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Radiocarbon datings in a previous study suggested that Moshyttan in Nora bergslag is the oldest blast furnace in Sweden and Europe. The aim of this study was specifically to study the origin of the Moshyttan blast furnace to answer the question: when was the blast furnace at Moshyttan established? To this end, a 2.5 m sediment record was collected from Fickeln, a lake 600 m downstream of Moshyttan, in March 2012. The geochemical properties of the sediment record were analyzed for major and trace elements using XRF. The organic content was calculated from the ash residue following the mercury analyses as a proxy for organic matter. Pollen and charcoal were analyzed using a standardized method. A age- depth model was created based on four radiocarbon datings of the sediment profile. The pollen data suggest that early land use consisted of forest grazing from about AD 220, and agriculture from about AD 880. An increase in Pb and charcoal particles about AD 880 indicates early metallurgy in the area. The first significant evidence of the establishment of a blastfurnace was between AD 1020 and AD 1090 marked by a decrease in organic content combined with a strong increase of ore related metals such as Pb, Zn, Cu and a strong increase of charcoal particles. Within the uncertainty of the age-depth modeling, the results from this study offers support to Wetterholms radiocarbon datings, thus making Moshyttan the oldest known blast furnace in Sweden and Europe.

The aim of this literature study is to compare and discuss different fields of paleolimnology, with a focus on three main research areas – eutrophication, acidification, and climate change. Pioneering work and the development of paleolimnological methods around these three areas were reviewed and synthesized. Paleolimnology started out as limnology and paleoecology, but has evolved tremendously over the past decades. Early paleolimnological studies focused on lake ontogeny and mechanics in the catchment such as weathering. The focus eventually shifted to nutrient loadings during the 1960s – 1970s as the debate on human induced eutrophication emerged. The important question to answer was which nutrient was the limiting factor in eutrophication. Acidification was the next topic of investigation during the 1980s – 1990s, and paleolimnology developed methods to infer past pH change based on chironomids and diatom fossils preserved in lake sediment. This research resulted in calibration sets and proxies which can be used to reconstruct past conditions. The paleolimnological community eventually shifted focus in the late 1990s to climate change and began to use lake sediment to reconstruct past climatic trends using multiproxy studies such as diatoms, chironomids and geochemistry. Varved lake sediment offered a much needed terrestrial high resolution option to the ice core records. History plays a fundamental role in all environmental issues and paleolimnology has the ability to provide historical records of past environmental conditions. Paleolimnology will most likely play a key role in management and restoration in the future. As technology and training sets develop, fast and cheap ways to interpret sediment proxies will emerge and maybe even fully automated identification of proxies.

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Changes in monsoon patterns not only affect ecosystems and societies but also the global climate system in terms of heat energy and humidity transfer from the equator to higher latitudes. However, understanding the mechanisms that drive monsoon variability on longer timescales remains a challenge, partly due to sparse paleoenvironmental and paleoclimatic data. This thesis, which contributes new hydroclimate data sets for the Asian monsoon region, seeks to advance our understanding of the mechanisms that contributed to Southeast Asian summer monsoon variability in the past. Moreover, it explores how past climatic conditions may have impacted societies and ecosystems. In this study lake sediment and peat sequences from northeastern and southern Thailand have been investigated using organic geochemistry, and more specifically the stable carbon and hydrogen isotopic composition of specific biomarkers (n-alkanes, botryococcenes, and highly branched isoprenoids). The hydrogen isotopic composition of leaf waxes (δDwax) in Thailand was shown to relate to the amount of precipitation and the extent of the El Niño Southern Oscillation.  Higher values of δDwax can be interpreted as reflecting relatively dry climatic conditions, whereas lower values relate to wetter conditions. The hydroclimate reconstruction for northeastern Thailand, based on the sedimentary record of Lake Kumphawapi, suggests higher moisture availability between ca. 10,700 cal. BP and ca. 7,000 cal. BP likely related to a strengthened early Holocene summer monsoon. Moisture availability decreased during the mid-Holocene, but seems to have increased again around 2,000 years ago and has fluctuated since. The high-resolution Lake Pa Kho peat sequence, which allows for a sub-centennial reconstruction of moisture availability, indicates that the wettest period occurred between ca. 700 and ca. 1000 CE whereas driest intervals were from ca. 50 BCE to ca. 700 CE and from ca. 1300 to ca. 1500 CE. Hydroclimate comparison of Pa Kho’s δDwax record with other paleoclimate records from the Asian-Pacific region suggests that El Niño-like conditions led to Northeastern Thailand being wetter, whereas La Niña-like conditions led to drier conditions. Regional hydroclimate variability also greatly influenced the Angkor Civilization, which flourished between ca. 845 and ca. 1450 CE. The shift from drier to wetter conditions coincided in time with the rise of the Angkor Civilization and likely favored the intense agriculture needed to sustain the empire. The gradual decline in moisture availability, which started after ca. 1000 years CE, could have stretched the hydrological capacity of Angkor to its limit. It is suggested that Angkor’s population resorted to unconventional water sources, such as wetlands, as population growth continued, but summer monsoon rains weakened. The 150-year long record of Lake Nong Thale Prong in southern Thailand offers insights into decadal-scale hydroclimatic changes that can be connected to the instrumental record. δDwax-based hydroclimate was drier from ~1857 to 1916 CE and ~1970 to 2010 CE and wetter from ~1916 to 1969 CE. Drier climatic conditions between ~1857 and 1916 CE coincided with oligotrophic lake waters and a dominance of the green algae Botryococcus braunii. Higher rainfall between ~1916 and 1969 CE concurred with an increase in diatom blooms while eutrophic lake water conditions were established between ~1970–2010 CE. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 3: Manuscript.</p> / Monsoon project

