Saltwater intrusion in coastal regions of North America

2009 ◽  
Vol 18 (1) ◽  
pp. 247-260 ◽  
Author(s):  
Paul M. Barlow ◽  
Eric G. Reichard
Keyword(s):  
North America ◽  
Saltwater Intrusion ◽  
Coastal Regions

scholarly journals Cretaceous vegetational change: a biomal perspective

1992 ◽  
Vol 6 ◽  
pp. 295-295
Author(s):  
Garland R. Upchurch
Keyword(s):  
Species Diversity ◽  
North America ◽  
Late Cretaceous ◽  
High Latitude ◽  
Deciduous Forest ◽  
Terrestrial Ecosystems ◽  
High Latitudes ◽  
Coastal Regions ◽  
Show Evidence ◽  
Angiosperm Pollen

The Cretaceous rise of flowering plants marked an important transition in the modernization of terrestrial ecosystems. Well documented is the diversification of angiosperm pollen during the mid-Cretaceous and the migration of angiosperms from low latitudes to middle and high latitudes during the Barremian to Cenomanian. Global compilations of “species” diversity indicate a rapid rise in angiosperm diversity during the Albian to Cenomanian. This rise parallels a decline in the species diversity of archaic pteridophytes and the gymnosperm orders Cycadales, Bennettitales, Ginkgoales, Czekanowskiales, and Caytoniales. Late Cretaceous floras show more gradual trends in species diversity than mid-Cretaceous floras.Megafloral reconstructions of vegetation and climate for North America and other continents indicate warm temperatures in coastal regions of middle to high latitudes. Cretaceous biomes, however, often cannot be compared closely with Recent biomes. During much of the Cretaceous, conifers and other gymnosperms shared dominance with angiosperms in tropical and subtropical vegetation, unlike the Recent. During the Late Cretaceous, tropical rainforest was areally restricted. The few known leaf megafloras from equatorial regions indicate subhumid, rather than rainforest, conditions. Desert and semi-desert were widespread at lower latitudes and are documented by the occurrence of evaporite minerals in China, Africa, Spain, Mexico, and South America. Mid-latitude vegetation consisted of open-canopy broadleaved and coniferous evergreen woodlands that existed under subhumid conditions and low seasonality. High-latitude vegetation of the Northern Hemisphere consisted of coniferous and broadleaved deciduous forest, rather than boreal forest and tundra. High-latitude vegetation from coastal regions of the Southern Hemisphere consisted of evergreen conifers and angiosperms. Rainforest conditions appear to have been largely restricted to polar latitudes.Data on relative abundance, though often incomplete, indicate that angiosperms became ecologically important in tropical to warm subtropical broadleaved evergreen forests and woodlands by the Cenomanian. However, their rise to dominance took longer in other biomes. Conifers formed an important component of many Late Cretaceous biomes, and the persistence of archaic gymnosperms was strongly influenced by climate. Deciduous Ginkgoales, Czekanowskiales, Bennettitales, and Caytoniales are rare to absent in Late Cretaceous megafloras from warm subtropical to tropical climates, but they persist in megafloras from cooler climates. Archaic conifers such as Frenelopsis occur in megafloras representing low-latitude desert and semi-desert, but they are generally absent in more humid assemblages. Within mid-latitude broadleaved and coniferous evergreen woodland from North America, conifers show evidence for co-dominance with angiosperms into the early Maastrichtian. However, this co-dominance appears to have ended by latest Maastrichtian, which implies that vegetational reorganization occurred during the last few million years of the Cretaceous in North America.

