Accumulation Of Organochlorine Compounds Research Articles

Back on top: Resuspended by dredging and other environmental disturbances, organochlorine compounds may affect the health of a dolphin population in a tropical estuary, Sepetiba Bay

Organochlorine compounds (OCs) are persistent organic pollutants linked to damaging the immune and endocrine systems, leading to a greater susceptibility to infectious diseases at high concentrations. Sepetiba Bay, in the Southeastern Brazilian coast, historically presents anthropogenic activities and environmental contamination that could negatively impact resident populations. In this context, this study aimed to investigate the temporal trends in the accumulation of organochlorine compounds over a 12-year database in the Guiana dolphins’ (Sotalia guianensis) resident population from Sepetiba Bay, including individuals collected before, during, and after an unusual mortality event triggered by morbillivirus (n = 85). The influence of biological parameters was also evaluated. The OCs concentrations in the blubber ranged from 0.98 to 739 μg/g of ΣPCB; 0.08–130 μg/g of ΣDDT; <0.002–4.56 μg/g of mirex; <0.002–1.84 μg/g of ΣHCH and <0.001–0.16 μg/g of HCB in lipid weight. Increased temporal trends were found for OCs in Guiana dolphins coinciding with periods of large events of dredging in the region. In this way, our findings suggest that the constant high OCs concentrations throughout the years in this Guiana dolphin population are a result of the constant environmental disturbance in the area, such as dredging. These elevated OCs levels, e.g., ΣPCB concentrations found above the known thresholds, may impair the response of the immune system during outbreak periods, which could lead the population to a progressive decline.

Pine needle and semi-permeable membrane device derived organochlorine compounds (OCPs) concentrations in air in Mersin Province to Taurus, Turkey

Organochlorine pesticides (OCPs) were analyzed in three different ages (half-, 1.5-, 2.5-year-old) for needles and semi permeable membrane devices (SPMDs) at three deployment periods from sea level to 1881 meter above sea level. Individual HCHs concentrations ranged between 1.4 and 129 pg/g fw depending on the age and sampling season while 2.5-year-old needles showed higher HCHs levels compared to half and 1.5- year-old. Correlation between elevation and HCH concentration in SPMDs was found but not in needle samples. Concentrations of HCHs in SPMDs indicated clearly cold condensation effect on accumulation in winter period and increased with altitude. Concentrations of DDTs in half and 1.5-year-old needles were lower than 2.5-year-old needles. The highest total concentration of DDTs was detected in 1-year-period SPMD. Higher concentrations were found in 2.5-year-old needles for other OCPs. Seasonal and altitude-dependent changes were not observed for other OCPs in SMPDs. Total accumulation of OCPs in SPMDs were found higher than in needles. On the contrary, an increased accumulation rate was observed for HCHs in SPMD. In general, Total concentrations of DDTs and HCHs were similar to total of other OCPs in all altitudes when dominating endosulfan wasnot taken into account in the computation of total concentration of other OCPs.

Long-term dynamics of the concentrations of organochlorine compounds and mercury in the sediments of the Сhernorechenskoe reservoir

The accumulation of organochlorine compounds (OCs) and mercury in the sediments of the Chernorechenskoe Reservoir since the mid-1960s to 2008 has been studied. Sedimentation rate and accumulation chronology of recovered sediments were reconstructed by the method of radioisotope dating . The sedimentation rate in the reservoir has been found to vary because of changes in reservoir volume and area in the late 1980s. Historical reconstruction of the input of OCs and mercury into the reservoir sediments in the recent 50 years has been performed. The period of 1950–1960 has been found to show considerable pollution of reservoir sediment by DDT and mercury. The spatial distribution of OCs and mercury has been determined in the top 5-cm layer of sediments in the Chernorechenskoe Reservoir. The deposition rates of OCs and total mercury into sediments in 2008 have been evaluated.

