Total organic carbon (TOC) is a critical parameter when investigating the health of aquatic ecosystems. This report details the findings of the study on fluctuations of TOC concentration in Fylleån catchment are between January 2001 and December 2023 (23-year period). The study provided valuable insights into the long-term trends in TOC concentrations and its association with changes in river water discharge and surface water temperatures. The study revealed significant spatial and temporal variations, with higher TOC levels in areas with intensive anthropogenic activities (downstream), and lower levels in forested regions (upstream). Temporally, TOC concentrations exhibit distinct seasonal patterns, peaking in late autumn and early winter due to increased organic runoff and decreasing in late spring and summer due to reduced precipitation and higher biological activity. Online datasets were downloaded to aid in the assessment of the presence of a seasonal trend in changes in riverine TOC concentration. The same dataset was used to calculate the correlation between seasonal TOC concentration and river discharge / surface water temperature. Upstream TOC concentration ranges were 5.5-13.97mg/l in winter, 5.97-11.07mg/l in spring, 8.63-20.37mg/l in summer and 7.07-20.73mg/l in autumn. Downstream TOC concentration ranges were 6.83-19.07mg/l in winter, 6.43-12.83mg/l in spring, 6.33-16.97mg/l in summer and 6.23-24.53mg/l in autumn. For all the three stations, standard deviation was lowest in spring (1.39, 1.58, & 1.45) and highest in autumn (4.09, 3.06, & 3.59) at Fylleån-fyllebro, Trönningeån-trönninge, and Lillån Ga Järnvägsbron respectively. There was a positive correlation between TOC concentrations and river discharge. Results for correlation between surface water temperature and seasonal TOC concentration were generally positive with only summers showing purely negative correlation. The study concluded that there are seasonal trends in TOC concentrations which are partly influenced by river discharge and surface water temperatures.

The aim of the diploma thesis was to evaluate the content of soil organic carbon in the area of Novohradsko. Soil organic carbon was monitored in its stable (SOC) and labile (WSOC) form, followed by the total organic carbon stock (Cpool). These soil parameters were determined in soils of different land cover types (forest, arable land, grassland) in the area formed by the catchments of Pasecký, Bedřichovský, Váčkový and Veverský stream. Data obtained in 2001, 2007 and 2014 were statistically analysed and the comparison of the data from different catchments was conducted. The results show the impact of different land use on the amount of soil organic carbon. In general, a higher amount of soil organic carbon were found in soils of grassland and forest soils, whereas a lower amounts were found in arable land. The comparison and the time development analysis show that there is a trend of the increase in quantity of stable fraction of soil organic carbon in all categories of land cover over the whole monitored period. The opposite trend of a continuous decrease over the whole of the monitored period in all categories of land cover was observed in amounts of labile fraction of soil organic carbon. It can be said that there is an increase in the stock of a stable fraction of soil organic carbon due to lower losses of the labile fraction of soil organic carbon in forest soils, arable soils and soils of grassland.

