scholarly journals Biogeochemical and Hydrological Drivers of Heterogeneous Nutrient Exports From Subterranean Estuaries

2021 ◽  
Vol 8 ◽  
Author(s):  
Andrea J. Pain ◽  
Jonathan B. Martin ◽  
Caitlin R. Young
Keyword(s):  
Land Use ◽  
Chemical Composition ◽  
Groundwater Discharge ◽  
Nutrient Concentrations ◽  
Nutrient Export ◽  
Coastal Zones ◽  
Fresh Groundwater ◽  
Redfield Ratio ◽  
Subterranean Estuary ◽  
Subterranean Estuaries

Submarine groundwater discharge (SGD) to coastal zones contributes terrestrial freshwater and nutrients that may support harmful algal blooms (HABs). The magnitude of nutrient exports via SGD depends on volumes of fresh groundwater discharge, its chemical composition, and modifications by biogeochemical processing within subterranean estuaries. Thus, the ability to upscale SGD exports requires knowing the range of chemical composition of inland groundwater and how those compositions may be transformed as fresh and saltwater mix within subterranean estuaries. These processes may create heterogeneous magnitudes of solute exports, even at small spatial scales, and such heterogeneities have rarely been assessed for regional or global SGD nutrient export estimates. To evaluate heterogeneity in subterranean estuary processes and nutrient export, we collected seasonal pore water samples in 2015–2016 at three proximal (<20 km) subterranean estuary sites in Indian River Lagoon, FL. Sites have homogenous hydrogeological settings, but differ in land use and coastal features, and include a mangrove site, an urban site, and a site offshore of a natural wetland. All sites exhibit little variation through time in nutrient concentrations and modeled SGD rates. In contrast, each site exhibits significantly different nutrient concentrations of potential fresh groundwater sources, fresh groundwater discharge volumes, and nutrient transformations within subterranean estuaries. Groundwater specific discharge correlates with nutrient concentrations, suggesting that higher residence times in the subterranean estuary increase biogeochemical transformations that reduce anthropogenic nutrient loads but increase in situ nutrient sources derived from organic matter remineralization. The differences in transformations lead to SGD nutrient contributions that differ by orders of magnitude between sites and have N:P ratios that are greater than the Redfield ratio (15) for the mangrove (29) and urban sites (28), but less than the Redfield ratio for the wetland site (8). These results indicate that heterogeneity of both absolute and relative nutrient export via SGD complicates integration of nutrient fluxes across regional coastal zones and evaluations of its impacts to coastal ecosystems. A better understanding of the drivers of heterogeneity, including subterranean estuary processes, land use, coastal topography, and vegetation dynamics could improve assessments of regional nutrient loading and upscaling for estimates of global solute cycles.

scholarly journals Studies on Groundwater Problems in an Area Subjected to Sea Water Ingression and Seepage Into Groundwater in Karaikal District Using GIS

2018 ◽  
Vol 7 (3.10) ◽  
pp. 150
Author(s):  
T Subramani ◽  
P Krishnan
Keyword(s):  
Water Quality ◽  
Coastal Waters ◽  
Submarine Groundwater Discharge ◽  
Sea Water ◽  
Groundwater Discharge ◽  
Treated Wastewater ◽  
Coastal Zones ◽  
Fresh Groundwater ◽  
Submarine Groundwater ◽  
Pumping Rates

Fresh groundwater quality and accessibility in coastal zones is influenced via seawater interruption into coastal aquifers, and coastal water quality and biological community status might be altogether influenced by groundwater pollutants that are transported into coastal waters by submarine groundwater discharge (SGD). SGD and its pertinent evaluation as one associating part  among the different principle local pathways of freshwater and tracer/poison contributions from land to sea and the coordinated framework working of both and as primary segments of the same coastal groundwater framework. An elective technique might be to control seawater interruption through fake groundwater revive, for example by adequately treated wastewater, which may impressively decrease long haul patterns of saltiness increment in pumped groundwater, notwithstanding for little simulated energize rates contrasted with pumping rates. Both the outside sources and the interior wellsprings of water seepage might be distinguished via doing infrared thermo-realistic assessments subsequent to directing water snugness tests, flooding tests or pressure driven tests as suitable. A contextual investigation was led to discover the examinations on groundwater issues in a region subjected to sea water ingression and seepage into groundwater in Karaikal   

scholarly journals Conceptual Mini-Catchment Typologies for Testing Dominant Controls of Nutrient Dynamics in Three Nordic Countries