Late Pleistocene stratigraphy of south-central British Columbia

1978 ◽  
Vol 15 (6) ◽  
pp. 971-980 ◽  
Author(s):  
Robert J. Fulton ◽  
Geoffrey W. Smith
Keyword(s):  
British Columbia ◽  
North America ◽  
Great Lakes ◽  
Late Pleistocene ◽  
Pacific Coast ◽  
Coastal Regions ◽  
South Central ◽  
The Pacific ◽  
Valley Area ◽  
Coast Region

The late Pleistocene deposits of south-central British Columbia record two major glacial and two major nonglacial periods of deposition. The oldest recognized Pleistocene deposits, called Westwold Sediments, were deposited during a nonglacial interval more than 60 000 years ago. Little information is available on the climate of this period, but permafrost may have been present at one time during final stages of deposition of Westwold Sediments. The latter part of this nonglacial period is probably correlative with the early Wisconsin Substage of the Great Lakes – St. Lawrence Valley area. However, deposition of the Westwold Sediments may have begun during the Sangamon Interglacial.Okanagan Centre Drift is the name applied to sediments deposited during the glaciation that followed deposition of Westwold Sediments. Okanagan Centre Drift is known to be older than 43 800 years BP and probably is older than 51 000. It is considered to correlate with an early Wisconsin glacial period.Bessette Sediments were deposited during the last major nonglacial period, which in south-central British Columbia persisted from at least 43 800 years BP (possibly more than 51 000) to about 19 000 years BP. This episode corresponds to Olympia Interglaciation of the Pacific Coast region and the mid-Wisconsin Substage of the Great Lakes – St. Lawrence Valley area. During parts of Olympia Interglaciation the climate was probably as warm as the present-day climate in the interior of British Columbia. Information from coastal regions indicates that there may have been periods of cooler and moister climate.Kamloops Lake Drift was deposited during the last major glaciation of south-central British Columbia. Ice occupied lowland areas from approximately 19 000 to 10 000 years BP. This period corresponds approximately to the Fraser Glaciation of the Pacific Coast region and the late Wisconsin Substage of central and eastern parts of North America.

METALTELLA SIMONI (KEYSERLING, 1878) (AMAUROBIIDAE) NEW TO CANADA, AND RECORDS FOR TEGENARIA GIGANTEA CHAMBERLIN AND IVIE, 1935, (AGELENIDAE) IN ALBERTA AND BRITISH COLUMBIA (ARACHNIDA: ARANEIDA)

1992 ◽  
Vol 124 (2) ◽  
pp. 419-420 ◽  
Author(s):  
Robin Leech ◽  
Marilyn Steiner
Keyword(s):  
United States ◽  
British Columbia ◽  
North America ◽  
The United States ◽  
Southern Brazil ◽  
Coastal Regions ◽  
Spider Species ◽  
Apparent Distribution

Metaltella simoni (Keyserling, 1878), an amaurobiid spider species precinctive to Argentina and Uruguay, and probably southern Brazil, is well established in the southeastern coastal regions of the United States (Leech 1972: 107). It was brought to North America by commercial and trade activities, hence the apparent distribution disjunction. The first Nearctic record is 23–30 July 1944, from Harahan, Louisiana (Leech 1972: 107).

scholarly journals NUMERICAL ANALYSIS OF EFFECTS OF HYDRAULIC GRADIENT ON MASS FLUX OF SALTWATER INTRUSION IN COASTAL AQUIFERS

2016 ◽  
Vol 22 (3) ◽  
pp. 7-17
Author(s):  
JAMES A. ADEGOKE ◽  
OLATUNDE I. POPOOLA ◽  
OLUDOTUN O. FALUY
Keyword(s):  
Numerical Analysis ◽  
Contaminant Transport ◽  
Mass Flux ◽  
Coastal Aquifers ◽  
Coastal Aquifer ◽  
Saltwater Intrusion ◽  
Hydraulic Head ◽  
Hydraulic Gradient ◽  
Coastal Regions ◽  
High Level

Coastal aquifers are distinguished from other aquifers because of saltwater intrusion effects, which cause contamination of groundwater in coastal regions. This study addressed the significance of hydraulic gradient and porosity of the coastal aquifers on contaminant transport of saltwater. Results showed hydraulic gradient of the aquifer has significant impact on the contaminant transport in coastal aquifer. When the hydraulic gradient between freshwater and saltwater is high and directed toward the sea, diffused rate of saltwater into the groundwater would be low. Therefore, hydraulic head of freshwater in coastal aquifer must be maintained at high level to control saltwater intrusion.

