Cost-effectiveness of the Baltic Sea Action Plan     

Katarina Elofsson 《Marine Policy》2010

The governments around the Baltic Sea have agreed on a new set of targets for nutrient load reductions. The major motive for this is new and better knowledge about the link between nutrient loads and water transparency in different parts of the sea. The Baltic Sea Action Plan (BSAP) defines target for transparency in different marine basins, the load reductions necessary to meet transparency targets and a scheme for the distribution of the abatement burden between countries adjacent to the sea.  相似文献   

泉州湾赤潮藻类优势种演替影响因子探讨   总被引：4，自引：1，他引：3  

江兴龙  宋立荣 《海洋与湖沼》2009,40(6):761-767

于2006年5—11月对东海泉州湾赤潮监控区设定4个采样站位,进行赤潮常规监测。结果表明,泉州湾藻类优势种由中肋骨条藻(Skeletonema costatum)、太平洋海链藻(Thalassiosira pacifica)、微小原甲藻(Prorocentrum minimum)、尖刺拟菱形藻(Pseudo-nitzschia pungens)、丹麦细柱藻(Leptocylindrus danicus)及旋链角毛藻(Chaetoceros curvisetus)等赤潮生物组成,虽然中肋骨条藻为最主要的优势种,但有3个站位出现了上述优势种的演替。通过深入分析该海域水质营养盐含量及组成结构的动态变化对赤潮藻类优势种演替的影响,发现由于不同的赤潮藻类种群具有各自的生态习性及适应环境的生长增殖策略,海域水质营养盐含量和组成结构的变化,会引起赤潮藻类种群增殖竞争力间强弱的相对变化,而种群增殖竞争力强的种类有可能迅速增殖取代原有的优势种而演替为新的优势种,这是一个动态的过程。  相似文献   

Application of an ecosystem model for the environmental assessment of the reclamation and mitigation plans for seagrass beds in Atsumi Bay   总被引：1，自引：0，他引：1  

Akio Sohma  Yasuyuki Sekiguchi  Kisaburo Nakata 《Estuarine, Coastal and Shelf Science》2009

An ecosystem model was used to evaluate the effects of reclaiming seagrass beds and creating artificial shallows with seagrass beds to mitigate the effects of the reclamation. The applied model can simulate the pelagic and benthic ecosystems including seagrass beds and tidal flats. The objectives of this study were (a) to investigate the likelihood of cultivating and maintaining seagrass beds in artificial shallows (Part 1), and (b) to understand the effects of the reclamation of seagrass beds and the creation of artificial shallows on the water quality in the estuary (Part 2). In Part 1, first, the nutrient turnover rates due to both biochemical and physical processes in the natural seagrass beds where reclamation is proposed were analyzed. Biological processes rather than physical processes were the most significant driving forces of nutrient cycles in seagrass beds. Second, the effects of filter feeding benthic fauna (suspension feeders) in the seagrass beds were analyzed. The scenario with suspension feeders resulted in higher transparency of the water column (8.7% decrease in the light attenuation coefficient) and an increase in nutrient supply (24.9% increase in NH₄-N in the water column) contributing to the high specific growth rate of seagrass. Third, the specific growth rate of seagrass on the proposed artificial shallows was measured. The value on the artificial shallows set at a depth of datum line minus 0.8 m (D.L. − 0.8 m) was approximately the same as that of the natural seagrass beds. In Part 2, first, water quality in the estuary was compared among the scenarios with/without natural seagrass beds and artificial shallows. Then, the defined values of the water purification capability of (a) artificial shallows with/without seagrass beds, and (b) natural seagrass beds per unit area were evaluated. The reclamation of the natural seagrass beds resulted in a decrease of the removal of phytoplankton and detritus from the pelagic system (i.e. resulted in a loss in the purification rate). In contrast, the creation of artificial shallows resulted in an increase of the removal of phytoplankton and detritus from the pelagic system (i.e. resulted in a gain in the purification rate). Based on an annual average, approximately twice as much phytoplankton was removed from the artificial shallows at the depth D.L. − 0.8 m, than at the depth, D.L. − 1.5 m, and the artificial shallows with seagrass beds removed pelagic DIN and DIP at a rate 120% higher than that without seagrass beds.  相似文献   

