus vesiculosus) had also risen. Irgarol concentrations in water were similar (~0.17 µg L⁻¹) in 1996 and 2004, while concentrations in bladder wrack halved from 1993 to 2004. The peak concentrations of copper and Irgarol in water have shifted indicating that the main source in the 1990 s were local boats, but in 2004 visiting boats.

Occurrence, distribution, and ecotoxicological risk assessment of selected pharmaceutical compounds in water from Lake Victoria, Uganda.

The occurrence of 24 pharmaceuticals (including 15 antibiotics, three analgesic/anti-inflammatory drugs, three anti-epileptic/antidepressant drugs, two beta blockers, and one lipid regulator) was investigated in 75 water samples collected from four bays in the Ugandan part of Lake Victoria. In addition, the potential environmental risk of the target pharmaceutical compounds to aquatic organisms in the aquatic ecosystem of Lake Victoria was assessed. Water samples were extracted using solid phase extraction and analyzed for pharmaceuticals using high-performance liquid chromatography coupled with triple quadrupole mass spectrometry (LC/MS/MS). Eighteen of the 24 pharmaceuticals occurred at quantifiable concentrations. Sulfamethoxazole (1-5600 ng L-1), trimethoprim (1-89 ng L-1), tetracycline (3-70 ng L-1), sulfacetamide (1-13 ng L-1), and ibuprofen (6-780 ng L-1) occurred at quantifiable concentrations in all water samples. Sulfamethazine (2-50 ng L-1), erythromycin (10-66 ng L-1), diclofenac (2-160 ng L-1), and carbamazepine (5-72 ng L-1) were only quantifiable in water samples from Murchison Bay. The highest concentrations of pharmaceuticals were found in Murchison Bay, the main recipient of sewage effluents, industrial and municipal waste from Kampala city via the Nakivubo channel. Ecotoxicological risk assessment showed that sulfamethoxazole, oxytetracycline, erythromycin, and diclofenac pose a high toxic risk to aquatic organisms in the lake, while ciprofloxacin, norfloxacin, and ibuprofen pose a medium risk. This study is the first of its kind to report the levels and ecotoxic risks of pharmaceutical compounds in Lake Victoria waters, of Uganda, and East Africa as a whole.

Impacts of a shallow shipwreck on a coral reef: A case study from St. Brandon's Atoll, Mauritius, Indian Ocean.

Shallow shipwrecks, can have severe ecological and toxicological impacts on coral atolls. In 2012, a tuna longliner ran aground on the reef crest of St Brandon's Atoll, Mauritius, broke up into three pieces which was moved by currents and storms into the lagoon. In the months following the grounding, the coral around the wreck became dead and black. Down-current from the wreck, a dense bloom of filamentous algae (Ulva sp.) attached to coral occurred. To determine the ecological effects of the wreck on the system, the marine biota around the wreck, in the algal bloom, and fish reference zones were counted in 2014. Metal concentrations in reference and affected coral was determined using inductively coupled plasma mass spectrometry (ICP/MS). A pronounced difference was seen in the metal concentration pattern between coral from the wreck- and algal zones, and the coral reference zone. While the wreck zone contained the highest abundance of fish, the fish reference zone had the highest species diversity but with fewer fish. We also counted eleven Critically Endangered hawksbill sea turtles Eretmochelys imbricata and significantly more sea cucumbers in the algal zone than the reference zones. The effects of shipwrecks on coral reefs must be considered a threat over periods of years and should be studied further.

Comparing water, bovine milk, and indoor residual spraying as possible sources of DDT and pyrethroid residues in breast milk.

The presence of pollutants in human breast milk is of major concern, especially in malaria control areas where 1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane (DDT) is currently used as indoor residual spray (IRS). The levels of DDT and pyrethroids (PYR) were determined in breast milk, bovine milk, and drinking water from northern KwaZulu-Natal, South Africa. Both reference and exposed mothers used the same market food, but the DDT levels in the exposed mothers (mean SigmaDDT 10 microg/g milk fat [mf]) were much higher than for the reference mothers (mean SigmaDDT 1.3 microg/g milk fat). This difference in residue levels indicates uptake from IRS-applied DDT, most likely via air and skin contact, and excludes food as the main source of pollutants. DDT levels in bovine milk (mean SigmaDDT 0.15 microg/g mf) from the exposed area were less than levels in breast milk from the reference area, and lower than the 20 microg/L maximum residue limit (MRL) set by the Food and Agriculture Organization (FAO). Mean SigmaDDT in water was 0.0065 microg/L, much lower then the WHO limit of the sum of all metabolites in drinking water of 1 microg/L, and therefore highly unlikely to have contributed to any extent toward levels in breast milk. Permethrin in breast milk (mean 1.1-1.6 microg/g milk fat) was probably derived from home garden and indoor use, while the other PYR (cypermethrin and cyfluthrin) at lower concentrations were probably derived from food and agricultural exposure. It is postulated that a better understanding of the indoor dynamics of DDT and other insecticides, through a concept of Total Homestead Environment Approach (THEA), is crucial for investigating options of reducing human exposure and uptake under malaria control conditions.