CO2 is a greenhouse gas which is significantly emitted by agricultural soils through the decomposition of plant residue and soil organic carbon. Carbon isotopes can be used in determining the source of the CO2, origin of the carbon, and the age of the CO2 emissions. This study investigates the transport of CO2 gas through agricultural soils using carbon isotopes 14C and 13C to complement concentration and production rate measurements in two comparative agricultural settings in Eastern Ontario, one of which has been modified by clearing and dredging of the adjacent riparian zone and one left undredged. Traditional radiocarbon dating measures time through loss by decay, while recent dating is based on matching measurements with the atmospheric 14CO2 signal (F14C) generated by nuclear bomb testing in the 1950s and 1960s. CO2 emissions were analyzed from soil core sections together with soil-probe gas samples and surface flux chamber samples collected from the study area. Soil cores were collected from 0- 90 cm at 7.5 cm increments and placed into IsoJar® microcosms for a period of one month. CO2 in-growth was monitored to provide production rates and samples for 14C and 13C analysis. The radiocarbon data for the microcosms showed that values increase with depth from the current fraction modern value of 1.00 F14C at the surface to an attenuated peak of 1.04 F14C at a depth of 30 to 40 cm and then decrease to values below 1.00 F14C. The data collected from the soil-probe gas showed a significant depletion in comparison to the microcosms and the surface chambers. The soil cores were subsequently analyzed by a selective leach oxidation protocol to sample decreasingly labile solid organic carbon. This involved placing the weighed soil samples into MilliQ water for 24 hours, before being passed through two sieves, 63 microns and 0.45 microns. The DOC leachate was collected and analyzed for 14C and 13C. The two solid soil fractions were then dried, treated with HCl to remove carbonate and then oxidized under vacuum with 5% H2O2 yielding CO2 and residual soil carbon for 14C and 13C. The radiocarbon analysis of these variously labile fractions, together with the microcosm and soil probe measurements, demonstrate that surface emissions at both sites are greatly dominated by CO2 from recently-sequestered labile organic carbon from the upper 30 cm with minor contribution from earlier, bomb-pulse carbon or from deeper pre-bomb carbon. No significant difference in age of emissions between the dredged and undredged sites was found.

Magistrantūros studijų baigiamajame darbe pateikiami dirvožemio organinės anglies, humuso, C/N santykio, mikroorganizmų biomasės anglies, dirvožemio kvėpavimo tyrimų duomenys, įvertinant skirtingus žemės dirbimo būdus skirtingais dirvožemio gylio sluoksniais. Lyginami 2009 ir 2013 metų atliktų tyrimų duomenys. Darbo objektas – giliau karbonatingas giliau glėjiškas rudžemis, kuriame 2009 ir 2013 metais buvo žirnių (Pisum sativum L.) pasėlis, kur tirta skirtingo žemės dirbimo įtaka dirvožemio organinės anglies ir mikroorganizmų biomasės anglies sankaupoms. Darbo metodai: eksperimentai įrengti keturiais pakartojimais. Pradinių laukelių plotas – 126 m2, apskaitinių – 84 m2. Variantai pakartojimų blokuose išdėstyti rendomizuotai. Dirvožemio kvėpavimas ir mikroorganizmų biomasės sankaupos įvertintos 2009 ir 2013 m. birželio mėn. žirnių pasėliuose. Dirvožemio organinės anglies ir mikroorganizmų biomasės sankaupoms vertinti viršutinio ariamojo Ap (0-10 cm) horizonto jungtiniai ėminiai 3 pakartojimais buvo surinkti su 2-4 cm skersmens dirvožemio grąžtu. Eksperimento variantai: tradicinis žemės dirbimas, supaprastintas žemės dirbimas, tiesioginė sėja, ekologinė žemdirbystės sistema, kur taikytas tradicinis žemės dirbimas. Darbo rezultatai. Skirtingi žemės dirbimo būdai ir ekologinės žemdirbystės sistema, taikant tradicinį žemės dirbimo būdą, turėjo įtakos dirvožemio organinės anglies, humuso, C/N santykio, kvėpavimo ir mikroorganizmų biomasės anglies sankaupoms. Didžiausios org. C... [toliau žr. visą tekstą] / The master work presents the results on soil organic carbon, humus, C/N ration, microbial biomass carbon, soil respiration in soil with different soil tillage systems in two soil depths (0-10; 10-20 cm). Results were obtained in 2009 and 2013 and presented. Object of the research – The Endocalcari-Endohypogleyic Cambisol, where in 2009 and 2013 pea crops (Pisum sativum L.) have been growing. Soil tillage impact on soil organic carbon and microbial biomass carbon pools has been investigated. Method of the research – experiments was installed in four replications. Research area – 126 m2, research plot – 84 m2. Variants in blocks were rendomized. Soil respiration and microbial biomass pools were investigated in 2009 and 2013 in June in pea crops. Experiment variants were as