Browsing by discipline "Maaperä- ja ympäristötiede"
Now showing items 21-28 of 28
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(2017)In recent years, research on the environmental impacts by acid sulfate soils have been in focus, but studies on sulfur gas emissions are relatively few. In contrast, emissions of SO2, H2S, COS, CS2 and (CH3)2S from different wetlands and other soils have been investigated more. Sulfur gases are difficult to study due to their high reactivity to environmental changes, regarding e.g. redox potential, temperature and water content. The aim of this thesis is to evaluate if sulfur gas analysis could be applied to the identification of acid sulfate soils, especially sulfidic materials. In autumn 2016, soil samples were taken from three agricultural fields in Ostrobothnia and Southern Ostrobothnia. The fields had been earlier classified as acid sulfate soils by the Geological Survey of Finland (GTK). The occurrence of sulfides in the soil material was identified based on the lowering of pH by aerobic incubation (10 weeks). In the laboratory, the sulfur gas emissions after a short incubation period were investigated with a gas chromatograph and a portable ChemPro100i gas detector (Environics Oy). The gas detector was additionally implemented directly in the field but the measurements were complicated by unfavorable weather conditions. Hydrogen sulfide (H2S) could not be identified in any soil sample and the occurrence of sulfur dioxide (SO2) was lower than expected. The unknown gas that was present in most samples and had the biggest peak areas is indirectly assumed to be carbonyl sulfide (COS). Based on the gas chromatographic analysis, the emissions of sulfur gases from soil samples were the larger, the larger was the pH-drop after the aerobic incubation. Five of the sensors (signals) in the gas detector showed a significant difference (p <0.05) in (sensor) resistance for sulfidic compared with non-sulfidic soil materials. Despite the promising results showing the potential of sulfur gas analysis to become a tool to aid the mapping of acid sulfate soils, more tests are needed, especially on the sulfur gas emissions from acid sulfate soils in the field during warm summer months.
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(2020)The main problems with cultivated peat soil are its weak carrying capacity, high greenhouse gas emissions, coldness, and acidity. There is very little research on using industrial by-products as soil amendments in peat soil. The aim of this thesis was to study the effects of industrial by-products paper mill sludge and gypsum on the sustainability of soil structure, greenhouse gas (CO2 and N2O) emissions and soils heat and gas dynamics in peat soil. The study was performed in the laboratory on samples taken from a field test. The tested treatments were unfertilized, control, gypsum 3 kg m-2, paper mill sludge 3 kg m-2, paper mill sludge 15 kg m-2 and paper mill sludge 15 kg m-2 + gypsum 3 kg m-2. The water-stable aggregates were determined by wet sieving with 0.25 mm mesh and 2 mm mesh at three different moisture contents. The greenhouse gas emissions of the soil were determined by gas chromatography at field capacity. The thermal properties of the soil were determined by measuring the thermal conductivity and diffusivity of the soil at field capacity and at saturation. In addition, soil pH, hydraulic conductivity of saturated soil, and water-holding capacity at matrix potentials pF 0; 0.4; 1; 2 and 4.2 were measured. Soil amendments had no effect on the water-stable aggregates in field moisture. The soils CO2 emissions increased with paper mill sludge treatments and decreased with gypsum treatment. Individual soil amendments had no effect on the N2O emissions of the soil, but the combined effect of paper mill sludge and gypsum increased the N2O emissions. The soils CH4 consumption decreased with gypsum treatment. Soil amendment treatments had no effect on soil thermal conductivity or thermal diffusivity at field capacity. However, in water-saturated samples the thermal conductivity and heat diffusivity of the soil was increased by the combined effect of paper mill sludge and gypsum. Unlike gypsum, paper mill sludge was found to have a clear liming effect. Soil amendments had no effect on the hydraulic water conductivity or water-holding capacity of saturated soil at any matrix potential. Based on the results, the soil amendments used did not have a major impact on the cultivation problems in peat soil, but further research on their use as soil amendments is needed.