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1776 ◽  
Author(s):  
Fatemeh Hashemi ◽  
Ina Pohle ◽  
Johannes W.M. Pullens ◽  
Henrik Tornbjerg ◽  
Katarina Kyllmar ◽  
...  
Keyword(s):  
Land Use ◽  
Nutrient Dynamics ◽  
Pollution Monitoring ◽  
Organic N ◽  
Particulate Phosphorus ◽  
Nutrient Concentrations ◽  
Data Series ◽  
Nutrient Export ◽  
Small Streams ◽  
Export Behaviour

Optimal nutrient pollution monitoring and management in catchments requires an in-depth understanding of spatial and temporal factors controlling nutrient dynamics. Such an understanding can potentially be obtained by analysing stream concentration–discharge (C-Q) relationships for hysteresis behaviours and export regimes. Here, a classification scheme including nine different C-Q types was applied to a total of 87 Nordic streams draining mini-catchments (0.1–65 km2). The classification applied is based on a combination of stream export behaviour (dilution, constant, enrichment) and hysteresis rotational pattern (clock-wise, no rotation, anti-clockwise). The scheme has been applied to an 8-year data series (2010–2017) from small streams in Denmark, Sweden, and Finland on daily discharge and discrete nutrient concentrations, including nitrate (NO3−), total organic N (TON), dissolved reactive phosphorus (DRP), and particulate phosphorus (PP). The dominant nutrient export regimes were enrichment for NO3− and constant for TON, DRP, and PP. Nutrient hysteresis patterns were primarily clockwise or no hysteresis. Similarities in types of C-Q relationships were investigated using Principal Component Analysis (PCA) considering effects of catchment size, land use, climate, and dominant soil type. The PCA analysis revealed that land use and air temperature were the dominant factors controlling nutrient C-Q types. Therefore, the nutrient export behaviour in streams draining Nordic mini-catchments seems to be dominantly controlled by their land use characteristics and, to a lesser extent, their climate.

A Strategy for Estimating Nutrient Concentrations Using Remote Sensing Datasets and Hydrological Modeling

2012 ◽  
Vol 3 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Vladimir J. Alarcon ◽  
William H. McAnally
Keyword(s):  
Remote Sensing ◽  
Land Use ◽  
Total Nitrogen ◽  
Total Phosphorus ◽  
Hydrological Modeling ◽  
Northern Region ◽  
Nutrient Concentrations ◽  
Nutrient Export

This paper presents a methodology for estimating nutrient concentrations of total phosphorus (TP) and total nitrogen (TN) through the use of hydrological modeling, remote sensing datasets, and nutrient export coefficients. The strategy is applied to the Upper Tombigbee watershed, located in the northern region of the states of Mississippi and Alabama, USA. USGS GIRAS (1986), NASA MODIS MOD12Q1 (2001-2004) land use datasets, and USGS-DEM topographical datasets were used to characterize the physiography of the watershed. TN and TP concentration values estimated using the methodology were compared to values reported in the literature.

scholarly journals Impact of catchment properties on aquatic chemistry in the rivers of Latvia

2010 ◽  
Vol 41 (3-4) ◽  
pp. 320-329 ◽  
Author(s):  
Ilga Kokorite ◽  
Maris Klavins ◽  
Valery Rodinov
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Chemical Composition ◽  
Spatial Variability ◽  
Human Impact ◽  
Inorganic Ions ◽  
Nutrient Concentrations ◽  
Aquatic Chemistry ◽  
Water Chemical Composition ◽  
Bedrock Geology

The relationships between land use characteristics and aquatic chemistry (nutrient concentrations, major inorganic ions and indicators of organic matter concentrations) were analyzed to determine factors controlling the runoff of dissolved substances, spatial variability of water chemical composition and possible impacts of pollution sources in Latvia. Groups of factors were found to determine the variability of nutrient, organic matter and major inorganic ions concentrations. Bedrock geology and weathering of soil minerals affect the concentrations of inorganic ions, but the nature of the relationships between nutrient concentrations and those of land use are good indicators of human impact.

