<p>Chlorine is an essential building block in the environment and can be found in most places. Chlorine participates in a complex biogeochemical cycle and has been discussed for many years and it is well documented that natural chlorination of organic compound takes place in many parts of the ecosystem. Chlorine can be inorganic (Clin) and organically bound (Clorg). Previous studies have shown that the transformation of Clin to Clorg is connected with the amount of organic matter and the microbial activity in the soil. So far, studies have been focused on forest soil and there is a need for analysing the natural chlorination in other soil types. The aim of this study was to provide chlorination rates in agricultural soil which does not weem to have been done previously. Three common agricultural soils experiencing different agricultural practice and different cropping systems were incubated with Na36Cl at 20o C in a 56 days radiotracer experiment. The results show that a chlorination of 36Clin to 36Clorg in agricultural soil occurred and the Clorg levels increased over time. The chlorination rates ranged from 0,040 to 0,063 μg Cl g dry weight soil-1 d1. This was 10-fold lower than rates previously measured in coniferous forest soil. However, when expressed as μg Cl g dry weight organic carbon-1 d-1, rates in the agricultural soil was only slightly (at the most 2-fold) lower than in coniferous forest. This study contributes with new knowledge of natural chlorination rates in agricultural soil and gives further evidence that the natural chlorination can be connected to the amount of organic matter in the soil.</p>

Chlorine is one of most common element on earth and it is essential in every living organism, but can also cause problems in the environment. Chlorine can exist both as inorganic (Clin) and organically bound (Clorg). Earlier was the common opinion that Clorg only occurs from anthropogenic sources, but the last years, research has shown that chlorine is a part of the biogeochemical cycle and Clorg also can have natural sources. Many chlorinated substances are poisonous, so the fact that they have a natural source created attention. Fertilizations with nitrogen in forest areas have shown unexpected consequences, such as an increase leakage of nitrogen to ground and surface water. Clear-cutting is a disturbance on the ecosystem and the environment is sensitive for disturbances. Because of the fact that both chlorine and fertilization can be environmental problems and that clear-cutting is a big disturbance in the nature, this study will investigate if there are changes of organic chlorine (Clorg) in soil water after clear-cutting and if fertilization with nitrogen has any influence on the concentration of Clorg. This study was made in a forest area in Värmland, Sweden (Hagfors). Chemical analyses were made in the laboratory though measuring AOX (absorbable organic halogens). The result of this study showed that clear-cutting probably has some effect on the Clorg concentration and that nitrogen doesn’t have any influence.

Chlorine is an essential building block in the environment and can be found in most places. Chlorine participates in a complex biogeochemical cycle and has been discussed for many years and it is well documented that natural chlorination of organic compound takes place in many parts of the ecosystem. Chlorine can be inorganic (Clin) and organically bound (Clorg). Previous studies have shown that the transformation of Clin to Clorg is connected with the amount of organic matter and the microbial activity in the soil. So far, studies have been focused on forest soil and there is a need for analysing the natural chlorination in other soil types. The aim of this study was to provide chlorination rates in agricultural soil which does not weem to have been done previously. Three common agricultural soils experiencing different agricultural practice and different cropping systems were incubated with Na36Cl at 20o C in a 56 days radiotracer experiment. The results show that a chlorination of 36Clin to 36Clorg in agricultural soil occurred and the Clorg levels increased over time. The chlorination rates ranged from 0,040 to 0,063 μg Cl g dry weight soil-1 d1. This was 10-fold lower than rates previously measured in coniferous forest soil. However, when expressed as μg Cl g dry weight organic carbon-1 d-1, rates in the agricultural soil was only slightly (at the most 2-fold) lower than in coniferous forest. This study contributes with new knowledge of natural chlorination rates in agricultural soil and gives further evidence that the natural chlorination can be connected to the amount of organic matter in the soil.

