Groundwater use is of fundamental importance to meet rapidly expanding urban, industrial, and agricultural water requirements, particularly in semiarid zones. To quantify the current rate of groundwater recharge is thus a prerequisite for efficient and sustainable groundwater resource management in these dry areas, where such resources are often the key to economic development. Increased groundwater recharge has been documented where native vegetation or forest/shrub land was converted to grassland or pasture, or where the land was cleared for agricultural purposes. The basic argument for increased recharge is that evapotranspiration, primarily interception and transpiration, is higher in shrublands than grasslands. Chloride mass balance (CMB) has been used to estimate ancient recharge, but recharge from recent land-use change has also been documented, specifically where vegetation has been altered and deep-rooted species replaced with shallow-rooted grasses. Chloride concentrations are inversely related to recharge rates: low Clconcentrations indicate high recharge rates as Cl- is leached from the system; high Cl concentrations indicate low recharge rates since Cl- accumulates as a result of evapotranspiration. The objectives were (1) to assess the hypothesis that removal of woody-shrub vegetation and replacement with grasses increases deep drainage, (2) to quantify the amount of deep drainage after land-use change, and (3) to provide science-based data for a better understanding of changing land-use impacts on deep drainage. Eight soils from five locations in the Central Rolling Red Plains near Abilene and Sweetwater were sampled. Each location consisted of a pair of similar soils with contrasting vegetative cover: shrubland and grassland. At each site three to five soil cores were taken as deep as possible and samples were taken by horizon, but horizons were split when their thickness exceeded 0.25 m. Soil Cl- profiles under shrubland at three sites showed that virtually no water escapes beyond the root zone. High Cl- concentrations and inventories reflect soil moisture fluxes that approached 0 mm yr-1 with depth. Evapotranspiration may be largely responsible for Cl- enrichment in those profiles. Surprisingly, soil moisture flux past 200 cm under juniper woodlands was the highest with 2.6 mm yr-1. Evapotranspirative Cl- enrichment in the upper 300 cm was not observed and may suggest a different water uptake mechanism for this plant community. Soil Cl- profiles showed increased recharge rates under grassland vegetation ecosystem. Estimated deep drainage past 200 cm of 0.1 to 1.3 mm yr-1 was observed. Low Cl- concentrations and inventories suggest a leaching environment that may be in response to changes in land use/land cover.

The concentrations of seventy-one hydrocarbons (HC) from C2 to C15 were measured simultaneously at two sites in Kaohsiung city in the morning (07-10), the afternoon (13-16), and the evening (18-21) on 14 days in spring 2003. Results show that the most abundant species of Kaohsiung¡¦s air is toluene (43.36-54.49 £gg m-3), followed by i-pentane, 1,2,4-trimethylbenzene, benzene, n-butane, propane and acetylene, in the range 10.36¡V17.11 £gg m-3. The concentrations of 14 halocarbons are in the range 0.25¡V4.57 £gg m-3. Alkanes (around 44.8%) represent the largest proportion of the total HC, followed by aromatics (35.1%), alkenes (15.5%) and halocarbons (5.4%). The afternoon HC concentrations are much lower than those in the morning and at night, due to relatively intense photochemical reaction and favorable dispersion conditions from noon to afternoon. Notable increases in daily HC concentrations are consistent with high temperature, and low HC concentrations on Sunday coincide with low traffic volume. Photochemical activity is investigated, and HC concentrations are found to decline as the NO2/NOx ratio increases. Correlation analyses imply that vehicle exhaust is the dominant source of atmospheric hydrocarbons in Kaohsiung. The profiles of traffic exhausts were also measured for 25 HC species during the morning and afternoon rush hours on four different days in all three traffic tunnels in Kaohsiung City. Results show that VOC concentrations increase with traffic flow rate, and emission profiles in the three tunnels are mostly in the range C2 ¡V C6. Besides the traffic conditions and vehicle type, the pattern of emissions in each tunnel was also influenced by other factors, such as vehicle age, nearby pollution sources, and the spatial or temporal variation of HC in the urban atmosphere. The ozone formation potential (OFP) in each tunnel was assessed based on the maximum incremental reactivities of the organic species, demonstrating that OFP increases with traffic flow rate. Vehicle distribution influences the contributions of organic group to OFP in a tunnel. Meanwhile, when