干旱半干旱地区草原灌丛荒漠化及其生物地球化学循环   总被引：1，自引：1，他引：0  

金钊  齐玉春  董云社 《地理科学进展》2007,26(4):23-32

干旱和半干旱地区草地生态系统木本植物入侵及其导致的草原灌丛化已经成为全球范 围普遍发生的现象, 是草地沙化和荒漠化的一个重要标志。干旱生态系统中, 此种类型的植被变 化将对区域和全球生物地球化学循环产生显著影响。过度放牧、区域气候干旱化和自然火过程是 导致灌丛入侵和发展的主要控制因子。草原灌丛化过程中, 草地生态系统分布较为均匀的土壤养 分及相关元素在水平和垂直方向发生分异, 关键生命元素C、N、P 、S 生物地球化学循环的变化 将对全球气候变化产生显著作用。全球气候变化与草原灌丛荒漠化之间存在潜在的反馈机制, 人 类扰动的影响将使这种反馈作用变得更加迅速和灵敏。  相似文献   

河流相沉积中准层序与短期基准面旋回对比研究——以四川中部须家河组为例   总被引：4，自引：1，他引：3  

高志勇 《地质学报》2007,81(1):109-118

通过详细分析曲流河沉积动力学特点,在四川中部须家河组建立了河流相沉积的准层序模式。曲流河沉积中可发育粒级向上变细准层序,也可以发育粒级向上变粗的准层序。辫状河准层序表现为粒级向上变细、河道水体向上变浅的准层序,而粒级向上变粗的准层序不发育。河流相准层序界面是河道砂体底部的冲刷侵蚀面,在粒级向上变粗的泛滥平原-决口扇或决口河道沉积中,准层序界面为暴露过泥岩与上部洪水期的暗色泥岩间的界面。将河流相准层序与短期基准面旋回进行精细的分析与对比认为,二者在层序地层学级次划分中时限相当,发育时间为0.01~0.05Ma;二者的界面是相同的,均为河道砂体底部的冲刷侵蚀面或者是暴露过泛滥平原泥岩、根土岩等。河流相中准层序与短期基准面旋回其实是相同时间内沉积的一套相同的沉积体,二者的不同只是分析的角度不同,其实质内容是一致的,即在曲流河短期基准面升降变化过程中,所保留下来的沉积物总是相对河水位是向上变浅的,由位于河水面以下的河道或边滩砂体向上变浅至河水面之上的天然堤、泛滥平原泥岩,此相序特征也正与准层序向上变浅的定义相同。  相似文献   

Chronostratigraphic constraints on Middle Pleistocene faunal assemblages and Acheulian industries from the Cretone lacustrine basin,central Italy          下载免费PDF全文

Fabrizio Marra  Piero Ceruleo  Brian Jicha  Luca Pandolfi  Carmelo Petronio  Leonardo Salari  Biagio Giaccio  Gianluca Sottili 《第四纪科学杂志》2016,31(7):641-658

  相似文献   

Paleoclimate studies and natural-resource management in the Murray-Darling Basin I: past,present and future climates     

K. Mills  P. Gell  P. P. Hesse  R. Jones  P. Kershaw  R. Drysdale 《Australian Journal of Earth Sciences》2013,60(5):547-560

This paper provides an incisive review of paleoclimate science and its relevance to natural-resource management within the Murray-Darling Basin (MDB). The drought of 1997–2010 focussed scientific, public and media attention on intrinsic climate variability and the confounding effect of human activity, especially in terms of water-resource management. Many policy and research reviews make statements about future planning with little consideration of climate change and without useful actionable knowledge. In order to understand future climate changes, modellers need, and demand, better paleoclimate data to constrain their model projections. Here, we present an insight into a number of existing long-term paleoclimate studies relevant to the MDB. Past records of climate, in response to orbital forcing (glacial–interglacial cycles) are found within, and immediately outside, the MDB. High-resolution temperature records, spanning the last 10⁵ years, exist from floodplains and cave speleothems, as well as evidence from lakes and their associated lunettes. More recently, historical climate records show major changes in relation to El Niño–Southern Oscillation cycles and decadal shifts in rainfall regimes. A considerable body of research currently exists on the past climates of southeastern Australia but, this has not been collated and validated over large spatial scales. It is clear that a number of knowledge gaps still exist, and there is a pressing need for the establishment of new paleoclimatic research within the MDB catchment and within adjacent, sensitive catchments if past climate science is to fulfil its potential to provide policy-relevant information to natural-resource management into the future.  相似文献   

Mise en évidence expérimentale des facteurs nutritifs limitants de la production du micro-nanoplancton et de l'ultraplancton dans une eau côtière de la Méditerranée orientale (Haïfa,Israël)     

D. J. Bonin  M. C. Bonin  T. Berman 《Aquatic Sciences - Research Across Boundaries》1989,51(2):129-152

Enrichment experiments were carried out on seawater samples from the Israeli coast to characterise the nature of nutrient limitation. Phytoplankton chlorophyll, ATP, PC, PN, PP and bicarbonate and orthophosphate uptake rates indicate that phosphorus limitation is more extreme than that of nitrogen. A large increase in total nitrogen observed with P enrichment suggests that a substantial nitrogen fixation is mediated by picocyanobacteria in this kind of oligotrophic mediterranean waters.