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(2016)The interactions between sediment chemistry and bacterial communities are multidirectional and complex. A hypoxia-driven decrease in dissolved oxygen (O2) leads to changes in sediment chemistry, bacterial community and ultimately alters their interactions. The sediment components very sensitive to changes in O2 are iron (Fe) and manganese (Mn) oxides. When O2 content decreases, they will be reduced by bacteria in order to obtain energy. This study was carried out with sediment samples collected from sites of different oxygen status in the Gulf of Finland. The focus was to unravel the interactions between sediment chemistry and bacterial communities by means of chemical extractions distinguishing between Fe and Mn pools of different solubility and, thus, bioavailability. For this purpose, a two-step chemical extraction was carried out in order to selectively quantify the easily reducible and more crystalline fractions of Fe and Mn oxides. The chemistry of phosphorus (P) is intrinsically linked to Fe and aluminum (Al) oxides but not to Mn oxides which are not able to retain P. Unlike Fe and Mn, Al is not a redox-sensitive element but its oxides are of importance in controlling the release of P from sediments by resorption of P. The extracts were analyzed for Fe, Mn, Al and P. Furthermore, a next generation high-input method was used to extract the DNA from the sediments. The results of the chemical extractions and taxonomical classification of the bacteria were statistically analyzed. Subsequently, the interactions between the easily-reducible fractions of Fe and Mn oxides and bacterial communities were established using correlations (correlation coefficient ≥ 0.7). The extractability of Fe and Mn increased in poorly-oxygenated and hypoxic conditions. Iron seemed to originate in the easily-reducible fraction, while Mn was in a less reactive form than Fe. As expected, the extractability of Al did not vary with changing oxygen status. In addition, the rather low extractability of P suggests a strong initial adsorption of P on Al oxides. In environment low in oxygen, P released from the Fe oxides was resorbed by Al oxides. We conclude that the major bacterial processes in the sediments are related to the reduction of sulfate and sulfur and decomposition of organic matter. The bacterial communities varied both vertically and horizontally. The vertical variation was mainly explained by the redox potential, while the horizontal variation was more complex and essentially related to easily-reducible Fe and total carbon and nitrogen in sediment. The correlations between the easily-reducible Fe and Mn and the bacterial communities revealed taxa that reduce Fe and/or Mn, some that oxidize metals, and others that could benefit from organic rich environments created by Fe, Mn and S-reducing bacteria. The correlations indicate causative relationships and indirect associations, which can provide leads for future research.
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(2016)Wastewater produced by the mining industry can be very acidic and high in dissolved metals. If released to the environment, it initiates diverse issues some of which are increasing acidity and high heavy metal concentrations. Wastewater treatment is traditionally done by using manufactured chemicals which is neither environmentally nor economically sound. The use of industrial by-product geomaterials is a low-cost alternative wastewater treatment method as these materials are anyway produced in other industries. In wastewater treatment with geomaterials, the element removal mechanism is based on precipitation and surface adsorption which are highly pH dependent. In this study, acidic multimetal wastewater from Talvivaara was treated with three byproducts (steel slag, apatite mine tailings and Sachtofer PR) of Finnish industries. Waste water was incubated with geomaterials for 1, 7 and 21 days, then titrated to pH 7. Effect of geomaterials and time on waste water pH and base consumption required to increasing the pH, as well as on concentrations of iron, aluminum, nickel, zinc, manganese, sodium and sulfur were studied. Untreated wastewater pH decreased with time due to hydrolyses of metals. Oxidation of ferrous iron to ferric iron also seemed to contribute to acidification of wastewater. Thus the base consumption increased significantly with incubation time. Among the used solids, steel slag most efficiently increased pH and consequently decreased the consumed base. Steel slag also showed the best results in element removal. It removed all or significant amount of dissolved iron, aluminum, nickel, manganese and sulfur. Tailings and Sachtofer PR showed poor results regarding element concentration by releasing several elements to the solution.