ranked in descending order of contribution to OFP in all tunnels, the organic groups followed the sequence alkenes, aromatics, and alkanes. The possible source categories affecting the atmospheric HC species were further analyzed using factor analysis. Results showed that the major sources of ambient HC at the Nan-Chie and Hsiung-Kong sites are: vehicle exhaust, petrol/diesel exhaust, industrial processes (for example, plastic/rubber process), combustion exhaust, solvent fugitive or business/consume exhaust. Based on the results of factor analysis, source profiles (or fingerprints) were selected and receptor modeling was conducted based on chemical mass balance (CMB). Results of receptor modeling indicated that, at Nan-Chie site, vehicle exhaust (46.33% and 56.36%) represent the largest proportion of total HC, followed by industrial processes (29.63% and 22.37%) in the morning (07-10) and the evening (18-21), respectively; but were industrial process (40.39%) and solvent fugitive exhaust (30.61%) in the afternoon (13-16). Similarly at Hsiung-Kong site, vehicle exhaust (around 46.19% and 49.29%) represent the largest proportion of total HC, followed by industrial processes (23.19% and 26.11%) in the morning and evening, respectively; but were solvent fugitive exhaust (38.85%), vehicle exhaust (28.95%) and industrial process (25.19%) in the afternoon. It is evident that relatively low traffic volumes in the afternoon at both sites reduce the contribution of traffic exhaust to ambient HC.

In this study, the occurrence and distribution of polychlorinated biphenyls (PCBs) were investigated via sampling studies conducted around a thermal power plant (Seyit&ouml / mer, K&uuml / tahya), a scrap metal yard (Kizilirmak, Kirikkale), transformer repair and maintenance facility (Lake Eymir, Ankara), and two organized industrial districts (izmit and Mersin), and 120 samples composed mainly of sediments were collected from those sites. Total PCBs ranged from not detected to 385 ng/g for all samples. Analysis of samples indicates enrichment of PCBs with special emphasis to sediments collected around the Seyit&ouml / mer thermal power plant. Congener specific results indicate domination of profiles by penta- and hexa-chlorobiphenyls. Overall, the PCB concentrations observed in sampling sites are comparable to the background levels of soil/sediments around the world. To identify relevant pollution sources, congener specific data were further evaluated in the subsequent process of source apportionment using Chemical Mass Balance (CMB) receptor model. A general overview of the source apportionment results indicate that equipments (transformers and capacitors) mainly used in the energy generation/transmission and high energy consuming industries as the major PCB sources. PCBs used in open applications were also predicted as sources depending on site characteristics. Overall, indications of contaminated sites are evident in a number of locations / yet, no major contamination is evident in any media according to the current relevant national regulatory actions. However, findings of this study suggest that, over expanded time exposure, threat to the environment and human health may be of concern.

This study examines the application of two receptor models, namely Positive Matrix Factorization (PMF) and Chemical Mass Balance (CMB), on the investigation of sites contaminated with PCBs. Both models are typically used for apportionment of pollution sources in atmospheric pollution studies, however have gained popularity in the last decade on the investigation of PCBs in soil/sediments. The aim of the study is four-fold / (i) to identify the status of PCB pollution in Lake Eymir area via sampling and analysis of PCBs in collected soil/sediment samples, (ii) to modify the CMB model software in terms of efficiency and user-friendliness (iii) to apply the CMB model to Lake Eymir area PCB data for apportionment of the sources as well as to gather preliminary information regarding degradation of PCBs by considering the history of pollution in the area (iv) to explore the use of PMF for both source apportionment and investigation of fate of PCBs in the environment via use of Monte-Carlo simulated artificial data sets. Total PCB concentrations (Aroclor based) were found to be in the range of below detection limit to 76.3 ng/g dw with a median of. 1.7 ng/g dw for samples collected from the channel between Lake Mogan and Lake Eymir. Application of the CMB model yield contribution of highly chlorinated PCB mixtures (Aroclor 1254 and Aroclor 1260 / typically used in transformers) as sources. The modified CMB model software provided user more efficient and user friendly working environment. Two uncertainty equations, developed and existing in literature, were found to be effective for better resolution of sources by the PMF model.