Long-Term Dynamics of the Concentrations of Organochlorine Compounds and Mercury in the Bottom Sediments of the Chernorechenskoe Reservoir

The accumulation of organochlorine compounds (OCs) and mercury in the bottom sediments of the Chernorechenskoe Reservoir since the mid-1960s to 2008 has been studied. Sedimentation rate and accumulation chronology of recovered sediments were reconstructed by the method of radioisotope dating . The sedimentation rate in the reservoir has been found to vary because of changes in reservoir volume and area in the late 1980s. Historical reconstruction of the input of OCs and mercury into the reservoir sediments in the recent 50 years has been performed. The period of 1950–1960 has been found to show considerable pollution of reservoir sediment by DDT and mercury. The spatial distribution of OCs and mercury has been determined in the top 5-cm layer of bottom sediments in the Chernorechenskoe Reservoir. The deposition rates of OCs and total mercury into bottom sediments in 2008 have been evaluated.

Хлорорганические соединения в ерше Scorpaena porcus Linnaeus, 1758 в акватории Севастополя (Чёрное море): пространственное распределение и биологический отклик на уровень накопления загрязнителей

Несмотря на запрет применения хлорорганических соединений (ХОС), они до настоящего времени аккумулируются в различных абиотических и биотических компонентах экосистемы Чёрного моря, в том числе в рыбах, вызывая негативные изменения в их метаболизме. Как район активного хозяйственного использования, севастопольская морская акватория подвергается значительному антропогенному воздействию. Уровень содержания ХОС в тканях морского ерша (скорпены) Scorpaena porcus Linnaeus, 1758, ведущего оседлый образ жизни и массово распространённого в прибрежных сообществах, может служить показателем степени загрязнения акватории данным поллютантом, а вид ― удобным индикатором. Газохроматографическим методом с использованием микродетектора электронного захвата определены качественный состав и концентрация хлорорганических пестицидов (п,п’-ДДТ и его метаболитов) и шести индикаторных конгенеров полихлорированных бифенилов в 58 пробах белых мышц, гонад и печени морского ерша, отловленного в 2016–2017 гг. в различных по степени загрязнённости бухтах региона Севастополя (Александровская, Казачья, Стрелецкая, Балаклавская, Ласпи), а также в открытой прибрежной акватории. Для определения отклика организма на уровень загрязнения в печени ерша исследовали комплекс биохимических маркеров: активность аланинаминотрансферазы, аспартатаминотрансферазы и каталазы, содержание альбумина, уровень окислительной модификации белков и концентрацию малонового диальдегида. Содержание ХОС в рыбах зависело от загрязнённости места их обитания. Наибольший уровень ХОС зафиксирован в органах ершей из бухт закрытого типа с затруднённым водообменом (Александровская, Стрелецкая и Балаклавская), наименьший ― в открытой бухте Ласпи. Накопление ХОС в органах ершей зависело от содержания липидов в исследованных тканях. Максимальные концентрации ХОС обнаружены в печени скорпен из всех изученных акваторий, минимальные ― в гонадах рыб из бухт и в белых мышцах особей из открытых районов. Полученные соотношения между содержанием ХОС в печени ерша и показателями комплекса биохимических маркеров свидетельствуют об ослаблении антиоксидантной защиты и о развитии окислительного стресса у рыб в результате накопления ксенобиотиков.

Influence of diet in the accumulation of organochlorine compounds in herons breeding in remote riverine environments

The composition of organochlorine compounds (OCs), pentachlorobenzene (PeCB), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), DDTs and polychlorobiphenyls (PCBs), has been analyzed in eggs from cattle egret (Bubulcus ibis) and little egret (Egretta garzetta), two species of herons (family Ardeidae), nesting at the same remote riverine environment (Aiguabarreig, Ebro River). These two species were selected to evaluate the importance of diet in the accumulation of OCs. Cattle egret essentially feeds on dry grassy habitats and follow cattle or other large animals whereas little egret feeds on fish, amphibians and crustaceans captured in shallow waters. The δ(15)N and δ(13)C isotopic composition of the sampled eggs was studied and the results were consistent with these species feeding habits. In both species, the compounds accumulated the most were the less volatile and more lipophilic, e.g. PCB congeners of higher chlorination, DDT and metabolites. The distinct foraging species preferences were reflected in significant higher concentrations in little egret than cattle egret of all pollutant groups analysed. These differences were statistically significant for DDTs and PCBs (p < 0.015 and p < 0.047, respectively), e.g. the p,p'-DDE and PCB concentrations were 6 and 4.5 times higher, respectively, in the former than the latter. This strong contrast indicates that in remote environments aquatic riverine ecosystems are more efficient OC reservoirs than the terrestrial ecosystem.

