Concentrations Of OCs Research Articles

Fiducial Reference Measurement for Greenhouse Gases (FRM4GHG)

The Total Carbon Column Observing Network (TCCON) and the Infrared Working Group of the Network for the Detection of Atmospheric Composition Change (NDACC-IRWG) are two ground-based networks that provide the retrieved concentrations of up to 30 atmospheric trace gases, using solar absorption spectrometry. Both networks provide reference measurements for the validation of satellites and models. TCCON concentrates on long-lived greenhouse gases (GHGs) for carbon cycle studies and validation. The number of sites is limited, and the geographical coverage is uneven, covering mainly Europe and the USA. A better distribution of stations is desired to improve the representativeness of the data for various atmospheric conditions and surface conditions and to cover a large latitudinal distribution. The two successive Fiducial Reference Measurements for Greenhouse Gases European Space Agency projects (FRM4GHG and FRM4GHG2) aim at the assessment of several low-cost portable instruments for precise measurements of GHGs to complement the existing ground-based sites. Several types of low spectral resolution Fourier transform infrared (FTIR) spectrometers manufactured by Bruker, namely an EM27/SUN, a Vertex70, a fiber-coupled IRCube, and a Laser Heterodyne spectro-Radiometer (LHR) developed by UK Rutherford Appleton Laboratory are the participating instruments to achieve the Fiducial Reference Measurements (FRMs) status. Intensive side-by-side measurements were performed using all four instruments next to the Bruker IFS 125HR high spectral resolution FTIR, performing measurements in the NIR (TCCON configuration) and MIR (NDACC configuration) spectral range. The remote sensing measurements were complemented by AirCore launches, which provided in situ vertical profiles of target gases traceable to the World Meteorological Organization (WMO) reference scale. The results of the intercomparisons are shown and discussed. Except for the EM27/SUN, all other instruments, including the reference TCCON spectrometer, needed modifications during the campaign period. The EM27/SUN and the Vertex70 provided stable and precise measurements of the target gases during the campaign with quantified small biases. As part of the FRM4GHG project, one EM27/SUN is now used as a travel standard for the verification of column-integrated GHG measurements. The extension of the Vertex70 to the MIR provides the opportunity to retrieve additional concentrations of N2O, CH4, HCHO, and OCS. These MIR data products are comparable to the retrieval results from the high-resolution IFS 125HR spectrometer as operated by the NDACC. Our studies show the potential for such types of spectrometers to be used as a travel standard for the MIR species. An enclosure system with a compact solar tracker and meteorological station has been developed to house the low spectral resolution portable FTIR systems for performing solar absorption measurements. This helps the spectrometers to be mobile and enables autonomous operation, which will help to complement the TCCON and NDACC networks by extending the observational capabilities at new sites for the observation of GHGs and additional air quality gases. The development of the retrieval software allows comparable processing of the Vertex70 type of spectra as the EM27/SUN ones, therefore bringing them under the umbrella of the COllaborative Carbon Column Observing Network (COCCON). A self-assessment following the CEOS-FRM Maturity Matrix shows that the COCCON is able to provide GHG data products of FRM quality and can be used for either short-term campaigns or long-term measurements to complement the high-resolution FTIR networks.

Ecotoxicity of sediments in Ho Chi Minh city’s canals

For an ecotoxicological screening of recently deposited sediments, samples were collected from Ho Chi Minh City’s canals in August 2015. The sediments were characterized by physico-chemical analysis of metals, PAHs, PCBs, and other organic micropollutants, and standard sediment toxicity testing. The results showed that the sediments from the canals from both the urban and suburban areas contained a mixture of contaminants with concentrations of several metals, PAHs, PCBs and OCs being above thresholds for effects to benthic organisms. The results of the chemical analyses were corroborated by toxicity detected in standard laboratory tests with crustaceans (ostracods) and insect (midge) larvae. Conspicuous concentrations at the μg/g level were found for the fragrances galaxolide and OTNE, and nonylphenol, triclosan and the UV filters octocrylene, 2-EHDP and EHMC were measured at all sampling sites at concentrations of several tens and even hundreds ng/g. Highest concentrations were measured for the pyrethroid insecticide permethrin in sediments from the urban area and for the pyrethroid insecticide bifenthrin in sediments from suburban areas (3692.9 ng/g dw and 477.6 ng/g dw, respectively). Insecticides were identified as the most probable contributors to the observed toxicity.