The high-volume air sampling (PS-1) and micro-orifice uniformdeposit impactor (MOUDI) were used to measure the concentrations ofpolycyclic aromatic hydrocarbons (PAHs) in the atmosphere for fourseasons at Tuzo-Yin and Hsiung-Kong site in Kaohsiung city, in the airof a agricultural residue open burning area in Jhu-Shan and Sin-Gang siteduring the rice straw non-burning and burning periods, together with thesize distributions. Also, the receptor model was employed to determinethe potential sources of PAHs. The results show that the highest concentrations of PAHs occurred inwinter, being 143.9 ng/m3 and 182.9 ng/m3 at Tzuo-Yin and Hsiung-Kongsite, respectively; while the lowest concentrations of PAHs occurred insummer, being 81.4 ng/m3 and 95.2 ng/m3. The low-weight PAHs in thetwo sites were abundant in gaseous phase, being 43.8−96.7% and65.2−97.5% at Tzuo-Yin and Hsiung-Kong site, respectively. Meanwhile,the high-weight PAHs were almost present in particulate phase, being40.5−95.2% and 24.8−94.1 % at Tzuo-Yin and Hsiung-Kong site,respectively. The average PAHs concentrations were 330.04 and 567.81 ng/m3during the rice straw non-burning and burning period in Jhu-Shan site, theaverage PAHs concentrations were 427.16 and 571.80 ng/m3 during therice straw non-burning and burning period in Sin-Gang site, respectively,in the rice straw burning period, which were higher than those on thenon-burning days. The results of by CMB receptor modeling indicated that the major sources of pollution was exhaust emission (49.5−63.3%) in Tzuo-Yin site,and was burning source (49.1−63.7%) in Hsiung-Kong site in Kaohsiungcity. The results of APCA model analysis indicated that the major sourcesof pollution was mobile source (gasoline and diesel) were 66.5¡Ó8.0%during the rice straw non-burning period, and was mobile (gasoline) andrice straw non-burning source were 57.3¡Ó6.9% during the rice strawburning period in Jhu-Shan site in Central Taiwan. The results of APCAmodel analysis indicated that the major sources of pollution was mobile(gasoline) and plastics incinerator source were 54.3¡Ó6.4% during the ricestraw non-burning period, and was burning incense in temple, rice straw,mobile (gasoline and diesel) source were 50.7¡Ó4.6% during the rice strawburning period in Sin-Gang site in Central Taiwan.

Based on a municipal wastewater treatment plant (WWTP) in Tampa, FL, a dynamic multiple-systems model was developed on the STELLA software platform to explore algae biomass production in wastewater by incorporating two photobioreactors into the WWTP‟s treatment train. Using a mass balance approach, the model examined the synergy through algal growth and substrate removal kinetics, as well as macroeconomic-level analyses of algal biomass conversion to biodiesel, biogas, or fertilizer. A sensitivity analysis showed that biomass production is highly dependent on Monod variables and harvesting regime, and profitability was sensitive to processing costs, market prices of products, and energy environment. The model demonstrated that adequate nutrients and carbon dioxide are available in the plant‟s influent to sustain algal growth. Biogas and fertilizer production were found to be profitable, but biodiesel was not, due to high processing costs under current technologies. Useful in determining the growth potential on a macro-level, the model is a tool for identifying focus areas for bench and pilot scale testing.