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洛川黄土剖面的粉砂与粘粒比值及粒度旋回     

胡碧茹  卢演俦 《岩石学报》1989,5(1):12-20

洛川黑木沟黄土剖面发育了一套完整的黄土地层。据剖面百余块标本粒度资料阐述了Kd=(粉砂(0.05-0.01mm％))/(粘粒(<0.005mm)％)的地质及物理意义。它反映了受风化的粉尘粒组与次生粒组之间的消长关系,Kd值变化既受风尘来源区干湿状况或生物气候条件的制约,又受风化成壤作用的制约。因此,Kd值可视为黄土、古土壤生成环境的一个指标。据Mφ(平均值)由粗到细的变化划为一个粒度旋回,全剖面共分11个旋回。每个旋回反映了一定的岩性地层组合及生物气候环境的变化。  相似文献   

Nitrogen and sulfur species in Antarctic aerosols at Mawson,Palmer Station,and Marsh (King George Island)   总被引：4，自引：0，他引：4  

D. L. Savoie  J. M. Prospero  R. J. Larsen  F. Huang  M. A. Izaguirre  T. Huang  T. H. Snowdon  L. Custals  C. G. Sanderson 《Journal of Atmospheric Chemistry》1993,17(2):95-122

High volume bulk aerosol samples were collected continuously at three Antarctic sites: Mawson (67.60° S, 62.50° E) from 20 February 1987 to 6 January 1992; Palmer Station (64.77° S, 64.06° W) from 3 April 1990 to 15 June 1991; and Marsh (62.18° S, 58.30° W) from 28 March 1990, to 1 May 1991. All samples were analyzed for Na⁺, SO ₄ ^2– , NO ₃ ^– , methanesulfonate (MSA), NH ₄ ⁺ ,²¹⁰Pb, and⁷Be. At Mawson for which we have a multiple year data set, the annual mean concentration of each species sometimes vary significantly from one year to the next: Na⁺, 68–151 ng m^–3; NO ₃ ^– , 25–30 ng m^–3; nss SO ₄ ^2– , 81–97 ng m^–3; MSA, 19–28 ng m^–3; NH ₄ ⁺ , 16–21 ng m^–3;²¹⁰Pb, 0.75–0.86 fCi m^–3. Results from multiple variable regression of non-sea-salt (nss) SO ₄ ^2– with MSA and NO ₃ ^– as the independent variables indicates that, at Mawson, the nss SO ₄ ^2– /MSA ratio resulting from the oxidation of dimethylsulfide (DMS) is 2.80±0.13, about 13% lower than our earlier estimate (3.22) that was based on 2.5 years of data. A similar analysis indicates that the ratio at Palmer is about 40% lower, 1.71±0.10, and more comparable to previous results over the southern oceans. These results when combined with previously published data suggest that the differences in the ratio may reflect a more rapid loss of MSA relative to nss SO ₄ ^2– during transport over Antarctica from the oceanic source region. The mean²¹⁰Pb concentrations at Palmer and Marsh and the mean NO ₃ ^– concentration at Palmer are about a factor of two lower than those at Mawson. The²¹⁰Pb distributions are consistent with a²¹⁰Pb minimum in the marine boundary layer in the region of 40°–60° S. These features and the similar seasonalities of NO ₃ ^– and²¹⁰Pb at Mawson support the conclusion that the primary source regions for NO ₃ ^– are continental. In contrast, the mean concentrations of MSA, nss SO ₄ ^2– , and NH ₄ ⁺ at Palmer are all higher than those at Mawson: MSA by a factor of 2; nss SO ₄ ^2– by 10%; and NH ₄ ⁺ by more than 50%. However, the factor differences exhibit substantial seasonal variability; the largest differences generally occur during the austral summer when the concentrations of most of the species are highest. NH ₄ ⁺ /(nss SO ₄ ^2– +MSA) equivalent ratios indicate that NH₃ neutralizes about 60% of the sulfur acids during December at both Mawson and Palmer, but only about 30% at Mawson during February and March.  相似文献