DDE in sediments of the Palos Verdes Shelf, California: in situ transformation rates and geochemical fate

From 1947 to 1971 the world's largest manufacturer of DDT discharged process wastes into the sewers of Los Angeles County. Roughly 870-1450 t of DDT were released to the ocean off Palos Verdes, CA, a portion of which (approximately 100 t) resides in sediments on the continental shelf and slope. The most abundant DDT compound in the sediments, p,p'-DDE, is degrading by reductive dechlorination, but the rate of transformation and factors controlling it are not well understood. In order to estimate in situ transformation rates and predict the long-term fate of p,p'-DDE, box cores were collected in 1992 and 2003 from a single location on the Palos Verdes Shelf and analyzed for 8 DDT compounds and 84 polychlorinated biphenyl (PCB) congeners. The PCBs show no evidence of dechlorination, and inventories did not change between 1992 and 2003. By contrast, the inventory of p,p'-DDE decreased by 43%, whereas that of p,p'-DDMU, the putative reductive dechlorination product, increased by 34%. The first-order transformation rate for p,p'-DDE at the study site is 0.051 +/- 0.006 yr(-1). A multistep reaction model suggests that inventories of p,p'-DDE and p,p'-DDMU will continue to decline, whereas that of p,p'-DDNU will reach a maximum around 2014.     

Development of a solid-phase microextraction-based method for sampling of persistent chlorinated hydrocarbons in an urbanized coastal environment

Solid-phase microextraction (SPME) has been used as an in situ sampling technique for a wide range of volatile organic chemicals, but SPME field sampling of nonvolatile organic pollutants has not been reported. This paper describes the development of an SPME-based sampling method employing a poly(dimethylsiloxane) (PDMS)-coated (100-microm thickness) fiber as the sorbent phase. The laboratory-calibrated PDMS-coated fibers were used to construct SPME samplers, and field tests were conducted at three coastal locations off southern California to determine the equilibrium sampling time and compare the efficacy of the SPME samplers with that of an Infiltrex 100 water pumping system (Axys Environmental Systems Ltd., Sidney, British Columbia, Canada). p,p'-DDE and o,p'-DDE were the components consistently detected in the SPME samples among 42 polychlorinated biphenyl congeners and 17 chlorinated pesticidestargeted. SPME samplers deployed attwo locations with moderate and high levels of contamination for 18 and 30 d, respectively, attained statistically identical concentrations of p,p'-DDE and o,p'-DDE. In addition, SPME samplers deployed for 23 and 43 d, respectively, at a location of low contamination also contained statistically identical concentrations of p,p'-DDE. These results indicate that equilibrium could be reached within 18 to 23 d. The concentrations of p,p'-DDE, o,p'-DDE, or p,p'-DDD obtained with the SPME samplers and the Infiltrex 100 system were virtually identical. In particular, two water column concentration profiles of p,p'-DDE and o,p'-DDE acquired by the SPME samplers at a highly contaminated site on the Palos Verdes Shelf overlapped with the profiles obtained by the Infiltrex 100 system in 1997. The field tests not only reveal the advantages of the SPME samplers compared to the Infiltrex 100 system and other integrative passive devices but also indicate the need to improve the sensitivity of the SPME-based sampling technique.     

Contribution of dicofol to the current DDT pollution in China

High DDT concentrations and o,p'-DDT/p,p'-DDT ratios observed in the air over Taihu Lake, a lake near Shanghai, China, led us to suggest that current use of dicofol in the area north of the lake was the main source of the measured DDTs. To examine this hypothesis, samples of commercially available formulated dicofol in China were collected in 2003 to measure the impurities of DDT related compounds (DDTs). The o,p'-DDT/p,p'-DDT ratio in the samples was 7.0, close to the observed value in the air over Taihu Lake. Average contents of o,p'-DDT, p,p'-CI-DDT, o,p'-DDE, and p,p'-DDT in the samples were 114, 69, 44, and 17 g per kg dicofol, respectively. On the basis of a production and distribution survey, total input of DDTs to the environment from the dicofol use in China was estimated to be 8770 t between 1988 and 2002. "Dicofol type DDT pollution", defined as DDT pollution caused by dicofol use and characterized with high o,p'-DDT/p,p'-DDT ratio, might be serious in China, especially in southern and eastern China. The conversion of p,p'-CI-DDT to p,p'-DDE can lead to high p,p'-DDE/p,p'-DDT ratio and could mislead the evaluation of p,p'-DDT resident time in the environment. Therefore, more studies on p,p'-CI-DDT in the environment are needed.     