Biogeochemical controls on climatically active gases and atmospheric sulfate aerosols in the western Pacific

The Pacific Ocean plays an important role in regulating the budget of climatically active gases and the burden of sulfate aerosols. Here, a field investigation was conducted to clarify the key processes and factors controlling climatically active gases, including dimethyl sulfide (DMS), carbonyl sulfide (OCS), carbon disulfide (CS2), and carbon dioxide (CO2), in both surface seawater and the lower atmosphere of the western Pacific. In addition, the relative contributions of different sources to atmospheric sulfate aerosols were quantitatively estimated, and their causes were explored. The maximum concentrations of DMS, OCS and CS2 and the minimum partial pressure of CO2 (pCO2) were observed in the Kuroshio-Oyashio Extension. Kuroshio-induced mesoscale eddies brought abundant nutrients and organic matter from the subsurface layer of Oyashio into the euphotic layer, thus enhancing primary productivity and accelerating the photoreaction of organic matter. These processes led to higher concentrations of DMS, OCS and CS2 and lower pCO2. However, the oligotrophic subsurface layer in the subtropical gyre and the strong barrier layer in the equatorial waters suppressed the upward fluxes of nutrients and organic matter, resulting in lower surface concentrations of DMS, OCS, and CS2 in these areas. Being far from the continents, atmospheric concentrations of DMS, OCS and CS2 and pCO2 in the western Pacific generally were observed to depend on the local sea-to-air exchange and may be regulated by atmospheric oxidation and mixing of air masses. In general, oceanic DMS emissions played an important role in the formation of sulfate aerosols in the western Pacific (accounting for ∼19.5% of total sulfate aerosols), especially in the Kuroshio-Oyashio Extension (∼32.3%). These processes in seawater may also determine the variations and emissions of other climatically active gases from biogenic and photochemical sources.

Organochlorine exposure and health effects in stranded Steller sea lions (Eumetopias jubatus) and Pacific harbor seals (Phoca vitulina richardii) from Oregon and southern Washington coasts

AbstractOrganochlorine (OC) pesticides and polychlorinated biphenyls (PCBs) have been detected in a variety of marine mammal species at levels associated with adverse health effects. Little is known about OC levels and impacts on health in pinnipeds with different life histories. We determined the health and levels of 18 OC pesticides and 16 PCB congeners in blubber samples from 20 Steller sea lions and 39 Pacific harbor seals stranded from Oregon and Southern Washington. The most commonly detected OC at the highest concentration was p,p′‐ dichlorodiphenyldichloroethylene (DDE). PCBs were detected in all samples as well. Hypothesis testing indicated that diseased Steller sea lions (males and females combined) had higher contaminant concentrations than healthy Steller sea lions, and diseased Pacific harbor seals had higher concentrations of total OCs than healthy animals. Differences were also noted between diseased and healthy animals when looking at individual sexes of each species. Diseased Steller sea lions had higher mean contaminant levels than diseased harbor seals and healthy Steller sea lions had higher mean contaminant concentrations than healthy Pacific harbor seals. These results show that species differences exist in both contaminant loads and sensitivity to contaminants, which may be due to differences in life histories and physiology.

Associations between organohalogen exposure and thyroid- and steroid-related gene responses in St. Lawrence Estuary belugas and minke whales

Elevated concentrations of persistent organic pollutants (POPs) and emerging halogenated flame retardants (HFRs) have been reported in tissues of the endangered St. Lawrence Estuary (Canada) beluga population as well as in minke whales visiting that same feeding area. This study examined the linkages between blubber concentrations of POPs and emerging HFRs, and transcription in skin of genes involved in the regulation of thyroid and steroid axes in belugas and minke whales from the St. Lawrence Estuary. In belugas, concentrations of PCBs, OCs and hexabromobenzene (HBB) were positively correlated with the transcription of thyroid- and/or steroid-related genes, while Dec-604 CB concentrations were negatively associated with the transcription of glucocorticoid and thyroid genes. In minke whales, PBDE concentrations changed positively with Esrβ transcript levels and HBB concentrations negatively with Nr3c1 transcripts. Present results suggest that several biological functions including reproduction and energetic metabolism may represent potential targets for organohalogens in these whales.

