Browsing by study line "Hydrogeologia ja ympäristögeologia"
Now showing items 1-20 of 30
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(2019)Arsenic (As) is a metalloid naturally present in the environment. Arsenic species vary in toxicity. Metal mining has contributed to the anthropogenic input of arsenic to groundwaters and surface waters. In this study, water samples were collected from 20 sample points in three mining-impacted study areas in Finland: the former Ylöjärvi Cu–W–As and Haveri Au–Cu mines, and the active Pyhäsalmi Zn–Cu mine. Six groundwater well samples, eleven surface water samples and three tailings seepage collection ditch samples were analyzed for dissolved arsenic speciation by HPLC-ICP-MS and for geochemical composition by ICP-MS, titration, and ion chromatography. Dissolved arsenic concentrations ranged from 14.2 to 6649 µg L-1 in samples collected at the Ylöjärvi study area, from 0.5 to 6.2 µg L-1 in samples collected at the Haveri study area, and from 0.2 to 9.4 µg L-1 in samples collected at the Pyhäsalmi study area. In all study areas, measured dissolved arsenic concentrations showed a general decrease from the tailings to the surroundings. Speciation analysis showed that two of the samples collected at the Ylöjärvi study area had arsenite [As(III)] as the dominant form of dissolved inorganic arsenic (iAs), three had arsenate [As(V)] as the dominant form of dissolved iAs, and four had a mixture of both. In the water samples collected at the Haveri and Pyhäsalmi study areas, all concentrations of dissolved arsenic species were below method detection limits. Also, none of the 22 water samples analyzed for arsenic speciation had dissolved MMA or DMA concentrations above method detection limits. Identification of dissolved arsenic species in the sampled waters in Haveri and Pyhäsalmi, and of MMA and DMA in all sampled waters requires more detailed study. A significant 2-tailed Pearson correlation between dissolved arsenic and dissolved molybdenum (Mo) (r=0.80**, n=20), and dissolved arsenic and dissolved potassium (K) (0.68**, n=19) suggests that in these three study areas the distributions of dissolved arsenic and Mo, as well as dissolved arsenic and K may be controlled by the same environmental variables. Anomalously high maximum concentrations of dissolved Al, Ca, Co, Cu, Fe, Ni, and SO4 were measured in surface water samples collected at the Ylöjärvi and Haveri study areas, and in a seepage collection ditch sample collected at the Pyhäsalmi study area.
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(2023)Northern peatlands are important carbon storing ecosystems, contributing to carbon cycle as sinks and sources. The two most important greenhouse gases in the carbon cycle are carbon dioxide (CO2) and methane (CH4). The study area of this work consists of two sloping fens in the Kuusamo area. from which the peat geochemistry and peat properties (peat stratigraphy, ash content, and bulk density) are studied. In addition, the chronology, carbon-nitrogen ratio, carbon content, and carbon accumulation are studied in the Puukkosuo from the three sampling sites. In the characterization of peat geochemistry, Puukkosuo in the dolomitic rock area and Suvisuo in the volcanic rock area were divided into different geochemical zones based on the cluster analysis. The paludification in the Puukkosuo area has started around 10 000 years ago, and the accumulation of peat have been ongoing in the whole peat basin after 1000 years. The geochemical zones in the Puukkosuo can be divided into five different groups, from which the deepest part of the peatland basin can be separated due to the high heavy metal concentrations in the oldest peat. Most of the bulk peat is differentiated into alternating groups, from which the changes in the peat nutrients are recorded. The margins of the Puukkosuo are separated based on the geochemical properties. The top part of the northwestern edge can be characterized as high concentrations of atmospheric origin elements, whereas the effect of the nearby road can be noted in the concentrations of the top part of the southeastern edge. The amount of carbon accumulated has varied throughout the development of Puukkosuo, and the highest rates are recorded in the lower part of the peat profiles in all study sites. Highest carbon-nitrogen -ratios are recorded near the basal peat samples especially in the deepest part of the Puukkosuo. The long-term carbon accumulation differs from the other long-term averages in the boreal zone. The largest differences were recorded in the deepest part of the basin in the long-term carbon accumulation rates during the Early Holocene. The respective value in the Puukkosuo is four times higher (60 g m-2 yr-1) in contrast to others. During the Late Holocene the long-term carbon accumulation rates correspond to the other average values in the boreal peatlands (25 g m-2 yr-1).
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(2020)AA Sakatti Mining Oy is researching the possibility of conducting mining operations in Sakatti ore deposit, located partially under the protected Viiankiaapa mire. In order to understand the waters in mining development site, the interactions of surface waters, shallow aquifers, and deep bedrock groundwaters must be understood. To estimate these interactions, hydrogeochemical characterization, together with four tracer methods were used: Tritium/helium, dichlorodifluoromethane and sulfur hexafluoride, stable isotopes of hydrogen and oxygen, and carbon-14. Most of the shallow groundwater samples are similar to the natural precipitation and groundwater in their chemical composition, being of Calcium bicarbonate type. B-11-17HYD013 was an exception, containing much more Cl and SO4. The samples from the deep 17MOS8193 all show a very typical composition for this type of a borehole, on the line between the saline Sodium sulphate and Sodium chloride water types. The samples from the 12MOS8102, as well as the river water samples and the Rytikuru spring sample are located between these two end members. The hydrogen and oxygen isotope values divided the samples into two distinct groups: those that show evaporation signal in the source water, and those that do not. The most likely source for the evaporated signal in the groundwaters is in the surface water pools in the Viiankiaapa mire, which have then infiltrated into the groundwater and followed the known groundwater flow gradient into the observation wells near the River Kitinen. Tritium showed no inclusion of recently recharged water in the deep 17MOS8193, and dated most of the shallow wells with screen below bedrock surface to be recharged in the 70’s and 80’s. B-10-17HYD017 had an older apparent age from 1955, and B-14-17HYD006 was curiously dated to be recharged in 2018. 14C gave apparent age of over 30 000 a for the deep 17MOS8193. The slight contents of 14C could be caused by slight contamination during sampling meaning the age is a minimum. The sample M-4-12MOS8102 got an apparent age of ~3 500 a, which could in turn be an overestimate due to ancient carbon being dissolved from the local bedrock fractures. CFC-12 showed apparent recharge dates from 1963 to 1975 in the shallow wells, and no recently recharged water in the deep 17MOS8193, and so was generally in line with the 14C and Tritium results, although some contamination had happened. SF6 concentrations exceeded possible concentrations considering other results, most likely due to underground generation, and the method was dismissed. By trace element composition, all samples from the deep 17MOS8139 are distinct from other samples and saw slight dilution in concentrations of most elements in the span of the test pumping. Other samples are more mixed and difficult to interpret, but some trends and connections are visible, such as the higher contents in wells with screens below the bedrock surface than those with screens above the bedrock surface, and the exceptionally high contents of many elements in B-13-17HYD004. Overall, the study did benefit from the large array of methods, showing no interaction between the deep bedrock groundwaters and shallow groundwaters or surface waters. The evaporated signal from the Viiankiaapa was clearly visible in the samples close to the River Kitinen.