Organochlorine pesticides and polychlorinated biphenyls in sprats from the southern Baltic, 1981

102 samples of the muscle tissue of sprat netted in 1981 in the southern part of the Baltic Sea were analysed for polychlorinated biphenyls (PCBs), DDT and its analogues (DDE and DDD), hexachlorobenzene (HCB), and isomers of benzenehexachloride (alpha-, beta-, gamma-, and delta-BHC). The mean values obtained related to wet weight for sprat muscle meat were: 6.4 micrograms HCB/kg, 11 micrograms alpha-BHC/kg, 20 micrograms gamma-BHC/kg, 33 micrograms p,p'-DDE/kg, 42 micrograms p,p'-DDD/kg, 31 micrograms p,p'-DDT/kg, 110 micrograms sigma DDT/kg and 670 micrograms PCB/kg; beta-BHC was detectable in trace amounts and delta-BHC was undetected. The results are compared with values reported previously by other authors.     

Organochlorine pesticides and polychlorinated biphenyls in livers of cod from the southern Baltic, 1983

Hexachlorobenzene (HCB), alpha-, beta-, gamma- and delta-benzenehexachloride (BHC; HCH), p,p'-DDE, o,p'-DDD, o,p'-DDT, p,p'-DDD and p,p'-DDT (sigma DDT) and polychlorinated biphenyls (PCB) levels have been determined in livers of 210 cod (Gadus morhua) netted during 1983 in a different regions in the southern part of the Baltic Sea. The mean levels found for cod livers related to wet weight (mg/kg) were: 0.096 HCB, 0.15 alpha-BHC, beta-BHC was found in trace amounts, 0.098 gamma-BHC, delta-BHC remained undetected, 0.26 sigma BHC, 1.1 p,p'-DDE, o,p'-DDD and o,p'-DDT remained undetected, 1.1 p,p'-DDD, 0.39 p,p'-DDT, 2.6 sigma DDT and 7.2 PCB. The levels of sigma DDT, sigma BHC and HCB found are comparable with those noted in livers taken from cod of the same length class and netted in 1981, whilst-for PCB somewhat lower levels were found. Because of heavy contamination with PCBs, sigma DDT, sigma BHC and HCB the livers of cod caught in Baltic Sea still remain insuitable for human consumption.     

Factors controlling the rate of DDE dechlorination to DDMU in Palos Verdes margin sediments under anaerobic conditions

Marine sediments off the coast of the Palos Verdes Peninsula in California have been designated a Superfund site primarily because of the presence of DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethene]. For decades, it was believed that DDE was not microbially transformed, but anaerobic bacteria in the Palos Verdes sediments reductively dechlorinate DDEto DDMU [1-chloro-2,2-bis(p-chlorophenyl)ethene], which is also found in the sediments. The effects of electron donor to sulfate ratio, available carbon, sampling sites, sediment depth, and temperature on the rate and extent of DDE dechlorination in anaerobic Palos Verdes sediment microcosms were investigated. Dechlorination rates varied, depending on the site and depth from which the sediments were collected, but DDE dechlorination occurred with sediments from all locations studied. Sulfate and low temperatures slowed dechlorination, but in the presence of sulfate and at in situ temperature, the dechlorination rates observed in the microcosms agree well with the observed rate of DDE disappearance from the Palos Verdes margin sediments.     

