首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Clupea harengus pallasi deposit their eggs in the coastal zone, which is the most dynamic part of the sea in respect to its regime. Salimity is one of the most variable factors on the spawning grounds. Observations were made in the seas of the European North and Far East, and in experiments where salinities varied from 0 to 70. Study of the influence of salinity on the development of sea herring eggs is of interest for several reasons. Firstly, salinity fluctuation patterns differ in different parts of a given habitat. In each area inhabited, salinity boundaries exist within which eggs can develop normally. Secondly, the levels of limiting salinities on spawning grounds differ noticeably in different seas. Hence, attention was paid to population-specific differences in the responses of eggs to salinity. Finally, detailed knowledge on the responses of sexual cells to low-salinity conditions helps to elucidate the ecological situation in areas with reduced salinity, and the reproductive potential of the population considered. Sexual cells of numerous populations of Pacific herring are capable of fertilization over a wide range of salinities. Fertilizability in low salinities and, partially, also in high salinities, reveals a population specificity. The responses of the eggs ofC. harengus pallasi to reduced salinities differ from those ofC. harengus harengus. Osmotic resistance of eggs to low salinities is considerably higher in the first-mentioned subspecies. Under salinity stress, eggs reveal individual differences which are not seen under optimum conditions of salinity. In all populations studied, responses to salinity change during embryology.  相似文献   

2.
In 1982 and 1983, blooms of the planktonic alga Phaeocystis pouchetii were studied in the East Frisian coastal waters off Norderney, FRG. Morphological variability of the colonies, population development, effects on inorganic nutrient and oxygen budget, and the role in the seasonal plankton bloom sequence were investigated. in both years two separate Ph. pouchetii blooms occurred in late spring and early summer that were formed by the globosa-type exclusively. The pouchetii-type was only present during the interval between the first and second blooms in 1982. Growth conditions for Ph. pouchetii seem to be most favourable after a breakdown of a diatom bloom when the silicate reserves have been exhausted, phosphate concentrations are relatively low, but a rich supply of dissolved inorganic nitrogen is available. Contrary to diatom blooms, Ph. pouchetii blooms result in a high production of particulate organic carbon (POC). Another characteristic is the release of great amounts of dissolved organic substances, which cause extensive sea foam formation during the peaks and the subsequent breakdown of the blooms. Due to increased assimilation during mass development and intense disintegration after the breakdown, variations of the oxygen content of the water are significant. Presumably the intensity of blooms has increased in the past decade as indicated by sea foam formation which has actually been excessive in some years.  相似文献   

3.
李玉芳  宋淑玲 《环境化学》2020,39(1):138-147
多溴联苯醚(polybrominated diphenyl ethers,PBDEs)是一种溴代阻燃剂,稳定性强,并具有生物蓄积性和长距离迁移特性.海洋环境是疏水性PBDEs的全球汇集点,自本世纪初研究者在海洋生物中陆续发现了PBDEs.本文分析了近16年来我国环渤海,东部沿海及南海北部三个沿海地区鱼/贝类中PBDEs的暴露水平现状及分布特征.现有的研究结果表明:环渤海、东部沿海以及南海北部地区鱼类中PBDEs总体暴露含量差异显著,分别为0.56—215.81 ng·g-1lw(脂重)、ND—77.0 ng·g-1lw和ND—167 ng·g-1lw;贝类样品PBDEs含量最高为渤海莱州湾地区230—720 ng·g-1lw,其次是浙江台州地区58.33—78.98 ng·g-1dw(干重);渤海沿岸鱼类中PBDEs浓度呈现上升的趋势,南海北部鱼类中的PBDEs浓度呈下降趋势,东部沿海地区鱼类体内PBDEs浓度没有明显变化;3个沿海区鱼类中PBDEs的同系物暴露特征总体表现为低...  相似文献   