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(2013)Liming agricultural fields with byproducts from steel industry is quite widespread, even though behavior of some heavy metals in soil is not well known. Especially chemistry of vanadium in soil is poorly understood and is very complicated due to it´s several oxidation states. Particularly soil pH and oxidation-reduction conditions are effecting to the occurrence of vanadium. It can be found in the environment mostly with oxidation states of +3, +4 and +5 with increasing solubility as the oxidation state increases. This study was made as a part of the doctoral thesis research of Inka Reijonen concerning bioavailability and toxicity of chromium and vanadium. Effects of soil organic matter content and pH on reactions of vanadyl (VO2+) were studied. The study beginned with systematic experiments that included incubation of air dried and sieved soil samples with vanadium(+4) added to the soil as VOSO4. Soil pH had been adjusted to three levels (acid soil, soil natural pH and alkaline soil) and vanadium was added as increasing concentrations. The effects of soil pH and organic matter content were examined with successive extractions. By using this method shares of different fractions of vanadium as a soluble compound and adsorbed to the surface of oxides, organic matter or mineral matter, could be studied. In addition, the same method was used to study the behavior of vanadium in field conditions where steel slag had been used for liming. The methods that were used seemed to fit for moderate concentrations of vanadium since some limitations occurred with higher concentrations. Vanadium was observed to retain mainly in organic matter in low soil pH and hence the movement into deeper soil layers was minor. Increase of pH increased the solubility of vanadium in the soil, which was assumed to be a result of oxidation of a vanadyl(+4) into a vanadate(+5). Liming a field with steel slag was observed to increase soil pH and increase the share of vanadium adsorbed to oxides and organic matter. The share of soluble vanadium in field conditions was very small compared to the total amount of vanadium in the soil. On the other hand, the share of soluble fraction was observed to increase in high vanadium concentrations as results of incubation experiments.
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(2017)Suomalaisessa havupuuvaltaisessa metsämaassa typpi on yleensä kasvien kasvua rajoittavana tekijänä. Tämä aiheutuu siitä, että typpi on tällaisessa kasvualustassa sellaisessa orgaanisessa muodossa, joka ei ole kasveille käyttökelpoista. Typpi voi olla kompleksoitunut esimerkiksi tiettyihin kasvien tuottamiin sekundaarisiin metaboliatuotteisiin, kuten tanniineihin. Metsäekosysteemeissä tärkeinä typen kiertoon vaikuttavina tekijöinä ovat puiden ja aluskasvien sienijuuret. Niiden toiminta auttaa kasveja saamaan orgaanisessa muodossa olevaa typpeä irti, jolloin ne saavat kilpailuedun muihin kasveihin verrattuna. Tämän tutkimuksen tarkoituksena oli selvittää millainen vaikutus mikrokosmoksessa kasvaneilla varpukasveilla (kanerva (Calluna vulgaris), mustikka (Vaccinium myrtillus) ja puolukka (Vaccinium vitis-idaea)) sekä männyllä (Pinus sylvestris) on typen käyttäytymiseen metsämaan orgaanisessa kerroksessa. Mukana oli myös kontrollimaa, jossa ei ollut kasvillisuutta. Koejäsenistä määritettiin orgaaninen aines hehkutushäviöllä, pH, mineraalityppi- ja liukoinen aminohappopitoisuus kuoppalevymenetelmällä, kokonaishiili, kokonaistyppi ja C/N-suhde sekä maan liukoinen orgaaninen hiili ja liukoinen typpi. Lisäksi maasta määritettiin hydrolysoituva ja vaikeasti hajoava typpi MSA-uutolla sekä maasta ja kasvien juurista totaalifenolit ja kondensoituneet tanniinit. Kiintoaineksen kokonaistyppipitoisuus oli kontrollimaassa korkein ja C/N-suhde oli odotusten mukaisesti matalin kontrollimaassa. Kontrollimaassa olivat suurimmat ammoniumtyppi- ja liukoisen orgaanisen typen pitoisuudet sekä korkein pH. Nitraattityppi jäi kaikissa koejäsenissä alle määritysrajan. Liukoinen aminohappopitoisuus oli korkein mäntymaassa ja varpumaissa matalin. Kondensoituneiden tanniinien ja totaalifenolien pitoisuus oli suurin kanervan ja pienin männyn juurissa. Lisäksi kanervamaassa olivat suurimmat kondensoituneiden tanniinien ja totaalifenolien pitoisuudet. Kasvilajilla oli selkeä vaikutus orgaanisen typen liukoisuuteen maassa. Mänty näytti tehostavan aminohappojen vapautumista orgaanisesta aineksesta mykorritsojensa avulla. Lisäksi varpukasveilla ja männyllä näytti olevan eroavaisuutta orgaanisen typen käytössä. Tulosten perusteella kanerva, puolukka ja mustikka tuottavat enemmän fenolisia yhdisteitä, jotka voivat sitoa typpeä vaikeasti hajotettavaan orgaaniseen muotoon mäntyyn verrattuna. Lisäksi varpukasvimaiden matala pH voi olla edesauttavana tekijänä polyfenoli-proteiini-kompleksien syntymisessä ja näin ollen vaikuttaa typen kiertoon metsämaassa.