Pollutant accumulation patterns in nestlings of an avian top predator: biochemical and metabolic effects

The exposure to persistent pollutants such as organochlorine compounds (OCs) or metals has been associated with declines in top predator populations, which can accumulate high amounts of these pollutants from their prey. However, understanding how variation in OC and metal accumulation in wild species affects their biochemical and physiological responses is a big challenge, especially for endangered predators like the Bonelli's eagle (Aquila fasciata). This bird of prey is an interesting study model because the differences in diet composition among populations and territories can account for important pollutant uptake variations. We compared OC and metal accumulation in blood of Bonelli's eagle nestlings from three populations across Spain as a function of origin, age class (nestlings vs. adults), sex and number of siblings per nest, and related accumulation patterns to responses indicative of body condition, biochemistry and antioxidant status. Nestlings from Catalonia, the most industrialized area, showed the highest concentrations of PCBs and arsenic, and the lowest concentrations of zinc. The two former substances, together with DDTs, exerted an overall influence on nestling's physiology. PCBs and arsenic were associated with reduced retinol levels, pointing to oxidative damage in exposed individuals, which was also consistent with the low zinc levels in individuals from the polluted region. Increased plasma DDT levels were related to reduced body condition and lower levels of triglycerides. Mercury accumulation in Castile and Leon was higher in nestlings that were alone in the nest than in nestlings that shared it with a sibling; this suggests an increased mercury uptake from secondary prey in territories where preferred prey (i.e. rabbits) are scarce, which are also the territories where productivity is reduced. Overall, the results reveal a spatial variation in pollutant accumulation patterns and associated physiological effects, and suggest the major role that territory quality may have in such patterns.

Organochlorine compounds in European catfish (Silurus glanis) living in river areas under the influence of a chlor-alkali plant (Ebro River basin)

European catfish, Silurus glanis, were used as sentinel organisms of the influence of recent and past discharges of organochlorine compounds (OCs) from a chlor-alkali plant located in the Ebro River. The fish concentrations of hexachlorobenzene (HCB), polychlorobiphenyls (PCBs) and DDTs were very high along the last 100km of the river, including the irrigation channels, e.g. 1.2–27ng/g wet weight of HCB, 6.3–100ng/g ww of PCBs and 1–270ng/g ww of total DDT compounds. These concentrations were much higher than those found upstream from the chlor-alkali discharge site, 0.2ng/g ww for HCB, 5.6ng/g ww for PCBs and 7.5ng/g for DDT compounds. These concentrations were also standing out among those previously described in this fish species.The European catfish collected in sites under lower water flows, Ribarroja reservoir and irrigation channels, showed higher muscle lipid content, 1.09–7.2%, than those from sites of higher current intensities, river bed, 0.27%–0.67%. In these lower water current areas catfish exhibited OC ww concentrations that were correlated to % lipids. These differences suggest that normalization to lipid content is necessary for comparison of the OC accumulation in specimens from riverine systems living under different flow intensities. Accordingly, OC concentrations referred to lipid content showed more uniform downriver distribution which was consistent with a single focal point as main source of these compounds for the European catfish collected in the last 100km of river stretch. This geographic distribution was also consistent with the uniform composition of PCB congeners in the studied European catfish.The distribution of DDT compounds was predominated by 4,4′-DDE which is common in most currently examined fish from aquatic environments. However, it included a high proportion of 4,4′-DDD and 2,4′-DDD which was consistent with the high contribution of benthic organisms from anoxic environments in the diet of these fish.

