Mikrobiologiset indikaattorit öljyllä pilaantuneen maan kunnon ja kunnostumisen arvioinnissa

Soil is an unrenewable natural resource under increasing anthropogenic pressure. One of the main threats to soils, compromising their ability to provide us with the goods and ecosystem services we expect, is pollution. Oil hydrocarbons are the most common soil contaminants, and they disturb not just the biota but also the physicochemical properties of soils. Indigenous soil micro-organisms respond rapidly to changes in the soil ecosystem, and are chronically in direct contact with the hydrophobic pollutants on the soil surfaces. Soil microbial variables could thus serve as an intrinsically relevant indicator of soil quality, to be used in the ecological risk assessment of contaminated and remediated soils. Two contrasting studies were designed to investigate soil microbial ecological responses to hydrocarbons, together with parallel changes in soil physicochemical and ecotoxicological properties. The aim was to identify quantitative or qualitative microbiological variables that would be practicable and broadly applicable for the assessment of the quality and restoration of oil-polluted soil. Soil bacteria commonly react on hydrocarbons as a beneficial substrate, which lead to a positive response in the classical microbiological soil quality indicators; negative impacts were accurately reflected only after severe contamination. Hydrocarbon contaminants become less bioavailable due to weathering processes, and their potentially toxic effects decrease faster than the total concentration. Indigenous hydrocarbon degrader bacteria, naturally present in any terrestrial environment, use specific mechanisms to improve access to the hydrocarbon molecules adsorbed on soil surfaces. Thus when contaminants are unavailable even to the specialised degraders, they should pose no hazard to other biota either. Change in the ratio of hydrocarbon degrader numbers to total microbes was detected to predictably indicate pollutant effects and bioavailability. Also bacterial diversity, a qualitative community characteristic, decreased as a response to hydrocarbons. Stabilisation of community evenness, and community structure that reflected clean reference soil, indicated community recovery. If long-term temporal monitoring is difficult and appropriate clean reference soil unavailable, such comparison could possibly be based on DNA-based community analysis, reflecting past+present, and RNA-based community analysis, showing exclusively present conditions. Microbial ecological indicators cannot replace chemical oil analyses, but they are theoretically relevant and operationally practicable additional tools for ecological risk assessment. As such, they can guide ecologically informed and sustainable ecosophisticated management of oil-contaminated lands.Maaperä on pitkälti uusiutumaton, ihmistoimien uhkaama luonnonvara. Yksi yleisimmistä uhkista on saastuminen, joka alentaa maan kykyä tarjota sekä maa- ja metsätaloustuotteita että ekosysteemipalveluita. Saastuttavista aineista yleisimpiä ovat öljyhiilivedyt, jotka häiritsevät maaeliöstön välttämättömiä toimintoja sekä suoraan että epäsuorasti. Maaperän mikro-organismit bakteerit, arkit ja sienet reagoivan muutoksiin nopeasti ja ovat suorassa kontaktissa maapartikkelien pinnoilla olevien rasvaliukoisten kontaminanttien kanssa. Täten maan mikrobiologisia ominaisuuksia kuvaavat indikaattorit voisivat palvella öljyllä pilaantuneen maan kunnon ja kunnostumisen arvioinnissa. Akuutteja ja kroonisia mikrobiekologisia vasteita öljyyn maassa tutkittiin kahdessa kokeessa. Tavoitteena oli tunnistaa määrällisiä tai laadullisia mikrobimuuttujia, jotka olisivat helposti ja laajasti sovellettavissa öljyllä pilaantuneiden ja kunnostettujen maiden laadun arviointiin. Haasteena laatumittareiden löytämiselle oli, että maamikrobisto tyypillisesti reagoi hiilivetyihin lisäravintona. Yleisesti ehdotetut maaperän laadun mikrobiologiset indikaattorit todettiin epäherkiksi, sillä vielä kohtalaisella saastutustasolla ne antoivat negatiivisen sijasta positiivinen vasteen. Säistymisen myötä öljyn biosaatavuus maassa heikkenee, joten haittavaikutukset vähenevät nopeammin kuin kemiallisilla uutoilla mitattava kokonaismäärä. Missä tahansa maaympäristössä tavattavilla luontaisilla öljynhajottajabakteereilla on erityiskeinoja edistää ravintona palvelevien öljyhiilivetyjen biosaatavuutta. Täten yleisen biosaatavuuden ja toksisuuden pitäisi olla minimaalista, kun öljy ei ole enää hajottajienkaan käytettävissä. Erojen hajottajamikrobien ja kokonaismikrobiston määräsuhteissa havaittiin indikoivan ennustettavasti öljyn vaikutuksia ja biosaatavuutta. Myös maamikrobiston laadulliset ominaisuudet muuttuvat öljyn vaikutuksesta. Saastuminen laski bakteeriyhteisön monimuotoisuutta. Monimuotoisuuden nousu, samoin kuin puhtaan verrokkimaan bakteeriyhteisöä muistuttava yhteisö, indikoivat maamikrobiston toipumista öljykontaminaatiosta. Jos pitkäaikaisseuranta on mahdotonta ja vastaavaa puhdasta verrokkimaata ei ole saatavilla, voisi vertailun mahdollisesti tehdä DNA:n (mennyt+nykyinen yhteisö) sekä RNA:n (vain nykyinen yhteisö) erojen pohjalta. Maamikrobiologiset testit eivät korvaa kemiallisia öljyhiilivety-määrityksiä, mutta ne tarjoavat teoreettisesti relevantin ja käyttökelpoisen lisätyökalun ekologiseen riskinarviointiin. Täten mikrobiekologiset indikaattorit voivat ohjata öljyllä pilaantuneiden maiden ekologisesti tiedostavaa ja kestävää käyttöä