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(2010)Suomessa on pitkät suoviljelyn perinteet. Suon muuttaminen viljelykelpoiseksi pelloksi edellyttää raivauksen ja ojituksen lisäksi maanparannustoimenpiteitä. Turvepellon viljely aiheuttaa muutoksia maan rakenteessa ja voi johtaa vähitellen maa-alueen luokituksen siirtymiseen turvemaiden luokasta multamaaksi ja lopulta kivennäismaaksi. Turve- ja multamaiden osuus viljelyssä olevasta peltoalasta on noin 14 %, mutta niiden ympäristövaikutukset ovat pinta-alallista osuutta suuremmat. Viljelykäytössä olevia orgaanisia maita on tutkittu vähemmän kuin viljeltyjä kivennäismaita. Orgaanisen aineksen tutkimuksen merkitys ei rajoitu pelkästään turve- ja multamaihin, sillä myös kivennäismaan sisältämällä humukseksi muuttuneella orgaanisella aineksella on tärkeä rooli veden pidättäjänä, kasvinravinnevarastona ja monipuolisena reaktiopintana. Tässä tutkimuksessa määritettiin kolmen rahkaturpeen ja kolmen saraturpeen vesiliukoisten ravinteiden pitoisuuksia kolmelta näytteenottosyvyydeltä. Homogenoimattomille, näytteenottokosteudessa säilytetyille turpeille tehtiin uutto kahdella menetelmällä, jotka olivat veden kanssa ravisteluun perustuva huiskutusmenetelmä ja veden painovoimaiseen suotautumiseen perustuva suotautumismenetelmä. Suotautumismenetelmä toteutettiin maa-vesi-uuttosuhteella 1:5, kun taas huiskutusmenetelmässä käytettiin kahta uuttosuhdetta (1:5 ja 1:10). Turveuutteet kalvosuodatettiin (0,45 ?m) ja suodoksesta analysoitiin liukoiset orgaanisen ja epäorgaanisen hiilen ja typen pitoisuudet sekä metallikationien (Na, Mg, Mn, Fe, Cu, Zn) varautuneet ja varauksettomat spesiekset. Lisäksi määritettiin liukoinen epäorgaaninen fosfori suodoksesta ja kokonaisfosfori suodattamattomasta turveuutteesta. Uuttosuhteen 1:5 suodoksista tehtiin osa määrityksistä ja uuttosuhteen 1:10 suodoksista kaikki edellä mainitut määritykset. Tutkimuksessa oli paljon muuttujia, joten mittaustuloksiin tulee suhtautua suuntaa antavina. Vesiliukoisten ravinteiden analyysit tehtiin turpeen vesiuutteesta, joten saatuja pitoisuuksia ei voi suoraan verrata turpeen kokonaisravinteisuuteen tai todellisen maaveden pitoisuuksiin. Turveuutteen typestä esiintyi suurempi osa epäorgaanisessa muodossa kuin orgaanisessa. Helposti huuhtoutuvan nitraattitypen osuus oli erityisesti saraturpeilla suuri, pintakerroksessa selvästi yli puolet liukoisesta kokonaistypestä. Turpeen liukoinen hiili esiintyi odotetusti lähes kokonaan orgaanisessa muodossa. Suodattamattomasta näytteestä määritetyn kiintoainesta sisältävän kokonaisfosforin pitoisuudet olivat 20?1000-kertaisia verrattuna suoraan käyttökelpoiseen vesiliukoiseen fosfaattifosforiin. Ravinnekationeista magnesium, natrium ja mangaani esiintyivät liuoksessa pääosin varauksellisina kationeina, kun taas raudasta, sinkistä ja kuparista puolet tai enemmän oli varauksettomassa kompleksoituneessa muodossa. Ravinteen esiintymismuoto vaikuttaa sen liikkumiseen maaperässä sekä sen mobilisoitumiseen vesiympäristössä. Orgaaniselta viljelymaalta huuhtoutuu ravinteita sekä liukoisessa muodossa että partikkelimuotoisen orgaanisen aineksen rakenneosana tai siihen kemiallisesti pidättyneenä. Ympäristön kannalta huuhtoutuvista ravinteista haitallisimpia ovat leville käyttökelpoiset vesiliukoiset epäorgaaniset muodot, joita ovat NO3-, NH4+ ja PO42-.