followed: conventional tillage, reduced tillage, no tillage and ecological soil management with conventional tillage. Research results. Different soil tillage systems and ecological soil management system with conventional tillage had impact on soil organic carbon, humus, C/N ration, soil respiration and microbial biomass carbon pools. The highest org. C, humus, microbial biomass carbon concentrations and soil respiration intensity have been found in ecological soil management system. The fertilization with siderate crop may effect it mainly. The lower soil tillage intensity influenced the increase in org. C, humus concentration in 0-10 cm soil depth. In other hand, also along with lower tillage intensity... [to full text]

The explosive 2,4,6-trinitrotoluene (TNT) is currently a main ingredient in munitions; however the compound has failed to meet the new sensitivity requirements. The replacement compound being tested is 2,4-dinitroanisole (DNAN). DNAN is less sensitive to shock, high temperatures, and has good detonation characteristics. However, DNAN is more soluble than TNT, which can influence transport and fate behavior and thus bio-availability and human exposure potential. The objective of this study was to investigate the environmental fate and transport of DNAN in soil, with specific focus on sorption processes. Batch and column experiments were conducted using soils collected from military installations located across the United States. The soils were characterized for pH, electrical conductivity, specific surface area, cation exchange capacity, and organic carbon content. In the batch rate studies, change in DNAN concentration with time was evaluated using the first order equation, while adsorption isotherms were fitted using linear and Freundlich equations. Solution mass-loss rate coefficients ranged between 0.0002 h(-1) and 0.0068 h(-1). DNAN was strongly adsorbed by soils with linear adsorption coefficients ranging between 0.6 and 6.3 L g(-1), and Freundlich coefficients between 1.3 and 34 mg(1-n) L-n kg(-1). Both linear and Freundlich adsorption coefficients were positively correlated with the amount of organic carbon and cation exchange capacity of the soil, indicating that similar to TNT, organic matter and clay minerals may influence adsorption of DNAN. The results of the miscible-displacement column experiments confirmed the impact of sorption on retardation of DNAN during transport. It was also shown that under flow conditions DNAN transforms readily with formation of amino transformation products, 2-ANAN and 4-ANAN. The magnitudes of retardation and transformation observed in this study result in significant attenuation potential for DNAN, which would be anticipated to contribute to a reduced risk for contamination of ground water from soil residues.

In Sweden, drinking water is easy to access and often taken for granted. The drinking water systems have to be maintained in order to keep the high quality. The Uppsala esker, which is a part of the Uppsala municipality’s water system, provides a large number of the municipality’s population with drinking water. The Uppsala esker has been used to produce drinking water since 1956 by infiltrating water from the Fyris river into the esker. This reduces the amount of organic material in the water. A reduction is desirable since the organic material is causing odorous water and binds to substances that may harm people’s health. The reduction of organic material has been assumed to depend on degradation carried out by microorganisms above the esker’s groundwater table, dilution with additional groundwater and attachment of organic material to the esker’s material. However, recent studies have shown that only 10-15 % of the organic material is degraded above the groundwater table. The aim with this master thesis was to examine if the mineralization of the organic material in the anaerobic part of the Uppsala esker is greater than previously assumed. The size of the fungal and bacterial communities have also been examined as well as how microorganisms and the degradation of organic material relates to different chemical and physical factors in the soil. To get an understanding of the organic material’s degradability, soil was incubated and the aerobic respiration with gas chromatograph was measured. The bacteria and fungi were quantified using quantitative real-rime PCR. Various chemical and physical factors, such as the content of organic carbon and amount of aluminium, were already available. Pearson’s product-moment correlation coefficient (Pearson's r) was used to examine the the linear correlation between two variables. Wilcoxon’s rank score test was used to determine which of the differences between different sampling areas that were significant. The results showed that bacteria dominate in the Uppsala esker