Bacterial community changes in response to oil contamination and perennial crop cultivation

We investigated bacterial community dynamics in response to used motor oil contamination and perennial crop cultivation by 16S rRNA gene amplicon sequencing in a 4-year field study. Actinobacteria, Proteobacteria, Chloroflexi, Acidobacteria, and Gemmatimonadetes were the major bacterial phyla, and Rhodococcus was the most abundant genus. Initially, oil contamination decreased the overall bacterial diversity. Actinobacteria, Betaproteobacteria, and Gammaproteobacteria were sensitive to oil contamination, exhibiting clear succession with time. However, bacterial communities changed over time, regardless of oil contamination and crop cultivation. The abundance difference of most OTUs between oil-contaminated and non-contaminated plots remained the same in later sampling years after the initial abundance difference induced by oil spike. The abundances of three oil-favored actinobacteria (Lysinimonas, Microbacteriaceae, and Marmoricola) and one betaproteobacterium (Aquabacterium) changed in different manner over time in oil-contaminated and non-contaminated soil. We propose that these taxa are potential bio-indicators for monitoring recovery from motor oil contamination in boreal soil. The effect of crop cultivation on bacterial communities became significant only after the crops achieved stable growth, likely associated with plant material decomposition by Bacteroidetes, Armatimonadetes and Fibrobacteres.Peer reviewe

Response of Soil Bacterial Community Diversity and Composition to Time, Fertilization, and Plant Species in a Sub-Boreal Climate

Pastures are an important part of crop and food systems in cold climates. Understanding how fertilization and plant species affect soil bacterial community diversity and composition is the key for understanding the role of soil bacteria in sustainable agriculture. To study the response of soil bacteria to different fertilization and cropping managements, a 3-year (2013-2015) field study was established. In the split-plot design, fertilizer treatment (unfertilized control, organic fertilizer, and synthetic fertilizer) was the main plot factor, and plant treatment [clear fallow, red clover (Trifolium pratense), timothy (Phleum pratense), and a mixture of red clover and timothy] was the sub-plot factor. Soil bacterial community diversity and composition, soil properties, and crop growth were investigated through two growing seasons in 2014 and 2015, with different nitrogen input levels. The community diversity measures (richness, Shannon diversity, and Shannon evenness) and composition changed over time (P<0.05) and at different time scales. The community diversity was lower in 2014 than in 2015. The temporal differences were greater than the differences between treatments. The overall correlations of Shannon diversity to soil pH, NO3-, NH4+, and surplus nitrogen were positive and that of bacterial richness to crop dry matter yield was negative (P<0.05). The major differences in diversity and community composition were found between fallow and planted treatments and between organic and synthetic fertilizer treatments. The differences between the planted plots were restricted to individual operational taxonomic units (OTUs). Soil moisture, total carbon content, and total nitrogen content correlated consistently with the community composition (P<0.05). Compared to the unfertilized control, the nitrogen fertilizer loading enhanced the temporal change of community composition in pure timothy and in the mixture more than that in red clover, which further emphasizes the complexity of interactions between fertilization and cropping treatments on soil bacteria.Peer reviewe

Biostimulation proved to be the most efficient method in the comparison of in situ soil remediation treatments after a simulated oil spill accident

The use of in situ techniques in soil remediation is still rare in Finland and most other European countries due to the uncertainty of the effectiveness of the techniques especially in cold regions and also due to their potential side effects on the environment. In this study, we compared the biostimulation, chemical oxidation, and natural attenuation treatments in natural conditions and pilot scale during a 16-month experiment. A real fuel spill accident was used as a model for experiment setup and soil contamination. We found that biostimulation significantly decreased the contaminant leachate into the water, including also the non-aqueous phase liquid (NAPL). The total NAPL leachate was 19 % lower in the biostimulation treatment that in the untreated soil and 34 % lower in the biostimulation than oxidation treatment. Soil bacterial growth and community changes were first observed due to the increased carbon content via oil amendment and later due to the enhanced nutrient content via biostimulation. Overall, the most effective treatment for fresh contaminated soil was biostimulation, which enhanced the biodegradation of easily available oil in the mobile phase and consequently reduced contaminant leakage through the soil. The chemical oxidation did not enhance soil cleanup and resulted in the mobilization of contaminants. Our results suggest that biostimulation can decrease or even prevent oil migration in recently contaminated areas and can thus be considered as a potentially safe in situ treatment also in groundwater areas.Peer reviewe