<p>Chlorine is one of most common element on earth and it is essential in every living organism, but can also cause problems in the environment. Chlorine can exist both as inorganic (Clin) and organically bound (Clorg). Earlier was the common opinion that Clorg only occurs from anthropogenic sources, but the last years, research has shown that chlorine is a part of the biogeochemical cycle and Clorg also can have natural sources. Many chlorinated substances are poisonous, so the fact that they have a natural source created attention. Fertilizations with nitrogen in forest areas have shown unexpected consequences, such as an increase leakage of nitrogen to ground and surface water. Clear-cutting is a disturbance on the ecosystem and the environment is sensitive for disturbances. Because of the fact that both chlorine and fertilization can be environmental problems and that clear-cutting is a big disturbance in the nature, this study will investigate if there are changes of organic chlorine (Clorg) in soil water after clear-cutting and if fertilization with nitrogen has any influence on the concentration of Clorg. This study was made in a forest area in Värmland, Sweden (Hagfors). Chemical analyses were made in the laboratory though measuring AOX (absorbable organic halogens). The result of this study showed that clear-cutting probably has some effect on the Clorg concentration and that nitrogen doesn’t have any influence.</p>

Research has shown that formation of chlorinated organic matter occurs naturally and that organic chlorine is as abundant as the chloride ion in organic soils. A large number of organisms are known to convert inorganic chloride (Clin) to organic chlorine (Clorg) (e.g. bacteria, lichen, fungi and algae) and some enzymes associated to these organisms are capable of chlorinating soil organic matter. The aim with the study was to compare organic matter chlorination rates in soils from several different locations dominated by either coniferous forest or pasture. Soil from eight samples sites in the southern of Sweden were incubated at 20°C with addition of 36Clin in a 138 days long radiotracer experiment. The results show that transformation of 36Clin to 36Clorg occurred and that the amounts of 36Clorg increased over time. The chlorination rate was higher in the samples from coniferous forest than in samples containing pasture soil, where the specific chlorination rate was 3-4 times smaller. This study contributes new information about chlorination in various soil types and soil from different locations in southern central Sweden. The similarity between the chlorination rates measured in coniferous forest soils so far indicate that up scaling to regional estimates may be less problematic than expected.

The pollution of soil and groundwater have increased due to the leakage of ptrolium products and organic chemicals in the country recently,and Taiwan face with small region and dense population,so the pollution maybe exposed through relevant way such as quality of water,soil,air,crop and fish and so on to affect human health and cause risk of jeopardise directly or indiretly. The study is to aimed at chlorinated compounds for domestic,and use methods of risk assessment to analyze necessity and urgency of renovation for be contaiminted compound and downstream influence.And then according to result to make relevant management strategies and projets to control risk level and influence for contaiminated compound. In this study,we collect information relate to case,in accordence to health and risk assessment methods for soil and groundwater contaminated sites and some softwares of CRYSTAL BALL and BIOCHLO by Environmental Protection Bureau to estimate the site which was evaluated chlorinated compound (trichloroethylene,TCE),and considerate whether they affect residents healy nearby,use some hydrogeological survey of sites to process second-level health risk assessments. First,use commercial software of CRYSTAL BALL execute uncertainty and sensitivity analysis. Not only does the analysis probe into overall parameters variaty how to affect risk value but also they process analysis and results by different combinations of paremeter.From this result, we can confirm that the large parameter values for affecting risk is transmission of pollutants and is similar to previous studies assessment and analysis.Other parameter cause less influence for risk variaty such as age level of receptor,group,the way of contact,time and water quntity.The study discovers TCE pollutants concentration will make change of risk value by accompany with groundwater move to downstream distance. That means receptor of distance of contamination resource cause large influence. The far distance represents can product the larger function for TCE pollutant, and causes less cancer risk for receptor, conversely, it causes higher cancer risk. Subsequently, we also use BIOCHLOR assessment software by U.S.A Enviromental Protection Bureau. from the result to determine whether the site have potential of anaerrobic reductive dechlorination or not and estimate natural attenuation possibility.The actual situation of the site gets the three score in the weight total.This display do not prove that chlorinated compounds can procedd biogical decomposition in the anaerobic invironment without more correct value in the stage.We recommend looking for another renovations. The study selects more important sensitive parameters through risk assessment result for the site and work out the way of renovations which is suitable for this case by schedule of object. The investigation has found that residents indeed extracted groundwater for agriculture irrigation, but not drank water directly. In order to avoid the worst situation happens from the view of risk, we will consider two aspects of regulation and technology for plan. First, in order to administration control for the aspect of regulation we will consider how to prohibit residents to extract groundwater effectively. For instance, prohibit or limit to set up underground well, provide substitute drink water, set up notice sign and underground water quality monitor measure regularity. Second, for the sake of preventing pollutant group spread and adopt measure for the aspect of technology, for example pollution remediation technology (include soil gas extraction, air injection method at present) and containment control technology (include hydraulic containment, permeability reactive barrier, natural biological remediation, etc) to manage effectively possible events in the site and prepare well prevention in advance. We also adopt good communication with local residents to let residents understand executive content for renovation and reduce their resistance in favor of making progress for renovation and achieve risk management objective.

