ORCID Profile
0000-0002-3114-4053
Current Organisations
University of Alabama
,
Texas A&M University at Galveston
,
Leibniz-Zentrum für Marine Tropenforschung GmbH
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Publisher: Copernicus GmbH
Date: 12-2017
Abstract: Abstract. In tropical karstic regions, knowledge about the timing and quantity of land–ocean groundwater nutrient fluxes is important, as those nutrients may affect coastal ecosystems and contaminate coastal springs. High aquifer permeability of the karst, combined with high recharge and discharge during heavy rain events, leads to a close connectivity between groundwater in the hinterland and the coastal zone. The alteration between drier periods and heavy rain events can lead to a high temporal variability of groundwater discharge associated nutrient fluxes from the hinterland towards the coast. We studied the timing of land-ocean groundwater nutrient fluxes in the tropical karstic region of Gunung Kidul (southern Java Indonesia) from November 2015 until December 2016. Satellite infrared imagery revealed two major areas of direct submarine and coastal groundwater discharge. δ18O and δD signatures, nutrient concentrations, combined with precipitation and groundwater discharge data, indicate a rapid groundwater recharge and transport from the catchment area towards the coastal ocean. Measured groundwater discharge rates varied from less than 1 m3/s up to 16.6 m3/s and were dominantly controlled by recharge in the hinterland and surface infiltration during the rainy season. Nitrate fluxes ranged from 5 × 103 to 139 × 103 mol/day and DSi fluxes from 50 × 103 to 310 × 103 mol/day. High nitrate concentrations coinciding with phases of high discharge lead to particularly high nitrate fluxes. This counter intuitive temporal connection might be due to fertilization during the onset of the wet season and the retention of nutrients from untreated sewage in the soil and in sinkholes during dryer periods, which are then washed into the aquifer during heavy rain events. In the tropical karstic region of southern Java, extraordinarily high land-ocean nutrient fluxes occur therefore during the onset of periods with high discharge, which makes coastal water and coastal springs prone to contamination during this time, while flood recession and dry periods are characterized by lower nutrient fluxes. In tropical karstic regions the timing of land–ocean groundwater nutrient fluxes is thus highly variable, which may lead to ecological implications. High nutrient fluxes during certain times of the year may explain the sudden occurrence of harmful algae blooms in coastal environments and have to be considered in coastal groundwater management.
Publisher: Elsevier BV
Date: 06-2018
DOI: 10.1016/J.SCITOTENV.2018.01.281
Abstract: Groundwater discharge is known to transport nutrients into estuaries at several locations around the world. However, few studies report groundwater-associated nutrient fluxes from tropical developing regions such as Southeast Asia, even though this area shows the strongest human modifications in the coastal zone worldwide. We investigated groundwater nutrient flux into two streams and estuaries (Awur and Sekumbu Bay) in the urban area of Jepara, Indonesia, and its relation with the land usage surrounding the estuaries. We found that average concentrations of NO
Publisher: Elsevier BV
Date: 10-2018
Publisher: Copernicus GmbH
Date: 12-2017
Publisher: Frontiers Media SA
Date: 14-05-2021
DOI: 10.3389/FEART.2021.601293
Abstract: Subterranean estuaries the, subsurface mixing zones of terrestrial groundwater and seawater, substantially influence solute fluxes to the oceans. Solutes brought by groundwater from land and solutes brought from the sea can undergo biogeochemical reactions. These are often mediated by microbes and controlled by reactions with coastal sediments, and determine the composition of fluids discharging from STEs (i.e., submarine groundwater discharge), which may have consequences showing in coastal ecosystems. While at the local scale (meters), processes have been intensively studied, the impact of subterranean estuary processes on solute fluxes to the coastal ocean remains poorly constrained at the regional scale (kilometers). In the present communication, we review the processes that occur in STEs, focusing mainly on fluid flow and biogeochemical transformations of nitrogen, phosphorus, carbon, sulfur and trace metals. We highlight the spatio-temporal dynamics and measurable manifestations of those processes. The objective of this contribution is to provide a perspective on how tracer studies, geophysical methods, remote sensing and hydrogeological modeling could exploit such manifestations to estimate the regional-scale impact of processes in STEs on solute fluxes to the coastal ocean.
Publisher: Public Library of Science (PLoS)
Date: 29-06-2020
Publisher: Elsevier BV
Date: 11-2019
DOI: 10.1016/J.SCITOTENV.2019.06.193
Abstract: Submarine groundwater discharge (SGD) can be an important pathway for chemical or biological pollutants from land to the ocean around the world. However, studies on the microbial communities associated with SGD in Southeast Asia, which has been hypothesized as SGD hotspot, remain scarce. In this study, we examined the microbial community composition with 16S rRNA gene sequencing along the hydrological continuum of an SGD site in a tropical urban area of Indonesia. Of the observed parameters in this study, salinity and temperature were the most determinant variables explaining patterns in microbial community composition. The bacterial taxon Burkholderiaceae was predominantly found in low salinity s les, including those from terrestrial groundwater and brackish pore water, while cyanobacteria of the genus Synechococcus sp. CC9902 were indicative of saline SGD and seawater s les. The composition of microbial taxa in each s le pointed to the influence of shallow terrestrial groundwater in the beach pore water, while seawater recirculation dominated the SGD s ling points situated further offshore. We identified taxa containing fecal indicators and potential pathogens at the SGD compartments however, while a likely explanation, we could not conclude with certainty that SGD was a conduit for these bacteria. Overall, the results from this study show that microbial community analysis can highlight hydrological processes and water quality at the SGD site thus, they could be useful for environmental policymakers to formulate water management strategies in coastal areas.
Publisher: American Chemical Society (ACS)
Date: 29-07-2021
Publisher: Elsevier BV
Date: 05-2019
No related grants have been discovered for Dini Adyasari.