Oliver Koit

Oliver Koit
Tallinn University | TLU · Institute of Ecology

PhD

About

25
Publications
6,067
Reads
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87
Citations
Citations since 2017
23 Research Items
86 Citations
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Introduction
I work at the Institute of Ecology, School of Natural Sciences and Health, Tallinn University. I do research in hydrogeology. My scientific interest is focused on the interactions between surface and groundwater, I am especially interested in the hydrodynamics and hydrochemistry of karst aquifers. The full list of my publications and projects can be seen here: https://www.etis.ee/CV/Oliver_Koit/eng?lang=ENG
Additional affiliations
September 2016 - April 2022
Tallinn University
Position
  • PhD Student
September 2014 - June 2016
Tallinn University
Position
  • Master's Student
Education
September 2014 - June 2016
Tallinn University
Field of study
  • Geoecology
September 2011 - June 2014
Tallinn University
Field of study
  • Geoecology

Publications

Publications (25)
Article
Artificial and natural tracers have been frequently used to study the water interactions in the river-karst aquifer continuum. Dissolved organic matter (expressed in the form of total or dissolved organic carbon) has proven to be an effective soil-related parameter when studying the recharge behavior of karst aquifers in many cases. In this study w...
Article
Full-text available
Karst aquifers provide drinking water for 10% of the world’s population, support agriculture, groundwater-dependent activities, and ecosystems. These aquifers are characterised by complex groundwater-flow systems, hence, they are extremely vulnerable and protecting them requires an in-depth understanding of the systems. Poor data accessibility has...
Article
A pilot study was carried out in the Matsi spring fen, southern Estonia to test a proposed methodology (Terasmaa et al., 2020) for identifying potential effects of groundwater bodies on groundwater dependent terrestrial ecosystems (GDTE). A comprehensive hydrochemical and isotopic dataset was collected and analyzed using multivariate statistical me...
Thesis
Full-text available
About 10-25% of the world's population gets their drinking water from high-yielding karst aquifers. In Estonia, where carbonate rocks underlay approximately 62% of the territory, karst aquifers supply about a third of the global population with potable water. In Estonia, karst aquifers supply roughly a third of annually abstracted domestic groundwa...
Article
In Estonia, karst aquifers supply roughly a third of annually abstracted domestic groundwater. Karst systems recharged by allogenic humic-rich streams originating from mire-dominated watersheds are common in Lower Estonia (lowlands). This study aimed to characterize the hydrology and hydraulics of two binary lowland karst systems: Salajõe (SKS) and...
Chapter
Full-text available
Harrastusteaduse kasutamises keskkonna- ja hüdroloogilises seires ei ole maa- ilma mõistes midagi uut. Mitmetes riikides on vabatahtlike seire programmid töös juba aastaid ning nende abil loodud andmekogud on väga väärtuslikud just pikkade aegridade saamiseks. Vabatahtlike abiga keskkonnaandmete kogumine on suhteliselt aja- ja kuluefektiivne, see...
Conference Paper
Full-text available
According to the EU WFD, the Member States sharing transboundary GWBs should carry out joint evaluation of the groundwater resources. To ensure this, it is important to establish a representative cross-border groundwater monitoring network. The transboundary area of Estonia (EE) and Latvia (LV) is sparsely populated and features a relatively scarce...
Conference Paper
Full-text available
As groundwater does not follow human-drawn boundaries such as country borders, groundwater pollution in one country can adversely affect groundwater quality and availability in a neighboring country. It is vital to develop a conceptual understanding of shared groundwater resources not only to ensure their protection but also to avoid future conflic...
Article
Full-text available
Groundwater pollution by agrochemicals such as nitrogen fertilizers can cause complex biogeochemical transformations to take place in groundwater-dependent ecosystems. To explore the interaction between nitrogen load and groundwater-dependent, spring-fed ecosystems, a study was conducted in Latvia in an area of suspected high nitrate (NO 3 ⁻ ) vuln...
Article
Full-text available
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Technical Report
Full-text available