Spatial and temporal variations in the atmospheric concentrations of “Stockholm Convention” organochlorine pesticides in Kuwait

The study reports fortnightly atmospheric concentrations of organochlorine pesticides concomitantly measured at an urban, “industrial” and a remote location over a twelve month period in Kuwait to examine seasonal variability and urban-rural concentration gradients. The average±SD (and range) of the ΣOC concentrations measured throughout the study period in decreasing order were urban, 505±305 (range, 33–1352) pgm−3, remote, 204±124 (4.5–556) pgm−3, and “industrial” 155±103 (8.8–533) pgm−3. The concentrations of most OCs measured in this study, except for DDT and its metabolites, were higher at urban locations relative to their concentrations at remote location, in line with the literature on POPs regarding urban conurbations being sources of industrial chemicals. The most abundant pesticides measured throughout this study were dieldrin, pentachlorobenzene, hexachlorobenzene, ΣDDTs, ΣHCHs, and oxychlordane. Hexachlorobenzene concentrations were generally higher than those of pentachlorobenzene and are both strongly negatively correlated with temperature (p<0.05) at all sampling locations. Mean summertime concentrations were higher for hexachlorocyclohexanes, chlordanes, dieldrin, and DDT isomers, except for pp-DDT. This may suggest that concentrations of these compounds may be driven by temperature.

Higher atmospheric levels and contribution of black carbon in soil-air partitioning of organochlorines in Lesser Himalaya

Due to influence of wind patterns (monsoon and westerlies) and anthropogenic activities, lower stretch of Himalaya is at direct exposure to persistent organic pollutants (POPs). Current study was designed to monitor atmospheric concentrations of long lived organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) using polyurethane passive air sampling in the Lesser Himalayan Region (LHR) of Pakistan. Levels of ∑HCHs, ∑DDTs and ∑PCBs were observed in a range between 3 and 210 pg m−3, 0.75–67.1 pg m−3 and 8.49–458 pg m−3, respectively. Though, air mass trajectories over LHR indicated long range transport as atmospheric source input which was further explained by Clausius–Clapeyron plots between ln P and inverse of temperature (1000/T; K) where all OCPs and most of the PCBs have shown insignificant relationship (r2 = 5E-06–0.41; p-value = 0.06–0.995). However, local source emissions and valley transport may also implicate based on spatial distribution and altitudinal patterns. Additionally, soil-air partitioning of organochlorines was assessed using octanol-air partition (KOA) and black carbon-air partition (KBC) based models. Regression results indicated combined influence of both organic matter (r2 = 0.298–0.85) and black carbon (r2 = 0.31–0.86) via absorption and adsorption, respectively in soil-air partitioning of OCs in LHR. This paper sheds light on the atmospheric concentrations of OCs and help in better understanding of the processes involved in fate and transport of organic pollutants in Himalayan region. Further investigations are required to understand the role of carbon moieties in fate and transport of other groups of organic pollutants at higher altitudes of Himalayan region.

Contaminant (PAHs, OCs, PCBs and trace metals) concentrations are declining in axial tissue of sand flathead (Platycephalus bassensis) collected from an urbanised catchment (Port Phillip Bay, Australia)

Concentrations of PAHs, OCs, PCBs and trace metals were determined in the white muscle of sand flathead Platycephalus bassensis collected at 6 locations in Port Phillip Bay during 2015. No PAHs, OCs or PCBs were detected in the white muscle of sand flathead at any of the locations, however measurable levels of As, Cu, Hg, Se and Zn were detected at all sites. Only As and Hg exhibited regional difference in white muscle concentrations, with As present only in a non-toxic organic form and Hg measured at levels that are comparable to levels reported in reference sites in other studies. All contaminants detected in the white muscle of sand flathead collected in Port Phillip Bay in 2015 were below Australian Food Standards guideline values, and by world standards, the Port Phillip Bay sand flathead population is considered minimally contaminated. Furthermore, tissue contaminant concentrations appear to be decreasing over time.