Changes to ice sheet surface mass balance (SMB) are going to play a significant role in future sea level rise (SLR), particularly for the Greenland ice sheet. The Coupled Model Intercomparison Project Phase 5 (CMIP5) found that Greenland ice sheet (GIS) response to changes in SMB is expected to contribute 9 ± 4 cm to sea level by 2100 (Fettweis et al 2013), though other estimates suggest the possibility of an even larger response. Modern ice sheet geometry and surface velocities are common metrics for determining a model’s predictability of future climate. However, care must be taken to robustly quantify prediction uncertainty because errors in boundary conditions such as SMB can be compensated by (and therefore practically inseparable from) errors in other aspects of the model, complicating calculations of total uncertainty. We find that SMB calculated using the Community Earth System Model (CESM) differs from established standards due to errors in the CESM SMB boundary condition. During the long ice sheet initialization process, small SMB errors such as these have an opportunity to amplify into larger uncertainties in GIS sensitivity to climate change. These uncertainties manifest themselves in ice sheet surface geometry changes, ice mass loss, and subsequent SLR. While any bias in SMB is not desirable, it is not yet clear how sensitive SLR projections are to boundary condition forcing errors. We explore several levels of SMB forcing bias in order to analyze their influence on future SLR. We evaluate ensembles of ice sheets forced by 4 different levels of SMB forcing error, covering a range of errors similar to SMB biases between CESM and RACMO SMB. We find that GIS SMB biases on the order of 1 m/yr result in 7.8 ± 3.4 cm SLR between 1850 and 2100, corresponding to 100% uncertainty at the 2σ level. However, we find unexpected feedbacks between SMB and surface geometry in the northern GIS. We propose that the use of elevation classes may be incorrectly altering the feedback mechanisms in that part of the ice sheet. / text

This report compares surface elevation change and volume change esti- mates from three methods: repeat track (RT), crossover (CX), and overlapping footprints (OFP). These three methods use different approaches to group- ing elevation point measurements taken at different measurement epochs and estimating elevation change. Volume changes are calculated from elevation changes in the same manner for all three methods but differences in sampling resolution between the methods affect volume change estimates in different ways. The recently reprocessed Release 633 version of elevation measurements from the Geoscience Laser Altimeter System (GLAS), flown on the Ice, Cloud and land Elevation Satellite (ICESat), are used in this analysis. Both elevation changes and volume changes are compared for both the Greenland Ice Sheet (GrIS) and the Antarctic Ice Sheet (AIS). Additionally, uncertainties in the estimates for each method are quantified and compared. Results are separated by drainage systems and by above/below 2000 m surface elevation for the GrIS. For the AIS, results are aggregated to the East, West, and Penin- vi sula regions. Volume change estimates agree well for the three methods for the GrIS, with estimates of -227.75 ± 2.12 km³/yr, -249.30 ± 3.42 km³/yr, and -218.24 ± 7.39 km³/yr for the RT, CX, and OFP methods, respectively. These estimates are similar to those published from previous studies. For the AIS, however, larger discrepancies are found in the estimates. This stems primarily from a large discrepancy in the volume change estimate of the East AIS, where the RT, CX, and OFP methods estimate volume changes of 33.39 ± 1.42 km³/yr, 46.42 ± 5.46 km³/yr, and -2.72 ± 2.12 km³/yr, respectively. It's not entirely clear why this large discrepancy exists in this particular region, and elevation change estimates for a few particular drainage systems in this region are examined. Previously published volume changes for the AIS also show a large scatter and more work must be done to reconcile the various estimates. Finally, the volume change uncertainties reported do not completely account for the discrepancies in most regions. Additional analysis must be done to completely quantify all error sources. / text

