scholarly journals Drilling, construction, water chemistry, water levels, and regional potentiometric surface of the upper carbonate-rock aquifer in Clark County, Nevada, 2009–2015

2019 ◽  
Author(s):  
Jon W. Wilson
Keyword(s):  
Water Chemistry ◽  
Carbonate Rock ◽  
Water Levels ◽  
Clark County ◽  
Potentiometric Surface

Water levels in carbonate rock terranes

1972 ◽  
Vol 16 (1) ◽  
pp. 65
Keyword(s):  
Carbonate Rock ◽  
Water Levels

scholarly journals Complex effects of acidification, habitat properties and fish stock on littoral macroinvertebrate assemblages in montane standing waters

2022 ◽  
Author(s):  
Jana Petruželová ◽  
Jindřiška Bojková ◽  
Jan Sychra ◽  
Vanda Šorfová ◽  
Vendula Polášková ◽  
...  
Keyword(s):  
Species Composition ◽  
Water Chemistry ◽  
Water Levels ◽  
Habitat Characteristics ◽  
Fish Stock ◽  
Littoral Vegetation ◽  
Habitat Properties ◽  
Standing Waters ◽  
The Impact ◽  
Local Habitat

Littoral macroinvertebrates in acidified waterbodies are affected by the interaction of acidification and local environmental conditions. Understanding the interplay of these factors in the structuring of communities is essential for interpreting responses to and/or recovery from acidification. Here, we analyse the species composition and richness of littoral macroinvertebrates in a range of acidified montane standing waters in relation to water chemistry, littoral characteristics and fish stock. The main species composition gradients were related to pH and conductivity; however, considerable variation along these gradients was associated with local habitat characteristics (changing water levels and littoral structure) and concentration of ionic aluminium and dissolved organic carbon. Although fish stock effects were confounded by correlated acidity, we observed a significant decline in abundance of macroinvertebrates vulnerable to fish predation at sites with fish stock. Overall, littoral macroinvertebrates of acidic waterbodies were diverse due to the heterogeneity of local habitat properties, despite they were dominated by acid-tolerant species. Acidic humic sites with dense, heterogeneous littoral vegetation were species-rich, hosting numerous habitat specialists and rare species, while chronically acidified lakes with high aluminium concentrations and sparse littoral vegetation had species-poor assemblages, characteristic of strong acid-stress. Water level manipulation resulted in serious assemblage impoverishment, overriding the effects of more favourable water chemistry. This study shows that the littoral fauna of acidic waterbodies is structured by complex effects induced by local factors in addition to acidity, resulting in acid-stressed assemblages with relatively high variability, emphasising a need to analyse local habitat factors when evaluating the impact of acidification on macroinvertebrates.

Water Levels in Carbonate Rock Terranesa

Ground Water ◽  
1971 ◽  
Vol 9 (3) ◽  
pp. 4-10 ◽  
Author(s):  
Harry E. LeGrand ◽  
V. T. Stringfield
Keyword(s):  
Carbonate Rock ◽  
Water Levels

On the long-term hydraulic gradient in the thick clayey aquitard in the Sarnia region, Ontario

1998 ◽  
Vol 35 (6) ◽  
pp. 986-1003 ◽  
Author(s):  
Muin M Husain ◽  
John A Cherry ◽  
Scott Fidler ◽  
Shaun K Frape
Keyword(s):  
Water Use ◽  
Hydraulic Gradient ◽  
Water Levels ◽  
Transient Condition ◽  
Large Area ◽  
Bottom Part ◽  
Transport Modelling ◽  
Well Drilling ◽  
Potentiometric Surface

Much of the southwestern part of Ontario between Lake Huron and Lake Erie has a thin freshwater aquifer overlain by an aquitard of Late Pleistocene clayey glaciolacustrine deposits and underlain by a thick Devonian shale aquitard. In a large area east of the St. Clair River, where the Quaternary aquitard is 30-50 m thick, groundwater of Pleistocene origin (identified by 18O and 2H signature) occurs in the aquifer and in the bottom part of the Quaternary aquitard. Numerous piezometer nests in the aquitard show a downward hydraulic gradient with depth. In some areas, the aquitard has downward gradients only in the upper part and upward gradient in the lower part, indicating a transient condition. The piezometer nests in the clayey aquitard also show an increase in Cl- concentration with depth. Long-term piezometer monitoring at two sites show a major shift in the aquitard hydraulic gradient since 1983 and a large rise in head in the underlying aquifer. Analyses of initial aquifer water levels, reported in well drilling records, indicate a large decline in the potentiometric surface of the aquifer between the 1940's and the 1970's followed by a recent rise in the surface in part of the region. This pattern is consistent with well drilling and water use records indicating that 7000 wells were installed in the aquifer in the three decades since 1940 and that groundwater use has greatly diminished in the past 10-15 years due to rural pipeline distribution of lake and river water. The hydraulic gradient in the aquitard is slowly adjusting to the rise in the aquifer potentiometric surface. One-dimensional solute transport modelling provides close matches to the vertical profiles of Cl- migrating upward from the aquifer since deglaciation, 15 000 - 18 000 years before present, by diffusion with little or no advection. The lack of advection indicates a near-neutral long-term hydraulic gradient. As the withdrawal rate of water from the aquifer continues to decline, it is expected that the hydraulic head in the aquitard in much of the area westward of the recharge area will continue to adjust for many decades.Key words: clay, aquitard, aquifer, water use, hydraulic gradient.

Phytoplankton community relationship to environmental variables in three Kenyan Rift Valley saline-alkaline lakes

2008 ◽  
Vol 59 (2) ◽  
pp. 125 ◽  
Author(s):  
Michael Schagerl ◽  
S. O. Oduor
Keyword(s):  
Water Chemistry ◽  
Water Temperature ◽  
Rift Valley ◽  
Phytoplankton Community ◽  
Ionic Composition ◽  
Light Attenuation ◽  
Water Levels ◽  
Total Alkalinity ◽  
Tropical Lakes ◽  
Nutrient Concentrations

Temporal changes in total alkalinity, ionic composition and nutrient concentrations were studied in the saline, alkaline endorheic Kenyan Rift Valley Lakes Bogoria, Nakuru and Elmentaita to understand the association of these variables with phytoplankton community structure. In total, 24 taxa were found, with L. Bogoria having the fewest species. Although the cyanobacterium Arthrospira fusiformis dominated the phytoplankton biomass, especially in L. Bogoria, other groups came into play especially during high water levels in L. Nakuru and L. Elmentaita. Cluster analysis based on species biomass resulted in four groups, characterised by 13 indicator taxa. Most of the variation in these groups appeared to be associated with hydrological stability and perhaps biological factors rather than water chemistry, which only explained 44% of the variance in taxa composition on the first four axes derived from redundancy analysis. Species numbers decreased with elevated conductivity and water temperature. Synechocystis sp. occurrence coincided with phosphorus, water temperature and conductivity increase, whereas the distributions of Arthrospira fusiformis and Arthrospira platensis were mainly influenced by both light attenuation and elevated nitrate concentrations. Increases in silica and ammonium and declines in conductivity, total phosphorus and water temperature enhanced diatom abundances. Not only do the results of the present study indicate the unexpectedly high variability of phytoplankton community composition and water chemistry in these three alkaline tropical lakes, but also the data assist our understanding of the factors influencing flamingo populations on these lakes, which are significant conservation reserves and tourist attractions.

Sign in / Sign up

Export Citation Format

Share Document