Distribution profiles of selected organic pollutants in soils and sediments of industrial, residential and agricultural areas of South Africa.

Currently very little data exists on the presence of persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) in the South African environment. To address this data gap a preliminary study of a highly industrialised area of South Africa, the Vaal Triangle, was done. Soil and sediment samples from the Vaal Triangle, as well as other areas in central South Africa, were analysed with high resolution gas chromatography-high resolution mass spectrometry (HRGC/HRMS) for the presence of PAHs, polychlorinated biphenyls (PCBs), dioxin-like chemicals and organochlorine pesticides (OCPs). Results showed that these chemicals are present in the South African environment with concentrations ranging between 39,000 ng g(-1) for SigmaPAHs and 0.01 ng g(-1) for dicofol. Principal component analysis (PCA) indicated different pollution sources in industrial and agricultural areas.

A retrospective analysis of contamination and periphyton PICT patterns for the antifoulant irgarol 1051, around a small marina on the Swedish west coast.

Irgarol is a triazine photosystem II (PSII) inhibitor that has been used in Sweden as an antifouling ingredient since the 1990s. Early microcosm studies indicated that periphyton was sensitive to irgarol at concentrations regularly found in harbours and marinas. However, field studies of irgarol effects on the Swedish west coast in 1994, using the pollution-induced community tolerance (PICT) approach, failed to detect any effects of the toxicant in the field. A PICT study involves sampling of replicate communities in a gradient of contamination, and a comparison of their community tolerance levels, with an increase being an indication that sensitive species have been eliminated and replaced by more tolerant ones. Typically, short-term assays are used to quantify the community tolerance levels. Later PICT studies in the same area over a 10 year period demonstrate that irgarol tolerance levels have increased, although the contamination pattern has been stable. Our results support the hypothesis that that the PICT potential was low initially, due to a small differential sensitivity between the community members, and that a persistent selection pressure was required to favour and enrich irgarol-tolerant species or genotypes.

Evaluating gas chromatography with a halogen-specific detector for the determination of disinfection by-products in drinking water.

The occurrence of disinfection by-products (DBPs) in drinking water has become an issue of concern during the past decades. The DBPs pose health risks and are suspected to cause various cancer forms, be genotoxic, and have negative developmental effects. The vast chemical diversity of DBPs makes comprehensive monitoring challenging. Only few of the DBPs are regulated and included in analytical protocols. In this study, a method for simultaneous measurement of 20 DBPs from five different structural classes (both regulated and non-regulated) was investigated and further developed for 11 DBPs using solid-phase extraction and gas chromatography coupled with a halogen-specific detector (XSD). The XSD was highly selective towards halogenated DBPs, providing chromatograms with little noise. The method allowed detection down to 0.05 µg L-1 and showed promising results for the simultaneous determination of a range of neutral DBP classes. Compounds from two classes of emerging DBPs, more cytotoxic than the "traditional" regulated DBPs, were successfully determined using this method. However, haloacetic acids (HAAs) should be analyzed separately as some HAA methyl esters may degrade giving false positives of trihalomethanes (THMs). The method was tested on real water samples from two municipal waterworks where the target DBP concentrations were found below the regulatory limits of Sweden.

Innovative drinking water treatment techniques reduce the disinfection-induced oxidative stress and genotoxic activity.

Disinfection of drinking water using chlorine can lead to the formation of genotoxic by-products when chlorine reacts with natural organic matter (NOM). A vast number of such disinfection by-products (DBPs) have been identified, making it almost impossible to routinely monitor all DBPs with chemical analysis. In this study, a bioanalytical approach was used, measuring oxidative stress (Nrf2 activity), genotoxicity (micronucleus test), and aryl hydrocarbon receptor (AhR) activation to evaluate an innovative water treatment process, including suspended ion exchange, ozonation, in-line coagulation, ceramic microfiltration, and granular activated carbon. Chlorination was performed in laboratory scale after each step in the treatment process in order to investigate the effect of each treatment process to the formation of DBPs. Suspended ion exchange had a high capacity to remove dissolved organic carbon (DOC) and to decrease UV absorbance and Nrf2 activity in non-chlorinated water. High-dose chlorination (10 mg Cl2 L-1) of raw water caused a drastic induction of Nrf2 activity, which was decreased by 70% in water chlorinated after suspended ion exchange. Further reduction of Nrf2 activity following chlorination was achieved by ozonation and the concomitant treatment steps. The ozonation treatment resulted in decreased Nrf2 activity in spite of unchanged DOC levels. However, a strong correlation was found between UV absorbing compounds and Nrf2 activity, demonstrating that Nrf2 inducing DBPs were formed from pre-cursors of a specific NOM fraction, constituted of mainly aromatic compounds. Moreover, high-dose chlorination of raw water induced genotoxicity. In similarity to the DOC levels, UV absorbance and Nrf2 activity, the disinfection-induced genotoxicity was also reduced by each treatment step of the innovative water treatment technique. AhR activity was observed in the water produced by the conventional process and in the raw water, but the activity was clearly decreased by the ozonation step in the innovative water treatment process.