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(2018)This work was carried out to find out, in what manner exposure to or the avoidance of sun's ultraviolet radiation (UV) affects the reproduction of water fleas (Daphnia magna) at different copper (Cu) concentrations. A 21-day long reproduction test containing two stress factors was performed adapting the OECD chemical testing standard number 211 ”Daphnia magna Reproduction Test” from the year 1998. Using an element contents analysis (ICP MS) that was done of the water fleas which have participated in the reproduction test, it was studied whether the UV affects Cu accumulation in Daphnia magna. UVB radiation has been reported being harmful to many aquatic organisms directly by harmful biological effects as well as indirectly due to the radiation interacting with chemicals occurring in the environment so that the toxicity of chemicals will increase. Thus UV is an environmental factor that may cause effects to be taken into account when assessing the effects of emissions of chemicals. Copper levels were 3, 9, 30, 90 and 300 µg Cu increment per liter of Elendt M7 growth medium, which contains 1.6 µg Cu / l as a nutrient. UV exposure was carried out using solar radiation so that half of the test units (+UV) was placed under UV-permeable polyethylene film and the other half (−UV) under UV-protection foil (Wipa-foil clear SR). At the beginning of the test, there were ten parallel individual water fleas in each UV and Cu treatment combination and 14 parallel Cu blanks at both UV levels. To test run the experimental apparatus, that had been built in Viikki Helsinki under a plexiglas canopy absorbing 40 % of UV, a shorter pre-test was made in the midsummer. The actual reproduction test was performed in July–August. One important element of the experimental part of this study was to examine the test apparatus according to the demands of the testing standard. Because of methodological problems, amount of the feeding (0.027 ± 0.006 mg C / Daphnia / day) was only 13–27 % of the requirements of the standard. Reproduction of the control water fleas remained at only about a third of the minimum requirement of the standard, so the test wasn't valid. The response variable was the average cumulative number of living offspring produced per surviving parent animal at the end of the test. The NOEC and LOEC values for reproduction were 30 µg Cu / l and 90 µg Cu / l expressed in the Cu spiking levels (Tukey, p < 0.001). They were inaccurate, because they were based on too few concentrations chosen from too large a range. Already the Cu spiking 90 µg / l was extremely high on the grounds of survival, because among the −UV test units the mortality was 70 % and in the +UV test units 60 %. In the lower spikings than 90 µg / l there was no mortality caused by the test factors. Copper bioaccumulation assay suffered from contamination. The UV exposure without Cu spikings did not affect statistically significantly cumulative offspring production (t-test, p = 0.87, df = 26). On the average, the UV factor had a significant increasing effect (ANOVA, p < 0.01) on the production over all the Cu levels: the average cumulative number of offspring produced (± SD) was in the −UV level 22.8 ± 6.3 (n = 45) and in the +UV level 24.4 ± 5.2 (n = 48). Interaction was perceived between UV and Cu spiking at extended risk level (ANOVA, 0.05 < p < 0.1) so that the UV exposure trend-wise dampened the decrease of production in the spiking level of 90 µg / l. Statistically significant (p < 0.01) interaction effect of UV and spiking to offspring production was found after fitting a non-linear model for the data set using a second degree polynome for the Cu spiking and performing a regression analysis. This unexpected interaction requires further examination using the same flow-through growth medium for both of the UV levels. In such flow-through test design the changes in growth media possibly caused by the UV do not affect the results. In order to avoid exposing the −UV water fleas to radiation pulses during the daily examination, they must be only handled in UV protected space, unlike was done in this work.
Now showing items 21-28 of 28