Melting glaciers: a probable source of DDT to the Antarctic marine ecosystem

Persistent organic pollutants reach polar regions by long-range atmospheric transport and biomagnify through the food web accumulating in higher trophic level predators. We analyzed Adélie penguin (Pygoscelis adeliae) samples collected from 2004 to 2006 to evaluate current levels of sigmaDDT (p,p'-DDT + p,p'-DDE) in these birds, which are confined to Antarctica. Ratios of p,p'-DDT to p,p'-DDE in Adélie penguins have declined significantly since 1964 indicating current exposure to old rather than new sources of sigmaDDT. However, sigmaDDT has not declined in Adélie penguins from the Western Antarctic Peninsula for more than 30 years and the presence of p,p'-DDT in these birds indicates that there is a current source of DDT to the Antarctic marine food web. DDT has been banned or severely restricted since peak use in the 1970s, implicating glacier meltwater as a likely source for DDT contamination in coastal Antarctic seas. Our estimates indicate that 1-4 kg x y(-1) sigmaDDT are currently being released into coastal waters along the Western Antarctic Ice Sheet due to glacier ablation.     

Organochlorine pesticides in the air around the Taihu Lake, China

Organochlorine (OC) pesticides have been used broadly in China's past, yet very little is known about their atmospheric concentrations and transport. In this work, air samples were collected in the Taihu Lake Region, China, from July 23 to August 11, 2002, to measure concentrations of OC pesticides in air. The average concentrations of alpha and gamma- hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), heptachlor (HEPT), alpha-endosulfan, p,p'-DDT, p,p'-DDE, p,p'-DDD, and o,p'-DDT in the air were 74 and 46, 47, 53, 307, 124, 212, 36, and 767 pg m(-3), respectively. It was interesting to note that the concentrations of p,p'-DDT, p,p'-DDE, and o,p'-DDT were all very high, even though the use of technical DDT has been banned in China since 1983. Moreover, the average concentration ratios of o,p'-DDT/p,p'-DDT and p,p'-DDE/p,p'-DDT were as high as 6.3 and 1.8. This suggested that there could be an unknown source of DDT-related compounds (DDTs), especially o,p'-DDT and p,p'-DDE. It is very likely that this unknown source was the application of dicofol, an acaricide manufactured from technical DDT and used mainly on cotton fields to treat mites in China. Backward trajectory analysis also provided consistent evidence that the high air concentrations of DDTs were related to trajectories from the area north of the Yangtze River, where cotton fields account for a significant fraction of land use.     

Measurement of DDT fluxes from a historically treated agricultural soil in Canada

Organocohlorine pesticide (OCP) residues in agricultural soils are of concern due to the uptake of these compounds by crops, accumulation in the foodchain, and reemission from soils to the atmosphere. Although it has been about three decades since DDT was banned for agricultural uses in Canada, residues persist in soils of some agricultural areas. Emission of DDT compounds to the atmosphere from a historically treated field in southern Ontario was determined in fall 2004 and spring 2005. The sigmaDDTs concentration in the high organic matter (71%) soil was 19 +/- 4 microg g(-1) dry weight. Concentration gradients in the air were measured at 5, 20, 72, and 200 cm above soil using glass fiber filter-polyurethane foam cartridges. Air concentrations of sigmaDDTs averaged 5.7 +/- 5.1 ng m(-3) at 5 cm and decreased to 1.3 +/- 0.8 ng m(-3) at 200 cm and were 60-300 times higher than levels measured at a background site 30 km away. Soil-air fugacity fractions, fs/(fs + fa), of p,p'-DDE, p,p'-DDD, and p,p'-DDT ranged from 0.42 to 0.91 using air concentrations measured above the soil and > or = 0.99 using background air concentrations, indicating that the soil was a net source to the background air. Fractionation of DDT compounds during volatilization was predicted using either liquid-phase vapor pressures (PL) or octanol-air partition coefficients (KOA). Relative emissions of p,p'-DDE and p,p'-DDT were better described by PL than KOA, whereas either PL or KOA successfully accounted for the fractionation of p,p'-DDT and o,p'-DDT. Soil-to-air fluxes were calculated from air concentration gradients and turbulent exchange coefficients determined from micrometeorological measurements. Average fluxes of sigmaDDTs were 90 +/- 24 ng m(-2) h(-1) in fall and 660 +/- 370 ng m(-2) h(-1) in spring. Higher soil temperatures in spring accounted for the higher fluxes. A volatilization half-life of approximately 200 y was estimated for sigmaDDT in the upper 5 cm of the soil column, assuming the average flux rate for 12 h d-(1) over 8 months of the year. Thus, in the absence of other dissipation processes, the soil will continue to be a source of atmospheric contamination for a very long time.     

