Chlorobiphenyls in the blubber of harbour porpoises (Phocoena phocoena) from the UK: Levels and trends 1991-2005     

Robin J. Law  Philippe Bersuder  Rob Deaville  Paul D. Jepson 《Marine pollution bulletin》2010,60(3):470-145

Harbour porpoises sampled within the UK Cetacean Strandings Investigation Programme have been analysed for 25 chlorobiphenyl congeners. In all, 440 porpoises stranded or bycaught during the period 1991-2005 were studied. There are regional differences in the trend in summed congener concentrations over time but, despite controls on PCBs having been in place for decades, they are declining only slowly. Their toxic impacts in UK porpoises - increased susceptibility to infectious disease mortality in the most contaminated individuals - looks likely to continue for some time yet. Further efforts to limit or eliminate PCB discharges to the marine environment are still needed.  相似文献   

粉沙质海岸港区航道减淤工程措施研究     

吴今权  章始红  孙林云  贾立新 《海洋工程》2012,30(1):98-105

通过对唐山港京唐港区附近海岸演变进行调查和分析,结合唐山港京唐港区建港近二十年的现场观测资料,对港区附近的泥沙运动和港口航道泥沙淤积机理进行分析,对2003年10月强风暴潮期间,港口航道发生严重的泥沙骤於进行了研究,为解决港口航道特别是外航道的泥沙淤积问题,提出粉沙质海岸港区航道挡沙和固沙的工程措施,并通过物理模型对挡沙固沙措施的工程效果进行了模型试验。试验结果表明挡沙和固沙工程方案对航道泥沙减淤效果很明显,其中,挡沙方案目前已应用到唐山港京唐港区二期挡沙堤改造、三期挡沙堤的设计和建设工程中,已发挥其挡沙减淤的作用。  相似文献   

Evidence of a significant wind‐driven circulation in Akaroa Harbour. Part 2: Results from the application of a width averaged hydrodynamic numerical model (CE‐QUAL‐W2)     

Darlene N. Heuff  Robert H. Spigel  Alex H. Ross 《新西兰海洋与淡水研究杂志》2013,47(5):1111-1127

Results from the application of the two‐dimensional, laterally‐averaged hydrodynamic model, CE‐QUAL‐W2 to Akaroa Harbour, New Zealand were compared with 3 months of temperature and current data to investigate the connection between significant wind‐driven circulation and vertical mixing. Results indicate that in general, CE‐QUAL‐W2 reproduced realistic values for width‐averaged along‐Harbour current speeds and water column temperature structure. However, during periods of strong winds, the mixed layer depth was predicted to be shallower than observed; c. one‐third as compared to c. one‐half. Simulations of tidally‐driven flow highlighted the restrictions of the two‐dimensionality imposed by the model, though this type of flow was not found to result in appreciable mixing of the water column. Data from an independent field survey supported the validity of the use of CE‐QUAL‐W2 under (at least) light‐to‐moderate sea‐breeze conditions.  相似文献   

A new large‐diameter piston corer and core‐liner cutter     

A. Langford  J. C. McDougall  N. Robertson 《新西兰海洋与淡水研究杂志》2013,47(4):595-601

A newly developed piston sediment corer utilising a neat‐fitting piston operating within a 2 7/8‐in.‐diameter plastic liner has successfully cored heavy gravel, coarse shell and sandy sediments.

A quick fit and release junction for pipe lengths and cutter has been devised.  相似文献   

Impacts of a bivalve mass mortality event on an estuarine food web and bivalve grazing pressure     

Hannah F. E. Jones  Conrad A. Pilditch  David P. Hamilton  Karin R. Bryan 《新西兰海洋与淡水研究杂志》2013,47(3):370-392

Declines in bivalve populations have been quite common worldwide, often associated with coastal development, pollution and climate change. In addition to the impacts of these chronic stressors, occasional mass mortality events may have severe consequences on ecosystem services and biodiversity. In this study, we examined the impact of a mass mortality event of the clam (Austrovenus stutchburyi) on an estuarine food web and the grazing pressure exerted by the bivalve population. In February 2009, c. 60% of the clam population died in Whangateau Harbour, New Zealand. Population clearance rate calculations suggest that the clam population do not exert significant top-down control on phytoplankton biomass in the estuary, and thus the impact of the mortality event on bivalve grazing pressure was less severe than the reduction in abundance would suggest. A trophic model shows that phytoplankton play a limited role in the estuary food web, which is instead dominated by microphytobenthos and clams. This study highlights the importance of microphytobenthos in shallow estuaries, and the application of the trophic model is a useful tool that can identify key components of the ecosystem and could help inform monitoring programmes.  相似文献   

Recruitment to the macrobenthos of Macomona liliana (bivalvia: Tellinidae) in Manukau Harbour,New Zealand     

D. S. Roper  R. D. Pridmore  S. F. Thrush 《新西兰海洋与淡水研究杂志》2013,47(3-4):385-392

The population biology of the wedge shell Macomona liliana (Iredale, 1915) was studied at six sites on intertidal sandflats in Manukau Harbour over 2 years. Differences were found in the densities of bivalves between sites, and at each site large seasonal fluctuations in densities were also observed. Within‐site density fluctuations were mainly the result of changes in the numbers of juveniles (< 5 mm long). Length‐frequency distributions were dominated by a single mode associated with new recruits. The only major inter‐site difference was the scarcity of large bivalves at one site. Recruitment to the macrobenthos occurred over an extended period (summer to late winter or spring), but with markedly different levels of recruitment in the two successive years. Length‐frequency plots indicated that growth in the first year was 2–3 mm. The possible involvement of hydrodynamics, inter‐ and intraspecific interactions, and pollution on recruitment, and the importance of mortality and migration to post‐settlement survival are discussed.  相似文献   

