Bioremediation of chlorinated aliphatic hydrocarbon (CAH) compounds commonly found at contaminated sites has been an area of focus in recent years. The cometabolic transformation of CAH compounds is important at sites where the redox condition does not favor natural attenuation or populations of indigenous microorganisms are relatively low. At sites where the ground-water system is aerobic, monitored natural attenuation strategies will not meet remediation objectives, or both, enhanced bioremediation via cometabolism is an option. Models are needed to simulate cometabolism in an effort to improve performance and design. The SEAM3D Cometabolism Package was designed to address this need. The objective of this report is to model field data to determine the ability of SEAM3D to simulate the performance of cometabolism. A ground-water flow and transport model was designed based on reported parameters used in the field experiments at Moffett Field. Electron donor and acceptor breakthrough curves were also simulated in an effort to calibrate the model. Several data sets describing the cometabolism of CAHs were used in the cometabolism modeling for calibration to field data. The cometabolism modeling showed areas of best fit calibration with modification to the model parameters reported for the pilot tests at Moffett Field. The overall performance of the SEAM3D Cometabolism Package described in this report establishes validation of the model using field experiment results from the literature. Additional model validation is recommended for other contaminants. / Master of Science

Sites where 2-chlorobutadiene-1,3 (chloroprene) and 2,3-dichlorobutadiene-1,3 (DCBD) are synthesized for use in chlorobutyl rubber have the potential to release a mixture of at least five chlorinated butenes and butadienes including trans-1,4-dichlorobutene-2 (1,4-DCB-2), 3,4-dichlorobutene-1 (3,4-DCB-1), 2,3,4-trichlorobutene-1 (2,3,4-TCB-1), chloroprene and DCBD into the groundwater environment. Granular iron has been shown to be effective in the remediation of groundwater contaminated with chlorinated organic compounds by reductive dechlorination. To evaluate the possibility of using granular iron in the remediation of the above contaminants a series of batch and column experiments were conducted at the laboratory scale. Chlorine mass balance calculations showed that each compound, with the exception of DCBD, could be fully dechlorinated by the use of granular iron. Kinetic data and proposed reaction pathways, however, suggest that DCBD can also be fully dechlorinated by granular iron. Normalization of observed pseudo-first-order reaction half-lives indicated that compounds were degrading much slower in batch experiments than in column experiments. This, along with the observation that temperature did not affect degradation in batch experiments, led to the conclusion that mass transport to the iron surfaces was limiting degradation rates in batch experiments. Results showed that the three chlorinated butenes degraded much faster (normalized column half-lives ranged from 1.6 to 5.2 min) than the two chlorinated butadienes (normalized column half-lives ranged from 115 to 197 min). Chlorinated and non-chlorinated intermediates were identified. It was determined that all contaminants degrade to 1,3-butadiene as a reaction intermediate which then degraded to a mixture of non-harmful end products consisting of 1-butene, cis-2-butene, trans-2-butene and n-butane. The reaction pathway from 1,4-DCB-2 to 1,3-butadiene was proposed to be a reductive elimination similar to reductive β-elimination. 3,4-DCB-1 and 2,3,4-TCB-1 were proposed to undergo reductive β-elimination reactions resulting in 1,3-butadiene and chloroprene intermediates, respectively. Degradation of chloroprene and DCBD occurred via hydrogenolysis pathways while 1,3-butadiene underwent catalytic hydrogenation resulting in the observed end products. The results suggest that granular iron may be an effective treatment for groundwater contaminated with these compounds.

