Ecological effects from the balance between new and recycled nitrogen in Texas coastal waters     

R. Warren Flint  Gary L. Powell  Richard D. Kalke 《Estuaries and Coasts》1986,9(4):284-294

Benthic nutrient recycling is a significant source of dissolved nitrogen for south Texas coastal waters in the region of the Corpus Christi Bay estuary. Studies indicate that 90% of the dissolved nitrogen supply for phytoplankton production is derived from sediments in the upper-estuary, whereas benthic regeneration supplies only 33% of the dissolved nitrogen required for primary production outside the barrier island in coastal waters (15 m depth). In the upper-estuary relationships were observed between fluvial flow, water-column dissolved nitrogen, and phytoplankton productivity. In the middle-estuary relationships were observed between sediment recycling rates and water-column dissolved nitrogen. Beyond the barrier island, relationships were observed between fluvial flow and water-column dissolved nitrogen during high flow periods, while benthic regeneration appeared to be the major nutrient source during low flow periods. We suggest that combined effects from new and recycled nutrient sources buffer south Texas coastal productivity against long periods of low nutrient input from fluvial flow. The comparison of biological responses at several trophic levels to temporal variability in nitrogen recycling and fluvial flow indicated the importance of freshwater nitrogen inputs in stimulating primary production. Freshwater nitrogen inputs also appeared to sustain long-term productivity by replacing nutrients lost from the system by extended reliance upon recycling.  相似文献   

Estuarine benthos: Long-term community structure variations,corpus Christi Bay,Texas     

R. W. Flint  J. A. Younk 《Estuaries and Coasts》1983,6(2):126-141

A study of the benthic communities in Corpus Christi Bay was carried out between 1974 and 1979 to identify both natural and human-induced variations in community dynamics of the benthos over a long time period of monthly samples collection. General results of the investigation were comparable to previous shorter-term studies of this estuary in respect to species list of dominant fauna, total densities and species diversity measures. The present study emphasized two habitats: a channel 15 m deep and a shoal less than 3.5 m deep. Channel stations exhibited lower species numbers, densities, and species diversity than shoal sites but in contrast showed more even distributions of population numbers between species (equitability) than shoal sites. Hierarchical classification procedures identified community structure patterns that were associated with a major disturbance to the area, dredging, as well as minor, more frequent disturbances associated with large ship traffic and shrimp trawling activities in the channel. The community variable of species number and total density were also related to changes in salinity patterns in the study area. The results of this long-term study illustrated the resilience of benthic communities to disturbance. They also provided supportive evidence to hypotheses concerning the high resistence of communities to disturbance in inconstant environments and the source of colonists in these environments after a major disturbance to the bottom.  相似文献   

Sedimentary Waves and Reconstruction of Bottom Currents in the Novaya Zemlya Trough of the Kara Sea     

Baranov  B. V.  Flint  M. V.  Rimskiy-Korsakov  N. A.  Poyarkov  S. G.  Dozorova  K. A. 《Doklady Earth Sciences》2021,498(1):432-435

Doklady Earth Sciences - Reconstruction of bottom currents has been performed for the first time using the distribution of sedimentary waves in the Novaya Zemlya Trough in the Kara Sea based on the...  相似文献   

Marine environmental monitoring in the shelf zone of the Black Sea: Assessment of the current state of the pelagic ecosystem     

E. G. Arashkevich  N. E. Louppova  A. B. Nikishina  L. A. Pautova  V. K. Chasovnikov  A. V. Drits  O. I. Podymov  N. D. Romanova  R. R. Stanichnaya  A. G. Zatsepin  S. B. Kuklev  M. V. Flint 《Oceanology》2015,55(6):871-876

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Stratigraphic hierarchy and three-dimensional evolution of an exhumed submarine slope channel system     

Daniel Bell  David M. Hodgson  Anna S. M. Pontén  Larissa A. S. Hansen  Stephen S. Flint  Ian A. Kane 《Sedimentology》2020,67(6):3259-3289

Submarine slope channel systems have complicated three-dimensional geometries and facies distributions, which are challenging to resolve using subsurface data. Outcrop analogues can provide sub-seismic-scale detail, although most exhumed systems only afford two-dimensional constraints on the depositional architecture. A rare example of an accessible fine-grained slope channel complex set situated in a tectonically quiescent basin that offers seismic-scale, down-dip and across-strike exposures is the Klein Hangklip area, Tanqua-Karoo Basin, South Africa. This study investigates the three-dimensional architecture of this channel complex set to characterise the stratigraphic evolution of a submarine channel-fill and the implications this has for both sediment transport to the deep-oceans and reservoir quality distribution. Correlated sedimentary logs and mapping of key surfaces across a 3 km² area reveal that: (i) the oldest channel elements in channel complexes infill relatively deep channel cuts and have low aspect-ratios. Later channel elements are bound by comparatively flat erosion surfaces and have high aspect-ratios; (ii) facies changes across depositional strike are consistent and predictable; conversely, facies change in successive down depositional dip positions indicating longitudinal variability in depositional processes; (iii) stratigraphic architecture is consistent and predictable at seismic-scale both down-dip and across-strike in three-dimensions; (iv) channel-base-deposits exhibit spatial heterogeneity on one to hundreds of metres length-scales, which can inhibit accurate recognition and interpretations drawn from one-dimensional or limited two-dimensional datasets; and (v) channel-base-deposit character is linked to sediment bypass magnitude and longevity, which suggests that time-partitioning is biased towards conduit excavation and maintenance rather than the fill-phase. The data provide insights into the stratigraphic evolution and architecture of slope channel-fills on fine-grained continental margins and can be utilised to improve predictions derived from lower resolution and one-dimensional well data.  相似文献   

