scholarly journals Catchment tracers reveal discharge, recharge and sources of groundwater-borne pollutants in a novel lake modelling approach

2018 ◽  
Vol 15 (4) ◽  
pp. 1203-1216 ◽  
Author(s):  
Emil Kristensen ◽  
Mikkel Madsen-Østerbye ◽  
Philippe Massicotte ◽  
Ole Pedersen ◽  
Stiig Markager ◽  
...  
Keyword(s):  
Cluster Analysis ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Groundwater Recharge ◽  
Groundwater Discharge ◽  
Tracer Concentration ◽  
Recharge Rate ◽  
Degradation Rates ◽  
Groundwater Recharge Rate ◽  
Groundwater Wells

Abstract. Groundwater-borne contaminants such as nutrients, dissolved organic carbon (DOC), coloured dissolved organic matter (CDOM) and pesticides can have an impact the biological quality of lakes. The sources of pollutants can, however, be difficult to identify due to high heterogeneity in groundwater flow patterns. This study presents a novel approach for fast hydrological surveys of small groundwater-fed lakes using multiple groundwater-borne tracers. Water samples were collected from the lake and temporary groundwater wells, installed every 50 m within a distance of 5–45 m to the shore, were analysed for tracer concentrations of CDOM, DOC, total dissolved nitrogen (TDN, groundwater only), total nitrogen (TN, lake only), total dissolved phosphorus (TDP, groundwater only), total phosphorus (TP, lake only), δ18O ∕ δ16O isotope ratios and fluorescent dissolved organic matter (FDOM) components derived from parallel factor analysis (PARAFAC). The isolation of groundwater recharge areas was based on δ18O measurements and areas with a high groundwater recharge rate were identified using a microbially influenced FDOM component. Groundwater discharge sites and the fractions of water delivered from the individual sites were isolated with the Community Assembly via Trait Selection model (CATS). The CATS model utilized tracer measurements of TDP, TDN, DOC and CDOM from the groundwater samples and related these to the tracer measurements of TN, TP, DOC and CDOM in the lake. A direct comparison between the lake and the inflowing groundwater was possible as degradation rates of the tracers in the lake were taken into account and related to a range of water retention times (WRTs) of the lake (0.25–3.5 years in 0.25-year increments). These estimations showed that WRTs above 2 years required a higher tracer concentration of inflowing water than found in any of the groundwater wells around the lake. From the estimations of inflowing tracer concentration, the CATS model isolated groundwater discharge sites located mainly in the eastern part of the lake with a single site in the southern part. Observations from the eastern part of the lake revealed an impermeable clay layer that promotes discharge during heavy precipitation events, which would otherwise be difficult to identify using traditional hydrological methods. In comparison to the lake concentrations, high tracer concentrations in the southern part showed that only a smaller fraction of water could originate from this area, thereby confirming the model results. A Euclidean cluster analysis of δ18O isotopes identified recharge sites corresponding to areas adjacent to drainage channels, and a cluster analysis of the microbially influenced FDOM component C4 further identified five sites that showed a tendency towards high groundwater recharge rate. In conclusion, it was found that this methodology can be applied to smaller lakes within a short time frame, providing useful information regarding the WRT of the lake and more importantly the groundwater recharge and discharge sites around the lake. Thus, it is a tool for specific management of the catchment.

scholarly journals Catchment tracers reveal discharge, recharge and sources of groundwater-borne pollutants in a novel lake modelling approach

2017 ◽  
Author(s):  
Emil Kristensen ◽  
Mikkel Madsen-Østerbye ◽  
Philippe Massicotte ◽  
Ole Pedersen ◽  
Stiig Markager ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Groundwater Recharge ◽  
Groundwater Discharge ◽  
Time Frame ◽  
Dissolved Phosphorus ◽  
Sources Of Pollution ◽  
Total Dissolved Nitrogen ◽  
Fluorescent Dissolved Organic Matter ◽  
Degradation Rates