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(2019)The European Water Framework Directive aims at restoring all water bodies in good ecological conditions by the year 2023. For this aim, understanding the responses of these ecosystems to current and future pressures is a requisite. Lakes Hältingträsk and Storträsk are located in Östersundom, a latent developing suburban area in eastern Helsinki. Alterations to the catchment in Hältingträsk as a consequence of urbanization will likely change the conditions of the lake. Storträsk, part of Sipoonkorpi nature reserve is primarily influenced by recreational activities. Ecological status of both lakes is likely to alter under the ongoing urban development. For this reason, the reference conditions of Hältingträsk and the resilience of both lakes to human stressors must be assessed. A long term record from Hältingträsk, with special focus on the most recent section, as well as a short core from Storträsk targeting the most recent events, are analyzed for different palaeobiological and geochemical proxies. The sequence from Hältingträsk is evaluated with diatom assemblages, trace metal analyses, lithological description of sediments through loss-on-ignition and inferred chlorophyll a. For Storträsk, a high-resolution study of diatom communities and photosynthetic pigments is performed. Both sequences are framed with an age-depth model based on radiogenic dating techniques. In addition, the results are analyzed with statistical tools and fossil diatom data is used to reconstruct lake water pH. The results describe the evolution of Hältingträsk through the mid-Holocene until recent times; the diatom assemblages indicates the area was part of Ancylus Lake and, later of Litorina Sea, and that it was isolated from the Baltic Basin at 6500 cal BP. This is supported by the high concentrations of Fe and Mn, showing the presence of metallic nodules common in marine environments. The change in sediments and the predominance of fragilarioid diatoms, display the succession of the lake (from gloe to flada). Afterwards, the ontogeny of the lake and the development of surrounding peat bog can be tracked with changes in the diatom community and decrease in heavy metals concentrations. The reconstructed pH reveals that Hältingträsk is a naturally acidic lake. Furthermore, signals of agricultural activities and industrialization are recorded in the area, as well as their development, is recorded through shifts in the diatom community and the oscillation of trace metals of both local (Cu, Ni and V) and long (Pb, Zn and Cd) transport. Finally, climatic anomalies such as the Little Ice Age and current climate warming are imprinted in the diatom assemblages and the photosynthetic pigments. The high resolution of subsampling from Storträsk displayed little variation. The faint changes could be attributed to CaCO3 treatment, fish introduction or recent climate warming. However, discern the influence of each of these stressors was not possible.
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(2021)Etelä-Pohjanmaalla Kurikassa maaperän rakennettavuusominaisuudet ovat hankalat maaperän mittavien hienoaineskerrostumien vuoksi. Näiden kerrostumien alueellista jakautumista ei tiedetä, joten tämän työn tarkoituksena on toteuttaa maaperästä geoteknisiin pohjatutkimuksiin perustuva alueellinen 3D-malli Kurikan kaupungin rakennuslupaa-arkiston pohjatutkimusaineistoja käyttäen. Pohjatutkimukset koostuvat yksittäisiin rakennuskohteisiin toteutetuista maaperäkairauksista. Aineistona käytettäviä tutkimuskohteita on yhteensä kymmenen ja kairauksia 3D-mallissa on käytössä 112. Pohjatutkimusaineistoista digitoitiin kohde ja kairaus kerrallaan maalajitieto sekä kairauksen kuormitusominaisuudet. Digitointiin käytettiin suomalaisen 3D-Systemsin 3D-Win –ohjelmistoa. 3D-malli toteutettiin Leapfrog Geo® -ohjelmistolla. Mallin ensimmäisessä vaiheessa maaperä jaettiin kahdeksaan yksikköön. Lopullisessa yksinkertaistetussa mallissa maaperän hienoainesyksiköt yhdistettiin yhdeksi yksiköksi. Saatuja malleja verrattiin alueelta olevaan tyyppileikkaukseen. Malleilla arvioidaan millä aineiston resoluutiolla saadaan mallille paras ennustusvoima. 3D-mallien toteutus onnistui. Mallin mukaan alueella on kahdeksan maalajiyksikköä (vanhimmasta nuorimpaan): moreenit, hiekat, siltit, savet, liejusavet, siltit 2, savet 2 sekä pinnassa humus- ja täyttömaat. Useilla mallin yksiköistä (siltit, savet ja liejusavet) on samankaltaiset geotekniset ominaisuudet, joten ne yhdistettiin yhdeksi hienoainesyksiköksi. Yksinkertaistetun mallin yksiköitä verrattiin alueelta olevaan tyyppileikkaukseen. Tyyppileikkauksen sedimenttisarja ja mallin hienoainesyksikkö vastaavat hyvin toisiaan. Tämän työn tulosten perusteella geoteknisiin pohjatutkimuksiin perustuvassa maaperän 3D-mallinnuksessa hienoainesyksiköiden osalta yksinkertaistettu malli on ennustettavuuden kannalta luotettavampi kuin kompleksinen malli.