Towards understanding the variability in biospheric CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; fluxes: using FTIR spectrometry and a chemical transport model to investigate the sources and sinks of carbonyl sulfide and its link to CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;

Abstract. Understanding carbon dioxide (CO2) biospheric processes is of great importance because the terrestrial exchange drives the seasonal and interannual variability of CO2 in the atmosphere. Atmospheric inversions based on CO2 concentration measurements alone can only determine net biosphere fluxes, but not differentiate between photosynthesis (uptake) and respiration (production). Carbonyl sulfide (OCS) could provide an important additional constraint: it is also taken up by plants during photosynthesis but not emitted during respiration, and therefore is a potential means to differentiate between these processes. Solar absorption Fourier Transform InfraRed (FTIR) spectrometry allows for the retrievals of the atmospheric concentrations of both CO2 and OCS from measured solar absorption spectra. Here, we investigate co-located and quasi-simultaneous FTIR measurements of OCS and CO2 performed at five selected sites located in the Northern Hemisphere. These measurements are compared to simulations of OCS and CO2 using a chemical transport model (GEOS-Chem). The coupled biospheric fluxes of OCS and CO2 from the simple biosphere model (SiB) are used in the study. The CO2 simulation with SiB fluxes agrees with the measurements well, while the OCS simulation reproduced a weaker drawdown than FTIR measurements at selected sites, and a smaller latitudinal gradient in the Northern Hemisphere during growing season when comparing with HIPPO (HIAPER Pole-to-Pole Observations) data spanning both hemispheres. An offset in the timing of the seasonal cycle minimum between SiB simulation and measurements is also seen. Using OCS as a photosynthesis proxy can help to understand how the biospheric processes are reproduced in models and to further understand the carbon cycle in the real world.

Response of phase II detoxification enzymes in Phragmites australis plants exposed to organochlorines

Mixed pollution is a characteristic of many industrial sites and constructed wetlands. Plants possessing an enzymatic detoxifying system that is able to handle xenobiotics seems to be a viable option for the removal of mixed persistent contaminants such organochlorines (OCs: monochlorobenzene (MCB), 1,4-dichlorobenzene (DCB), 1,2,4-trichlorobenzene (TCB), γ-hexachlorocyclohexane (HCH)). In this study, Phragmites australis plants were exposed to sub-lethal concentrations of OCs (7 days), in single-exposure (0.8 to 10 mg l(-1)) and in mixture of OCs (0.2 mg l(-1) MCB + 0.2 mg l(-1) DCB + 2.5 mg l(-1) TCB + 0.175 mg l(-1) HCH). Studies were conducted on the detoxification phase II enzymes; glutathione S-transferases (GST), and glucosyltransferases (UGT). Measurements of GST and UGT activities revealed that OCs may be buffered by glutathione and glucose conjugation. There appeared to be a correlation between the effects on phase II enzymes and the degree of chlorination of the benzene ring with, for example, the greatest effects being obtained for HCH exposure. In the case of mixed pollution, the induction of some GST isoenzymes (CDNB, 35 % non-significant) and UGT (118 %) in leaves and the inhibition of phase II enzymes in the other organs were measured. UGTs appear to be key enzymes in the detoxification of OCs.

Individual variation in biomarkers of health: Influence of persistent organic pollutants in Great skuas (Stercorarius skua) breeding at different geographical locations