Organochlorine pesticides and polychlorinated biphenyls in cod from the southern Baltic, 1983

Hexachlorobenzene (HCB), alpha-, beta-, gamma- and delta-benzenehexachloride (BHC; HCH), p,p'-DDE, o,p'-DDD, o,p'-DDT, p,p'-DDD and p,p'-DDT (sigma DDT) and polychlorinated biphenyls (PCB) levels have been determined in muscle tissue of 207 cod (Gadus morhua) netted during 1983 in different regions in the southern part of the Baltic Sea. The mean levels found for cod muscle tissue (microgram/kg) related to wet weight were: 0.65 HCB, 1.2 alpha-BHC, 9.0 beta-BHC, 2.8 gamma-BHC, delta-BHC remained undetected, 13 sigma BHC, 4.4 p,p'-DDE, o,p'-DDD and o,p'-DDT remained undetected, 4.0 p,p'-DDD, 1.8 p,p'-DDT, 10 sigma DDT and 55 PCBs. The results are compared with levels found in cod caught in different regions of the Baltic Sea during 1967-1983, and reported previously by other authors.     

Organochlorine pesticides and polychlorinated biphenyls in flatfish from the southern Baltic, 1983

Hexachlorobenzene (HCB), alpha-, beta-, gamma- and delta-benzenehexachloride (BHC; HCH), p,p'-DDE, o,p'-DDD, o,p'-DDT, p,p'-DDD and p,p'-DDT (espilon DDT) and polychlorinated biphenlys (PCBs) levels have been determined in muscle tissue of 37 turbots Psetta maxima, 27 plaices Pleuronectes platessa and 106 flounders Platichthys flesus netted during 1983 in a different regions in the southern part of the Baltic Sea. The mean levels found for flatfish muscle tissue related to wet weight were: 0.7, 0.88 and 1.1 microgram/kg HCB; 1.3, 2.6 and 3.0 micrograms/kg alpha-BHC; 11, 10 and 11 micrograms/kg beta-BHC; 4.4, 4.9 and 5.5 micrograms/kg gamma-BHC; delta-BHC remained undetected; 17, 18 and 20 micrograms/kg epsilon BHC; 5.1, 5.2 and 8.7 micrograms/kg p,p'-DDE; o,p'-DDD remained undetected; o,p'-DDT was detected in 10 of 106 samples of the muscle tissue of flounder at the mean level of 17 micrograms/kg; 4.6, 5.0 and 7.6 micrograms/kg p,p'-DDD; 3.1, 4.0 and 11 micrograms/kg p,p'-DDT; 13, 14 and 29 micrograms/kg epsilon DDT and 71, 66 and 94 micrograms/kg PCBs for turbot, plaice and flounder, respectively. Generally, the levels of organochlorine pesticides and PCBs in wet muscle tissue of fish followed the increased lipids content of muscles. Some local differences in pollution pattern of organochlorines have occurred. The results are compared with levels found in flatfish collected in a different regions of the Baltic Sea during 1966-1981, and reported previously by other authors.     

Organochlorine pesticides and polychlorinated biphenyls in sprats from the southern Baltic, 1983