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(2020)A promising Cu-Ni-PGE containing sulphide ore deposit was discovered in 2009 by Anglo American and since the company has continued studies aiming towards utilisation of the deposit. The discovered deposit lies underneath a Natura 2000 protected mire complex, Viiankiaapa, in Sodankylä municipality in Finnish Lapland. The research and exploration activities in the area are performed with mitigation and preventing actions in order to minimize the deterioration impact to the delicate ecosystem. The more detailed understanding of the hydrogeochemistry of the mire environment in its current state can assist: in monitoring, mitigating and preventing of potential environmental effects due to future mining operations as well as planning the monitoring program. Hydrogeochemical studies, consisting of water and peat sampling at eight sampling points, were carried out along a 1.6 km long study line. Water samples were collected from the surface of the mire as well as within the peat layer and the bottom of the peat layer. Water samples were collected using a mini-piezometer. The analyses for the water samples involved: major components, trace elements and δ18O & δ2H. Groundwater influence in the different sampling points as well as different sections of the peat was investigated using the mentioned chemical and isotopic properties. Peat sampling focused on finding samples which would have different hydraulic properties in order to find the influence of peat in the hydrology in the mire. Hydraulic conductivity of peat samples was determined using rigid wall permeameter test setup. The chemical and physical methods were supplemented by a ground penetrating radar survey completed with 30 and 100 MHz antennas. Studies of peat showed that the hydraulic conductivity varies substantially even inside the rather small study area. Widely recognized correlation between hydraulic conductivity and depth was not observed statistically, but the sampling sites individually show a clear connection with depth and hydraulic conductivity. The influence of the hydraulic properties of peat on to the flow of water in the mire was observed to be significant. In cases where the hydraulic conductivity of peat was very low, water flow may be prevented altogether. This was confirmed with the use of chemical analyses. With higher hydraulic conductivity, groundwater influence was seen more or less throughout the peat profile.
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(2023)Tutkimuksessa pyrittiin selvittämään pohjaveden virtaussuunnat Hyvinkäänkylän vedenottamolle, I Salpausselän ja Hyvinkäänkylän harjun välisiä hydraulisia yhteyksiä ja alueellisten ruhjevyöhykkeiden vaikutusta pohjaveden virtaussuuntiin. Tutkimusalue sijaitsee Hyvinkään pohjavesialueella ja on tärkeä kunnan vesihuollon kannalta. Tutkimusmenetelmänä käytettiin MODFLOW-virtausmallinnusta, jonka pohjalle luotiin hydrostratigrafinen 3D-malli LeapFrog-ohjelmistolla. Virtausmallinnus toteutettiin Modelmuse-ohjelmistolla. Tulokset osoittavat, että Vantaanjoen pohjoispuolella I Salpausselän ja Hyvinkäänkylän harjun välinen hydraulinen yhteys on olemassa: molemmista virtaa vettä kohti vedenottamoa. Suurin osa vedenottamon vedestä tulee tutkimusalueen pohjoisosasta I Salpausselältä ja Hyvinkäänkylän harjun pohjoisosasta, mutta harjun eteläosasta Vantaanjoen alitse virtaava vesimäärä on huomattava. Lisäksi tulokset osoittavat, että Vantaanjoen eteläpuolisella alueella Hirvisuon-Lammenkorven seudulla I Salpausselän ja Hyvinkäänkylän harjun välillä ei ole virtausmallin perusteella todettavissa hydraulista yhteyttä. Näiden alueiden vedet virtaavat mallin mukaan pääasiassa Vantaanjokeen, mutta vedenottamon pumppausmäärää nostettaessa Hirvisuon-Lammenkorven alueelta virtaa mallin mukaan pieniä määriä pohjavettä vedenottamon suuntaan. Ruhjevyöhykkeen lisääminen virtausmalliin Vantaanjoen ja Hyvinkäänkylän vedenottamon ympäristöön pienensi mallin virhettä, mutta vyöhykkeen paksuus, vedenjohtavuus ja todellinen vaikutus pohjaveden virtaussuuntiin ovat vielä kysymyksiä, joihin vastaaminen vaatii lisätutkimuksia.
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(2020)Artificial groundwater is produced in Jäniksenlinna water treatment facility in Tuusula by infiltrating surface water from the lake Päijänne to the Jäniksenlinna aquifer. The geochemical properties of the artificial groundwater vary and challenge the water purification process in the Jäniksenlinna facility. The objective of the study was to solve the geochemical quality of the water in different locations inside the aquifer area and in the different steps of the water purification process and to solve the changes in the geochemistry of the water caused by the seasonal changes. The study was put into effect by collecting 20 water samples, 16 of which were from different locations inside the aquifer area and 4 of which were from the different steps of the water purification process in the water plant. The samples were collected during the spring 2018 and repeated during the summer 2018. Each water sample was analyzed for major ions by ion chromatography, trace elements by ICP-MS method and stable isotopes of hydrogen and oxygen with the help of Picarro device. Additionally, each sample was analyzed in the field for electric conductivity, pH and temperature and in laboratory for alkalinity, pH and electric conductivity. The results from the spring and from the summer were handled separately since they differed with statistically significant levels from each other. The results were treated with statistical methods and visualized with tables, graphs, photos from the sampling points and maps. The results show that season changed the proportion of the natural and the artificial groundwater in the sampling points. However the season had no effect on the existence of the artificial groundwater in the sampling points. The proportion of the artificial groundwater was highest while the groundwater level was low, that is during the summer. The sampling points were selected with different distances to the infiltration area. However, the amount of infiltrated water did not decrease with the growing distance to the infiltration area, since the geological structures of the aquifer define the water flow inside the aquifer. The amount of artificial groundwater was lower in one sampling point closer to the infiltration area than in two sampling points further away the infiltration area. The water purification process removes the excess iron and manganese from the artificial groundwater and produces water which fulfills the standards set for the drinking water. The amount of iron and manganese in the drinking water might get even lower by conducting the water from the well 12 to the iron and manganese removal. The study covered the spring and the summer seasons, but in order to study the whole annual picture, the sampling should cover the autumn and the winter seasons as well. Flow modelling could give better picture of the formation of the artificial groundwater in Jäniksenlinna.