Tracing the source of 3,3'-dichlorobiphenyl found in samples collected in and around Halifax Harbour   总被引：1，自引：0，他引：1  

King TL  Yeats P  Hellou J  Niven S 《Marine pollution bulletin》2002,44(7):590-596

3,3'-dichlorobiphenyl (IUPAC No. 11), a chlorobiphenyl (CB) that is not generally analysed in environmental studies of CBs, is found, sometimes at high concentrations, in water, suspended particulate material, biota and sediments from Halifax Harbour, NS, Canada. The results presented demonstrate the need for investigations of non-Aroclor CBs like CB 11. Not only can they have rather elevated environmental concentrations like those reported here for CB 11, but they also can be members of the more toxic non-ortho class of CBs and thus important from a toxicity standpoint. The focus of this paper was to investigate the possible sources of CB 11, a trace constituent of commercial mixtures, but dominant in various environmental compartments of Halifax Harbour.  相似文献   

Estimate of long-term sediment discharge at tidal inlets using water level data from a tide gauge     

Shu Gao  Michael Collins 《地球表面变化过程与地形》1994,19(8):699-714

A simple approach to the estimate of long-term sediment discharge through an entrance to a tidal basin is described. Using the method, cross-sectional mean current speeds are derived, on the basis of the definition of an ‘apparent tidal basin area’, from records of water level data from a single tide gauge. The obtained time-series of current speeds are then used to define ‘local’ current speeds, through the use of a sectional distribution function for the currents. Sediment transport formulae are then applied, using the obtained speed data and other relevant parameters contained within the formulae and frequency distribution functions with regard to wave and tidal current characteristics, to estimate sediment discharge through the entrance. Analytical procedures of the method are described in detail, in an example from Christchurch Harbour (southern England).  相似文献   

The use of ‘bomb spike’ calibration and high-precision AMS C analyses to date salt-marsh sediments deposited during the past three centuries     

William A. Marshall  W. Roland Gehrels  Mark H. Garnett  Stewart P.H.T. Freeman  Colin Maden  Sheng Xu   《Quaternary Research》2007,68(3):325-337

A combination of ‘bomb spike’ calibration and conventional calibration of AMS ¹⁴C dating has been used to determine a detailed age-depth model for a 1-m sediment section collected from a salt marsh in Poole Harbour, southern England. These data were compared with the chronology obtained from ²¹⁰Pb analysis and ¹³⁷Cs age markers. We report post bomb values of over 1.46 F¹⁴C (> 146% modern ¹⁴C), and both the rising and falling limbs of the atmospheric ‘bomb spike’ are identified. Five pre-bomb samples were analysed using multi-target high-precision 2‰ AMS analysis, and after the replicates were combined the one-sigma uncertainty was as low as ± 9 ¹⁴C yr on some ages. These data, and an additional three normal-precision pre-bomb ¹⁴C samples, were calibrated using CALIB 5.0 and the chronology constrained using the ‘prior knowledge’ of independent age markers obtained from the analysis of pollen and spheroidal carbonaceous particle (SCPs). No agreement was found between the ¹⁴C ‘bomb spike’ dates and the CRS ²¹⁰Pb chronology modelled for this sequence. In addition, poor agreement was found between the signal of the 1960s weapons test fallout indicated by the ¹⁴C ‘bomb spike’ dates and the timing suggested by the ¹³⁷Cs data. This disagreement is attributed to the influence of the local discharge of ¹³⁷Cs from the former UKAEA site at Winfrith. We use our new chronology to confirm the existence of an acceleration in sedimentation rates in Poole Harbour during the last 100 yr previously reported for this site by Long et al. (Long, A.J., Scaife, R.G., Edwards, R.J. 1999. Pine Pollen in intertidal sediments from Poole Harbour, UK; implications for late-Holocene sediment accretion rates and sea-level rise. Quaternary International, 55, 3–16.), and conclude that ‘bomb spike’ ¹⁴C calibration dating may offer a more robust alternative to the use of ²¹⁰Pb chronologies for dating sediment deposition in salt-marsh environments. In addition, we demonstrate how the use of high-precision AMS analysis has the potential for reducing some of the uncertainties involved in the high-resolution dating of recent salt-marsh sediments.  相似文献   

Examining the neighbourhood‐level predictors of fear of crime in Christchurch,New Zealand          下载免费PDF全文

Gregory Breetzke  Amber L. Pearson 《New Zealand geographer》2015,71(2):91-104

The fear of crime can significantly reduce the quality of life of individuals, yet little is known about what neighbourhood‐level factors drive feelings of vulnerability in New Zealand. Even less is known about the impact that recorded crime has on individuals' fear in the country. In this study, we examined the neighbourhood‐level factors related to fear of crime in Christchurch, focusing specifically on whether recorded crime in neighbourhoods influences fear. The fear of crime in Christchurch was found to be the greatest in more affluent, ethnically homogenous and residentially stable neighbourhoods, while recorded crime levels were found to be relatively lower in these neighbourhoods.  相似文献