13 research outputs found
Coastal scenic assessment and tourism management in western Cuba
Coastal scenic assessments via checklist tables (18 natural, 8 human related parameters), can provide
benchmark measures regarding desirable/non-desirable beach conditions and also classify sites. The
scenic value for 43 sites in western Cuba was investigated, with the aim of helping managers improve
bathing areas, especially for tourism purposes. Sites were categorised from Class 1, (top grade scenery),
between La Habana and Matanzas, as extremely attractive, with white sand, turquoise water and
additional scenic elements. Class 2 sites were located in Varadero, and their high scores were greatly due
to appropriate human interventions, e.g. beach nourishment and dune restoration works. Classes 3 to 5
(the latter having very poor scenery), included sites with low scores for natural parameters. For these
sites, coastal managers can do little to alleviate scenic impact, apart from addressing the human parameters,
where improvement is possible, e.g. by litter removal together with the present chaotic protective
structures
Sources of land-derived runoff to a coral reef-fringed embayment identified using geochemical tracers in nearshore sediment traps
This paper is not subject to U.S. copyright. The definitive version was published in Estuarine, Coastal and Shelf Science 85 (2009): 459-471, doi:10.1016/j.ecss.2009.09.014.Geochemical tracers, including Ba, Co, Th, 7Be, 137Cs and 210Pb, and magnetic properties were used to characterize terrestrial runoff collected in nearshore time-series sediment traps in Hanalei Bay, Kauai, during flood and dry conditions in summer 2006, and to fingerprint possible runoff sources in the lower watershed. In combination, the tracers indicate that runoff during a flood in August could have come from cultivated taro fields bordering the lower reach of the river. Land-based runoff associated with summer floods may have a greater impact on coral reef communities in Hanalei Bay than in winter because sediment persists for several months. During dry periods, sediment carried by the Hanalei River appears to have been mobilized primarily by undercutting of low 7Be, low 137Cs riverbanks composed of soil weathered from tholeiitic basalt with low Ba and Co concentrations. Following a moderate rainfall event in September, high 7Be sediment carried by the Hanalei River was probably mobilized by overland flow in the upper watershed. Ba-desorption in low-salinity coastal water limited its use to a qualitative runoff tracer in nearshore sediment. 210Pb had limited usefulness as a terrestrial tracer in the nearshore due to a large dissolved oceanic source and scavenging onto resuspended bottom sediment. 210Pb-scavenging does, however, illustrate the role resuspension could play in the accumulation of particle-reactive contaminants in nearshore sediment. Co and 137Cs were not affected by desorption or geochemical scavenging and showed the greatest potential as quantitative sediment provenance indicators in material collected in nearshore sediment traps
Nitrogen transport, transformation, and retention in the Three Gorges Reservoir: A mass balance approach
Dam construction in river systems affects the biogeochemistry of nitrogen (N), yet most studies on N cycling in reservoirs do not consider the transformations and retention of the different N species. This study addresses the N inputs, transport, transformations, and retention in the Three Gorges Reservoir (TGR) in the Changjiang River, the world largest water storage project, during its filling phase in 2004–2007. The results indicate that dissolved inorganic nitrogen (DIN) was the most abundant N form in the TGR and particulate N was only 2% to the total N flow and retention. About 34% of the dissolved organic nitrogen (DON), 64% of nitrite, and 44% of ammonia were retained by transformation within the TGR in 2007. Time-series data show that about 8% of inflowing total dissolved N was lost by denitrification and sedimentation. Transformations of DON, nitrite and ammonia caused an increase of the nitrate load by 6%; and at the same time the DIN flux increased by 4% while the water moved through the TGR, which is the balance between formation and retention of DIN. The large contribution of biogeochemical transformations to nitrate loading in the TGR indicates the importance of internal processing for the river N species composition