Sites where 2-chlorobutadiene-1,3 (chloroprene) and 2,3-dichlorobutadiene-1,3 (DCBD) are synthesized for use in chlorobutyl rubber have the potential to release a mixture of at least five chlorinated butenes and butadienes including trans-1,4-dichlorobutene-2 (1,4-DCB-2), 3,4-dichlorobutene-1 (3,4-DCB-1), 2,3,4-trichlorobutene-1 (2,3,4-TCB-1), chloroprene and DCBD into the groundwater environment. Granular iron has been shown to be effective in the remediation of groundwater contaminated with chlorinated organic compounds by reductive dechlorination. To evaluate the possibility of using granular iron in the remediation of the above contaminants a series of batch and column experiments were conducted at the laboratory scale. Chlorine mass balance calculations showed that each compound, with the exception of DCBD, could be fully dechlorinated by the use of granular iron. Kinetic data and proposed reaction pathways, however, suggest that DCBD can also be fully dechlorinated by granular iron. Normalization of observed pseudo-first-order reaction half-lives indicated that compounds were degrading much slower in batch experiments than in column experiments. This, along with the observation that temperature did not affect degradation in batch experiments, led to the conclusion that mass transport to the iron surfaces was limiting degradation rates in batch experiments. Results showed that the three chlorinated butenes degraded much faster (normalized column half-lives ranged from 1.6 to 5.2 min) than the two chlorinated butadienes (normalized column half-lives ranged from 115 to 197 min). Chlorinated and non-chlorinated intermediates were identified. It was determined that all contaminants degrade to 1,3-butadiene as a reaction intermediate which then degraded to a mixture of non-harmful end products consisting of 1-butene, cis-2-butene, trans-2-butene and n-butane. The reaction pathway from 1,4-DCB-2 to 1,3-butadiene was proposed to be a reductive elimination similar to reductive β-elimination. 3,4-DCB-1 and 2,3,4-TCB-1 were proposed to undergo reductive β-elimination reactions resulting in 1,3-butadiene and chloroprene intermediates, respectively. Degradation of chloroprene and DCBD occurred via hydrogenolysis pathways while 1,3-butadiene underwent catalytic hydrogenation resulting in the observed end products. The results suggest that granular iron may be an effective treatment for groundwater contaminated with these compounds.

A systematic methodology for quantitative structure-activity relationship (QSAR) development in environmental toxicology is provided. The methodology is summarized in a strategy with six sequential steps. The strategy rests on two cornerstones, namely (1) the use of statistical design to select a series of representative compounds (the so-called training set) on which to base a QSAR, and (2) the multivariate modelling of the relationship between physicochemical and biological properties of the training set compounds. The first step of the strategy is the division of chemicals into classes of structurally similar compounds. Briefly, steps 2 to 6 are: (2) physico-chemical and structural characterization of the compounds in a class, (3) selection of a training set of representative compounds, (4) biological testing of the selected training set, (5) QSAR model development, and (6) experimental validation of the QSAR and predictions for non-tested compounds. The thesis summarizes the results obtained from the application of the strategy to the class of halogenated aliphatic compounds. Biological measurements were made in four biological test systems, reflecting acute toxicity, mutagenicity, relative cytotoxicity and genotoxicity. QSARs were developed relating each biological endpoint to the structural descriptors of the compounds. Multivariate PLS modelling was used in the data analysis. The developed QSARs were used for predicting the biological activity pattern of the non-tested compounds in the class. These predictions may be used as a starting point for a priority ranking for further biological testing of these compounds. The strategy has not been developed solely for establishing QSARs for the halogenated aliphatics class. On the contrary, this work is intended to demonstrate a generally applicable QSAR methodology. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1991</p> / digitalisering@umu