Hexachlorobenzene (HCB), alpha-, beta-, gamma-, and delta-benzenehexachloride (BHC; HCH), p,p'-DDE, o,p'-DDD, o,p'-DDT, p,p'-DDD and p,p'-DDT (sigma DDT) and polychlorinated biphenyls (PCB) levels have been determined in muscle tissue of 214 sprats (Sprattus sprattus) netted during 1983 in a different regions in the southern part of the Baltic Sea. The mean levels found for sprats muscle tissue related to wet weight were: 17 micrograms HCB/kg, 33 micrograms alpha-BHC/kg, 52 micrograms beta-BHC/kg, 33 micrograms gamma-BHC/kg, delta-BHC remained undetected, 120 micrograms sigma BHC/kg, 110 micrograms p,p'-DDE/kg, o,p'-DDD remained undetected, o,p'-DDT was detected in 2 of 214 samples at the mean level 24 micrograms/kg, 94 micrograms p,p'-DDD/kg, 115 micrograms p,p'-DDT/kg, 320 micrograms sigma DDT/kg and 800 micrograms PCB/kg. The levels of organochlorine pesticides reported are two to three times higher than those reported for wet muscles of sprats sampled in the same area two years before, whilst for PCB the levels differ slightly. When based on light-petroleum extractable lipids, the corresponding levels of organochlorine pesticides were also higher and for PCB the residue levels dropped. The results are compared with levels found in sprats collected in a different regions of the Baltic Sea during 1969-1983, and reported previously by other authors.     

Fullerene-Enhanced Accumulation of p,p'-DDE in Agricultural Crop Species

The effect of C(60) fullerene exposure on the accumulation of dichlorodiphenyldichloroethylene (p,p'-DDE; DDT metabolite) by Cucurbita pepo L. (zucchini), Glycine max L. (soybean), and Solanum lycopersicum L. (tomato) was determined. The plants were grown in 125 mL jars of vermiculite amended with 0 or 40 mg of C(60) fullerenes. Prior to planting, the jars were amended with 40 mL solution containing 100 ng/mL of p,p'-DDE with 0 or 100 mg/L humic acid. During three weeks of growth, plants were watered with the same p,p'-DDE containing solutions. Total shoot p,p'-DDE levels in nonfullerene exposed tomato, soybean, and zucchini were 26.9, 131, and 675 ng, respectively; total root DDE content for the three plants was 402, 5970, and 5830 ng, respectively. Fullerenes increased the shoot p,p'-DDE content of zucchini by 29%; contaminant levels in soybean shoots were decreased by 48% but tomato shoot content was unaffected. The root and total plant p,p'-DDE content of all three species was significantly increased by fullerene exposure; enhanced contaminant uptake ranged from 30 to 65%. Humic acid, regardless of fullerene presence or plant type, significantly decreased the p,p'-DDE uptake. Fullerenes were detected in the roots of all plants but were not detected in plant shoots in the initial study. In a follow up study with zucchini designed to maximize biomass for extraction, over half the analyzed stems contained fullerenes at 60.5 to 4490 ng/g. These findings show that the carbon-based nanomaterials may significantly alter the accumulation and potentially the toxicity of cocontaminants in agricultural systems.     

Organochlorine pesticides and polychlorinated biphenyls in herring from the southern Baltic, 1983

Hexachlorobenzene (HCB), alpha-, beta-, gamma- and delta-benzenehexachloride (BHC, HCH), p,p'-DDE, o,p'-DDD, o,p'-DDT, p,p'-DDD and p,p'-DDT (sigma DDT) and polychlorinated biphenyls (PCB) levels have been determined in muscle tissue of 187 herring (Clupea harengus) netted during 1983 in a different regions in the southern part of the Baltic Sea. The mean levels found for herring muscle tissue related to wet weight (microgram/kg) were: 14 HCB, 18 alpha-BHC, 23 beta-BHC, 14 gamma-BHC, delta-BHC remained undetected, 56 sigma BHC, 115 p,p'-DDE, o,p'-DDD and o,p'-DDT remained undetected, 84 p,p'-DDD, 51 p,p'-DDT, 250 sigma DDT and 530 PCB. The levels of organochlorine pesticides determined in wet muscles or extractable lipids of herring are nearly 2-3 times as high as those noted in fish sampled in the same area in two years before, whilst for PCBs the wet weight levels were comparable, and when based on a lipid weight are somewhat higher. The results are compared with levels found in herring collected in different regions of the Baltic Sea during 1965-1983, and reported previously by other authors.     