Abstract. Groundwater borne contaminants such as e.g., nutrients, dissolved organic carbon (DOC), coloured dissolved organic matter (CDOM) and pesticides impact the biological quality of lakes. The sources of pollution can, however, be difficult to identify due to high heterogeneity in groundwater flow patterns. This study presents a novel approach for fast hydrological surveys of small groundwater-fed lakes using multiple groundwater-borne tracers. Water samples were collected from groundwater wells installed every 50 m within 5–45 m from the shore and were analysed for tracer concentrations of CDOM, DOC, total dissolved nitrogen (TDN), total dissolved phosphorus (TDP), 𝛿18O isotopes and fluorescent dissolved organic matter (FDOM) components derived from parallel factor analysis (PARAFAC). Based on tracer concentrations and degradation rates, the maximum WRT was estimated to 2 years. Isolation of groundwater recharge areas were based on 𝛿18O measurements and sites with high a degree of recharge was isolated using PARAFAC component C4. Groundwater discharge sites and the fractions of water delivered from the sites were isolated with the Community Assembly via Trait Selection model (CATS) for WRTs between 0.25 and 2 years. The identified recharge sites corresponded to areas adjacent to drainage channels and a cluster analysis of component C4 further identified five sites which showed a tendency of high groundwater recharge rates. Isolated groundwater discharge sites were located in the eastern part of the lake and a single site in the southern part. Observations from the eastern part of the lake revealed an impermeable clay layer that promotes discharge during short precipitation events, which would be difficult to identify using traditional hydrological methods. High tracer concentrations in the southern part in relation to lake concentrations showed that only a smaller fraction of water could originate from this area, thereby confirming the model results. The methodology used can be applied to smaller lakes yielding results within a short time frame with information related to the WRT of the lake.

scholarly journals Bioavailability and bacterial degradation rates of dissolved organic matter in a temperate coastal area during an annual cycle

2009 ◽  
Vol 113 (3-4) ◽  
pp. 219-226 ◽  
Author(s):  
Christian Lønborg ◽  
Keith Davidson ◽  
Xosé A. Álvarez–Salgado ◽  
Axel E.J. Miller
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Annual Cycle ◽  
Coastal Area ◽  
Bacterial Degradation ◽  
Degradation Rates

Submarine groundwater discharge (SGD) in the springs of Sahlenburg tidal flat, Germany: a geochemical approach. 

2021 ◽  
Author(s):  
Roger Carvalho da Silva ◽  
Hannelore Waska ◽  
Kai Schwalfenberg ◽  
Thorsten Dittmar
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Tidal Flat ◽  
Submarine Groundwater Discharge ◽  
Groundwater Discharge ◽  
Fresh Groundwater ◽  
Large Reservoir ◽  
Flat Area ◽  
Submarine Groundwater ◽  
Groundwater Springs