In this study, optimization of a new multimethod for the analysis of PAH, PCB, aliphatics and aromatics in water have been done at Eurofins in Lidköping. Since the method is intended for routine analysis during a high sample flow, great focus was placed on the efficiency of the sample preparation. The company’s main goal was to replace the extraction solvent n-hexane that has been used in one of the methods that this multimethod has the intention to replace. This is because n-hexane is CMR-classified, and the company prioritizes phasing out the substance from all analyses. The original idea was to use n-pentane as the extraction solvent, but as it is very fluid and highly volatile, this study aimed to choose a solvent other than n-pentane if possible. At the same time, aim was also set on shortening the shaking time during the extraction from 45 minutes. The solvents tested and compared were n-pentane, diethyl ether/n-pentane (15/85 v/v%), cyclohexane, diethyl ether/cyclohexane (15/85 v/v%), n-heptane and diethyl ether/n-heptane (15/85 v/v%). During the project, different types of addition trials were carried out to evaluate which solvent extracted the substances to the highest degree and which solvent was the most practical to work with. Both positive and negative results were obtained, with diethyl ether/n-heptane proving to be the best solvent both from a practical point of view and in terms of extraction rate. However, the n-heptane was not shown to have the expected purity, which meant that the method had to use n-pentane as the extraction solvent despite the advantages demonstrated with diethyl ether/n-heptane. On the other hand, the phasing out of n-hexane was successful, and tests carried out at different extraction times showed that the method was robust, and that the extraction time could be shortened to 30 minutes while still obtaining desirable results. / I detta arbete har optimering av provberedningen hos en ny multimetod för analys av PAH, PCB, alifater och aromater i vatten utförts hos Eurofins i Lidköping. Eftersom metoden är avsedd för rutinanalys vid högt provflöde från kundprov lades stort fokus på provberedningens effektivitet. Företagets huvudmål var att byta ut extraktionslösningsmedlet n-hexan som har använts i en av de metoder som multimetoden ska ersätta. Detta för att n-hexan är CMR-klassat och företaget prioriterar att fasa ut ämnet från samtliga analyser. Ursprungstanken var att använda n-pentan som extraktionslösningsmedel, men då det är väldigt lättflytande och lättflyktigt syftade detta projekt till att välja något annat lösningsmedel än n-pentan om möjligt. Samtidigt lades fokus på att försöka korta ner skaktiden under extraktionen från 45 minuter. De lösningsmedel som testades och jämfördes var n-pentan, dietyleter/n-pentan (15/85 v/v%), cyklohexan, dietyleter/cyklohexan (15/85 v/v%), n-heptan och dietyleter/n-heptan (15/85 v/v%). Under projektet utfördes olika typer av tillsatsförsök för att utvärdera vilket lösningsmedel som extraherade ämnena i högst grad och vilket lösningsmedel som var mest praktiskt att arbeta med. Det erhölls både positiva och negativa resultat, där dietyleter/n-heptan visades vara det bästa lösningsmedlet ur både praktisk synpunkt och i extraktionsgrad. Däremot visades n-heptanen inte ha den renheten som förväntats, vilket gjorde att metoden fick använda sig av n-pentan som extraktionslösningsmedel trots fördelarna som påvisats med dietyleter/n-heptan. Däremot lyckades därmed utfasningen av n-hexan, samt att tester gjorda vid olika extraktionstider visade att metoden var robust och att extraktionstiden kunde kortas ner till 30 minuter och fortfarande ge önskvärda resultat.