4.
Baltic salmons were caught from two Latvian rivers during the spawning seasons of 2010 and 2011 for the determination of seventeen 2,3,7,8-chlorine-substituted dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and 12 dioxin-like polychlorinated biphenyls (PCBs). A partially automated clean-up procedure was used for sample preparation, followed by capillary gas chromatography hyphenated to high-resolution mass spectrometry. The concentrations of PCDD/F&;PCB-TEQ ranged from 6.6 to 18.2?ng?kg?1 fresh weight and this confirms the previous reports of relatively high concentrations of PCDD/Fs, and especially of dioxin-like PCBs in Baltic wild salmon, in most samples exceeding maximum recommended levels (MRLs) in toxicity equivalency quotients (PCDD/F-PCB-TEQ) of the World Health Organization (WHO 1998) according to EC COMMISSION REGULATION No 1881/2006. The results suggest that high consumption of Baltic wild salmon could entail the risk of exceeding the TDI for adults and teenagers. Extra care must be taken when Baltic wild salmon is included in childrens's diet to avoid exceedance of the recommended TDI of 4?pg?kg?1 body weight for this group.  相似文献   

5.
Concentrations of perfluorooctanesulfonate (PFOS), perfluorooctanoic acid (PFOA) and other perfluorinated compounds (PFCs) were measured in water and sediment from coastal Bohai Bay and surrounding rivers flowing into the bay. Of the 15 PFCs measured, PFOS and PFOA were detected with the greatest frequency. Concentrations in water ranged from<0.2 to 31 ng·L?1 and<1.0 to 82 ng·L?1 for PFOS and PFOA, respectively. Concentrations of PFOS and PFOA in sediments ranged from<0.1 to 2.0 ng·g?1 dw and<0.1 to 0.5 ng·g?1 dw, respectively. Concentrations of PFCs in Bohai Bay were less than those observed in other areas in Asia, but greater concentrations of ∑PFCs were observed in the Dalin River with concentrations increasing from upstream to downstream, and the greatest concentrations in sediment were observed in tidal flats. The ratio of ∑PFCs in sediment and water indicated that sediment could serve as a significant sink for PFUnA.  相似文献   

6.
In October 2000, a mass mortality of blacktip sharks (Carcharhinus limbatus) and Atlantic sharpnose sharks (Rhizoprionodon terraenovae) in northwest Florida occurred in conjunction with a Karenia brevis red tide bloom. Before this incident, no information existed on red tide-induced shark mortalities or baseline brevetoxin levels in sharks and rays from red tide-endemic areas. We report here that brevetoxin accumulation in live and red tide-killed elasmobranchs is common during K. brevis blooms and non-bloom periods. Strong relationships were found between the frequency of red tide blooms and the average brevetoxin concentrations in elasmobranch tissues. The presence of brevetoxins in Atlantic coast sharks in the absence of documented K. brevis blooms may suggest that blooms are occurring in areas that are not well monitored. Although red tide-related shark mortalities are rarely observed, the presence of brevetoxins in shark embryos raises questions about the effects these toxins may have on the reproductive success of sharks.  相似文献   

7.
As one of China’s great metropolises, Shanghai is suffering from the impact of manufacture and the use of chemical industrial products, and it faces serious pollution from polychlorinated biphenyls (PCBs). Therefore, in this study, in order to assess the seasonal and spatial character of contamination from chemical industrial zones, the concentrations of PCBs have been measured in various environmental media, including soil, leaves, and atmospheric particulate samples collected in a chemical industrial zone of Shanghai and compared with samples from presumably unpolluted sites of rural areas. In soils, the PCB concentrations ranged from 0.5 ng g−1 (unpolluted site) to 586.85 ng g−1 (chlor-alkali industry site). The concentrations of PCBs in evergreen leaves ranged from 0.3 ng g−1 to 32.46 ng g−1, and more chlorinated biphenyls congeners, such as penta-biphenyls and hexa-biphenyls, were the dominant contributors in winter and spring. Seasonal differences and the constitution patterns of congeners might be affected by the temperature and industrial activities. The PCB concentrations in the leaves of deciduous trees increase over time as the leaves grow. The PCB concentration in atmospheric particulates was in the range of 9.22–14.15 × 103 pg m−3, which might be the result of influence from climate and industrial activities. The relativity of PCB contents among the environmental media was discussed. The results in this paper provide an important profile of the current contamination status of a key chemical industrial zone in China.  相似文献   