The Skelton Glacier is one of the many smaller outlet glaciers located in the Transantarctic Mountains, where it drains ice into the Ross Ice Shelf. These outlet glaciers are important when determining the past, present, and future state of the mass balance of the East Antarctic Ice Sheet. This research uses satellite imagery acquired over a period of 15 years to obtain a high resolution velocity field for the Skelton Glacier which is then used to calculate the mass flux and mass balance at ten flux gates along the glacier using the input-output method. The high resolution velocity field is combined with ice thickness data and accumulation data from other sources to obtain the total mass balance. The high resolution velocity field of the Skelton Glacier was created using European Remote-Sensing Satellite 1 and 2 (ERS-1/2) Synthetic Aperture Radar (SAR) data acquired in 1996 with the processing technique of SAR interferometry (InSAR). Because of the lack of differential InSAR pairs, new auxiliary data from the ICESat and TanDEM-X mission were included into the analysis. A velocity field was created at a spatial resolution of 50m which was validated with in situ GPS measurements from 2011/12, and compared to lower resolution velocity fields of the Skelton Glacier. The ice velocity field is at improved accuracy for this area compared to previous studies and is thought to be representative for the mean ice velocity. The analysis of ice flux at several flux gates allowed an improved error estimation of the applied technique to estimate the overall mass balance. Mass flux estimates along the glacier were calculated using the new velocity field and additional thickness data, which was then compared to two accumulation datasets to give mass balance estimates along the glacier at selected flux gates. The mass flux through the grounding line was found to be 1.2165 Gt a⁻¹, which needs to be balanced in a state of mass balance equilibrium by a mean annual snow accumulation of about 185 mm a⁻¹ water equivalent over the total catchment area determined with 6569 km². The mass balance at the grounding line is slightly negative, but the second flux gate is thought to be more representative of the mass balance, which is estimated to be 0.0441 Gt a⁻¹. Error analysis of the mass balance estimates found uncertainties in this data to be approximately 0.110 Gt a⁻¹. It is concluded from the analysis that further improvements in the overall mass balance estimate can be primarily obtained by a better knowledge of ice thickness and snow accumulation.

Perfluoroalkyl substances (PFASs) are man-made chemicals. Their unique properties make them beneficial for a wide range of industrial and consumer product applications, such as in aqueous film forming foam (AFFF), durable water repellent clothing, hydraulic oils and food packaging materials. Perfluoroalkyl acids (PFAAs), a class of PFASs, are highly persistent in the environment, and long chain PFAAs are bioaccumulative and toxic. International regulation and voluntary actions by the industry have been implemented and led to a recent reduction of primary emissions of PFAAs to the environment. However, point sources such as AFFF training sites as well as diffuse sources continue to contaminate water bodies, soil and biota. Reducing environmental pollution with PFAAs has therefore become a regulatory priority. Designing successful measures to reduce the PFAA contamination requires an understanding of the sources, transport and fate of PFAAs in the environment. Four scientific publications are included in this PhD thesis, which aimed at increasing the holistic understanding of the fate of PFAAs in aquatic systems. This was achieved by chemical trace analysis combined with mass balance modeling. The following topics were covered: Dispersion and fate of PFAAs from an AFFF-impacted site (Paper I), recirculation of PFAAs in the aquatic environment with focus on waste water treatment plants (WWTPs, Paper II), mass balance of PFAAs in the Baltic Sea (Paper III) and transport and fate of PFAAs in two