Atmospheric transport and accumulation of organochlorine compounds on the southern slopes of the Himalayas, Nepal

Studies have been devoted to the transport and accumulation of persistent organic pollutants (POPs) in mountain environments. The Himalayas have the widest altitude gradient of any mountain range, but few studies examining the environmental behavior of POPs have been performed in the Himalayas. In this study, air, soil, and leaf samples were collected along a transect on the southern slope of the Himalayas, Nepal (altitude: 135–5100 m). Local emission occurred in the lowlands, and POPs were transported by uplift along the slope. During the atmospheric transport, the HCB proportion increased from the lowlands (20%) to high elevation (>50%), whereas the proportions of DDTs decreased. The largest residue of soil POPs appeared at an altitude of approximately 2500 m, and may be related to absorption by vegetation and precipitation. The net deposition tendencies at the air–soil surface indicated that the Himalayas may be a ‘sink’ for DDTs and PCBs.

Variation in organochlorine accumulation in relation to the life history of the Japanese eel Anguilla japonica

Members of the catadromous eel live in various fresh, brackish and marine habitats. Therefore, these eels can accumulate organic pollutants and are a suitable bioindicator species for determining the levels of organic contaminants within different water bodies. The ecological risk for organochlorine compounds (OCs) in Anguilla japonica with various migration patterns, such as freshwater, estuarine and marine residences, was examined to understand the specific accumulation patterns. The concentrations of HCB, ∑HCHs, ∑CHLs and ∑DDTs in the silver stage (maturing) eel were significantly higher than those in the yellow stage (immature) eel, in accordance with the higher lipid contents in the former versus the latter. The OC accumulations were clearly different among migratory types in the eel. The ecological risk of OCs increased as the freshwater residence period in the eel lengthened. The migratory histories and the lipid contents directly affected the OC accumulation in the catadromous eel species.

Differences in organochlorine accumulation accompanying life history in the catadromous eel Anguilla japonica and the marine eel Conger myriaster

In order to examine the ecological risk for organic pollutants in diadromous fish migrating between sea and freshwater, organochlorine compounds (OCs) were determined in the catadromous eel Anguilla japonica having marine, estuarine and freshwater residence life histories. The eels were collected in Japanese coastal areas. We also compared the OCs accumulation with the marine eel Conger myriaster, which has a similar life history as A. japonica in the marine environment. The ontogenic changes in the otolith strontium (Sr) and calcium (Ca) concentrations were examined along the life history transect to discriminate the migration type. There were generally three different patterns, which were categorized as 'marine residence' (spent most of their life in the sea and did not enter freshwater), 'estuarine residence' (inhabited estuaries or switched between different habitats), and 'freshwater residence' (entered and remained in freshwater river habitats after arrival in the estuary) according to the otolith Sr:Ca ratio. There were generally no correlations between OCs such as Dichlorodiphenyltrichloroethanes (DDTs), Hexachlorobenzene (HCB), Hexachlorocyclohexanes (HCHs) and Chlordanes (CHLs) accumulation and each biological characteristic such as TL, BW and age in A. japonica. A positive correlation between the lipid content and concentrations of OCs were found. Additionally, the concentrations of HCB, ∑HCHs, ∑CHLs and ∑DDTs in A. japonica were significantly higher than those of C. myriaster, associating with the higher lipid contents (14% on average) in the former than the latter eels (9% on average). A negative linear relationship was found between the otolith Sr:Ca ratios and concentration of each OCs in A. japonica. The ecological risk of OCs increase as the freshwater residence period in the eel becomes longer. It is clear that migratory histories and lipid contents directly affected OCs accumulation in the anguillid eels.

Levels of organochlorine pesticides and polychlorinated biphenyls in the critically endangered Iberian lynx and other sympatric carnivores in Spain

Accumulation of organochlorine compounds is well studied in aquatic food chains whereas little information is available from terrestrial food chains. This study presents data of organochlorine levels in tissue and plasma samples of 15 critically endangered Iberian lynx (Lynx pardinus) and other 55 wild carnivores belonging to five species from three natural areas of Spain (Doñana National Park, Sierra Morena and Lozoya River) and explores their relationship with species diet. The Iberian lynx, with a diet based on the consumption of rabbit, had lower PCB levels (geometric means, plasma: <0.01ngmL−1, liver: 0.4ngg−1 wet weight, fat: 87ngg−1lipid weight) than other carnivores with more anthropic and opportunistic foraging behavior, such as the red fox (Vulpes vulpes; plasma: 1.11ngmL−1, liver: 459ngg−1, fat: 1984ngg−1), or with diets including reptiles at higher proportion, such as the Egyptian mongoose (Herpestes ichneumon; plasma: 7.15ngmL−1, liver: 216ngg−1, fat: 540ngg−1), or the common genet (Genetta genetta; liver: 466ngg−1, fat: 3854ngg−1). Chlorinated pesticides showed interspecific variations similar to PCBs. Organochlorine levels have declined since the 80s in carnivores from Doñana National Park, but PCB levels are still of concern in Eurasian otters (Lutra lutra; liver: 3873–5426ngg−1) from the industrialized region of Madrid.