Dead Zones Discovered in Coastal Waters

Dead Zones ◽  
2021 ◽  
pp. 21-35
Author(s):  
David L. Kirchman
Keyword(s):  
North America ◽  
Gulf Of Mexico ◽  
Chesapeake Bay ◽  
Dead Zone ◽  
The Black Sea ◽  
Low Oxygen ◽  
Coastal Regions ◽  
Dead Zones ◽  
The World ◽  
The Baltic

This chapter describes the discovery of coastal dead zones, such as the Gulf of Mexico and Chesapeake Bay in North America and the Baltic and Black Seas in Europe. Gene Turner sailed out of Pascagoula, Mississippi, in the spring of 1975, on the first of seven cruises that led to the discovery of the Gulf of Mexico dead zone. In the Chesapeake Bay, an unlikely environmentalist, Charles Officer, sounded the alarm in 1984. The biggest dead zone, however, is the Baltic Sea. Even as early as 1969, ecologists feared hypoxia was turning the Baltic into a “biological desert.” The northwest shelf of the Black Sea turned hypoxic in the 1970s, which killed bottom-dwelling fish like goby and flounder. Many coastal regions around the world have low oxygen waters that devastate marine life and habitats. The early studies emphasized one or two of three ingredients—sewage, fresh water, and plant nutrients—thought to be essential in creating a dead zone. This chapter and Chapter 3 discuss these ingredients before revealing which is most important.

scholarly journals Using an airborne electromagnetic method to map saltwater intrusion in the northern Salinas Valley, California

Geophysics ◽  
2020 ◽  
Vol 85 (4) ◽  
pp. B119-B131
Author(s):  
Ian Gottschalk ◽  
Rosemary Knight ◽  
Theodore Asch ◽  
Jared Abraham ◽  
James Cannia
Keyword(s):  
Electrical Resistivity ◽  
Saltwater Intrusion ◽  
Groundwater Resources ◽  
Mitigation Strategies ◽  
Electromagnetic Signal ◽  
Confined Aquifer ◽  
Coastal Regions ◽  
Low Resistivity ◽  
Salinas Valley ◽  
Airborne Electromagnetic

Saltwater intrusion can pose a serious threat to groundwater quality in coastal regions. Estimating the extent of saltwater intrusion is vital for groundwater managers to plan appropriate mitigation strategies. The airborne electromagnetic (AEM) method is commonly used to evaluate groundwater resources, but it is challenging to apply in coastal environments because the low resistivity of saltwater-saturated aquifers attenuates the electromagnetic signal quickly and the relationship between electrical resistivity and pore water salinity is complex. However, if successful, the AEM method can supply information to address questions of critical importance in coastal regions. We investigated the extent of, and controls on, saltwater intrusion using the AEM method in the northern Salinas Valley, CA, USA. We collected 635 line-km of AEM data in the study area, the inversion results of which produced estimates of the electrical resistivity of the subsurface, reaching depths of between 50 and approximately 200 m below the ground surface. We have developed a relationship between the AEM electrical resistivity model and groundwater salinity, calibrated from borehole geophysical and water quality measurements, which allowed us to generate images revealing the distribution of saltwater and fresher groundwater in the study area. This fresher groundwater (defined as “a source of drinking water”) was successfully mapped out in the unconfined aquifer (the Dune Sand Aquifer) and the uppermost confined aquifer (the 180-Foot Aquifer) in the study area, illustrating a groundwater recharge process that helps mitigate saltwater intrusion in the 180-Foot Aquifer. Deep, low-resistivity bodies also were mapped, indicating regions where saltwater likely is migrating vertically from the 180-Foot Aquifer into the lower confined aquifer (the 400-Foot Aquifer). The findings from this case study demonstrate the value of acquiring AEM data for investigating the distribution of salinity in coastal aquifers impacted by saltwater intrusion.