Bacterial Diversity in a Dynamic and Extreme Sub-Arctic Watercourse (Pasvik River, Norwegian Arctic)

Microbial communities promptly respond to the environmental perturbations, especially in the Arctic and sub-Arctic systems that are highly impacted by climate change, and fluctuations in the diversity level of microbial assemblages could give insights on their expected response. 16S rRNA gene amplicon sequencing was applied to describe the bacterial community composition in water and sediment through the sub-Arctic Pasvik River. Our results showed that river water and sediment harbored distinct communities in terms of diversity and composition at genus level. The distribution of the bacterial communities was mainly affected by both salinity and temperature in sediment samples, and by oxygen in water samples. Glacial meltwaters and runoff waters from melting ice probably influenced the composition of the bacterial community at upper and middle river sites. Interestingly, marine-derived bacteria consistently accounted for a small proportion of the total sequences and were also more prominent in the inner part of the river. Results evidenced that particular conditions occurring at sampling sites (such as algal blooms, heavy metal contamination and anaerobiosis) may select species at local scale from a shared bacterial pool, thus favoring certain bacterial taxa. Conversely, the few phylotypes specifically detected in some sites are probably due to localized external inputs introducing allochthonous microbial groups

Successful aerobic bioremediation of groundwater contaminated with higher chlorinated phenols by indigenous degrader bacteria

The xenobiotic priority pollutant pentachlorophenol has been used as a timber preservative in a polychlorophenol bulk synthesis product containing also tetrachlorophenol and trichlorophenol. Highly soluble chlorophenol salts have leaked into groundwater, causing severe contamination of large aquifers. Natural attenuation of higher-chlorinated phenols (HCPs: pentachlorophenol + tetrachlorophenol) at historically polluted sites has been inefficient, but a 4-year full scale in situ biostimulation of a chlorophenol-contaminated aquifer by circulation and re-infiltration of aerated groundwater was remarkably successful: pentachlorophenol decreased from 400 μg L−1 toPeer reviewe

Enrichment, isolation and biodegradation potential of psychrotolerant polychlorinated-​biphenyl degrading bacteria from the Kongsfjorden (Svalbard Islands, High Arctic Norway)

Persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), have been detected in abiotic Arctic matrices: surface sediments and seawater from coastal areas in the Kongsfjorden were collected and analyzed. Levels of PCBs varied depending on the sampling site. Total PCB concentrations were between 11.63 (site C2W) and 27.69 pg l− 1 (site AW). These levels were comparable to those reported previously in lake sediments from the northern Svalbard. The occurrence and biodegradation potential of cold-adapted PCB-oxidizing bacteria in seawater and sediment along the fjord was also evaluated. After enrichment with biphenyl, 246 isolates were obtained with 45 of them that were able to grow in the presence of the PCB mixture Aroclor 1242, as the sole carbon source. The catabolic gene bphA was harbored by 17 isolates with affiliates to the genera Algoriphagus, Devosia and Salinibacterium that have been never reported as able to utilize PCBs, thus deserving further investigation. The total removal of Aroclor 1242 and selected PCB congeners was evaluated at 4 and 15 °C for eight bphA-harboring isolates and Gelidibacter sp. DS-10. With few exceptions, tested strains showed greater efficiency at 15 than at 4 °C. Isolates were able to reduce most chromatographic peaks by > 50%, with some di- and trichlorobiphenyls that were quite totally removed (> 90%)

The lifelong socioeconomic disadvantage of single-mother background - the Helsinki Birth Cohort study 1934-1944

Background: Growing up with one parent is associated with economic hardship and health disadvantages, but there is limited evidence of its lifetime consequences. We examined whether being born to an unmarried mother is associated with socioeconomic position and marital history over the lifespan. Methods: We analysed data from the Helsinki Birth Cohort Study including birth, child welfare clinic and school healthcare records from people born in Helsinki, Finland, between 1934 and 1944. Using a unique personal identification number, we linked these data to information on adult socioeconomic position from census data at 5-year intervals between 1970 and 2000, obtained from Statistics Finland. Results: Compared to children of married mothers, children of unmarried mothers were more likely to have lower educational attainment and occupational status (odds ratio for basic vs. tertiary education 3.40; 95 % confidence interval 2.17 to 5.20; for lowest vs. highest occupational category 2.75; 1.92 to 3.95). They were also less likely to reach the highest income third in adulthood and more likely to stay unmarried themselves. The associations were also present when adjusted for childhood socioeconomic position. Conclusion: Being born to an unmarried mother, in a society where marriage is the norm, is associated with socioeconomic disadvantage throughout life, over and above the disadvantage associated with childhood family occupational status. This disadvantage may in part mediate the association between low childhood socioeconomic position and health in later life.Peer reviewe

Maternal Grand Multiparity and the Risk of Severe Mental Disorders in Adult Offspring

Peer reviewe