An evaluation of the sexual differences in the accumulation of organochlorine compounds in children at birth and at the age of 4 years

This study of the body burden and serum concentrations of organochlorine compounds (OCs), represents a general population in a cohort from Menorca Island (birth 1997-1998) of children at birth and at 4 years of age; the study has shown that the concentrations of hexachlorobenzene (HCB), 4,4'-DDE, 4,4'-DDT, polychlorobiphenyl (PCB) congeners #153, #138 and #180 and total PCBs in sera collected at 4 years are much higher in breastfed children than in those fed with formula, e.g. HCB 0.48 vs 0.21 ng/ml, beta-HCH 0.32 vs 0.24 ng/ml, total DDTs 2.2 vs 0.57 ng/ml and total PCBs 1.4 vs 0.52 ng/ml. Comparison of gender differences in 4 years old children shows higher concentrations of all examined OCs in females than in males with the exception of HCB and PeCB in breastfed children, which are higher in males than in females, e.g. beta-HCH 0.34 vs 0.28 ng/ml, total DDTs 2.6 vs 1.7 ng/ml and total PCBs 1.6 vs 1.0 ng/ml for breastfed children and beta-HCH 0.23 vs 0.19 ng/ml, total DDTs 0.59 vs 0.48 ng/ml and total PCBs 0.58 vs 0.45 ng/ml for formula fed children. Gender comparison of the body burden between children fed with breastmilk or formula also shows higher concentrations in females than in males, e.g. beta-HCH 0.47 vs 0.35 microg, total DDTs 3.0 vs 1.8 microg and total PCBs 1.9 vs 1.2 microg for breastfed children, and beta-HCH 0.39 vs 0.17 microg, total DDTs 0.48 vs 0.27 microg and total PCBs 0.66 vs 0.55 microg for formula fed children. The results may suggest a higher capacity in female children for the retention of OCs incorporated through breastfeeding. However, these results should be taken with caution because the differences of the gender averages have low statistically significance when evaluated with the Student test.

In pancreatic ductal adenocarcinoma blood concentrations of some organochlorine compounds and coffee intake are independently associated with KRAS mutations

While KRAS activation is a fundamental initiating event in the aetiopathogenesis of pancreatic ductal adenocarcinoma (PDA), environmental factors influencing the occurrence and persistence of KRAS mutations remain largely unknown. The objective was to test the hypothesis that in PDA there are aetiopathogenic relationships among concentrations of some organochlorine compounds (OCs) and the mutational status of the KRAS oncogene, as well as among the latter and coffee intake. Incident cases of PDA were interviewed and had blood drawn at hospital admission (N = 103). OCs were measured by high-resolution gas chromatography with electron capture detection. Cases whose tumours harboured a KRAS mutation had higher concentrations of p,p'-dichlorodiphenyltrichloroethane (DDT), p,p'-dichlorodiphenyldichloroethene (DDE) and polychlorinated biphenyls (PCBs) 138, 153 and 180 than cases with wild-type KRAS, but differences were statistically significant only for p,p'-DDT and PCBs 138 and 153. The association between coffee intake and KRAS mutations remained significant (P-trend < 0.015) when most OCs where accounted for. When p,p'-DDT, PCB 153, coffee and alcohol intake were included in the same model, all were associated with KRAS (P = 0.042, 0.007, 0.016 and 0.025, respectively). p,p'-DDT, p,p'-DDE and PCB 138 were significantly associated with the two most prevalent KRAS mutations (Val and Asp). OCs and coffee may have independent roles in the aetiopathogenesis of PDA through modulation of KRAS activation, acquisition or persistence, plausibly through non-genotoxic or epigenetic mechanisms. Given that KRAS mutations are the most frequent abnormality of oncogenes in human cancers, and the lifelong accumulation of OCs in humans, refutation or replication of the findings is required before any implications are assessed.