Persistent organic pollutants (POPs) have been shown to cause adverse effects on a number of biomarkers of health in birds. POPs may impair immune function and alter the stress response, defined as a suite of behavioral and physiological responses to environmental perturbations. Recent studies have also proposed that POPs can induce oxidative stress. Nevertheless, there is a lack of studies simultaneously assessing the potential damaging effects of POPs on the latter biomarkers. In this study, we examined the contribution of legacy (organochlorines; (OCs)) and emerging (flame retardants; PBDEs) POPs to individual variations in stress levels (feather corticosterone), humoral immunity (plasma immunoglobulin Y levels) and oxidative stress occurring in three breeding colonies of a top predator seabird, the Great skua (Stercorarius skua), distributed from temperate regions to the high Arctic: Shetland (60oN), Iceland (63°N) and Bjørnøya (74°N). Our results demonstrated that plasma concentrations of OCs in Great skuas from Bjørnøya are among the highest in North Atlantic seabirds, with up to 7900μg/kg (ww) ∑OCs. Yet, a latitudinal gradient in POP levels was observed with all compounds being significantly higher in Bjørnøya than in Iceland and Shetland (on average 4–7 fold higher for OCs and 2.5–4.5 for PBDEs, respectively). Contrary to our predictions, skuas breeding at the least contaminated site (i.e., Shetland) experienced the poorest physiological condition; i.e., the highest levels of stress hormones (25% higher) and oxidative stress (50% higher) and the lowest immunoglobulin levels (15% lower) compared to the two other colonies. Finally, our results failed to point out consistent within-colony relationships between biomarkers of health and POPs. Overall, it is suggested that other ecological factors such as food availability could constrain physiological indicators more than anthropogenic contaminants.

Levels and distribution of polybrominated diphenyl ethers and organochlorine compounds in sea turtles from Japan

Three species of sea turtles (green, hawksbill and loggerhead turtles) stranded along the coasts or caught (by-catch) around Ishigaki Island and Kochi, Japan were collected between 1998 and 2006 and analyzed for six organohalogen compounds viz., PBDEs, PCBs, DDTs, CHLs, HCHs and HCB. The present study is the first and foremost to report the occurrence of organohalogen compounds in the sea turtles from Japan. Among the compounds analyzed, concentrations of PCBs, DDTs and CHLs were the highest in all the turtle samples. PBDEs were ubiquitously present in all the turtle species. Comparing with the other two species, concentrations of organohalogens in green turtle were relatively low and decreasing trend in the concentrations were noted with increasing carapace length. Concentrations of OCs in sea turtles from the coasts of Ishigaki Island and Kochi were relatively low as compared to those from other locations in the world.

Salmon Farms as a Source of Organohalogenated Contaminants in Wild Fish

Organohalogenated contaminants (OHCs), including organochlorines (OCs; PCB, and OC-pesticides), brominated flame retardants (BFRs; polybrominated diphenyl ethers [PBDE], hexabromocyclododecane [HBCD]) and perfluorooctane sulfonate (PFOS), were measured in livers of Atlantic cod (Gadus morhua) and saithe (Pollachius virens) caught in the vicinity of salmon farms (n = 75) and control sites (n = 80) in three regions (59°-70°N) in Norway. Forty-five percent of the farm-associated (FA) fish (60% of the saithe and 30% of the cod) and none of the control fish had salmon feed (aquaculture food pellets) in their digestive tracts. Concentrations of OCs and BFRs were about 50% higher and dominated more by persistent compounds in Atlantic cod compared to saithe. After controlling for a set of confounding variables (location, sex, size, weight, gonads size, hepatosomatic index, and % lipids in the liver), the concentrations of ∑OC and ∑BDE were 50% higher in FA cod compared to control fish, whereas they were 20% higher in FA saithe than control fish. Hence, salmon farms are a source of lipid-soluble OHCs to wild marine fish, but variation in life-history and habitat use seems to affect the levels of OHCs in the different fish species. In contrast to the lipid-soluble OHCs, control fish had 67% higher PFOS levels than FA fish, which suggests that natural food contains higher loads of this compound than the commercial feed used in salmon farms. Some OHCs are known to act as endocrine disruptors, thus further work is required to determine if OHCs negatively affect reproductive processes of wild fish associated with salmon farms.

Determination of Organochlorine Pesticides Residues in Human Adipose Tissue, Data from Cukurova, Turkey

We determined and compared the levels of BHC and DDT isomers and metabolites and HCB in the adipose tissue of 82 cases of autopsies performed at the Morgue Department of Adana Branch of the Council of Forensic Medicine. The relationships between the age, gender, and body mass indexes of cases, and the accumulation of OCs residues were also investigated. Detectable concentrations of p,p'-DDE were found in 100% of adipose tissue samples. Concentrations of OCs in female adipose tissues were significantly higher than male adipose tissues (p < 0.05). The presented work is highly significant, being the first study pointing out the chronic exposure to organochlorine pesticides in Cukurova region.