and the infiltration basins. Complex binding by iron- and aluminium compounds do not affect the degradation of organic matter, nor decrease the presence of fungi and bacteria in the esker and the infiltration basins. It seems as if the degradation rate’s sensitivity decreases with the depth. The amount of bacteria and fungi decreased with the distance to the infiltration basin, but not the quality of the organic material, if measured by the respiration rate divided by the amount of organic carbon. / I Sverige är tillgången på dricksvatten god. Det ses ofta som en självklarhet och för att detta synsätt ska kunna fortsätta krävs att dricksvattensystemen underhålls på ett bra sätt. Uppsalaåsen, som är en del av Uppsalas dricksvattensystem, förser stora delar av kommunens befolkning med dricksvatten. Uppsalaåsen har använts för konstgjord grundvattenbildning för att framställa dricksvatten sedan 1956. Detta innebär att vatten från Fyrisån filtreras genom åsen. På så sätt minskas halten organiskt material i vattnet. Anledningen till att en minskning eftersträvas är att det organiska materialet orsakar illaluktande vatten samtidigt som hälsoskadliga ämnen kan binda till det. Reduceringen av organiskt material i det infiltrerade vattnet har antagits bero på mikroorganismers nedbrytning av organiskt material ovan grundvattenytan, utspädning med övrigt grundvatten och fastläggning av organiskt material på åsmaterialet. Tidigare studier av liknande system för artificiell grundvattenbildning har dock visat att bara 10-15 % av det organiska materialet bryts ned ovan grundvattenytan. Examensarbetets syfte har varit att undersöka om nedbrrytningen av det organiska materialet under grundvattenytan i Uppsalaåsen är större än vad som tidigare antagits. Det har även undersökts om svampar eller bakterier dominerar liksom hur materialets kvalitet och mikrobsamhället påverkas av kemiska och fysiska faktorer i marken. Undersökningarna utfördes genom att inkubera jordprov där den aeroba respirationen mättes med gaskromatograf för att få en uppfattning om kolets nedbrytbarhet. qPCR användes för kvantifiering av bakterier och svampar. Mätvärden för olika kemiska och fysiska faktorer, såsom halten organiskt kol och mängden aluminium, erhölls från tidigare utförda analyser. Pearsons korrelationskoefficient (Pearson’s r) beräknades för att undersöka hur olika variabler samvarierade med varandra. Ett Wilcoxon rank score test användes för att undersöka vilka av skillnaderna mellan olika provtagningsplatser som var signifikanta. Resultaten visade att det finns fler bakterier än svampar i Uppsalaåsen och i filtreringsbassängerna. Komplexbindning av organiskt material av järn och aluminiumföreningar verkar inte hindra dess nedbrytning, eller minska förekomsten av svampar och bakterier i filtersanden och åsmaterialet. Respirationshastighetens temperaturkänslighet tycks minska något med djupet. Mängden bakterier och svampar avtar med avståndet från infiltrationspunkterna men kvaliteten på det organiska materialet, uppskattad som respirationshastigheten uttryckt per gram organiskt kol, avtar inte.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Tidal freshwater marshes (TFMs) are unique ecosystems that bridge the gap between terrestrial and aquatic ecosystems and are important in the sequestration of soil organic carbon. With the ever changing global climate, TFMs are left vulnerable to downstream effects of rising sea level and salt water intrusion due to increases in flooding by saline waters. These changes often act over large spatial and temporal scales resulting in significant impacts to local and regional environments. This multidisciplinary study assessed the amount and lability of desorbed organic carbon in tidal freshwater marsh soils from the Waccamaw River Marsh, South Carolina and Sweet Hall, a marsh on the Pamunkey River, Virginia. Soils from each marsh were extracted at 0-35 practical salinity units (psu) and the dissolved organic carbon (DOC) concentration, and carbon lability of the leachates were measured. At increasing levels of salinity, soil desorption amounts were higher in the Waccamaw River marsh interior and similar between the Waccamaw River creekbank and Sweet Hall levee. A larger fraction of desorbed DOC was consumed in the more organic soils from the Waccamaw River marsh in comparison to the more mineral soil from Sweet Hall Marsh. Finally, the rate of decay of the desorbed carbon was highest in the Sweet Hall levee soils, indicating more labile desorbed carbon, while the Waccamaw River Marsh soils had lower decay rates indicating less labile desorbed carbon. By understanding how salt water intrusion affects desorption and lability of soil organic carbon, in coastal marshes, we may be able to better understand how increasing sea levels may affect carbon storage in coastal ecosystems.