scholarly journals Source contributions of sulfur and nitrogen deposition – an HTAP II multi model study on hemispheric transport

2018 ◽  
Author(s):  
Jiani Tan ◽  
Joshua S. Fu ◽  
Frank Dentener ◽  
Jian Sun ◽  
Louisa Emmons ◽  
...  
Keyword(s):  
Air Pollution ◽  
North America ◽  
East Asia ◽  
South Asia ◽  
Air Pollutants ◽  
Coastal Regions ◽  
The North ◽  
Source Regions ◽  
Low Emission ◽  
The Impact

Abstract. Abstract. With rising emissions by human activities, enhanced concentrations of air pollutants have been detected in hemispheric air flows in recent years, aggravating the regional air pollution and deposition burden. However, contributions of hemispheric air pollution to deposition at global scale have been given little attention in the literature. In this light, we assess the impact of hemispheric transport on sulfur (S) and nitrogen (N) deposition for 6 world regions: North America, Europe, South Asia, East Asia, Middle East and Russia in 2010, by using the multi-model ensemble results from the 2nd phase of Task Force Hemispheric Transport of Air Pollution (HTAP II) with and without 20 % emission perturbation experiments. About 27–58 %, 26–46 % and 12–23 % of local S, NOx and NH3 emissions are transported and removed by deposition outside of the source regions annually, with 5 % higher fraction of export in winter and 5 % lower in summer. For receptor regions, 20 % emission reduction in source regions affects the deposition in receptor regions by 1–10 % for continental non-coastal regions and 1–15 % for coastal regions and open oceans. Significant influences are found from North America to the North Atlantic Ocean (5–15 %), from South Asia to western East Asia (2–10 %) and from East Asia to the North Pacific Ocean (5–10 %) and western North America (5–8 %). The impact on deposition caused by transport between neighbouring regions (i.e. Europe and Russia) occurs throughout the whole year (slightly stronger in winter), while that by transport over long distances (i.e. from East Asia to North America) mainly takes place in spring and fall, which is consistent with the seasonality found for hemispheric transport of air pollutants. Deposition in emission intense regions such as East Asia is dominated (~ 80 %) by own region emission, while deposition in low emission regions such as Russia is almost equally affected by own region emission (~ 40 %) and foreign impact (~ 23–45 %). We also find that deposition on the coastal regions or near coastal open ocean is twice more sensitive to hemispheric transport than non-coastal continental regions, especially for regions (i.e. west coast of North America) in the downwind location of major emission source regions. This study highlights the significant impact of hemispheric transport on deposition in coastal regions, open ocean and low emission regions. Further research is proposed for improving ecosystem and human health in these regions, with regards to the enhanced hemispheric transport.

scholarly journals NUMERICAL ANALYSIS OF EFFECTS OF HYDRAULIC GRADIENT ON MASS FLUX OF SALTWATER INTRUSION IN COASTAL AQUIFERS

2017 ◽  
Vol 22 (3) ◽  
Author(s):  
JAMES A. ADEGOKE ◽  
OLATUNDE I. POPOOLA ◽  
OLUDOTUN O. FALUY
Keyword(s):  
Numerical Analysis ◽  
Contaminant Transport ◽  
Mass Flux ◽  
Coastal Aquifers ◽  
Coastal Aquifer ◽  
Saltwater Intrusion ◽  
Hydraulic Head ◽  
Hydraulic Gradient ◽  
Coastal Regions ◽  
High Level

<p>Coastal aquifers are distinguished from other aquifers because of saltwater intrusion effects, which cause contamination of groundwater in coastal regions. This study addressed the significance of hydraulic gradient and porosity of the coastal aquifers on contaminant transport of saltwater. Results showed hydraulic gradient of the aquifer has significant impact on the contaminant transport in coastal aquifer. When the hydraulic gradient between freshwater and saltwater is high and directed toward the sea, diffused rate of saltwater into the groundwater would be low. Therefore, hydraulic head of freshwater in coastal aquifer must be maintained at high level to control saltwater intrusion.</p>

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