<p>The concentration and storage of organic chlorine and chloride were determined in soil, to a depth of 40 cm, in a coniferous forest in the Stubbetorp catchment area in south-east Sweden. Also, the spatial distribution of the two forms of chlorine was determined. Soil samples were collected at 49 of the nodes in a grid with approximately 105 m between the nodes. The analysis of spatial variability suggested that no spatial autocorrelation was present either within the variable organic chlorine or chloride. This means that no sample was more influenced by another nearby sample, as compared to other samples further away. Instead, linear interpolation was used to construct contour maps of the concentrations. </p><p>The contour maps indicated that the two forms of chlorine have similar spatial patterns and the highest concentrations could be found in the main valley area, with moss soil and forest dominated by pine (Pinus sylvestris (L.)). The two variables showed a significant positive correlation. This could be due to the fact that chloride is the limiting factor for formation in Swedish soil or that the two forms of chlorine are only indirectly related through variables as soil moisture or organic matter. The storage of organic chlorine when a depth of 40 cm was taken into account was seven times the storage compared to an earlier study where only the top-soil was sampled. </p><p>The storage of organic chlorine in the area is of such size that changes in this storage are likely to have an impact on the transport of chloride. The fact that no spatial autocorrelation could be found in either of the variables suggests that the scale chosen is not suitable for describing spatial autocorrelation on a smaller level, due to processes e.g. microbially induced formation. At the same time the chosen scale is probably too small for detecting spatial autocorrelation on the larger scale due to e.g. deposition and precipitation.</p>

<p><p>Chlorine is an element commonly found in the environment of our planet, in the atmosphere, the earth crust and the oceans. Chlorine occurs in two forms, inorganic chloride (Cl_in) and organically bound chlorine (Cl_org), also called organochlorine. For a long time, the organic halogens (among them the organic chlorine) had been considered as produced only by human activities. However, the research of the recent decades suggests a considerably amount of naturally produced organic chlorine in soil and water. Through the research, a hypothesis have emerged, suggesting that there occur a formation of organic chlorine in the top soil layer where chloride is consuming, while the organic chlorine is degrading on deeper soil levels, causing a release of chloride. The study in this thesis attempts to explore the transportation of organic chlorine through soil. 49 soil water samples were collected at three transects, S04, S12 and S22, nearby a stream in northern Sweden and analysed for Cl_org, using an AOX-analyser. The results suggest a decrease in concentrations of Cl_org by soil depth for transects S04 and S12. The study also indicates that concentrations of Cl_org are decreasing with increasing distance from the stream, where the highest mean concentration was found in the organic matter-rich riparian transect S04. Further conclusions are that the spring flood and changes in groundwater level may influence the concentrations of Cl_org.</p></p> / <p><p>Ämnet klor är vanligt förekommande på vår planet och finns både i atmosfären, jordskorpan och världens oceaner. Klor uppträder i två olika former: oorganisk klorid (Cl_in) och organiskt bundet klor (Cl_org). De organiska halogenerna (bland vilka organiskt klor ingår) har under lång tid ansetts härstamma från enbart antropogena källor. De senaste decenniernas forskning har dock tytt på en naturlig produktion av organiskt klor i mark och vatten. Genom denna forskning har en hypotes tagit form som föreslår en bildning av organiskt klor i de övre marklagren, där klorid binds, medan det i djupare marklager sker en nedbrytning av det organiska kloret vilket medför ett frigörande av klorid. Denna studie syftar till att studera transporten av organiskt klor genom mark. 49 stycken markvattenprover insamlades vid tre provpunkter (S04, S12 och S22) på ett avrinningsområde i norra Sverige och analyserades med hjälp av ett AOX-instrument. Resultaten tyder på en minskning av Cl_org med ökande markdjup för provpunkterna S04 och S12. Studien visar även en minskning i koncentration av organiskt klor med ökande avstånd till vattendraget, där den högsta medelkoncentrationen återfanns i provpunkten S04 som ligger nära bäcken och är rik på organiskt material. Vidare slutsater är att vattenflödena under vårflod samt variasionen i grundvattennivå har en påverkan på koncentrationerna av Cl_org.</p></p>