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(2022)The research subject is Waste Rock and Tailings Storage Facilities of a Finnish mine in planning. The storage facilities are considered as they will be in the operative phase of the mine. Waste rock is categorized according to its sulfur and metal content as well as buffering capabilities in to two classes; low-sulfur and high-sulfur waste rock. Waste rock is deposited in the form of piles at two different storage facilities determined by their classification. Tailings are deposited as wet slurry within embankment, where most of the tailings are partially or fully saturated with water. The aim of this study was to research contingencies in the quality assesment of seepage water produced by storage facilities. Seepage water in the mine in planning has previously been assessed with humidity cell tests, which serves as the source material for this thesis. The humidity cell tests are performed in laboratory conditions which do not respond to actual mining area conditions, thus the seepage water quality assesment cannot be done based on these tests alone. Instead they are used as source material to assess the quality of the seepage water. The effects of the conditions of humidity cell testing are the contingencies in seepage water quality assessment. The effects of the conditions studied in this thesis are temperature, rainfall, reactive mass of the waste rock and tailings as well as channeling of rain water in the waste rock storage facility. In the composition of seepage water the concentrations of sulfates and metals was examined. Humidity cell test results were fitted to the conditions in the mining area by lab-to-field scaling. The scaling correction factor or complement is based on the effects of the laboratory and mining area conditions on the quality of the seepage water that are defined in the scaling. The effect of condition factors on water quality assessment was investigated by changing the value of the scaling factor and comparing the resulting water compositions. Futhermore, the water quality estimate obtained as a result of the scaling was fed into an equilibrium modeling program to to study the precipitation reactions in the leachate and the amount of precipitation. Based on the scaling results, the sulfate and metal concentrations in the seepage water increased as the proportion of fines, reactive mass, leachable surface area, or temperature increased. If rainfall increased, the concentrations of metals and sulfates decreased. The above properties were observed for each mine wastes examined (low-sulfur and high-sulfur waste rock, tailings). The intensity of the increase or decrease in concentrations was dependent on the acidity of the seepage water of the mine waste. In the alkaline seepage water of low-sulfur waste rock and tailings, the increase in the value of the condition factor, with the exception of rainfall, led to greater changes in concentrations than in the acidic seepage water of high-sulfur waste rock. The seepage water of the high-sulfur waste rock was acidic and therefore the solubility of the metals was high and the changes in acidity didn’t significantly affect the precipitation of the substances. The final conclusion of the work was that the most significant uncertainties for the assessment of leachate quality are the grain size distribution and channeling of water in the waste rock pile, and the thickness of reactive layer in the tailings storage facility. Based on the sensitivity analysis, the effects of climate change did not significantly affect the water quality, as the simultaneous increase in temperature and precipitation offset each other's effects. It should be noted, however, that a more in-depth examination of the effects of climate change would require a seasonal examination of precipitation and temperature. In addition, variations in prolonged rainy and dry seasons should be considered, as they may have significant momentary effects on the seepage water quality.
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(2021)Itämeren pohja on ollut vähähappinen tai kokonaan hapeton useita kertoja viimeisten 8000 vuoden aikana. Holoseenin lämpömaksimin aikana, Litorinameren suojaisessa mataloituvassa lahdessa nykyisen Kurikan alueelle on kerrostunut aikaresoluutioltaan poikkeuksellisen hienosyinen sedimenttisarja, joka kertoo pohjan happitilanteen muutoksista. Ajallisesti sedimenttisarja kattaa paikallisen deglasiaation, Ancylusjärvivaiheen ja Litorinameren kehityksen paikalliseen kuroutumiseen asti, ajoittuen jaksolle n. 10 800–4 500. Magneettiset mineraalit ovat herkkiä ympäristön prokseja ja niiden kerrostumisen jälkeiseen diageneesiin liittyy joko detritaalisten magneettisten mineraalien muuttuminen tai uusien magneettisten mineraalien syntyminen. Koska muutoksia tapahtuu sekä hapettavissa että pelkistävissä ympäristöissä, voidaan magneettisia mineraaleja käyttää tutkittaessa sedimenttien diageneettisiä prosesseja ja ympäristöjä. Esimerkiksi greigiitti on rautasulfidi, jonka esiintyminen indikoi hapetonta ympäristöä. Greigiittiä voi syntyä diageneesissa sulfaatin pelkistymisen tai metaanin anaerobisen hapettumisen seurauksena. Lisäksi magnetotaktiset bakteerit tuottavat greigiittiä magnetosomeihinsa. Ympäristömagneettiset ominaisuudet kertovat greigiitin synty-ympäristön redox-olosuhteista. Huhtikuussa 2019 kerätystä 40 