Bone mineral density in Swedish otters ( Lutra lutra) in relation to PCB and DDE concentrations

The aim of this study is to elucidate if DDE (dichlorodiphenyldichloroethylene) or PCB (polybrominated diphenyls), are responsible for the pathological alterations observed in Swedish otter bone tissues. Femurs from 86 male otters collected between 1832 and 2004 were measured using peripheral quantitative computed tomography (pQCT). Some otters had very high and others fairly low concentrations of OCs (ranging between 1.4–970 mg ΣPCB/kg l.w. and 0.0–24 mg DDE/kg l.w. in muscle tissue). Positive relationships were found between three of the four cortical bone variables analysed (area, content and thickness) and ΣPCB concentration, while no significant relationships with DDE concentration were found. None of the trabecular variables were significantly related to PCB or DDE concentration. Three of the four trabecular bone variables showed decreasing values in the beginning and increasing values at the end of period 1974–2004. No temporal trends were found for cortical bone variables. OC concentrations decreased between 1974 and 2004.

Geological sulfur isotopes indicate elevated OCS in the Archean atmosphere, solving faint young sun paradox

Distributions of sulfur isotopes in geological samples would provide a record of atmospheric composition if the mechanism producing the isotope effects could be described quantitatively. We determined the UV absorption spectra of 32SO2, 33SO2, and 34SO2 and use them to interpret the geological record. The calculated isotopic fractionation factors for SO2 photolysis give mass independent distributions that are highly sensitive to the atmospheric concentrations of O2, O3, CO2, H2O, CS2, NH3, N2O, H2S, OCS, and SO2 itself. Various UV-shielding scenarios are considered and we conclude that the negative Delta33S observed in the Archean sulfate deposits can only be explained by OCS shielding. Of relevant Archean gases, OCS has the unique ability to prevent SO2 photolysis by sunlight at lambda >202 nm. Scenarios run using a photochemical box model show that ppm levels of OCS will accumulate in a CO-rich, reducing Archean atmosphere. The radiative forcing, due to this level of OCS, is able to resolve the faint young sun paradox. Further, the decline of atmospheric OCS may have caused the late Archean glaciation.

Gender Difference in the Effects of Organochlorines and Mercury Exposure on Thyroid Hormones Levels

ISEE-618 Objective: Organochlorines pollutants (OCs) and mercury (Hg) are widespread environmental pollutants, characterized by their accumulation in the food web chain. PCBs are known endocrine disruptors particularly with respect to thyroid function and/or action. Little data are available on thyrotoxic effects of OCs in adult men and women although recent studies have reported a striking excess of hypothyroidism and a higher prevalence of thyroid disorders in women in relation to OCs exposure. The objectives of the study are to examine THs levels in relation to blood concentrations of OCs and Hg for men and women. Materials and Methods: This cross-sectional study was carried out in 2 fishing communities in Quebec, Canada. An interviewer-administered questionnaire was used to assess species specific fish consumption and a self-administered questionnaire was used to collect sociodemographics, work and medical history. The group (N=213) consisted of 125 (59%) men and 88 (41%) women) with an average age of 49.2 ± 13.1 years old. Results: Overall, OCs concentrations were low and thyroid hormone secretion was within the normal range. For women, TT3 was negatively related to PCB-138, PCB-153, noncoplanar congeners, Arochlor 1260, dioxine-like congeners σ PCBs and DDE levels, but no relation was observed between TT4, TSH, and OCs. On the contrary, for men TT4 decreased in relation to dioxine-like congeners and σ PCBs concentrations and TSH increased significantly in relation to PCB-180, Arochlor 1260, σ PCBs, noncoplanar and dioxine-like congeners levels. However no relation was noted between TT4, TSH, and POCs. The only significant decrease of TT3 levels was in relation to σ POCs. In regard to Hg body burden, for men, a positive relationship was observed between blood total Hg and THs. Conclusions: These findings suggest that at even low levels of exposure, these persistent environmental contaminants can interfere with thyroid status and that there may be important gender differences.

