Clay dispersal and the geochemistry of manganese in the Northern Gulf of California

Daesslé, Luis Walter; Ramos, Susana; Carriquiry, José D.; Camacho-Ibar, Víctor F.

doi:10.1016/s0278-4343(02)00007-9

Cited by 23 publications

(18 citation statements)

References 23 publications

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“…We also found that sediment transport has a tendency to cross the basin toward the Baja California coast, an area known as very shallow. In agreement with the present investigation, a recent study using geochemical tracers (Daesslé et al 2002) reveals a transport of sediment in the Colorado River Delta, which is deposited in areas adjacent to the coast of Baja California.…”

Section: Discussionsupporting

confidence: 93%

Numerical experiments on the long-term morphodynamics of the Colorado River Delta

Montaño

Carbajal

2007

Ocean Dynamics

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The interaction among tidal currents, sediment transport, and long-term changes of the sea bottom in the Colorado River Delta have been investigated applying a two dimensional nonlinear hydrodynamic-numerical finite differences model. The system was forced by the dominant M 2 tidal component at the open boundary. We carried out calculations to study the morphodynamics of the actual bathymetry caused by the bedload sediment transport. To investigate the origin of actual morphological features, we performed experiments using a smoothed bathymetry, in which the islands Montague, Gore, and Pelícano were eliminated. Under the imposed tidal hydrodynamics, the results indicate that the bedload transport contributes significantly in the genesis of sandbanks and in the formation and maintaining of the Montague and Gore Islands.

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Section: Discussionsupporting

confidence: 93%

Numerical experiments on the long-term morphodynamics of the Colorado River Delta

Montaño

Carbajal

2007

Ocean Dynamics

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“…As the bore travels, it generates turbulence and bottom sediment re-suspension, yielding higher concentrations of suspended sediment at the head of estuary and promoting large scale mobilization of sediment into the upper Gulf of California, mainly through the western (Baja California) tidal channel (Carriquiry and Sánchez 1999). Fine-grained material is further transported into de Gulf of California mainly along the coast of Baja California by tidal currents, baroclinic circulation and gravity current events (Carriquiry et al 2001;Á lvarez and Jones 2002;Daesslé et al 2002;Palacios-Hernánez et al 2002). According to Alvarez and Jones, net near-bed sediment fluxes out of the upper Gulf of California due to gravity currents may reach 2.5 g m -2 s -1 during neap tides.…”

Section: Study Areamentioning

confidence: 99%

“…Later research by Daesslé et al (2002) suggests an active re-suspension and dispersion of clay-sized material derived from the delta and adjacent platforms along the Baja California coast toward the deeper basins in the central Gulf of California (Fig. 1).…”

Section: Introductionmentioning

confidence: 96%

“…1). These clays are characterized by their relatively high metal contents and a characteristic partitioning of Mn within the more labile sediment phases (Daesslé et al 2002(Daesslé et al , 2004). It appears, however, that sediments from the upper Gulf of California (UGC) remain relatively unaffected by anthropogenic metal-input (Shumilin et al 2002), with only minor enrichments of As in buried (\1 m) sediments (Daesslé et al 2009).…”

Section: Introductionmentioning

confidence: 99%

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The effects of damming on the materials flux in the Colorado River delta

et al. 2010

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During the last century, the Colorado River delta (CRD) has been dramatically altered by the diversion of river water for use in human activities. This alteration has eliminated the delivery of fresh water to the Gulf of California radically transforming the former estuary into an inverse-estuary. Under the new conditions, the new materials budget was estimated at the mouth of the Colorado River in terms of salts, total suspended sediments, organic suspended matter and nutrients. The results of this study show that, because of the asymmetry of the tidal wave, the variability of seston concentration follows a sedimentation pattern of three successive stages: re-suspension (erosion at ebb flow) [ dilution (during flood flow) [ sedimentation (at the end of the flood stage). The tidal asymmetry during neap tides was characterized by longer ebb (at least, 30 min longer) than flood and more intense ebb currents (as much as 43% higher), hence characterizing an ebbdominated system. The CRD is characterized by high nutrients concentrations. Maximal levels are: nitrates (41 lM), phosphates (2.6 lM) and silicates (68 lM), nitrite (15 lM). The mass balance indicates that the system acts as a net exporter of suspended sediment with rates as high as 7 tons per tidal cycle. This behavior indicates that the CRD is in a destructive stage as a result of the lack of freshwater inflow and supply of sediment into the system.

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“…Therefore, the results regarding pollution from land activities are of limited relevance. In this sense, once organic and chemical pollutants reach the sea they can be dispersed from a few to hundreds of kilometres away from their sources on land (Ernst et al, 2001;Daesslé et al, 2002); significant changes in the discharge of major rivers can generate very different patterns of sediment dispersion (Carriquiry and Sánchez, 1999;Carriquiry et al, 2001;Daesslé et al, 2002), and even areas considered pristine have been found to be polluted by heavy metals derived from human activities located far away (Spongberg, 2004;Méndez et al, 2005). Nonetheless, concentrations of organic and chemical matter remain higher close to their source areas (Bástidas et al, 1999;Spongberg, 2004) where bioaccumulation in organisms is also greatest, as shown for dolphins by Litz et al (2007) in a metropolitan-rural comparison.…”

Section: Discussionmentioning

confidence: 99%

A proposal to define vulnerability of cetacean areas to human development: variables and analysis procedures applied to the Gulf of California

Cubero-Pardo

Donovan

Urbán‐Ramírez

2011

Aquatic Conservation

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ABSTRACT1. Understanding spatial interactions between specific sources of anthropogenic impact on cetaceans and the ecological conditions intrinsic to these mammals, has several applications for conservation and management. Here cetacean habitats are classified into vulnerability levels by combining human development metrics and cetacean characteristics, allowing areas identified as more vulnerable to be given management priority.2. Ten bio-physical and anthropogenic factors were identified as key shapers of cetacean habitats and, using the Gulf of California as a case study, 18 variables were defined to measure those factors. Principal component analysis (PCA) and GIS were used to distill the relationships across all variables, in order to obtain a vulnerability index. Aggregates of variables were also investigated to map the spatial distribution of anthropogenic impacts and cetacean characteristics (species richness, relative abundance of encounter, residence condition, diet specificity and threat status). For this latter purpose, separate indices representing five 'categories' (pollution from land sources, urban development, potential for accidents, resource depletion and fragility of cetacean areas) and three 'vulnerability components' (risk of hazards, intrinsic resilience and damage) were calculated.3. The methodology clearly differentiated the study area according to levels for each 'category' and 'vulnerability component', as well as to levels of vulnerability of cetacean areas in relation to human activities; and identified those variables with the greatest contributions, without recourse to the subjective criteria common in other approaches. The analyses were conducted using environmental units generated by the Marine Ecological Zoning Plan for the Gulf of California (OEMGC, by its Spanish acronym) which tied model outputs to this planning framework. The variables selected were easily obtainable through governmental and research institutions which make them suitable for adaptive management purposes.

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Clay dispersal and the geochemistry of manganese in the Northern Gulf of California

Cited by 23 publications

References 23 publications

Numerical experiments on the long-term morphodynamics of the Colorado River Delta

Numerical experiments on the long-term morphodynamics of the Colorado River Delta

The effects of damming on the materials flux in the Colorado River delta

A proposal to define vulnerability of cetacean areas to human development: variables and analysis procedures applied to the Gulf of California

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