Syftet med denna rapport var att utreda hur föroreningsmängder och föroreningskoncentrationer i dagvattendammars sediment påverkas av markanvändningen i avrinningsområdet. Sedimentprovtagning skedde under april 2019 i tre dagvattendammar i Gävle, med olika markanvändningar: industri, villaområde samt två avrinningsområden innehållande trafik. Markanvändningen ”trafik vid Västerbacken” hade en trafikintensitet på cirka 2000 bilar/dygn och ”trafik vid Hamnleden” en intensitet på 7000 bilar/dygn. Provtagningen utfördes med rysskannborr och sedimentdjup mättes för att kvantifiera sedimentvolymen i dagvattendammarna. Proverna skickades till laboratorie för analys av metaller, fosfor, alifater, aromater samt polycykliska aromatiska kolväten [PAH]. Dagvattendammen med markanvändning industriområde hade sedimentet med högst föroreningskoncentrationer, följt av villaområde – trafik vid Hamnleden – trafik vid Västerbacken. Resultaten för denna studie visar att inga markanta skillnader kan ses vid jämförelse av föroreningskoncentrationer i sedimentet, utifrån omgivande markanvändning. Markanvändningarna visade liknande koncentrationsmönster i de grafiska figurer som jämfördes. Resultatet kan bero på att dagvattendammarna ligger geografiskt nära och därmed kan bli påverkade av samma atmosfäriska nedfall och bakgrundshalter. Det förväntades inte att föroreningskoncentrationerna i villaområdets sediment skulle vara näst högst. En förklaring kan vara den högre halten organiskt material i villaområdets sediment, vissa föroreningar tenderar att binda starkt till organiskt material. Däremot sågs stora skillnader mellan dagvattendammarnas föroreningsmängder i sedimentet (jämförelsetalet ”fastlagd förorening per år”), vilket återspeglades av sedimentvolymen. Störst mängd föroreningar och störst sedimentvolym sågs i dagvattendammen med markanvändning industriområde. I fallande skala följde trafik vid Hamnleden – trafik vid Västerbacken – villaområde. Resultatet kan bero på skillnader i andel partikulära fraktioner i dagvattnet från respektive markanvändning, där industriområdet i så fall har störst andel partikulära fraktioner enligt resultatet i denna studie. Beräkningar utfördes i StormTac för teoretisk föroreningstransport i inkommande dagvatten till dagvattendammarna. Beräkningarna genererade i totalmängder (lösta och partikulära fraktioner). När föroreningstransporten jämfördes med ”fastlagd förorening per år” för villaområde sågs att föroreningstransportens mängder var markant större, vilket delvis kan förklaras med att totalmängder jämfördes med partikulära mängder. En slutsats som dras är att omgivande markanvändning påverkar föroreningsmängderna i sedimentet och sedimentvolymen, snarare än koncentrationerna. / This thesis addresses how human activities in the catchment area could influence the contaminant concentrations and amounts of contaminants in the sediments of stormwater ponds. Sediment sampling was done in April 2019. The storm water ponds had different land uses: industrial, residential (detached area) and two land uses of traffic with different intensities; “traffic by Hamnleden” (7000 cars/day) and “traffic by Västerbacken” (2000 cars/day). Samples were taken with a Russian corer and sediment depth was measured to quantify sediment volume. Samples were sent to laboratory for analysis of metals, phosphorus, aliphatics, aromatics and polycyclic aromatic hydrocarbons [PAH]. The stormwater pond with industry as land use had the highest concentration of contaminants in the sediment, followed by residential area – traffic by Hamnleden – traffic by Västerbacken. The results of this study showed that the land use concentrations of contaminants were all similar, and the patterns of concentration in the graphic figures were similar. The results could be explained by the narrow geographic area in which the three storm water ponds are situated. They could be affected by the same atmospheric downfall which could even out the concentrations. It was not expected that the residential area would have one of the highest concentrations in the sediment. This could be explained by the high content of organic matter, as some contaminants create strong chemical bonding with organic matter. Bigger differences were seen for the amounts of contaminants in the sediments and the comparative figure “fixated amount of contaminant per year”. The land use industry had the highest amount of contaminants followed by traffic by Hamnleden – traffic by Västerbacken – residential area. This is probably due to differences in particle quota in the storm water coming from the land uses. Calculations were done for the amount of transported contaminants in stormwater, via the watershed management tool and model StormTac. The calculated transportation of contaminants resulted in total amounts of contaminants, meaning both dissolved and particulate fractions. The calculations from StormTac were compared with the comparative figure “fixated amount of contaminant per year” for the land use residential area, and the amounts were significantly higher for the calculated transportation. This could partly be explained by comparing total amounts with particulate amounts. A conclusion of this report is that land use affects the amounts of contaminants and sediment volume in the studied storm water ponds, rather than the concentrations.