Assessment of edible marine species in the Adriatic Sea for contamination from polychlorinated biphenyls and organochlorine insecticides

It is estimated that 90% of human exposure to persistent organic pollutants is through food, and fish and shellfish represent an important source of contamination for polychlorinated biphenyls (PCBs) and organochlorine insecticides. To evaluate the levels of seafood contamination coming from the central Adriatic Sea, Italy, a study involving several pools of shellfish, crustaceans, and fish was carried out. Several marine species were selected by their abundance, wide distribution, and common use in the Italian diet and sampled and analyzed during 2004. The concentration of total (sigma) PCBs exceeded that of total dichlorodiphenyltrichloroethanes (DDTs) in all samples. Atlantic mackerel showed the highest concentrations of PCBs, ranging from 514 to 1772 ng/g of fat weight, and DDTs, ranging from 52 to 656 ng/g of fat weight. The lowest concentrations of PCBs and DDTs were found in cephalopods and mussels. Despite this, to protect human health from these pollutants, legal limits have been established for fish and shellfish for DDTs but not PCBs. The most common representative PCB congeners, in all species, were PCB 153 and PCB 138; the most common DDT was p,p'-dichlorodiphenyldichloroethylene.     

Deriving site-specific 2,2-bis(chlorophenyl)-1,1-dichloroethylene quality criteria of water and sediment for protection of common tern populations in Bohai Bay, North China

In this paper we first present a method of deriving site-specific water and sediment quality criteria of chemicals for protecting wildlife populations. The method has two steps: (1) identification of the threshold concentration in specific tissue corresponding to a population benchmark response and (2) extrapolating quality criteria on the basis of the bioaccumulation in tissue from the water or sediment (e.g., the bioaccumulation factor (BAF) and biota/ sediment accumulation factor (BSAF)). The method was applied to derive 2,2-bis(chlorophenyl)-1,1-dichloroethylene (p,p'-DDE) quality criteria of water and sediment of Bohai Bay, China, for common tern populations. The benchmark concentration in eggs of the common tern was determined to be 663 ng/g wet weight from the relationship curve between concentration (biotic burden in eggs) and the intrinsic rate of population increase (r) calculated by an age-structured matrix approach. The p,p'-DDE concentrations (mean 58.79 and ranging from 13.14 to 326.60 ng/g wet weight) measured in common tern eggs (n = 35), collected from the Beidagang wetland on the coast of Bohai Bay in China, and those in surface water or sediment from literature values were combined to estimate the probability distribution of BAF and BSAF using the Monte Carlo method. Finally, the marine water and sediment quality criteria of p,p'-DDE in Bohai Bay were estimated to be 4 ng/L and 1.9 ng/g dry weight, respectively.     

Survey of PCB and organochlorine pesticide residues in meats and processed meat products collected in Osaka, Japan

Residues of PCB and organochlorine pesticides in meats (beef, pork and poultry) and processed meat products collected in Osaka, Japan were surveyed. For 35 years from 1970 to 2004, the concentrations of PCB, HCH isomers, DDT analogues and dieldrin in all meats appeared to decline with each passing year. The concentration of each isomer of HCH in all meats declined rapidly from the early to the late 1970's and showed a gentle decline thereafter; beta-HCH showed the highest residue rate of the isomers in all the time periods surveyed, except for pork and poultry samples in the early 1980's. The concentrations of DDT analogues in all meats also showed sharp declines from the late 1970's to the early 1980's, followed by a smaller decrease thereafter; the main residues were pp'-DDD, p,p'-DDE and p,p'-DDT, and the residue rate of p,p'-DDE increased over the years. The residue levels of organochlorine pesticides in processed meat products (raw materials: beef, pork, poultry and mixture of ground beef and pork) were surveyed for 15 years (from 1990 to 2004) and there were no significant differences in the values among the materials. The concentrations of each pesticide in processed meat products tended to be lower than those of the corresponding meat samples, respectively.     