Anthropogenic activities are increasing inorganic nitrogen (N) loadings to lakes in the northern hemisphere. In many boreal lakes phytoplankton are N limited, wherefore enhanced N input may affect the productivity of pelagic food webs. Simultaneously, global change causes increased inflows of terrestrial dissolved organic carbon (DOC) to boreal lakes. Between clear and humic lakes, whole lake primary and consumer production naturally differs. However, research is inconclusive as to what controls pelagic production in these lakes. Further, it is unclear how DOC affects the response of the pelagic food web to enhanced inorganic N availability. The overarching goal of this thesis was to study the effects of inorganic N and organic C for pelagic food webs in boreal lakes. In the thesis, I first identified the main drivers of pelagic production during summer in eight non-manipulated Swedish boreal lakes with naturally low or high DOC. Then I investigated how increased N availability affects the pelagic food chain, and how the response differs with DOC. Therefore, whole lake inorganic N fertilization experiments were conducted in six Swedish boreal lakes across a DOC gradient (low, medium, high) divided into three lake pairs (control, N enriched) with one reference and two impact years. In each lake, I also investigated the response of zooplankton growth using in situ mesocosm experiments excluding planktivores. I found that humic boreal lakes had lower phytoplankton production and biomass than clear water lakes. Further, phytoplankton community composition and food quality differed with DOC. However, high DOC did not reduce pelagic energy mobilization or zooplankton biomass, but promoted a higher dominance of cladoceran relative to copepod species. N addition clearly enhanced phytoplankton biomass and production in the experimental lakes. However, this stimulating N effect decreased with DOC as caused by light limitation. Further, the newly available phytoplankton energy derived from N addition was not efficiently transferred to zooplankton, which indicates a mismatch between producer energy supply and consumer energy use. Indeed, the mesocosm experiment revealed that decreased food quality of phytoplankton in response to N addition resulted in reduced food web performance, especially in clearer lakes. In humic lakes, zooplankton production and food web efficiency were clearly more resilient to N addition. In summary, my thesis suggests that any change in the landscape that enhances inorganic N availability will especially affect pelagic food webs in clear water lakes. In contrast, brownification will result in more lakes being resilient to eutrophication caused by enhanced N deposition.

Os sistemas integrados de produção agropecuária (SIPAs) diversificam e intensificam a produção rural, embora ainda careçam de avanços e detalhamento dos processos e mecanismos envolvidos nas relações solo-planta-atmosfera, essenciais para adaptá-los e modelá-los para as diferentes eco-regiões e condições edafoclimáticas. Esse estudo investigou os efeitos da intensificação de sistemas integrados de produção agropecuária na quantidade, qualidade e origem da matéria orgânica do solo (MOS) e na dinâmica do crescimento e da decomposição radicular de espécies vegetais durante os períodos de lavoura e de pastejo. O experimento foi conduzido na Embrapa Pecuária Sudeste no estado de São Paulo, região sudeste do Brasil. Dois SIPAs foram avaliados: integração-lavoura-pecuária (ILP) e integração lavoura-pecuária-floresta (ILPF). Duas áreas de referência foram utilizadas: pastagem extensiva (não degradada) e floresta estacional semidecidual (somente para avaliações sobre a MOS). Duas épocas de avaliação foram consideradas: período lavoura (verão de 2014/15) e período pastagem (inverno de 2015 e verão de 2015/16). A quantidade (teores e estoques de C e N), a qualidade (índices de manejo de C, frações leve, particulada e mineral) e a origem (?13C e ?15N) da MOS na camada de 0-0,40 m, e o crescimento e a decomposição dos sistemas radiculares das espécies vegetais e o fluxo de água no perfil do solo (0-70 cm) foram avaliados durante os períodos de lavoura e de pastagem. Adicionalmente, na ILPF também foram avaliados estes parâmetros de plantas e solos em três distâncias das linhas de cultivo do eucalipto (1,9; 4,5 e 7,3 m). Converter a pastagem