排序方式： 共有14条查询结果，搜索用时 789 毫秒
11.
Itziar Tueros ngel Borja Joana Larreta J. Germn Rodríguez Victoriano Valencia Esmeralda Milln 《Marine pollution bulletin》2009,58(9):1389-1400
The European Water Framework Directive (WFD) establishes a framework for the protection and improvement of estuarine (transitional) and coastal waters, attempting to achieve good water status by 2015; this includes, within the assessment, biological and chemical elements. The European Commission has proposed a list of priority dangerous substances (including metals such as Cd, Hg, Ni and Pb), with the corresponding list of environmental quality standards (EQS), to assess chemical status, but only for waters. In this contribution, a long-term (1995–2007) dataset of transitional and coastal water and sediment trace elements concentrations, from the Basque Country (northern Spain), has been used to investigate the response of these systems to water treatment programmes. Moreover, the approach proposed in the WFD, for assessing water chemical status (the ‘one out, all out’ approach), is compared with the integration of water and sediment data, into a unique assessment. For this exercise, background levels are used as reference conditions, identifying the boundary between high and good chemical status. EQS are used as the boundary between good and moderate chemical status. This contribution reveals that the first approach can lead to misclassification, with the second approach representing the pattern shown by the long-term data trends. Finally, the management implications, using each approach are discussed. 相似文献
12.
Nerea Goikoetxea Ángel Borja Almudena Fontán Manuel González Victoriano Valencia 《Continental Shelf Research》2009,29(8):1060-1069
The Oceanographic Society of Gipuzkoa has recorded daily sea-surface temperature (SST) measurements, since 2nd July 1946, on a (nearly) daily basis. Sixty years of SST measurements (1947–2007) have been considered, in order to analyse the hydrographic trends and anomalies at the southeastern Bay of Biscay. The study reviews initially the consistency and reliability of the time-series; and trends and anomaly patterns. Then, the periodicity of the series; a reference period, for analysing seasonality during the period 2001–2007; and oceano-meteorological coupling within the period 2001–2007, with reference to the baseline period, have been determined. Within this context, a slight cooling trend has been observed for the whole of the time-series, in contrast to the warming over the last three-decadal period. Regarding the periodicity of the series, several cycles have been identified, with periods of about 8, 11 and 18 years; these represent the influence of climate cycles over the (local) SST series. Additionally, seasonal anomaly patterns between 2001 and 2007 have been examined based upon the selected reference period (1980–2002). Several extreme seasonal events have been observed, such as warm summer SST values in 2003 and 2006 and cold winter values in 2005. Such events can be explained by the “deseasonality” phenomenon, observed throughout the study period. In addition to the direct influence of atmospherical parameters, such as air temperature and irradiance on SST, dynamical variables (turbulence and upwelling–downwelling) account also for this coupling. Overall, despite the marginal location and surface character of the time-series, it reveals anomalies that agree with those described for larger zones of the northeastern Atlantic Ocean; hence, it can be characterised as being a reliable and representative long-term SST series. 相似文献
13.
Seoane S Garmendia M Revilla M Borja A Franco J Orive E Valencia V 《Marine pollution bulletin》2011,62(7):1484-1497
Inverted microscopy is widespread employed for the analysis of phytoplankton composition within water quality monitoring networks. However, the analysis at the lowest taxonomical level is not always required for ecological status assessment. In addition, inverted microscopy can underestimate the small phytoplankton, and not always distinguish photoautotrophic from heterotrophic cells. In this study, as alternative tools, epifluorescence microscopy and High Performance Liquid Chromatography (HPLC) were employed to characterize phytoplankton communities within waters of different trophic condition. Epifluorescence microscopy confirmed its effectiveness to count the small phytoplankton. Furthermore, significant correlations between nutrients of anthropogenic origin and nanoplankton abundances were found. However, this technique resulted very time-consuming. HPLC together with the CHEMTAX program was more appropriate than inverted microscopy, in terms of cost-effectiveness. Also, the main variability patterns observed in the phytoplankton community structure by HPLC coincided with previous findings in the study area. Nevertheless, a rapid screening at the inverted microscope is recommended. 相似文献
14.
Jaume Dinarès-Turell Juan Ignacio Baceta Victoriano Pujalte Xabier Orue-Etxebarria Gilen Bernaola 《地学学报》2002,14(5):371-378
ABSTRACT Detailed magnetostratigraphic work at the Palaeocene/Eocene boundary interval in the Zumaia section has led to a precise delineation of the position of polarity Chron C25n from −35.0 m (or −35.7 m) to −25.2 m below the base of the Carbon Isotopic Excursion that marks the Palaeocene/Eocene boundary. This chronostratigraphic constraint suggests that the lithological carbonate–marl couplets making up most of the studied section are the expression of orbital precession cycles, and confirms the expanded and continuous nature of the section, with mean sediment accumulation rates of ∼ 2.5 cm kyr−1 . The new data render Zumaia a unique land-based marine section with available magnetostratigraphic data coupled to cyclostratigraphy. The revised chronostratigraphic framework presented supports previous cyclostratigraphic calibration of the latest Palaeocene geomagnetic timescale; it should facilitate better assessment of the different chemobiostratigraphic events that span this critical interval as a consequence of past climate and oceanographic change. Consequently, the Zumaia section is proposed as a candidate Global Stratotype Section and Point (GSSP) for the Palaeocene/Eocene boundary. 相似文献