Svensk Kärnbränslehantering AB Swedish Nuclear Fuel and Waste Management Co Box 250, SE-101 24 Stockholm Phone +46 8 459 84 00 Chlorine cycling and fates of 36 Cl in terrestrial environments Chlorine cycling and fates of 36 Cl in terrestrial environments

This report concerns a study which was conducted for SKB. The conclusions and viewpoints presented in the report are those of the authors. SKB may draw modified conclusions, based on additional literature sources and/or expert opinions. A pdf version of this document can be downloaded from www.skb.se. 3 Abstract Cl), a radioisotope of chlorine (Cl) with a half-life of 301,000 years, is present in some types of nuclear waste and is disposed in repositories for radioactive waste. As the release of 36 Cl from such repositories to the near surface environment has to be taken into account it is of interest to predict possible fates of 36 Cl under various conditions as a part of the safety assessments of repositories for radioactive waste. This report aims to summarise the state of the art knowledge on Cl cycling in terrestrial environments. The view on Cl cycling in terrestrial environments is changing due to recent research and it is clear that the chloride ion (Cl -) is more reactive than previously believed. We group the major findings in three categories below according to the amount of data in support of the findings. From the result presented in this report it is evident that: • There is an ubiquitous and extensive natural chlorination of organic matter in terrestrial ecosystems. • The abundance of naturally formed chlorinated organic compounds (Cl org ) frequently exceeds the abundance of Cl -, particularly in soils. Thereby Cl org in many cases dominates the total Cl pool. • This has important implications for Cl transport. When reaching surface soils Cl -will not be a suitable tracer of water and will instead enter other Cl pools (Cl org and biomass) that prolong residence times in the system. • Cl -dominates import and export from terrestrial ecosystems while Cl org and biomass Cl can dominate the standing stock Cl within terrestrial ecosystems. • Both Cl and Cl org pools have to be considered separately in future monitoring programs addressing Cl cycling. Further, there are also indications (in need of confirmation by additional studies) that: • There is a rapid and large uptake of Cl -by organisms and an accumulation in green plant parts. A surprisingly large proportion of total catchment Cl (up to 60%) can be found in the terrestrial biomass. • Emissions of total volatile organohalogens could be a significant export pathway of Cl from the systems. • Some of the Cl org may be very persistent and resist degradation better than average organic matter. This may lead to selective preservation of some Cl org (with associated low bioavailability). • There is a production of Cl org in tissues of e.g. plants and animals and Cl can accumulate as chlorinated fatty acids in organisms. Most other nevertheless important aspects are largely unknown due to lack of data. Key unknowns include: • The development over time of major Cl pools and fluxes. As long as such data is lacking we cannot assess net changes over time. • How the precesses behind chlorination, dechlorination and transport patterns in terrestrial systems are regulated and affected by environmental factors. • The ecological roles of the chlorine cycling in general. • The ecological role of the microbial chlorination in particular. • The chlorine cycling in aquatic environments -including Cl -and Cl org pools in sediment and water, are largely missing. Given the limited present information available, and particularly the lack of data with a temporal dimension and the lack of process understanding, predictive models are challenging. We also summarize currently available methods to study Cl in the environment. SKB TR-13-26 Sammanfattning 36 Cl), en radioisotop med en halveringstid på 301 000 år, förekommer i vissa typer av radioaktivt avfall. För att kunna förutse vad som händer om 36 Cl når markytan är det viktigt att veta hur klor kan omvandlas och transporteras i olika ekosystem. Denna rapport syftar till att sammanfatta kunskapsläget om klor i naturmiljöer med fokus på landmiljöer. Synen på klor i naturen är under omfattande förändring till följd av de senaste decenniernas forskning. Det står nu helt klart att klorid (Cl -) som tidigare betraktats som icke-reaktiv och totalt dominerande, istället är i hög grad reaktiv och inte alltid utgör den dominerande klorformen. Utifrån de studier som presenteras i rapporten är det tydligt att: • Det sker en omfattande naturlig klorering av organiskt material i många miljöer och inte minst i ytliga marklager. • Mängden organiskt bunden klor (Cl org ) är i många miljöer betydligt högre än mängden Cl -. Därmed dominerar Cl org ofta det totala klorförrådet i exempelvis mark. • Detta har stor inverkan på transporten av klor eftersom Cl org till stor del finns i partikulärt organiskt material medan Cl -är mycket vattenlösligt. Cl -som når ytliga marklager är t ex inte lämpligt som spårämne för markvattenflöden såsom tidigare antagits. Cl -kommer till stor del att bindas in till Cl org -förrådet och därmed förlänga uppehållstiden i ekosystemen. • Cl -dominerar både importen och exporten från terrestra ekosystem medan Cl org kan dominera stationära klorförråd i systemen. • Framtida mätningar med syfte att klargöra kloromsättning och klorflöden behöver beakta Cl -och Cl org separat. Därtill finns ett antal troligen viktiga indikationer som skulle behöva bekräftas av ytterligare studier. Dessa inkluderar att: • Det sker ett snabbt och omfattande upptag av Cl -av organismer och klor tycks ackumuleras i grön växtbiomassa. En stor andel av den totala klormängden i avrinningsområden (upp till 60% i en studie) har påträffats i den terrester biomassa. • Avgång av flyktiga klorerade kolväten kan vara en stor okänd exportväg för klor från ekosystem. • En del Cl org verkar vara betydligt mer motståndskraftigt mot nedbrytning än det genomsnittliga organiska materialet. Detta kan leda till att Cl org bevaras selektivt i mark och därmed också mindre tillgängligt för mikroorganismer. • Det sker en klorering av organiskt material i levande biomassa och klor kan ansamlas som klorerade fettsyror i organismer. Övriga aspekter på klor i naturen är till stora delar okända. Centrala okända aspekter inkluderar: • Hur klor-förråden utvecklas över tid. Detta är centralt för att förstå förändringar över tid och reglering i förråden. • Reglering av klorerings-, deklorerings-och transportprocesser, samt hur dessa påverkas av olika miljövariabler och miljöförhållanden. • Den ekologiska förklaringen till varför så många organismer utför klorering av organiskt material. • Omsättning av klor i akvatiska system. Här saknas separata data gällande Cl -och Cl org både i sediment och i vattenfasen. Rapporten fokuserar framför allt på terrestra aspekter av klorcykeln och innehåller också information om vanliga metoder för mätning av olika klorföreningar