metriä pitkästä sedimenttisarjasta määritettiin sedimentin litologia, magneettinen suskeptilibeetti, orgaanisen aineksen pitoisuus sekä raekoko. Tulosten perusteella sedimenttisarja jaettiin viiteen yksikköön (KY15-1–KY15-5). Yksiköistä KY15-2, KY15-3 ja KY15-4 selvitettiin ympäristömagneettiset ominaisuudet neljästä eri vyöhykkeestä. Suskeptibiliteettiaineiston toistotarkkuus varmennettiin korkeamman resoluution mittauksin ja ympäristömagneettisia tuloksia verrattiin suskeptibiliteettimittauksiin. Ympäristömagneettisten tulosten vertailu suskeptibliteetin arvoihin osoittaa, että suskeptibiliteettia voidaan käyttää ympäristömagneettisten ominaisuuksien rekonstruoimiseen Kurikan sedimenttisarjan sedimenttiyksiköissä, joissa sedimentaatio on verrattain tasaista eikä suuria raekokomuutoksia esiinny. Litorinamerivaiheen sedimentistä havaittiin single-domain (SD) kokoista (200-1000 nm) autigeenistä greigiittiä Kurikan sedimenttisarjassa ja ympäristömagneettiset tulokset indikoivat sen alkuperäksi sulfidista ympäristöä. Tutkimuskohteen sedimenttisarja eroaa muista Itämerestä tutkituista sedimenttisarjoista erityisesti Ancylusjärven sedimenttien ympäristömagneettisilta tuloksiltaan. Poiketen syvänteistä kerätyistä sedimenttisarjoista, ei Ancylusjärven savista tunnistettu greigiittiä, eikä sedimentissä nähty selviä sulfidikerroksia. Litologisten ja ympäristömagneettisten tulosten perusteella greigiitin (autigeeninen) syntymekanismi Kurikan sedimenttisarjassa on erilainen, kuin Itämeressä aiemmin havaitulla greigiittillä (magnetotaktisten bakteerien synnyttämä). Tutkimuksen tulokset viittaavat siihen, että greigiitin syntytavat voivat olla jopa altaan samoissa sedimenteissä toisistaan poikkeavat, ja että sedimentaatioympäristö vaikuttaa vahvasti greigiitin syntymiseen ja sen säilymiseen sedimentissä. Suskeptibiliteetin perusteella hypoksia on ollut Litorinameren aikana mataloituvassa merenlahdessa yleistä, mutta ei jatkuvaa. Isomman mittakaavan trendit hapettomuuden vaihtelussa ovat olleet perenniaalisia oletetulla aikaresoluutiolla, mutta aineisto ei sulje pois hapettomuuden kausittaisuutta. Litorinameren ajalta voidaan erottaa ainakin kaksi pitempiaikaista, muutamia satoja vuosia jatkuvaa, hapetonta tai vähähappista kautta. Greigiitin määrä kuitenkin vaihtelee jaksojen aikana, heijastaen vaihtelua pohjaolosuhteissa. Hypoksisten kausien välillä (~6500–7000 cal BP) on viitteitä lyhytaikaisista hapellisista jaksoista. Kyseinen ajanjakso on yhdistetty kirjallisuudessa korkeampiin suolatasoihin Itämeren altaassa, suhteellisen merenpinnan korkeampiin tasoihin sekä hapellisten olosuhteiden yleistymiseen.
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(2021)Järven kehityksen tunteminen auttaa rekonstruktioimaan ihmistoiminnan ja luonnollisten muutosten aiheuttamia tapahtumia järven kehityksessä. Näitä tapahtumia voidaan päätellä pohjasedimenttikooreista saatavien tietojen avulla. Tämä tutkimus tutkii pienen vuoristojärven kehitystä viimeisen 800 vuoden aikana. Tutkimuksen tavoitteena on selvittää sedimentaatiossa tapahtuneita poikkeamia sekä ihmistoiminnan vaikutusta niihin. Kohdejärvi Laka sijaitsee Tšekin lounaisosassa Sumavan luonnonsuojelualueella. Laka-järvi on pituudeltaan 300 metriä ja leveydeltään 100 metriä. Järven alueella vallitsee vuoristoilmasto, ja järvi on jäässä keskimäärin 4–5 kuukautta vuoden aikana. Järveä ympäröivä metsäalue toimi teollisesta toiminnasta aiheutuneiden rikki- ja typpipäästöjen nieluna 1950-luvulta 1980-luvun loppuun, mikä aiheutti happamoitumista. Työn aineisto on PEDECO-projektin yhteydessä tuotettua, jonka tekijä on saanut ohjaajaltaan valmiina käyttöönsä. Tutkimuksessa käytetty aineisto on tuotettu venäläisellä suokairalla otetusta sedimenttikoorista ja Limnos-nostimella otetusta pintasedimenttikoorista tehdyt analyysit. Tutkimuksessa käytetyt menetelmät ovat radiohiiliajoitus yli 70 vuotta vanhojen sedimenttien ajoittamiseen, 210Pb-ajoitus alle 70 vuotta vanhojen sedimenttien ajoittamiseen, raekokoanalyysi lajitteiden osuuksien määrittämiseen, infrapunan lähellä olevien aallonpituuksien spektrometria orgaanisen aineksen, mineraaliaineksen ja biogeenisen silikaatin osuuksien määrittämiseen, röntgensädefluoresenssi alkuainepitoisuuksien määrittämiseen, siitepölyanalyysi ja muiden palynomorfien analyysi kasvien ja muiden itiöperäisten eliöiden esiintyvyyden määrittämiseen. Lisäksi aineistoista tehtiin Pearsonin korrelaatio ja pääkomponenttianalyysi, joiden avulla määritettiin eri muuttujien suhteita toisiinsa. Tuloksista näkyy kolme erilaista aikakautta järven kehityksessä: luonnontilainen 1200-luvulta 1600-luvulle, vähäistä ihmistoiminnan vaikutusta 1600-luvulta 1850-luvulle ja huomattavaa ihmistoiminnan vaikutusta 1850- luvulta nykyaikaan. Luonnollisista muutoksista järven kehitykseen vaikutti eniten sademäärien muutokset. Myös paikalliset tuulen ja hyönteisten aiheuttamat metsätuhot vaikuttivat järven kehitykseen. Ihmistoiminnan suurimmat vaikutukset aiheutuivat järven patoamisesta, sekä veden ajoittaisista juoksutuksista padon läpi. Kun veden juoksutus padon läpi lopetettiin 1920-luvulla, järven pinta nousi ja sen pinta-ala kasvoi. Veden alle jääneestä maaperästä liukeni veteen runsaasti eri alkuaineita, mikä aiheutti monien alkuaineiden kohdalla suurimmat pitoisuudet koko tutkimuksen ajanjakson aikana. Lisäksi järveen päätyi jonkin verran teollisuuden aiheuttamia päästöjä kaukokulkeumana.