8.
本文对浙江省台州市路桥和温岭两个电子垃圾循环区域母乳中多氯联苯(PCBs)污染现状进行了研究.路桥本地人群(n=16)、温岭本地人群(n=27)及在台州居住不足5年的外地人群(n=9)母乳中PCBs的中值浓度分别为195 ng·g-1脂重(lw)、138 ng·g-1lw和59.1 ng·g-1lw.路桥和温岭人群母乳中PCBs浓度显著高于在台州居住不足5年的外地人群(P<0.001),也远高于浙江省及中国背景区域水平.CB-118、CB-153和CB-138是台州母乳中最主要的3种同类物,与台州膳食样本中PCBs的指纹特征类似.路桥本地人群婴儿通过饮用母乳日摄入的PCBs量(EDI)(1024 ng·kg-1bw·d-1)略高于加拿大卫生部建议的成人对PCBs日耐受量(1000 ng·kg-1bw·d-1),温岭本地人群乳儿的EDI值(491 ng·kg-1bw·d-1)远高于我国12个省市EDI的均值(54.6 ng·kg-1bw·d-1),表明台州本地人群母乳喂养的婴儿处于较高的PCBs暴露风险中.母乳中PCBs浓度与母亲年龄、孕前体重指数、产次和婴儿的体重及性别无显著相关性.  相似文献   

9.
Environmental Geochemistry and Health - Given the background of current global initiatives for controlling persistent organic pollutants (POPs), an overview of the scientific knowledge about the...  相似文献   

10.
象山港沉积物与生物体中多氯联苯分布特征与暴露风险   总被引:2,自引:0,他引:2  
  相似文献   

11.
Xu  Jing  Qian  Wangyang  Li  Juying  Zhang  Xiaofei  He  Jian  Kong  Deyang 《Environmental geochemistry and health》2019,41(5):2315-2327

Polybrominated diphenyl ethers (PBDEs) are a class of organic pollutants. They are used as flame retardants that caused worldwide environmental concern. This study investigated the occurrence of PBDEs in soils and dusts from three plastic manufacture plants and surrounding areas in Eastern China. A total of 13 PBDE congeners were detected using gas chromatography-mass spectrometer (electron impact ionization). The total concentrations of PBDEs range from 2.21 to 558, 19.7–4916, and 8.70–18,451 ng/g dry weight in the soils of three sampling areas, with mean of 1004 ng/g d w; in dusts, the concentrations range from 7240 to 10,469, 684–4482, and 193–3989 ng/g d w, with an overall mean of 3619 ng/g d w. The most abundant congener is the BDE-209, followed by BDE-153 and BDE-85. This indicates that the brominated flame retardant added in the plastic manufacture is mainly the commodity decabromodiphenyl ether. In comparison with other polluted areas around the world, the PBDE concentrations in the soils of the plastic manufacture plants are similar to those in soils of waste plastic disposal areas and PBDEs production sites, but orders of magnitude higher than those in agricultural soils, mountain soils and rural soils. Daily exposure was estimated using the average concentrations of the pollution sites. The hazard quotient shows that the PBDEs pose considerable human health risks, especially to children, to which attention should be paid.

  相似文献   

12.
以典型电子垃圾拆解区作为研究区域,采集土芯样品,研究不同深度土壤中多氯联苯(PCBs)的污染状况.研究表明,从事电子垃圾拆解时间较短的采样点A土芯以及从事拆解时间较长的采样点B土芯不同深度土壤中PCBs总含量分别为0.54—45.43 ng·g-1干重和2.16—543.96 ng·g-1干重,两个采样点均受到了不同程度的PCBs污染,B土芯较A土芯污染严重.A和B土芯中PCBs含量由上到下呈下降趋势,表层(0—5cm)最高,5—10 cm层分别减少96.4%和92.6%.A土芯不同深度土壤中PCBs组成有所差异;B土芯各层土壤中PCBs组成较接近,含量较高的PCBs同系物均为5-CBs和6-CBs.相关性分析表明,土芯中1-CBs至9-CBs有相同的污染来源,即电子垃圾拆解,1-CBs至9-CBs随土壤深度向下迁移的能力接近.  相似文献   