Phosphorylation based Models of Neurodegenerative Diseases

Aberrant protein phosphorylation is a hallmark of neurodegenerative diseases, such as Alzheimer's disease (AD) and tauopathies. Pathological phosphorylation is commonly observed as intracellular tau containing deposits correlating with neuronal death. Tau is a cytoskeletal protein, key to the stabilisation of the microtubules (MT), important ,for structural integrity and protein trafficking. Tau's ability to promote MTs is regulated by protein phosphorylation by kinases/phosphatases. In spontaneous AD, the activity/expression of kinases are enhanced w$ilst phosphatases are decreased. Alterations in phosphorylation have significant regulatory effects on neuronal signalling which may lead to deficits in neuronal signalling prior to neuronal death. Using cultured rat hippocampal neurons and pharmacological inhibitors of serine/threonine (Okadaic acid and Cantharidin) and tyrosine (Sodium orthovanadate) phosphatases, the consequences of increased phosphorylation for neuronal signalling were investigated. Using Fura-2 Ca2+ imaging, serine/threonine phosphatase inhibition was determined to exert bidirectional modulation on neuronal excitability. Low level short duration inhibition enhanced, whilst str9nger or more prolonged inhibition suppressed Ca2 + responses towards stimulation. Suppression of excitability was coincident with' a reduction in receptor expression and an increase in cytoskeletal phosphorylation. The data mimic changes in signalling utilising alternative means of modelling AD, suggesting that common ' phosphorylation cascades may be active within these models and in the disease process. Acute inhibition of tyrosine phosphatases evoked a prolonged Ca2 + response dependent on the activation of trans-plasma membrane Ca2+ channels. Prolonged inhibition of tyrosine phosphatases enhanced neuronal excitability. A novel sponge toxin polymeric 1,3-alkylpyridinium salts was employed as an agent for inducing tau over-expression in cultured neurons and further Ca2 + imaging studies conducted. Modulation on excitability was observed to be dependent on the level oftau expression. Overall, this thesis furthers the understanding of phospho-regulation of neuronal signalling ~oth physiologically, and pathologically and provides preliminary data for novel roles of tau in neuronal signalling regulation.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Chlorine cycling and the fate of Cl in terrestrial environments

Chlorine (Cl) in the terrestrial environment is of interest from multiple perspectives, including the use of chloride as a tracer forwater flow and contaminant transport, organochlorine pollutants, Cl cycling, radioactive waste (radioecology; 36Cl is of largeconcern) and plant science (Cl as essential element for living plants).During the past decades, there has been a rapid developmenttowards improved understanding of the terrestrial Cl cycle. There is a ubiquitous and extensive natural chlorination of organicmatter in terrestrial ecosystems where naturally formed chlorinated organic compounds (Clorg) in soil frequently exceed theabundance of chloride. Chloride dominates import and export from terrestrial ecosystems while soil Clorg and biomass Cl candominate the standing stock Cl. This has important implications for Cl transport, as chloride will enter the Cl pools resulting inprolonged residence times. Clearly, these pools must be considered separately in future monitoring programs addressing Clcycling. Moreover, there are indications that (1) large amounts of Cl can accumulate in biomass, in some cases representing themain Cl pool; (2) emissions of volatile organic chlorines could be a significant export pathway of Cl and (3) that there is aproduction of Clorg in tissues of, e.g. plants and animals and that Cl can accumulate as, e.g. chlorinated fatty acids in organisms.Yet, data focusing on ecosystem perspectives and combined spatiotemporal variability regarding various Cl pools are still scarce,and the processes and ecological roles of the extensive biological Cl cycling are still poorly understood.Funding agencies:Linkoping University; Swedish Nuclear Fuel and Waste Management Co (SKB)</p