Organochlorine Pesticide Residues Analyfrom Cow Milk: A Reviewsis

The pesticides have been widely used throughout the world since the middle of the 20th century. Organochlorine pesticides do not readily degrade in the environment and are lipophilic with a tendency to bioaccumulate, so they can be found at high concentrations in fatty foods, including the cow milk. The accumulation of organochlorine compounds in fatty foods is still a matter of major concern although the use of most organochlorine compounds (OCs) has been banned or restricted in the most of the countries, due to the uncertainty about the adverse effects that those residues may have after a lengthy exposure at low doses. The sequence steps in pesticide residues analysis are sampling, sample preparation, extraction, clean-up and identification and quantitative determination of pesticide residues. Since the early 1970s, most routine pesticide-residue determination has been conducted by gas chromatography (GC) coupled with electron capture detector (ECD) or/and mass spectrometry (MS).

Contamination by organochlorine compounds in the edible tissue of four sturgeon species from the Caspian Sea (Iran)

This study focused on accumulation of organochlorine compounds (OCs), including dichloro-diphenyl-trichloroethanes (DDTs), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), and polychlorinated biphenyls (PCBs) accumulation in the muscle of four sturgeon (Persian sturgeon, Acipenser persicus; Stellate sturgeon, Acipenser stellatus; Ship sturgeon, Acipenser nudiventris and Beluga sturgeon, Huso huso) from the southern Caspian Sea. The DDT group was prominent in all of the sturgeon muscle tested constituting almost half or more of the total organochlorine content. Contaminant concentration generally followed this order: DDTs > PCBs > HCHs > HCB. The OCs concentrations in Beluga sturgeon ( H. huso) were the highest and over four times higher than in the next highest species ( A. nudiventris). From an ecotoxicological point of view, the concentrations of OCs in experimental fishes do not reflect a comparatively clean and pollution-free environment; however, results from this study shown that the inflow of organic pollutants into the Caspian Sea has been reduced when compared with prior studies. Levels of measured OCs in sturgeon were relatively low, but the level of some OCs in some of the specimens tested exceeded the guidelines for food; therefore, the maximum allowable daily consumption rate for sturgeon from this watershed may be limited by DDTs and PCBs content for high risk populations.

Elevated organochlorines in the brain–hypothalamic–pituitary complex of intersexual shovelnose sturgeon

Organochlorine compounds (OCs), including polychlorinated biphenyls and organochlorine pesticides, were used on lands adjacent to the Middle Mississippi River (MMR; USA) from 1930 through 1988, and they continue to occur in MMR fish. These compounds are estrogenic and/or antiandrogenic, and they alter hormone production and reception within the brain and gonads of male fish, resulting in intersexuality and/or suppressed gonadal development. To assess how OCs affect reproduction of MMR fish, we quantified OC accumulation, intersexuality, and gonadal development in male shovelnose sturgeon (Scaphirhynchus platorynchus) throughout the MMR during the spring of 2003. Gonads were observed for intersexual characteristics, weighed to calculate the gonadosomatic index (GSI), and examined histologically. Tissue accumulation of OCs was quantified in gonads, brain-hypothalamic-pituitary (BHP) complex, and fillets. Four of 48 mature males were identified macroscopically as intersexuals, and a fifth was found through histology (a 10.4% incidence). Intersexuals accumulated higher concentrations of OCs in the BHP complex compared with those of mature males. In addition, GSI and OC accumulation within the BHP complex, gonads, and fillets of mature males were negatively related. Exposure to OCs before or during sexual differentiation likely induces intersexuality in MMR shovelnose sturgeon, and exposure throughout gonadal maturation inhibits gonadal development.

Influence of altitude and age in the accumulation of organochlorine compounds in fish from high mountain lakes.