pristine boreal stream catchments (Paper IV). Results from Paper I showed that AFFF-impacted sites at a former military airfield, which was abandoned for more than 30 years, continue to be point sources of PFAAs to recipients. The sum of PFAAs in the ground water and surface waters ranged from 740 to 51000 ng L-1 and &lt;0.5 to 79 ng L-1, respectively. PFOS in muscle tissue of European perch from a nearby lake ranged from 77 to 370 ng g-1 wet weight, representing among the highest values reported worldwide for fish muscle. In Paper II the relative importance of environmental recirculation of PFAAs versus new releases from the technosphere was investigated for PFAAs in WWTP influents. It was shown that tap water can be an important source of PFAAs to WWTPs in areas with elevated environmental levels. This needs to be taken into account when calculating emissions via WWTP effluents. PFAA mass balances over the WWTPs suggested that PFHxA and PFOA were formed from precursor compounds within the plants. Assembled PFAA mass balances for the Baltic Sea (Paper III) showed that river inflow and atmospheric deposition were the dominant input pathways, while wastewater treatment plant (WWTP) effluents discharging directly into the Baltic Sea made a minor contribution. The inputs of PFAAs were estimated to be higher than the outputs, suggesting a current increase of the PFAA inventory in the Baltic Sea. Also the mass balance study of PFAAs in two remote stream catchments presented in Paper IV revealed that inputs dominated over outputs for both catchments, indicating that a considerable portion of the PFAAs deposited from the atmosphere is retained in soil or in deep ground water and may be released to surface and marine water environments in the future / Perfluoralkilne tvari (PFASs) su umjetne kemikalije. Zbog svojih jedinstvenih svojstava široko su primjenjive u industriji i izradi proizvoda krajnje potrošnje kao što su pjena za gašenje požara (AFFF), vodootporna odjeća, hidraulična ulja i pakiranja za hranu. Perfluoralkilna kiselina (PFAAs) iz skupine perfluoralkilnih tvari iznimno je dugotrajna u okolišu, a dugolančane PFAAs su bioakumulativne i otrovne. Poduzeta međunarodna regulativa i dobrovoljne akcije vodile su nedavno smanjenoj primarnoj emisiji PFAAs u okoliš. Unatoč tome, primarni izvori, kao što su mjesta na kojima se provode treninzi za gašenje požara i difuzni izvori i dalje zagađuju vode, tlo i biotu. Zbog toga, smanjenje onečišćenja okoliša izazvanog PFAAs predstavlja regulatorni prioritet. Stvaranje uspješnih mjera kojima bi se smanjilo onečišćenje izazvano PFAAs zahtjeva razumijevanje izvora, prijenosa i sudbine tih tvari u okolišu. U ovaj doktorat uključena su četiri znanstvena članka kojima je cilj povećati sveukupno razumijevanje sudbine PFAAs u vodenim sustavima. To je postignuto kemijskom analizom elemenata u tragovima u kombinaciji s modeliranjem masene ravnoteže. Obrađene su sljedeće teme: Širenje i sudbina PFAAs na područjima zahvaćenim AFFF (Članak I), ponovna cirkulacija PFAAs u vodenom okolišu s naglaskom na postrojenja za pročišćavanje otpadnih voda (Članak II), masena ravnoteža PFAAs u Baltičkom moru (Članak III) te prijenos i sudbina PFAAs u dva udaljena sjeverna vodena toka (Članak IV).   Rezultati iz Članka I pokazali su da su područja zahvaćena AFFF na bivšem vojnom aerodromu napuštenom prije 30 godina i dalje je glavni izvor PFAA zagadenja okolisa. Zbroj PFAAs u podzemnim i površinskim vodama kreće se u rasponu od 740 do 51000 ng L-1 i &lt;0.5 do 79 ng L-1. PFOS u mišićnom tkivu grgeča iz obližnjeg jezera kreće se od 77 do 370 ng g-1 mokre težine, predstavljajući jednu od najviših vrijednosti u svijetu za riblje mišiće. Članak II istražuje relativnu važnost ponovne cirkulacije PFAAs imajući na umu novu emisiju PFAAs iz tehnosfere u postrojenjima za pročišćavanje otpadnih voda. Cirkulacija/kruženje u okolišu može se pojaviti kada PFAAs iz sustava pitke voda (rijeka, bunara i jezera) odlaze u otpadne vode. Prikazano je kako voda iz slavine može biti važan izvor PFAAs sustavima za pročišćavanje otpadnih voda u područjima s povišenim razinama zaštite okoliša. To se treba uzeti u obzir pri računanju