Joint methodology for identification and assessment of GDTEs was developed to identify GDTEs in trans-boundary Gauja-Koiva river basin (funded by Interreg EstLat project “GroundEco”). The methodology and best GDTEs assessment techniques were tested in two pilot areas – Matsi spring fen in Estonia and Kazu leja valley in Latvia. Finally, recommendat...
Chapter
Dynamic interactions between ground- and surface water are widely known, but the role of groundwater in terrestrial and aquatic ecosystems is often poorly understood and documented due to the spatiotemporal complexity. Many countries have not yet completed the assessment of groundwater dependent ecosystems (GDEs). GDEs are valuable ecosystems that...
Poster
Full-text available
A project that aims to enhance sustainable management of common groundwater resources and associated ecosystems in the transboundary Gauja-Koiva river basin (Latvia-Estonia). (1) selection of GDTE types (2) additional criteria in selecting GDTEs (3) identification of GDTEs in Gauja–Koiva river basin (4) quantity assessment and quality assessment...
Conference Paper
Full-text available
This research is carried out in the framework of the project "Joint management of groundwater dependent ecosystems in transboundary Gauja-Koiva river basin" (GroundEco, Est-Lat62) funded by ERDF Interreg Estonia-Latvia cooperation programme. The main aim of GroundEco is to develop a common understanding and joint methodology for the Estonian and La...
Conference Paper
Full-text available
Groundwater dependent ecosystems (GDEs) are valuable ecosystems that depend on groundwater input and cannot be considered and assessed separately. Dynamic interactions at the surface-groundwater interface are widely recognized, but the role of groundwater in terrestrial ecosystems is not well documented. Any changes in the water supply or chemical...
Poster
Full-text available
Dynamic interactions at the surface–ground water interface are widely recognised but due to the spatiotemporal complexity, the role of groundwater in terrestrial and aquatic ecosystems is poorly understood and documented. The majority of the countries have not finished the assessment of groundwater dependent ecosystems (GDEs). GDEs are valuable eco...
Article
Full-text available
Nearly half of Estonia’s territory is underlain by Silurian and Ordovician carbonate rocks which host extensive shallow karstified aquifers that contribute nearly a third of the annually abstracted domestic groundwater. Due to glacial erosions, the short duration of the post-glacial evolution of the territory and for other reasons, karst topography...
Conference Paper
Full-text available
Recent records of Proteus anguinus outside its historically known range (Gorički et al. 2017), discovered through detection of its DNA dissolved in groundwater (environmental DNA or eDNA), mark the beginning of a new era in the study and conservation of cryptic subterranean biodiversity. An upgraded technology, droplet digital PCR (ddPCR), initiall...
Conference Paper
Diverse shallow karst aquifers contribute approximately a third of consumed domestic groundwater in Estonia. Due to its geographical location and climatic conditions, mires are widespread in Estonia, forming the headwaters for numerous humic-rich rivers. Such streams are frequently sinking on the karst aquifer outcrops. In this study we combine hyd...
Article
Full-text available
Près de la moitié du territoire estonien repose sur des roches carbonatées du Silurien et de l’Ordovicien, qui abritent de très larges aquifères karstifiés peu profonds, lesquels constituent environ un tiers des eaux souterraines captées dans le pays annuellement. À cause des érosions glaciaires, de la courte durée de l’évolution post-glaciaire du...
Article
Full-text available
As karst aquifers are often characterised by non-linear behaviour, ascertaining the turning points in their hydraulic regime may provide essential information on the functioning of the aquifer. These characteristics also apply to the Silurian-Ordovician aquifer system, composed of diverse carbonate rocks, in Estonia. The aquifer system is an import...
Poster
Full-text available
Tuhala karst area is situated in Northern Estonia, on the lower course of the Tuhala River, which drains the Mahtra wetlands. Upper-Ordovician carbonate rocks outcrop in the area, covered by a 2-5 m thick layer of poorly permeable glacial till (K=0.001 m/d). Tuhala karst area is best known for a temporary karst spring, called the Witch’s Well that...
Article
Hagudi mire is situated in the Kohila karst region, northern Estonia and is surrounded by the Aandu, Hageri, Nõmme and Kadaka karst areas. The Hagudi mire was formed after the last glaciation by the terrestrialization of small lakes, which filled the Maidla bedrock valley at that time. As the mire was almost encircled by the escarpments of surround...

