Anthropogenic nutrient sources and loads from a Mediterranean catchment into a coastal lagoon: Mar Menor, Spain

The Mar Menor is a coastal lagoon increasingly threatened by urban and agricultural pressures. The main watercourse draining into the lagoon is the Rambla del Albujón. A fortnightly campaign carried out over one annual cycle enabled us to characterize the treated urban sewage effluents and agricultural sources which contribute to the nutrient fluxes in the watercourse. Multivariate analysis provided information for establishing chemical signatures and for assessing the relative influence of the various sources on the water quality at the outlet. Mass balances were used to examine net gains and losses, and cross-correlations with rainfall to analyze climatic influence and control factors in the trends of the nutrient flux. The rainfall pattern was significantly cross-correlated with nitrate and phosphorus fluxes from agricultural sources, while fluctuations in the resident population explained the phosphorus flux trend in urban sources. 50% of dissolved inorganic nitrogen was from agricultural sources, while 70% of total phosphate and 91% of total organic carbon were from urban point sources. The net amounts of all the nutrients fell as a result of plant uptake and/or denitrification in the channel. The control of urban point sources (phosphorus-enriched) is suggested as a promptly action for improving the health of the coastal lagoon.     

Composition of a protein-like fluorophore of dissolved organic matter in coastal wetland and estuarine ecosystems

This study demonstrates the compositional heterogeneity of a protein-like fluorescence emission signal (T-peak; excitation/emission maximum at 280/325 nm) of dissolved organic matter (DOM) samples collected from subtropical river and estuarine environments. Natural water samples were collected from the Florida Coastal Everglades ecosystem. The samples were ultrafiltered and excitation-emission fluorescence matrices were obtained. The T-peak intensity correlated positively with N concentration of the ultrafiltered DOM solution (UDON), although, the low correlation coefficient (r(2)=0.140, p<0.05) suggested the coexistence of proteins with other classes of compounds in the T-peak. As such, the T-peak was unbundled on size exclusion chromatography. The elution curves showed that the T-peak was composed of two compounds with distinct molecular weights (MW) with nominal MWs of about >5 x 10(4) (T(1)) and approximately 7.6 x 10(3) (T(2)) and with varying relative abundance among samples. The T(1)-peak intensity correlated strongly with [UDON] (r(2)=0.516, p<0.001), while T(2)-peak did not, which suggested that the T-peak is composed of a mixture of compounds with different chemical structures and ecological roles, namely proteinaceous materials and presumably phenolic moieties in humic-like substances. Natural source of the latter may include polyphenols leached from senescent plant materials, which are important precursors of humic substances. This idea is supported by the fact that polyphenols, such as gallic acid, an important constituent of hydrolysable tannins, and condensed tannins extracted from red mangrove (Rhizophora mangle) leaves exhibited the fluorescence peak in the close vicinity of the T-peak (260/346 and 275/313 nm, respectively). Based on this study the application of the T-peak as a proxy for [DON] in natural waters may have limitations in coastal zones with significant terrestrial DOM input.     

Recombinant Landscapes in the American City

How are urban actors, such as landscape designers, community groups, developers and local politicians, actively restructuring their environments to meet the challenges of the American city in the new global context? Grahame Shane outlines the approaches to landscape that have been emerging since the mid-20th century and are set to recombine urban assemblages whether they are located in historic city centres, postindustrial waterfronts or suburban sprawl. Copyright © 2007 John Wiley & Sons, Ltd.     

Habitat Creation Opportunities for Landward Coastal Re-alignment: Essex Case Studies

Relative sea-level fluctuations during the Holocene period have combined with medieval to present saline floodplain embanking to reduce the inter-tidal saltmarsh area in Essex from 40 000 ha to 4400 ha. The present loss by erosion is estimated at 2%/annum for the country, and the reduction in these areas is not only detrimental to related habitats but has caused an increasing requirement for flood-defence financial investment.
Recent initiatives by the Ministry of Agriculture, Fisheries and Food, the Environment Agency and English Nature have created mechanisms and opportunities to develop sustainable flood-control structures where coastal re-alignment has been the preferred option.
The Orplands frontage covers 2 km of sea wall which have been deliberately breached to allow 40 ha of rare saltmarsh to re-establish. At Abbotts Hall, an arable field of 20 ha has been converted to its former saltmarsh by creek re-establishment and tidal inundation by reversal of existing sluices. These two schemes have (a) regenerated habitats for halophytic and semi-halophytic plants, marine and brackish invertebrates, and (b) provided roost, feed and breeding areas for birds and nursery areas for marine fish fry. Apart from flood control and habitat creation, particular features were incorporated to provide niche locations for targeted types of wildlife.     

A novel indicator system for catalytic spectrophotometric determination and speciation of inorganic selenium species (Se(Ⅳ), Se(Ⅵ)) at trace levels in natural lake and river water samples

A novel catalytic kinetic method is proposed for the determination of Se(Ⅳ), Se(Ⅵ), and total inorganic selenium in water based on the catalytic effect of Se(Ⅳ) on the reduction of Celestine blue by sodium sulfide at pH 7.0 phosphate buffer. The fixed-time method was adopted for the determination and speciation of inorganic selenium. Under the optimum conditions, the two calibration graphs are linear with a good correlation coefficient in the range 2-20 and 20-200 μg·L-1 of Se(Ⅳ) for the fixed-time method a...     

福州西湖水环境现状调查与生态修复建议

为了更好地对福州西湖水环境进行保护,实现对其周边环境的综合整治,我们对福州西湖周边进行排污管道调查,同时在西湖设置了监测样点对水体进行水质监测。根据调查资料,在对西湖进行现状分析的基础上,我们提出将生态修复技术应用于西湖周边城市环境整改的建议。     

滨海地区圈层模式的规划应用——以大连市北海湾规划为例

随着我国规划行业的快速发展,圈层模式被广泛应用。圈层模式是通过中心对周边地区产生影响——吸引相关功能集聚,并由中心向外围呈规则状、向心式和层次性扩散的发展模式。大连市北海湾规划探讨了圈层模式在滨海地区规划中的实践及应用,提出了\"中心选择—半径评估—圈层划分—圈层规划\"的规划手法,以便更好地指导该类地区的用地布局、滨水空间的塑造和环境品质的提升,为类似地区的规划设计和开发建设提供参考。