emisije putem strojeva koji se koriste za pročišćenje otpadnih voda. Masena ravnoteža PFAA u postrojenjima za pročišćavanje otpadnih voda upućuje na to da su PFHxA i PFOA stvoreni kao prethodni spojevi unutar postrojenja. Prikupljene masene ravnoteže PFAA za Baltičko more (Članak III) pokazale su da su pritoke rijeka i atmosfersko taloženje dominantni ulazni putovi, dok postrojenja za pročišćenje otpadnih voda pridonose tek u manjoj mjeri. Ulaz PFAAs je procijenjen višim od izlaza, što objašnjava trenutno povećanje sadržaja PFAA u Baltičkom moru. Masena ravnoteža PFAAs u dva udaljena riječna toka predstavljena u Članku IV otkriva da ulaz dominira nad izlazom za oba riječna toka, što upućuje na značajan udio PFAAs koji je iz atmosfere zadržan u tlu ili podzemnim vodama te može biti ispušten u područja površinskih voda i mora. / Perfluorerade alkylsyror (PFAA) är kemikalier som är producerade av människan. Deras unika egenskaper gör att de kan användas i många olika industriella applikationer. PFAAs används i brandsläckningsskum, vattenavvisande kläder, hydrauliska oljor och matförpackningar. PFAAs har visat sig vara persistenta i miljön, och långkedjiga PFAA-homologer har visat sig vara bioackumulerbara samt ha en toxisk verkan. Reglering på internationell nivå tillsammans med initiativ från industrin har lett till minskning av direkta utsläpp. Punktkällor som brandövningsplatser samt andra diffusa källor fortsätter att förorena omgivande vattendrag, jordlager och fauna. Den utbredda föroreningen av PFAAs har därför blivit prioriterad för reglering. För att förstå utsläppen av PFAAs i miljön, hur de transporteras samt deras öde i miljön, är det viktigt att utföra studier som belyser dessa områden.   Denna doktorsavhandling inkluderar fyra vetenskapliga publikationer. Syftet med de underliggande studierna var att öka den holistiska förståelsen av PFAAs rörelse i akvatiska system. Studierna gjordes genom att kombinera kemiska analysmetoder med modellering. Följande  studier genomfördes; Transport och spridning av PFAAs från en brandövningsplats (Paper I), recyklering av PFAAs i den akvatiska miljön med fokus på vattenreningsverk (Paper II), massbalans av PFAAs i Östersjön (Paper III), transport och öde av PFAAs i två pristina vattendrag (Paper IV).   Resultat från (Paper I) visade att brandövningsplatser vid en flygplats som inte har varit i bruk i mer än 30 år, fortfarande är punktkällor av PFAAs till omgivande vattendrag. Summan av PFAAs koncentrationer i grundvattnet och ytvattnet sträckte sig från 740 till 51000 ng L-1 och &lt;0.5 till 79 ng L-1 i respektive vattendrag. Koncentrationen av PFOS i muskelvävnad från  aborre i en av sjöarna var 77 till 370 ng g-1 våtvikt. Dessa värden representerar några av de högsta uppmätta koncentrationerna i världen. I Paper II testades betydelsen av PFAAs från recirkulering i miljön i jämförelse med nya utsläpp från teknosfären. Recirkulering av PFAAs i miljön kan förekomma då PFAAs i inkommande vatten till reningsverk kommer från dricksvatten. Denna studie visar att dricksvatten kan vara en påtaglig källa av PFAAs till vattenreningsverk i områden med förhöjda halter av PFAAs i miljön. Detta måste tas hänsyn till när man beräknar emissioner med utgående vatten från vattenreningsverk. Massbalanser av PFAAs i reningsverken visar att PFHxA och PFOA bildades av prekursorämnen i vattenreningsverken. I Paper III beräknades massbalanserna av PFAAs i Östersjön, beräkningarna visar att floder och atmosfärisk nedebörd var de viktigaste källorna medan utsläppen från vattenreningsverk var markant lägre. Importen av PFAAs estimerades vara högre än exporten, varför vi tror att PFAAs mängden I Östersjön kommer att öka över tid. Vidare gjordes en mass balans av PFAAs i två avlägsna avrinningsområden (Paper IV). Resultaten visar att importen av PFAAs dominerar över exporten från båda avrinningsområdena. Detta indikerar att en stor del av PFAAs som kommer ner via nederbörd kommer att ansamlas i jorden eller i grundvattnet. Dessa PFAAs kan vid senare tillfälle komma att släppas ut till floder som rinner ut i marina vatten. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 2: Manuscript.</p><p> </p>