extensiva em ILP resultou em: (i) aumento da disponibilidade de nutrientes (Ca, Mg, K e P) no solo; (ii) incrementos nos estoques de C e N, bem como de frações lábeis da MOS; (iii) manutenção de maiores conteúdos de água no solo; e, (iv) ciclagem do C e N, com maiores produção e decomposição de raízes, inclusive em camadas mais profundas do solo. Implementar a ILPF sob área utilizada para ILP promoveu os seguintes efeitos: (i) redução nos conteúdos de água no solo; (ii) perdas nos teores das frações lábeis da MOS (iii) limitações na produção de raízes no período de lavoura (principalmente em locais próximos as árvores) e incrementos na decomposição radicular, acarretando em maiores taxas de ciclagem das raízes no solo; (iv) aumentos na ciclagem do C e N; e, (v) ocorrências de associações simbióticas nas raízes, tais como os fungos ectomicorrízicos, perceptíveis pela técnica de análises radiculares com uso de minirhizotron. De acordo com os resultados encontrados, sugere-se que o arranjo das árvores na ILPF seja reestruturado a partir do quarto ano de idade, quando estas limitaram o crescimento radicular e o aporte de matéria orgânica lábil, além de reduzir os conteúdos de água no solo. Entretanto, recomenda-se a intensificação da produção sob condições tropicais, pois a quantidade e a qualidade da MOS, e a produtividade e aprofundamento do sistema radicular foram incrementados ao longo do tempo sob SIPAs, principalmente na ILP / Integrated farming systems (IS) diversify and intensify rural production, although there are still gaps in advancing and detailing of the processes and mechanisms involved in the soil-plant-atmosphere relations, which are essential to adapt and model these systems for the different eco-regions and edafoclimatic conditions. This study investigated the effects of the intensification of IS on the quantity, quality and origin of soil organic matter (SOM) and on root growth and decomposition dynamics of plant species during cropping and grazing periods. The experiment was conducted at Embrapa Pecuária Sudeste, state of São Paulo, southeast region of Brazil. Two IS were evaluated: integrated crop-livestock system (ICL) and integrated crop-livestock-forest system (ICLF). Two references areas were used: extensive grazing (not degraded) and a semideciduous seasonal forest (only for SOM evaluations). Two evaluation periods were considered: cropping (summer of 2014/15) and grazing period (winter of 2015 and summer and winter of 2015/16). The quantity (C and N contents and stocks), quality (C management indexes, light, particulate and mineral SOM fractions) and the origin (?13C and ?15N) of SOM in the 0-0.40 m layer, and the growth and decomposition of the root systems of the plant species and water flow in the soil profile (0-0.7 m) were evaluated during cropping and grazing periods. In addition, in ICLF also these parameters of plants and soils were evaluated at three distances of eucalyptus rows (1.9, 4.5 and 7.3 m). The conversion of extensive grazing to ICL system resulted in: (i) increased availability of nutrients (Ca, Mg, K and P) in the soil; (ii) increases in C and N stocks, as well as labile fractions of SOM; (iii) maintenance of greater water content in the soil; and (iv) cycling of C and N, with higher root production and decomposition, even in deeper layers of the soil. Implementing the ICLF under the area used for ICL promoted the following effects: (i) reduction in soil water content; (iii) limitations in the root production in the cropping season (mainly in places near the trees) and increases in the root decomposition, resulting in higher cycling rates of the roots in the soil; (iv) increases in C and N cycling; and, (v) occurrence of symbiotic associations with the roots, such as ectomycorrhizal fungi, which were perceptible by the technique of root analysis using minirhizotrons. According to the results, it is suggested that the arrangement of the trees in the ICLF system need to be restructured after the fourth year of age, when they limited the root growth and the amount of labile organic matter, besides reducing the contents of water in the soil. However, farming intensification is recommended under tropical conditions, as the SOM quantity and quality, and the productivity and deepening of the root system were increased during cultivations in the IS, especially in the ICL system