Spatial distributions of volatile sulfur compounds in surface seawater and overlying atmosphere in the northwestern Pacific Ocean, eastern Indian Ocean, and Southern Ocean

Distributions of volatile sulfur compounds (carbonyl sulfide (COS), carbon disulfide (CS2), hydrogen sulfide (H2S), dimethyl sulfide (DMS)) in surface seawater and overlying atmosphere were measured in the northwestern Pacific, eastern Indian, and Southern Oceans (40°N–66°S, 40°E–140°E) in November–December 1996 during the 38th Japanese Antarctic Research Expedition cruise. Seawater measurements revealed that DMS was the dominant sulfur compound, with concentrations of 0.5–15.8 nM. High values were found in the Southern Ocean's marginal ice zone (84°E–63°E, 59°S–63°S), suggesting that the area during the bloom acts as an important source of atmospheric DMS. Atmospheric concentrations were 456–471 pptv for OCS, n.d. (not detected level) −13 pptv for CS2, n.d. −17 pptv for H2S, and n.d. −755 pptv for DMS. Concentrations of OCS were nearly constant. Concentrations of CS2 and H2S were high in terrigenic air masses and low in those of oceanic origin. Comparison of atmospheric DMS data and a steady state box model using sea‐to‐air fluxes of DMS and assumed OH radical concentrations revealed that atmospheric DMS concentrations in the equatorial region and most of the Southern Ocean were balanced with local oceanic emission residues and photochemical oxidation. Simultaneous measurements in the atmosphere showed DMS was the dominant sulfur gas that was oxidized rapidly to sulfate aerosols in the marine atmosphere.

Factors affecting the organochlorine pollutant load in biota of a rice field ecosystem (Ebro Delta, NE Spain)

The concentrations of PCBs, DDTs, HCHs, HCB and OCS were determined in sediments and associated biota, both invertebrates ( Physella acuta, Hirudo medicinalis, chironomid larvae, Hydrous pistaceus, Helochares lividus) and vertebrates ( Rana perezi), in a temporary aquatic system, a rice field in the Ebro Delta (NE Spain). The qualitative and quantitative distribution of organochlorine compounds in sediments and aquatic biota has been explained by two mechanisms: equilibrium partitioning and/or biomagnification through the trophic web. Nevertheless, bioaccumulation processes are by far more complex, since several biotic and abiotic factors contribute to the observed pollutant loads in the organisms. In this respect, the biological characteristics of the organisms considered (e.g. species, age, lipid contents, feeding habits, etc.), as well as ecological factors (e.g. the habitat of the species and vertical distribution), have been shown to account for the organochlorine levels observed.

Total blubber burden of organochlorine pollutants in phocid seals; methods and suggested standardization

The purpose of the present paper was to investigate methods for calculating the total blubber burden of organochlorine pollutants (OCs) in phocid seals. Harp seals ( Phoca groenlandica) were used as the model species. A sample of fat pre-breeding adult females ( N=9) and a sample of thin moulting adult females ( N=7) were collected. From each animal blubber samples from five different body sites (complete blubber columns and samples from different blubber layers), in addition to a sample from a homogenate derived from the entire blubber mass, were analyzed for selected OCs. Significant differences in the concentrations of major OC contaminants were found between inner and outer blubber layer. Within each seal group, no significant difference in OC concentrations was found between homogenates from whole blubber columns from the five different sites of the animals or when comparing these with the OC concentrations found in the blubber sample deriving from a homogenate of the entire blubber mass. When comparing the two seal groups, the mean OC concentrations were significantly higher in the thin seals. However, blubber burden of OCs measured directly and calculated indirectly were not significantly different, and did not vary between the two groups of seals. Since these seals are of the same age and sex group and from the same population, this is not an unexpected result. The present results suggest that comparison of blubber concentrations of OCs in phocid seals should be avoided, especially when comparing differences between geographical areas or for time–trend analyses. For this type of study, we suggest that the blubber burden of OCs is applied as standard in the future. Furthermore, since blubber depth at a specific sampling site is required when using the estimator for calculation of the percent blubber content in phocid seals (the LMD-index), we suggest that this sampling site (central dorsally) is introduced as a standard when sampling blubber for OC analyses in phocid seals.