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(2020)Pro gradu -tutkielma on osa Vantaanjoen ja Helsingin seudun vesiensuojeluyhdistys ry:n hanketta, jossa tutkitaan maanläjitystoiminnan tyypillisiä pinta- ja pohjavesivaikutuksia sekä havainnoidaan lohikalojen lisääntymisalueille tapahtuvia haittoja Vantaanjoen valuma-alueella. Maanläjitystoiminnan moninaisen luonteen vuoksi, toiminnan laajuudesta ja sen vaikutuksista ei ole olemassa luotettavaa tutkimuksiin perustuvaa tietoa. Tutkielmassa selvitettiin millaisia vaikutuksia pilaantumattomien ylijäämämaiden välivarastoinnilla ja läjityksellä on lähiympäristön pohja- ja pintaveden laatuun. Pilaantumattomien ylijäämämaiden osalta tutkimuksia tehtiin kolmessa eri kohteessa Vantaanjoen valuma-alueella. Tutkielma keskittyi valuma-alueella sijaitsevien ympäristöluvanvaraisten- ja muilla luvilla toimivien maanläjitysalueiden velvoitetarkkailutulosten kokoamiseen, tarkasteluun ja paikkatietoanalyysin kehittämiseen. Näiden kriteerien avulla voidaan arvioida läjitysalueiden vesille aiheuttamia riskejä. Tutkimukseen kuului lisäksi pohjaveden purkautumispaikkojen ja luonnonpurojen kartoitusta, vedenlaadun kenttämittauksia ja vesinäytteenottoa. Esiselvitysten perusteella odotettiin maanläjitysalueiden läheisyydessä olevissa pinta- ja pohjavesissä olevan tausta-arvoista kohonneita raskasmetalleja, talousveden laatuvaatimuksista poikkeavia pH-arvoja sekä sähkönjohtavuuden muutoksia. Tulosten perusteella pilaantumattomilla ylijäämämailla on lieviä haitallisia vaikutuksia niin pinta- ja kuin pohjaveden laadullisiin tekijöihin. Pinta- ja pohjavesissä todettiin alueittain kohonneita pitoisuuksia ja arvoja muun muassa sulfaatilla, sähkönjohtavuudella, liukoisessa muodossa raudalla, mangaanilla, uraanilla, rikillä sekä sinkillä. Tutkielman tulokset auttavat arvioimaan läjitysalueiden haitta-ainekuormituksia vesiympäristöön ja suunnittelemaan riskienhallintatoimenpiteitä kuormituksen rajoittamiseksi. Suppeita analyysipaketteja tulisi laajentaa raskasmetallien osalta, sillä vähäinen analyysivalikoima ei edusta kaikkia kohteita. Tavoitteena on ohjata maanläjitystoiminta sellaisille alueille, joilla vesiin kohdistuvat haitat voidaan hallita.
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(2023)Arctic and sub-Arctic areas have significant amounts of carbon dioxide and methane stored in the sediments which can affect the climate change. The role of groundwater in the carbon cycle in the northern regions is not well known. The processes related to the groundwater cycle depend on the structure and composition of the sediment, which in turn are determined by the way the sediment is formed. In this study, the sedimentary structures and the hydrogeological properties of the Haaralamminkangas groundwater system was investigated. The aim was also to obtain more thorough knowledge on the geological processes that have formed the sedimentary structures of the area. Geophysical survey, drilling data, grain size analysis, and water sample analyzes were used as research methods. A sedimentary structure interpretation and 3D model were created from the data. In addition, a conceptual hydrogeological model was produced, which means information about the presence of groundwater in the area, the hydraulic connections of different parts of the groundwatersystem, and how groundwater interacts with surface waters. The 3D model will later serve in the study of the connection between the role of groundwater and the carbon cycle. The sediments of the area was found to consist of Late Weichelian glacial sediments, fine-grained basin sediments, valley delta sand deposits, sandy gravels of the braded river system, and fine-grained flood sediments. The deposits have been formed in the following main events: Late-Weichelian glacial sedimentary processes, rapid accumulation of a sediment load on the bottom of the river valley and fluvial processes. In the study, previously unknown information about the thickness of the sedimentary structures in the study area was clarified. Local gravel layers and a possible buried esker system wich was observed in the study may have an effect on groundwater flow. The ground water system was found to extend beyond its present boundaries and a buried bedrock in the middle of the area divides the aquifer into separate parts, where the surface waters from Puukkosuo end up in. Oulankajoki was found to be seeping into the aquifer. The modeling of the change in the height of the Oulankajoki water level showed that the effect of the spring floods is directed towards the areas of Haaralamminranta and Kouruniitty.
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(2023)Methane is a powerful greenhouse gas that is released to the atmosphere in many ways from natural sources. While wetlands are seen as major sources, open water systems, including small boreal lakes, should also be considered when estimating methane emissions locally and globally. Methane is produced the sediments and has several oxidation processes and emission pathways. In this master’s thesis, the sediments of Lake Pääjärvi, southern Finland, were studied using two different porewater sampling methods to analyze methane concentrations and geochemical properties of the porewater. The sampling methods, the Rhizons filter and the cut syringe method, were both performed to total of five sampling sites. A sediment profile was made from two locations, PAME1 and PAME2, and single sampling at 10 cm depth from the other sites. The sampling sites were located on different parts of the lake at depths of 3–16 m. Additionally, the water column was sampled for methane and water quality, and sediment for grain size, organic matter, and the C:N-ratio. As a result, the sampling methods were successful, and the sediment profiles and the sites could be compared. While there was difference in the methane concentrations, reliability of the methods was not concluded. The Rhizons filter method gave higher methane concentrations in only one sampling site, whereas the cut syringe was dominant in all others. Influential factors on the differences could be the use of different sampling cores, or the different duration of sampling between the sampling sites. The sulfate-methane transition zone was recognized from the depth of 4.5–6.5 cm in PAME1 and circa 3 cm in PAME2. The only sediment feature that coincided with high methane concentrations was larger grain size, although the variation between sampling sites was not large. The methane concentrations in the epilimnion were higher than near the sediment-water interface, which suggested that the methane in Lake Pääjärvi originates mainly from the catchment area and not from the sediments.