Sedimentary records of DDT and HCH in the Pearl River Delta,South China

Tropical regions in developing countries are thought to be significant sources of organochlorine pesticides in the global context, owing to high rate of use and only a recent production ban or restriction on application of these pesticides. In the present paper, DDT and HCH in eight 210Pb-dated sedimentary cores from the Pearl River Delta, South China, were analyzed in order to reconstruct the time trends of these persistent organic pollutants in this tropical region. The sedimentary inventories of sigmaDDT and sigmaHCH through the cores ranged from 36.6 to 1109.5 ng/cm2 and from 11.2 to 226.3 ng/cm2, respectively, and their spatial distribution implies that the water flows from the Humen, Jiaomen, Hongqili, and Hengmen outlets rather than the Xijiang flow from Modaomen outlet, supplied the major historical input of DDT to the estuary. Although a production ban of technical HCH and DDT was imposed in China in 1983, their sedimentary fluxes display increasing trends or strong rebounds in the 1990s as recorded in the core profiles, characteristic of the increasing ratios of (DDE + DDD)/DDT and DDE/DDT. It is suggested that an enhanced land soil runoff in the process of large-scale land transform, as well as a higher river water flow in early 1990s, had mobilized these pesticides from soil to the sedimentary system in the region.     

Organochlorine pesticide residues in European sardine, horse mackerel and Atlantic mackerel from Portugal.

This paper reports the results for the surveillance of nine organochlorine pesticides (HCH isomers (alpha, beta, e, gamma), p,p'-DDD, p,p'-DDT, p,p'-DDE, p,p'-DDD, HCB and aldrin) in muscle of three fish species, European pilchard (Sardina pilchardus), Atlantic horse mackerel (Trachurus trachurus) and Atlantic mackerel (Scomber scombrus). Analytical methodology included n-hexane extraction, clean-up with 2% deactivated Florisil, and quantification with gas chromatography-electron capture detection (GC-ECD). The highest mean concentrations were found for p,p'-DDT in sardine and mackerel at levels of 30.1 and 109.9 microg kg(-1), respectively, and for p,p'-DDD in horse mackerel at 51.9 microg kg(-1). Three species had higher levels for S-DDT than S-HCH. The estimated daily intake of organochlorine pesticides in the three species showed that in sardine, the highest EDIs were found for aldrin, at 1.8 ng kg(-1) bw day(-1), which represents 1.8% of the acceptable daily intake (ADI), and for ss-HCH, at 4.0 ng kg(-1) bw day(-1), representing 0.4% of ADI. Lowest values were found for Atlantic mackerel. Statistical analysis to determine the differences in mean concentrations of pesticides between species, and any correlation between groups of residues related with each one of the species, was undertaken.     

五味子乙素对D-半乳糖致衰老小鼠学习记忆能力的改善作用

目的：观察五味子乙素（schisandrin B,SCB）对D-半乳糖致衰老小鼠学习记忆能力的改善作用。方法：ICR小鼠随机分为4 组,即正常对照组（灌胃蒸馏水,皮下注射生理盐水）、衰老模型组（灌胃蒸馏水,皮下注射220 mg/kg D-半乳糖）、SCB（M）组（灌胃20 mg/kg SCB,皮下注射D-半乳糖220 mg/kg）、SCB（C）组（灌胃20 mg/kg SCB,皮下注射生理盐水）,连续给药7 周。通过避暗实验及Morris水迷宫实验观察SCB对小鼠学习记忆能力的影响;通过WST-1法检测小鼠脑组织中超氧化物歧化酶（superoxide dismutase,SOD）活力;通过硫代巴比妥酸法检测小鼠脑组织中丙二醛（malondialdehyde,MDA）含量;通过实时定量聚合酶链式反应及Western blot法,检测小鼠脑组织中p19、p53、p21基因表达情况。结果：SCB能够明显改善D-半乳糖诱导的脑衰老小鼠的学习记忆能力,提高脑衰老小鼠脑组织中SOD活力,降低MDA水平,明显降低脑组织中的p19、p53、p21基因的表达水平。结论：SCB能够改善D-半乳糖诱导的小鼠脑衰老,该作用可能与其提高小鼠抗氧化能力及下调小鼠脑组织中p19、p53、p21基因表达水平有关。