Stratigraphic evolution of the upper slope and shelf edge in the Karoo Basin, South Africa     

R. Wild  S. S. Flint  D. M. Hodgson 《Basin Research》2009,21(5):502-527

The Permian Ecca Group of the Karoo Basin, South Africa preserves an extensive well-exposed siliciclastic basin floor, slope and shelf-edge delta succession. The Kookfontein Formation includes multiple sedimentary cycles that display clinoform geometries and are interpreted to represent the deposits of a slope to shelf succession. The succession exhibits progradational followed by aggradational stacking of deltaic cycles that is related to a change in shelf-edge trajectory, and lies within two depositional sequences. Sediment was transferred to the slope via overextension of deltas onto and over the shelf edge, resulting in failure and re-adjustment of local slope gradients. The depositional facies and architecture of the Kookfontein Formation record the change from a bypass- to accretion-dominated margin, which is interpreted to reflect a decrease in sediment transport efficiency as the slope gradient decreased, slope length increased and shelf-edge trajectory rose. During this time the delivery system changed from point-sourced basin-floor fans fed by slope channels to starved basin-floor with sand-rich slope clinoforms. This is an example of a progradational margin in which the younger slope system is interpreted to be of a different style to the older slope system that fed the underlying sand-rich basin floor fans.  相似文献   

Artificial recharge through a thick, heterogeneous unsaturated zone   总被引：2，自引：0，他引：2  

Izbicki JA  Flint AL  Stamos CL 《Ground water》2008,46(3):475-488

Thick, heterogeneous unsaturated zones away from large streams in desert areas have not previously been considered suitable for artificial recharge from ponds. To test the potential for recharge in these settings, 1.3 x 10(6) m(3) of water was infiltrated through a 0.36-ha pond along Oro Grande Wash near Victorville, California, between October 2002 and January 2006. The pond overlies a regional pumping depression 117 m below land surface and is located where thickness and permeability of unsaturated deposits allowed infiltration and saturated alluvial deposits were sufficiently permeable to allow recovery of water. Because large changes in water levels caused by nearby pumping would obscure arrival of water at the water table, downward movement of water was measured using sensors in the unsaturated zone. The downward rate of water movement was initially as high as 6 m/d and decreased with depth to 0.07 m/d; the initial time to reach the water table was 3 years. After the unsaturated zone was wetted, water reached the water table in 1 year. Soluble salts and nitrate moved readily with the infiltrated water, whereas arsenic and chromium were less mobile. Numerical simulations done using the computer program TOUGH2 duplicated the downward rate of water movement, accumulation of water on perched zones, and its arrival at the water table. Assuming 10 x 10(6) m(3) of recharge annually for 20 years, a regional ground water flow model predicted water level rises of 30 m beneath the ponds, and rises exceeding 3 m in most wells serving the nearby urban area.  相似文献   

Structural and Functional Characteristics of Zooplankton in the Ob Estuary and Adjacent Shelf Areas of the Kara Sea in Summer     

Drits  A. V.  Arashkevich  E. G.  Nedospasov  A. A.  Amelina  A. B.  Flint  M. V. 《Oceanology》2019,59(3):347-357

Oceanology - The study was carried out in the Ob estuary and the adjacent shelf of the Kara Sea in July 2016. For the first time data on the species composition, abundance and distribution as well...  相似文献   

Ecosystems of the Siberian Arctic Seas 2018 (Cruise 72 of the R/V Akademik Mstislav Keldysh)     

Flint  M. V.  Poyarkov  S. G.  Rimskii-Korsakov  N. A.  Miroshnikov  A. Yu. 《Oceanology》2019,59(3):460-463

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Phytoplankton of the Khatanga Bay,Shelf and Continental Slope of the Western Laptev Sea     

Sukhanova  I. N.  Flint  M. V.  Fedorov  A. V.  Sakharova  E. G.  Artemyev  V. A.  Makkaveev  P. N.  Nedospasov  A. A. 《Oceanology》2019,59(5):648-657

Oceanology - The studies were conducted along the transect (11 stations) from the inner part of Khatanga Bay in the south to the Laptev Sea continental slope in the north in September 17—20,...  相似文献