Assessment of land-use change in coastal areas through geographical information systems

2020 ◽  
Vol 13 (10) ◽  
Author(s):  
Verónica Lango-Reynoso ◽  
Karla Teresa González-Figueroa ◽  
Fabiola Lango-Reynoso ◽  
María del Refugio Castañeda-Chávez ◽  
Jesús Montoya-Mendoza
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Geographical Information Systems ◽  
Design Methodology ◽  
Scientific Information ◽  
Coastal Ecosystems ◽  
Coastal Areas ◽  
Geographical Information ◽  
Coastal Zones ◽  
Computer Based

Objective: This article describes and analyzes the main concepts of coastal ecosystems, these as a result of research concerning land-use change assessments in coastal areas. Design/Methodology/Approach: Scientific articles were searched using keywords in English and Spanish. Articles regarding land-use change assessment in coastal areas were selected, discarding those that although being on coastal zones and geographic and soil identification did not use Geographic Information System (GIS). Results: A GIS is a computer-based tool for evaluating the land-use change in coastal areas by quantifying variations. It is analyzed through GIS and its contributions; highlighting its importance and constant monitoring. Limitations of the study/Implications: This research analyzes national and international scientific information, published from 2007 to 2019, regarding the land-use change in coastal areas quantified with the digital GIS tool. Findings/Conclusions: GIS are useful tools in the identification and quantitative evaluation of changes in land-use in coastal ecosystems; which require constant evaluation due to their high dynamism.

scholarly journals Groundwater salinity variation in Upazila Assasuni (southwestern Bangladesh), as steered by surface clay layer thickness, relative elevation and present-day land use

2019 ◽  
Vol 23 (3) ◽  
pp. 1431-1451 ◽  
Author(s):  
Floris Loys Naus ◽  
Paul Schot ◽  
Koos Groen ◽  
Kazi Matin Ahmed ◽  
Jasper Griffioen
Keyword(s):  
Land Use ◽  
Drinking Water ◽  
Coastal Region ◽  
Shallow Depth ◽  
Hydrological Processes ◽  
Groundwater Salinity ◽  
Clay Layer ◽  
Fresh Groundwater ◽  
Salinity Variation ◽  
Clay Layers

Abstract. In the southwestern coastal region of Bangladesh, options for drinking water are limited by groundwater salinity. To protect and improve the drinking water supply, the large variation in groundwater salinity needs to be better understood. This study identifies the palaeo and present-day hydrological processes and their geographical or geological controls that determine variation in groundwater salinity in Upazila Assasuni in southwestern Bangladesh. Our approach involved three steps: a geological reconstruction, based on the literature; fieldwork to collect high-density hydrological and lithological data; and data processing to link the collected data to the geological reconstruction in order to infer the evolution of the groundwater salinity in the study area. Groundwater freshening and salinization patterns were deduced using PHREEQC cation exchange simulations and isotope data were used to derive relevant hydrological processes and water sources. We found that the factor steering the relative importance of palaeo and present-day hydrogeological conditions was the thickness of the Holocene surface clay layer. The groundwater in aquifers under thick surface clay layers is controlled by the palaeohydrological conditions prevailing when the aquifers were buried. The groundwater in aquifers under thin surface clay layers is affected by present-day processes, which vary depending on present-day surface elevation. Slightly higher-lying areas are recharged by rain and rainfed ponds and therefore have fresh groundwater at shallow depth. In contrast, the lower-lying areas with a thin surface clay layer have brackish–saline groundwater at shallow depth because of flooding by marine-influenced water, subsequent infiltration and salinization. Recently, aquaculture ponds in areas with a thin surface clay layer have increased the salinity in the underlying shallow aquifers. We hypothesize that to understand and predict shallow groundwater salinity variation in southwestern Bangladesh, the relative elevation and land use can be used as a first estimate in areas with a thin surface clay layer, while knowledge of palaeohydrogeological conditions is needed in areas with a thick surface clay layer.

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