13.
For monitoring and risk assessment, levels and distributions of Σ29 PCBs in paddy soil samples collected from Gwangyang (10 sites) and Ulsan (20 sites), heavily industrialized cities in Korea, were investigated using high-resolution gas chromatography/high-resolution mass spectrometry. Overall, total concentrations of Σ29 PCBs in Gwangyang (216.4–978.6 pg g?1 dw) and Ulsan (273.8–1824.1 pg g?1 dw) were higher than those (106.6–222.6 pg g?1 dw) in agricultural soil from Anseong in Korea. The TEQ (toxic equivalency) values from Gwangyang (0.06–0.40 ng TEQ kg?1 dw) and Ulsan (0.06–0.22 ng TEQ kg?1 dw) were higher than those (0.04–0.11 ng TEQ kg?1 dw) in Anseong but lower than the WHO threshold level (20 ng TEQ kg?1). However, one of the most toxic congeners, PCB 126, gave the highest concentration, possibly posing a risk to the biota. Seven indicator PCB congeners contributed to 50–80% of the total concentration of Σ29 PCBs, indicating the 7 PCBs can be used as valuable indicators for monitoring. The principal component analysis and cluster analysis for the homologue profiles of PCBs indicated that all the samples from both cities had the similar PCB contamination patterns, and the major sources of the PCB contamination were most likely from the usage of Aroclor 1254 than those of Aroclors 1242 and 1260. These PCB technical mixtures were possibly significantly used by various industries including iron and steel industries in Gwangyang and petrochemical and shipbuilding industries in Ulsan.  相似文献   

14.
The term “dioxins” is often used in a confusing way. In toxicological considerations—and also in the present report—the term is used to designate the PCDDs, the PCDFs and the coplanar (“dioxin-like”) PCBs, since these classes of compounds show the same type of toxicity. Because of the large number of congeners, relevant individual congeners are assigned with a toxic equivalency factor (TEF) that relate their toxicity to that of tetrachlorodibenzo-p-dioxin (TCDD) (2,3,7,8-TCDD) and are to be evaluated as dioxins. Each concentration of an individual congener in a mixture is multiplied with its TEF, and the resulting TCDD equivalents are added up and expressed as WHO-endorsed toxic equivalents (WHO-TEQ). Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are mainly the by-products of industrial processes (such as metallurgical processing, bleaching of paper pulp, and the manufacturing of some herbicides and pesticides) but they can also result from natural processes like volcanic eruptions and forest fires. Waste incineration, particularly if combustion is incomplete, is among the largest contributors to the release of PCDDs and PCDFs into the environment. Due to their persistence, PCDDs, PCDFs and PCBs are part of the so-called persistent organic pollutants group of compounds that also include some chlorinated pesticides. Since they have a high lipophilicity and resist transformation, they bio-accumulate in animal and human adipose tissues. Consumption of food is considered as the major source of non-occupational human exposure to PCDD/Fs with foodstuffs from animal origin accounting for more than 90% of the human body burden. With meat, dairy, and fish products being the main contributors. The aim of the present review was to summarize experimental data regarding dioxin emissions from contaminated and uncontaminated biological and environmental samples, from the available literature. The information will be presented chronologically with respect to distribution in human milk, serum; food, water, air, soils and sediments.  相似文献   

15.
16.
Resting eggs of four species of calanoid copepods and three species of cladocerans were collected from sediments up to 5cm depth from the Kiel Bay and adjacent waters in the southwestern Baltic Sea during April–May 1994. All but one species of cladoceran was successfully hatched/reared in the laboratory. In the Kiel Bay, egg abundances varied from 1.8x105 to 7.4x105 m-2. Hatching success of copepod eggs collected from all depths was high (49 to 94%), but was 0 to 79% for cladoceran eggs. Darkness did not seem to affect hatching. Eggs found in the 4 to 5 cm layer of sediment were estimated to be about 15 yr old, showing the presence of an egg bank in the Baltic. Formation of resting eggs may be a genetic trait acquired during the ice ages.  相似文献   