Chlorinated organic compounds (Clorg) are produced naturally in soil. Formation and degradation of Clorg affect the chlorine (Cl) cycling in terrestrial environments and chlorine can be retained or released from soil. Cl is known to have the same behaviour as radioactive chlorine-36 (36Cl), a long-lived radioisotope with a half-life of 300,000 years. 36Cl attracts interest because of its presence in radioactive waste, making 36Cl a potential risk for humans and animals due to possible biological uptake. This thesis studies the distribution and cycling of chloride (Cl–) and Clorg in terrestrial environments by using laboratory controlled soil incubation studies and a forest field study. The results show higher amounts of Cl– and Clorg and higher chlorination rates in coniferous forest soils than in pasture and agricultural soils. Tree species is the most important factor regulating Cl– and Clorg levels, whereas geographical location, atmospheric deposition, and soil type are less important. The root zone was the most active site of the chlorination process. Moreover, this thesis confirms that bulk Clorg dechlorination rates are similar to, or higher than, chlorination rates and that there are at least two major Clorg pools, one being dechlorinated quickly and one remarkably slower. While chlorination rates were negatively influenced by nitrogen additions, dechlorination rates, seem unaffected by nitrogen. The results implicate that Cl cycling is highly active in soils and Cl– and Clorg levels result from a dynamic equilibrium between chlorination and dechlorination. Influence of tree species and the rapid and slow cycling of some Cl pools, are critical to consider in studies of Cl in terrestrial environments. This information can be used to better understand Cl in risk-assessment modelling including inorganic and organic 36Cl. / Klorerade organiska föreningar (Clorg) bildas naturligt i mark och påverkar klorets kretslopp genom att de stannar kvar längre i marken. Detta stabila klor anses ha samma egenskaper som klor-36, som är en långlivad radioisotop med en halveringstid på 300 000 år. Klor-36 förekommer i olika typer av radioaktivt avfall och om klor-36 sprids i naturen finns det en potentiell risk för människor och djur genom biologiskt upptag. Syftet i denna avhandling är att öka kunskapen om fördelningen och cirkulationen av klorid (Cl-) och Clorg i terrestra miljöer med hjälp av studier i laboratoriemiljö samt en fältstudie i skogsmiljö. Resultaten visar att bildningshastigheten av Clorg är högst i barrskogsjord och rotzonen tycks vara en aktiv plats. Det finns också en större mängd Cl- och Clorg i barrskogsjordar än i betesmark och jordbruksmark. Den mest betydande faktorn som styr halterna av Cl- och Clorg är trädsort, medan geografiskt läge, atmosfäriskt nedfall, och jordmån är av mindre betydelse. Bildning och nedbrytning av Clorg sker med liknande hastigheter, men det tycks finnas två förråd av Clorg i jorden varav ett bryts ner snabbt och ett mer långsamt. Bildningshastigheten av Clorg är lägre i jordar med höga halter av kväve medan nedbrytningshastigheterna inte påverkas av kväve. Slutsatsen från studiernas resultat är att klor i hög grad är aktivt i mark och att Cl- och Clorg halterna bestäms av en dynamisk jämvikt mellan bildning och nedbrytning av Clorg. I studier av klor i terrestra miljöer bör trädsorters inverkan och nedbrytning av olika klorförråd beaktas då det kan ge varierande uppehållstider av Cl- och Clorg i mark. Denna information är viktig vid riskbedömningar av hur radioaktivt klor kan spridas och cirkulera vid en eventuell kärnkraftsolycka.

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