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Mineral supply in Viiankiaapa mire during the Holocene : evidenced by geochemistry and ash content (2021)In 2011 Anglo American published a promising multi metal ore deposit in Sodankylä, Northern Finland. The ore is named Sakatti, after a small pond in the vicinity of the discovering place. The ore is under the Viiankiaapa mire, which is part of national mire protecting program and Natura 2000 program. Viinkiaapa is at the eastern side of river Kitinen, which is known to have flooded, bringing mineral material to the mire. To prevent the possibly environment effects in the future, it is essential to know present conditions of the mire. The study area is at the southern part of the Viiankiaapa mire and consist of eight sampling sites for peat. The basal sediment of the study area was determined with ground penetrating radar profiles that pass the sampling sites. To study the mineral supply of the mire, nine elements (Na, Mg, Al, S, P, K, Ca, Mn, and Fe) were chosen for geochemical analyses and the ash content of the peat profiles was determined. The basal sediment is highly affected by the vicinity of the river Kitinen. Fluvial channels have eroded till, which was deposited during the last glacial period. At the eastern side of the study area possibly aeolian sand is detected. Depressions eroded by fluvial channels are filled by gyttja, typically below 179 m a.s.l. The geochemistry of the peat indicates that the early phase of the mire was characterized with higher mineral supply. At the eastern part of Viiankiaapa the mineral supply has decreased after the early phase of the mire. The mineral supply has been higher at the middle parts of the mire throughout the Holocene. The floods of the river Kitinen are the main source of the mineral supply. The decrease in the mineral supply indicates that the flooding events have reduced, and the normal floods inundate smaller area than the early floods.
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(2020)High amounts of H2 have been observed worldwide in deep bedrock aquifers. Sources and interaction processes of H2 within bedrock are poorly known so far, but recognizing those are important on order to identify risks related to various deep bedrock utilizing projects, such as repository of the nuclear waste. Aim of this study was to investigate if there is a correlation between H2 or fractionation factor α (H2O–H2) and the lithology of the host rock. In addition, several proposed low temperature H2 producing processes were reviewed via literature in order to investigate if α (H2O–H2) might help to identify the source of H2. In this study, H2 isotope data collected in previous studies in Finland from Pori, Pyhäsalmi, Juuka and Outokumpu deep bore holes representing various lithologies were used. In addition to α (H2O–H2), other parameters such as relative gas volumes, isotopic composition of water, temperature data, water pH, H2/He ratio of gasses were summarized. As part of the study, in the summer of 2019 new sampling was conducted in the Pinomäki borehole, in Pori by using tube sampling method and also field measurements were applied. Samples were later analyzed with ion chromatographic and spectrometric methods. In the results, isotope geochemical analyses were applied by using H2O–H2 system as a geothermometer. Results of the water analysis from Pori borehole were consistent with previous studies thus confirming two distinct water layers. Volume of H2 (0,4 %) differed considerably when compared with the previous study (28 %). Results of the isotopic composition of the hydrogen gas revealed extremely low values from -816 to -848 ‰ relative VSMOW which are among the most depleted δ2H-H2 values ever measured in the world. According to isotope analysis, in most of the boreholes in the study, except Outokumpu, H2 is not in equilibrium with groundwater when compared to in situ temperatures. α (H2O–H2) values were partially in similar range as fractionation related to some specific hydrogen forming processes, but there wasn’t a clear connection and values from different processes were overlapping each other. H2O–H2 system re-equilibrates relatively fast in a geologic timescale, which means that the possible isotopic fingerprint of H2 origin is lost. On the other hand, since H2 was clearly in a disequilibrium state, it might indicate the presence of possible active H2 forming processes. There wasn’t any clear correlation with host rock lithology and H2 concentration nor α (H2O–H2) either, except in Juuka, where lithology, α (H2O–H2), pH, and H2/He ratio summoned with high H2 volume (12,8 %) strongly indicates serpentinization as origin of H2. There are many challenges in the sampling of deep and narrow bore holes, especially related to the intention of preserving original conditions and also preventing gas contamination. In addition to further H2 sampling, recommendations for further studies include studying H2 producing reactors to investigate the effect of different H2 forming process to the isotope fractionation of H2.
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(2023)Global warming and anthropogenic activity will change the environmental conditions in the northern regions. For example, precipitation and river flow are expected to increase, the amount of organic matter ending up in the sea from land will increase, and its quality will change. The impact of changes in organic matter on northern coastal ecosystems and the carbon cycle is poorly known and these impacts need to be studied. In this study, the amount, quality and variations of organic matter accumulated in the surface sediments of the Bothnian Bay coastal areas in the northern part of the Baltic Sea and in the Liminka Bay over the past 100 years are studied by analyzing the concentrations of organic carbon and nitrogen (TOC and TN), C/N ratio, and the stable isotope ratios δ13C and δ15N, thus assessing environmental change in the coastal area of the Bothnian Sea. The accumulation of organic matter along the coast of Bothnian Bay is affected by both the proximity of the rivers and the land cover and land use of the river basin. More organic matter accumulates on the coasts (average 3.5 wt%) than further into the open sea (average 1.9 wt%). Contrary to presuppositions, there is no clear variation in the quality of organic matter between the coast and the open sea, but the observed change is north-south: in the northern areas, organic matter is more terrestrial and autochthonous, and in the southern areas it is more aquatic and allochthonous. The northern regions are characterized by large rivers with large amounts of forests and peatlands in the catchment areas. Further south, the rivers are smaller and carry less organic matter in quantity. Further north in the coastal ecosystem, the amount of primary production is lower and nitrogen does not limit primary production, as opposed to more southern areas. Primary production of ice may also have affected the organic matter deposited in the Bothnian Sea sediments. The amount of organic matter deposited in Liminka Bay has been on the rise over the past century, probably due to global warming, increased river flow and the impact of human activity. Based on the C/N ratio, the material has been more terrestrial in the 1930s to 1970s, after which the material has become more aquatic. In addition, aquatic primary production has increased in the Liminka Bay and nitrogen has begun to restrict primary production more. The study shows that climate and environmental change and human activities affect the amount and quality of organic matter in northern coastal areas, but further research is needed to determine more accurate ecosystem impacts.