<p>Submarine groundwater discharge (SGD) is an important connection between fresh groundwater and the marine ecosystem. The scientific interest in SGD has grown considerably during the last decades due to the recognition of SGD in coastal environments as a significant source of nutrients and pollutants.  The Sahlenburg area (Northern Germany) is known by its highly permeable sediments and high rainfall precipitation that produces a large reservoir of groundwater.  Such characteristics are essential for industry, agriculture and drinking water supply with a large regional importance. In addition, this groundwater discharges in the form of highly productive springs directly into the adjacent tidal flats, with so far unknown effects on the local biogeochemistry.  The aim of this study was to characterize the spatial distribution of salinity, fluorescence dissolved organic matter (FDOM), dissolved organic matter (DOC) and total dissolved nitrogen (TDN) of the springs of Sahlenburg tidal flat area in Cuxhaven, Germany. We hypothesize that the SGD composition is changing on its way through the tidal flat due to biogeochemical factors. This may affect the composition of the water in the final part of the pathway with more influence of seawater. Porewater springs were sampled in February 2019 during low tide in three different types of locations in the tidal flat area: nearshore where the springs are located close to the vegetated shoreline (salt marsh), offshore approximately 70 meters from the vegetation and in the middle from both locations. In addition, porewater from a nearby sandy beach (around 500 meters away from the area of spring sampling), and surface samples from a nearby lake and seawater, were obtained. Salinity and FDOM were measured in situ, and DOC and TDN in the laboratory.  The preliminary data showed low average values for salinity in all springs (0.2-1.4), as well as in beach porewater, indicating strong influence of fresh groundwater in the whole area. When comparing the three spring location types, the lowest salinities were found offshore, and the highest nearshore. This difference could be due to the size of the springs, since nearshore springs usually were smaller when compared to offshore springs. Furthermore, depressions in the tidal flat relief close to nearshore springs favored seawater retention in pools during low tide. Additionally, we found higher average values for DOC and FDOM in the nearshore when compared with the other spring areas, but lower compared to the lake, beach porewater and seawater. The average values for TDN (272-452 µmol L<sup>-1</sup>) in the groundwater springs were higher when compared to all other sample types (beach porewater, seawater, and lake water) in this study. These values suggest an anthropogenic input (e.g., agriculture influence) in the surrounding watershed and might stimulate primary productivity in the tidal flat. We conclude that groundwater springs in Sahlenburg tidal flat differ locally in their biogeochemistry due to different residence times, heterogeneity of sediment layers, and size of the springs.</p><p> </p>

scholarly journals Groundwater Recharge Assessment using Geographic Information System APLIS Method in Donorojo Karst Area, Pacitan

2021 ◽  
Vol 936 (1) ◽  
pp. 012027
Author(s):  
P V Hardyani ◽  
A S Bahri ◽  
T Hariyanto ◽  
W W Parnadi ◽  
Y Rosandi ◽  
...  
Keyword(s):  
Information System ◽  
Spatial Distribution ◽  
Groundwater Recharge ◽  
Geographical Information ◽  
Karst Area ◽  
Karst Aquifers ◽  
Recharge Rate ◽  
Recharge Rates ◽  
Groundwater Recharge Rate ◽  
Aplis Method

Abstract Karst aquifers can be a source of water supply, especially for the community in Donorojo District, which is one of the areas with the worst drought crisis in Pacitan Regency and requires a sustainable solution to the problem of water needs. Therefore, the study and management of karst formations are very important because of their abundance and potential in forming subsurface aquifer karst aquifers. The recharge rate is one of the basic parameters in the management of the consumption and maintenance of this resource. In addition, the distribution of aquifer locations, aquifer characteristics, and the quality of groundwater forming the aquifer need to be known. This study aims to assess aquifers in the Karst area of Donorojo, Pacitan based on recharge rate and spatial distribution. The APLIS method can estimate surface recharge rates and present the results as a map of the spatial distribution of aquifer recharge rates by utilizing a Geographical Information System (GIS). The results of the analysis using the APLIS method, the groundwater recharge rate in the Donorojo Pacitan karst area is divided into 4 classes, namely very low, low, moderate, and high. Almost the entire Donorojo karst area has a high groundwater recharge rate, this means that the area needs to be used as a groundwater protection zone and it is important to carry out good groundwater management, especially to overcome the problem of drought.

Estimation of historical groundwater recharge rate.

Soil Research ◽  
1982 ◽  
Vol 20 (3) ◽  
pp. 255 ◽  
Author(s):  
GB Allison ◽  
JR Forth
Keyword(s):  
Groundwater Recharge ◽  
Unconfined Aquifer ◽  
Recharge Rate ◽  
European Settlement ◽  
Groundwater Samples ◽  
Groundwater Recharge Rate ◽  
Chloride Concentrations

Chloride concentrations of groundwater samples have been used to show that present-day recharge to an unconfined aquifer is approximately 2.5 times that which occurred prior to European settlement.

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