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 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 Impacts of the aquaculture on the distribution of dissolved organic matter in the coastal Jeju Island, Korea, revealed by absorption and fluorescence spectroscopy

2021 ◽  
Author(s):  
Jeonghyun Kim ◽  
Yeseul Kim ◽  
Sung Eun Park ◽  
Tae-Hoon Kim ◽  
Bong-Guk Kim ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Organic Pollutant ◽  
Principal Component ◽  
Distribution Patterns ◽  
Jeju Island ◽  
Optical Signals ◽  
Molecular Weights ◽  
Total Dissolved Nitrogen ◽  
Fluorescent Dissolved Organic Matter

Abstract To demonstrate behavior of dissolved organic matter (DOM) derived from coastal aquaculture, dissolved organic carbon (DOC), total dissolved nitrogen (TDN), chromophoric dissolved organic matter (CDOM), and fluorescent dissolved organic matter (FDOM) were measured around the coastal Jeju Island, Korea. As reported by previous studies, pristine groundwater with extremely depleted DOC (< 30 µM) has been used as culturing water in the coastal aquafarms. However, the concentration of DOC within 1.5 km from the discharge outlet of the aquafarms was approximately two times higher than that in the groundwater. In addition, the concentration of TDN exponentially increased close to the discharge outlet. These distribution patterns indicate the aquafarm is a significant DOM source. Herein, principal component analysis including the absorption coefficient (a350), spectral slope coefficient (S250 − 600), specific UV absorbance (SUVA254), and five fluorescent components were applied to categorize DOM origins. We found two distinct groups: aquaculture activity for TDN with high molecular weights and natural biological activity for DOC enrichment. Our study has also critical implications for the efficient monitoring of anthropogenic organic pollutant from aquafarms using unique optical signals.

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

Production and degradation of fluorescent dissolved organic matter derived from bacteria

2017 ◽  
Vol 74 (1) ◽  
pp. 39-52 ◽  
Author(s):  
Ken Arai ◽  
Shigeki Wada ◽  
Koichi Shimotori ◽  
Yuko Omori ◽  
Takeo Hama
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Fluorescent Dissolved Organic Matter

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

&lt;p&gt;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.&amp;#160; The Sahlenburg area (Northern Germany) is known by its highly permeable sediments and high rainfall precipitation that produces a large reservoir of groundwater. &amp;#160;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. &amp;#160;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.&amp;#160; 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 &amp;#181;mol L&lt;sup&gt;-1&lt;/sup&gt;) 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.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

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