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(2020)Pedogenic ferromanganese nodules and concretions are prevalent redoximorphic features in tropical and sub-tropical soils. The nodules are typically highly enriched in Fe and Mn that are present as oxides, hydroxides and oxyhydroxides. The formation of nodules happens via precipitation and translocation of metals as the soil redox state undergoes cyclical changes between reductive and oxidizing settings. As the nodule elemental distribution and structure is primarily and expression of the prevailing soil redox conditions, Fe-Mn nodules have the potential to be a useful tool of paleoclimatological analysis. The Chinese Loess Plateau (CLP) is a terrestrial archive for study of changes in the monsoon climate system. During Late Miocene, the intensification of the Asian Monsoon system caused an increase in warmth and humidity in inland Eastern Asia during a global trend of increased aridity and decreasing temperatures. Fe-Mn nodules from three different soil horizons, formed 8.07, 7.7 and 3.7 Ma ago in Lantian, southern CLP, were studied to compare nodules from varying sedimentary settings formed under different moisture regimes. Using electron microscopy methods, the structure and elemental distribution of nodules were described to compare their redoximorphic features. Large Fe-Mn nodules from floodplain sediments (8.07 Ma) show a well-developed structure, high metal enrichment and signs of variations in rate of formation and dominant redox states. The soil redox conditions are likely primarily controlled by the river flooding. Nodules from two eolian deposits (7.7 Ma and 3.7 Ma) were, on average smaller and showed less metal enrichment, less elemental differentiation and less variance in the dominant redox conditions. Only small, poorly developed nodules were found from older eolian sediments whereas younger soil horizon contained larger nodules with evidence of higher hydromorphism. While potential for using the nodules from eolian sediments to assess changes in precipitation exists, the lack of paleoclimatological information in smaller nodules, the small sample count, limitations of the methods and variance in depositional settings increase the uncertainty of the interpretation.
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Pinta- ja pohjavesien vuorovaikutus Vesioronkankaan pohjavesialueella Imatralla, Kaakkois-Suomessa (2022)The aim of this study was to research surface water-groundwater interactions and groundwater flow directions with stable isotopes of water, dissolved silica, d-excess, electrical conductivity, pH and temperature in the Vesioronkangas groundwater area in the city of Imatra, South-Carelia. Elevations of groundwater pipe heads existing in year 2015 were measured and connected to N2000-elevation system, and their coordinates were checked. Groundwater levels were measured, and pipe coordinates checked in the summer of 2015. Water samples were collected in the late winter of 2016 and temperature, pH and electrical conductivity of the samples were determined on site with YSI multiparameter probe. The samples were analyzed in the University of Helsinki laboratory during the spring and summer of 2016. Stable isotopes δ18O and δD were analyzed with Picarro L1115-i device and dissolved silica with Agilent 4100 device. Electrical conductivity was measured again in the laboratory after heating the samples. In the cluster analysis, the water samples formed three groups that were already detectable on the basis of the stable isotope composition of the water and other physical and chemical variables: surface waters, groundwater-influenced surface waters/mixed waters and groundwaters. Maps and flow and structural modellings of the groundwater area were created with QGIS and TopoDrive programs and it seems that there is no hydraulic connection between Lake Saimaa and Lake Immalanjärvi even if there is a bedrock fracture zone. Groundwater flows to many directions in the area, almost all compass points.
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(2021)The study area is Hyrylä groundwater area, located in southern Finland, in the city center of Tuusula. Hyrylä groundwater area is class 1 groundwater area, and it is classified as a chemical risk area. The Koskenmäki water pumping plant, owned by Keski-Uudenmaan Vesi Kuntayhtymä, is in the groundwater area, where on average 1000 m3 of water is pumped daily for domestic use. The groundwater area is situated in a southwest to northeast orientated esker which is a part of a bigger esker series starting from I-Salpausselkä in Hyvinkää. There is a big southwest to northeast orientated shear zone in the bedrock under the groundwater area where Lake Tuusulanjärvi and Tuusula-river follow the shear zone. The aim of this study was to research the interactions between river water and groundwater in the Hyrylä groundwater area and to get a better understanding of the geology of the area. Additionally, the movements of the groundwater were studied. Based on earlier studies the groundwater is discharging to the Tuusula-river near the Koskenmäki water pumping plant and the river water has been recharging to the groundwater. There are contaminated areas surrounding the old gas station in Hyrylä, where the soil and groundwater are contaminated with oil hydrocarbons, hence it was important to study where the water to Koskenmäki water pumping plant is coming from. Effects of the shear zone to the movements of the groundwater and to the amount of water available for pumping were also examined. The groundwater-river water interactions were studied with thermal methods and seepage meters. Isotopic and chemical tracers were analyzed from the water samples, which were collected from the groundwater observation wells, groundwater discharging to Tuusula-river and from the river water itself. A 3D geological structure model of the groundwater area was made based on earlier gravimetric measurements and drillhole data. The water table measurements from the observation wells were taken at the same time when the water samples were collected. Based on the 3D structure model a groundwater flow model was made to explain the movements of groundwater in Hyrylä. The geology of the groundwater area was examined with ground-penetrating radar, but the measurements were not successful and did not give any useful data for making the 3D model. The results of this study show that the groundwater is discharging to the Tuusula-river near the Koskenmäki water pumping plant. Based on the water analyses done, there was only one water sample with surface water mixed in it. 3D modeling gave a clear picture of the bedrock surface and cross-sections of the soil structure. According to the groundwater flow model, groundwater is flowing to the Koskenmäki water pumping plant from southeast. To the shear zone groundwater flows mostly from east and southeast. From the northwest part of the groundwater area the groundwater is flowing via northeast to the northern parts of the shear zone. The contaminated areas are not in the flow path to Koskenmäki water pumping plant. Based on the water analyses, groundwater discharging to the western parts of Tuusula-river is from a different source than the water discharging to the eastern parts of the river. In the shear zone the groundwater flow direction is to the south and the groundwater discharges to the river southwest of the Koskenmäki water pumping plant.
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