17.
N. H. Marcus 《Marine Biology》1990,104(3):413-418
In Ireland, mussels on exposed rocky shores constitute an interbreeding mixture of two forms of mussels,Mytilus edulis L. and the Mediterranean musselM. galloprovincialis Lmk. This paper presents an in-depth analysis, carried out between October 1984 and December 1986, of genetic variability at two partially diagnostic loci,Odh andEst-D, in two exposed-shore populations ofMytilus spp. in the west of Ireland. Significant differences at theOdh locus were observed in the genetic composition of adult mussels from different tidal levels. These differences were repeatable whether one was analysing replicate samples at a single point in time, samples collected at different points in time, i.e., in different years, or samples collected from different shores. Mussels recruiting to artificial substrates set out for a period of one month at different tidal levels at one of these sites were also observed to be genetically different; mussels higher up the shore exhibited higher frequencies of those alleles characteristically at high frequency inM. galloprovincialis for both theOdh andEst-D loci. Hence, the genetic differences observed in adult mussels are much more exaggerated in juveniles and are already apparent within the first month of benthic life. Possible reasons for the observed microgeographic differentiation are discussed. It is concluded that the observed genetic differences between mussels at different tidal levels arise either in the pelagic/attachment stage or very shortly after settlement.  相似文献   

18.
Restriction-site variation in mitochondrial (mt) DNA was assayed among 1675 red drum (Sciaenops ocellatus Linnaeus) sampled from 20 localities along the southeastern coast of the USA (western Atlantic) and the Gulf of Mexico (Gulf). Up to four consecutive year-classes (cohorts) were sampled at most localities. Nucleotide-sequence divergence among 170 mtDNA haplotypes identified ranged (in percentage) from 0.184 to 1.913, with a mean (±SD) of 0.887 ± 0.300. Comparisons of mtDNA haplotype frequencies across year-classes within localities were non-significant, indicating temporal stability of breeding components within localities. Significant heterogeneity in mtDNA haplotype frequencies was found across all localities, between (pooled) samples from the western Atlantic and the Gulf, and among geographically spaced, regional groupings in the Gulf. Genetic divergence between subpopulations of red drum in the western Atlantic and Gulf follows a pattern exhibited in other marine fishes, and probably stems from physical (historical environmental heterogeneity, absence of suitable habitat, and current patterns) and, perhaps, behavioral factors. Genetic differences among red drum in the Gulf appear to be due largely to an isolation-by-distance effect that is attributable to behavioral factors. The latter may include female philopatry to natal bays or estuaries, limited offshore (coastwise) movement of females relative to their natal bay or estuary, or both. Genetic divergence among red drum in the Gulf occurs despite high gene flow (estimated as the number of genetic effective migrants in an island mode). Conservation and management of red drum should be based on the premise that strategies for a given bay or estuary will impact geographically proximal bays or estuaries more than distal ones. Trajectories of correlograms in spatial autocorrelation analysis suggest a geographic neighborhood size, relative to genetic migration of red drum from a bay or estuary, of roughly 500 to 600 km. Received: 22 July 1998 / Accepted: 19 November 1998  相似文献   

19.
Scallops (Placopecten magellanicus Gmelin) were collected during August 1989 from shallow water (10 m) and deep water (31 m) habitats at Sunnyside, Trinity Bay, Newfoundland, to compare the lipid composition of eggs and adductor muscle tissue. Less favorable food levels and lower temperature conditions associated with deeper water have previously been shown to produce slower growth and reduced fecundity in individuals from this habitat. Triacylglycerol reserves consistently accounted for 60% of the total lipids present in both groups. The total lipid content of the eggs and the composition of their triacylglycerol fatty acid pools were similar in shallow water and deep water scallops, indicating very little if any nutritional difference between the two groups. Relative to their counterparts from shallow water, individuals from deeper water contained higher proportions of docosahexaenoic acid [22:6(n-3)] in the egg phospholipids and higher levels of 24-methylenecholesterol (a phytosterol commonly found in diatoms) in the adductor muscle. Differences in fatty acid composition are interpreted as biochemical adjustments of cell membranes to increase membrane fluidity, thereby compensating for the lower temperatures prevailing at the greater depth.  相似文献   

20.
Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were analysed in surface soil samples collected in 2001–2002 at an open urban area of Madrid. In order to obtain representative samples, three collection points at the site were chosen. The most abundant PAHs and PCBs were phenanthrene, fluorene, pyrene, chrysene and benzo[a]pyrene and hexa- and heptachlorinated PCBs, respectively. The sum of selected PAHs (13 compounds) and PCBs (15 congeners) averaged 1 and 0.1?µg?g?1, respectively. PCB levels in winter were 2–10 times higher than summer ones, while seasonal variation for most of PAHs were not observed. Good correlations among all PCBs were found. Five PAHs were also well correlated.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号