Questions

Questions (2)
Question
I have a question concerning groundwater analysis. We have been sampling for major ions, including Fe since october 2016. As the AAS was out of operation for the first three months, half of the sampled water was frozen and preserved below zero until the AAS would be operational again and Fe concentration could be determined. Unfortunately the samples that were frozen were anion samples (not acidified). Now, as the samples are being analyzed, the concentrations seem to be below zero, which probably is due to Fe precipitation. Am i correct? The question is, if water samples which have been treated with microwave mineralization prior to AAS analysis, would still be somehow comparable and usable in statistical analysis with the rest of the ion concentrations?
Question
The pH would not be a good indicator as the bog water first flows along a 5 km mineral bedded stream and becomes more alkaline (from pH ~3 to ~ 5-6) before point-infiltrating into the karst system.
The method should be affordable to be carried out on monthly basis for few to tens of samples in the framework of a low-budget phd project.

Network

Cited By

Projects

Projects (4)
Project
. The main aim of WATSON is to collect, integrate, and synthesize current interdisciplinary scientific knowledge on the partitioning and mixing of water in the critical zone taking advantage of the unique tracing capability of water isotopes. These efforts will allow going beyond the current fragmented knowledge providing a novel conceptual framework on the interactions between groundwater recharge, soil water storage, and vegetation transpiration useful for water resources management across a variety of climatic settings. Context: Understanding water exchange within the critical zone, i.e.the dynamic skin of the Earth that extends from vegetation canopy to groundwater, is vital for addressing key environmental problems linked to the sustainable management of water resources. Approach: The Action activities are based on a network of early career and senior scientists from different complementary disciplines who are experts in the use of water isotopes, and stakeholders from governmental agencies and private companies from 19 COST countries and one Near Neighbour Country. Meetings and training events will involve scientists and water managers, facilitating communication between academia and stakeholders, promoting the transfer of the latest scientific findings, and helping to identify research gaps and management priorities. Deliverables: The ultimate goal of the network is to build capacity in the use of robust isotope approaches for water resource management. The deliverables include practical tools, such as maps of groundwater recharge and water sources used by vegetation in different European regions that will enable the translation of scientific cutting-edge knowledge into tangible recommendations to support European agencies responsible for water management in agro-forest systems.
Archived project
The project aims to promote sustainable management of shared groundwater resources in a trans-boundary area and implement EU Water policies, mainly Water Framework Directive. The goal will be achieved by (1) development of a common approach for status assessment of groundwater bodies, (2) implementation and testing of developed approach in the Latvian-Estonian trans boundary Gauja-Koiva and Salaca-Salatsi river basin districts, (3) development of common understanding about groundwater dependent ecosystem management, (4) raising public awareness and interest in groundwater management and protection. Find more about project and newest project results/events at bit.ly/WaterAct-project Partnerships: (1) Latvian Environment, Geology and Meteorology Centre, Hydrogeology Division (lead partner) (2) Ministry of the Environment of the Republic of Estonia (3) Geological Survey of Estonia (4)Tallinn University, Institute of Ecology (5) Nature Conservation Agency, Nature Protection Department (LV) (6) University of Latvia, Faculty of Geography and Earth Sciences (7) Vidzeme Planning Region (LV) (8) Estonian Environment Agency Project No. Est-Lat155 is financed by Interreg V - A Estonia - Latvia Cross - border cooperation programme (www.estlat.eu).
Archived project
To develop joint methodology for identification and assessment of groundwater dependent terrestrial ecosystems (GDTEs) in trans-boundary Gauja-Koiva (Latvia - Estonia) river basin. Developed methodology will be tested in two pilot areas (EE and LV) to propose best GDTE monitoring approaches to be included into national groundwater monitoring programmes. Pilot studies will consist of water quality and level monitoring, vegetation analysis, development of conceptual models and development and testing of low-cost sensors, thermal imaging and ground penetrating radar studies etc. Find more about project and newest project results/events at bit.ly/GroundEco Project No. Est-Lat62 is financed by Interreg V - A Estonia - Latvia Cross - border cooperation programme (www.estlat.eu).