The analysis of hexachlorobenzene, hexachlorocyclohexanes, polychlorobiphenyls, and DDTs in muscle of fish from high mountain lakes shows that a proportion of their concentration variance depends on fish age and lake altitude. Interestingly, the magnitude of this share corresponds linearly with the log-transformed vapor pressure (Vp) of the organochlorine compounds (OC). Thus, the distributions of OC with Vp < 10(-2.5) Pa are mostly determined by these two variables. Altitude gradients mainly respond to temperature differences, involving concentration increases of 25-150 times between 8.7 and -2.3 degrees C. The age effect encompasses concentration increments of 2.4-7.8 for average lake differences between 2 and 13 yr. However, both effects are independent since no correlation between fish age and lake altitude is observed. Fish liver concentrations exhibit the same pattern, but the correlations are only significantfor age, suggesting thatthe temperature trend is more related to long-term accumulation than episodic intake. The temperature effect is independent from compound origin. In addition, the sites situated at highest altitude, those most distant from possible ground pollution sources, are the most polluted. The results can be explained by condensation effects such as those described for the latitudinal trends that support the global distillation theory. However, in the high altitude lakes a temperature-dependent amplification mechanism, probably related to low metabolism and respiration at lowtemperatures, enhances OC accumulation in fish beyond the increases predicted from theoretical condensation and solubilization enthalpies. The observed temperature dependence suggests that a general remobilization of OC accumulated in high mountain areas could take place as a consequence of the general warming of these areas anticipated in the climatic change studies.

Accumulation of Organochlorine Compounds in Oysters (Crassostrea Gasar) of an Estuarine Environment: Case of A Tropical Lagoon in the Gulf of Guinea

As part of a pollution monitoring study, oysters (Crassostrea gasar) were sampled in June 1996, in order to determine the concentrations and distribution of chlorinated hydrocarbons in two stations (near Boulay Island and Riviera Golf) of the Ebrie Lagoon, in the Abidjan area. The chromatographic analysis of the oven dried samples revealed the presence of PCBs (2.13 to 86.22 ppb or ng/g dry weight), DDE (<0.48 to 169.55 ppb), DDD (<1.04 to 60.27 ppb), DDT (1.43 to 77.81 ppb, lindane (<0.22 to 91.64 ppb), aldrin (<0.30 to 154.1 ppb), endrin (<0.23 to 293.31 ppb) and dieldrin (<0.26 to 199.74 ppb). the results indicated high concentrations in oysters sampled near Boulay Island, due to industrial, agricultural and port activities going on in this area. Compared to DDD/ΣDDT and DDT/ΣDDT, the DDE/ΣDDT ratios were high indicating old DDT inputs. the ΣDDT/PCBs ratios were higher than 1 illustrated the predominance of organochlorine inputs from agriculture activities. the presence of lindane in both stations illustrated the problem of fishing with toxic products. Negative correlations found between dry tissue weight and organochlorine compounds concentrations showed that young oysters may concentrate more of these substances. More studies are needed in order to make any conclusions on their bioaccumulation trends.

Accumulation of persistent organochlorine compounds in mountains of western Canada

Persistent, semi-volatile organochlorine compounds, including toxic industrial pollutants and agricultural pesticides, are found everywhere on Earth, including in pristine polar and near-polar locations1,2,3,4. Higher than expected occurrences of these compounds in remote regions are the result of long-range transport in the atmosphere, precipitation and ‘cold condensation’ — the progressive volatilization in relatively warm locations and subsequent condensation in cooler environments3,4 which leads to enhanced concentrations at high latitudes. The upper reaches of high mountains are similar to high-latitude regions in that they too are characterized by relatively low average temperatures, but the accumulation of organochlorine compounds as a function of altitude has not yet been documented. Here we repororganochlorine deposition in snow from mountain ranges in western Canada that show a 10- to 100-fold increase between 770 and 3,100 m altitude. In the case of less-volatile compounds, the observed increase by a factor of 10 is simply due to a 10-fold increase in snowfall over the altitude range of the sampling sites. In the case of the more-volatile organochlorines, cold-condensation effects further enhance the concentration of these compounds with increasing altitude. These findings demonstrate that temperate-zone mountain regions, which tend to receive high levels of precipitation while being close to pollutant sources, are particularly susceptible to the accumulation of semivolatile organochlorine compounds.