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A common view in today’s society is that natural background conditions is found just prior to the start of the industrialization. By employing this view in environmental work, it neglects the human impact attributed to historical site-specific activities such as metallurgy. These activities have been widespread throughout Sweden, reaching far back into history. It is therefore necessary to determine the site-specific background conditions in order to assess the impact these activities have had. This study investigates the start of the blast furnace Alntorpshyttan in Bergslagen by conducting geochemical analyzes using sediment profiles in Norasjön as a natural archive. This was coupled with an indirect dating method based on the immigration spruce (Picea abies) and the historical atmospheric lead (Pb) pollution. The earliest sign of human activities takes place at 1800 BP, possibly due to farming activities. Based on the increases in iron coupled with increases in other ore-related elements (e.g., Magnesium and copper) I placed the start of Alntorpshyttan in the early/late 13th century. This is consistent with the rapid expansion of blast furnaces throughout Bergslagen. Based on these results, I conclude that historical small-scale metallurgical activities have had a significant impact on local lake systems and potentially a cumulative effect further downstream.

Results of mineral magnetic, mobile clement, and granulometric analyses of Holocene sediments from Buttermere and Crummock Water (two closely-linked lakes in the north-west of the English Lake District) are presented. These are used to: (1) identify effects of internal (lacustrine) and external (catchment) controls on sedimentation; (2) establish catchment source-lake sediment linkages and assess the value of mineral magnetic techniques in palaeolimnological studies; (3) identify major catchment environmental changes. Analyses of lake sediment fabrics (using sediment thin sections, SEM clay flake analysis, standard granulometric analysis, and mineral magnetic indicators of grain size change) indicate that river plume sedimentation is the normal sediment dispersal mechanism in these lakes. Thin (< = 3.0 mm) chlorite-rich laminae, found at intervals in the otherwise homogeneous Holocene sediment sequence, are probably formed by trapping and concentration of fine, platy particles within lake waters. They are subsequently deposited during lake overturn. This represents an "internal" control on sedimentation. A model of sedimentation processes operating in these lakes is developed, incorporating river plume sedimentation, episodic density surges, and lake thermal structure. Mineral magnetic measurements allow the objective subdivision of the lacustrine lithostratigraphy, identifying broad changes in lake sediment characteristics. Samples from both lake catchments are clustered into six magnetically distinct groups - despite the lithological complexity of the catchment. Comparison of these with the lake sediments has enabled identification of major sources during the Holocene. Following deposition of relatively unaltered bedrock-derived material during the Late-glacial ("primary" sources), secondary sources (which may include glacial diamicts, soils and stream sediments) dominate the lake sediments. Direct input of topsoil-derived sediment from circa 1000 A.D. onwards (during and following the main period of Norse settlement of the Lake District) is identified by its distinctive mineral magnetic characteristics, (high Xfd% values, >-4%). Industrially-derived magnetic spherules contribute significantly to the mineral magnetic characteristics of the more recent sediments, (mainly those post-dating circa 1900 A.D.). These are used to construct a proxy chronology for recent sediments. Catchment environmental changes arc mainly related to stabilisation of vegetation following deglaciation and, from circa 2,000 B.P., anthropogenic effects of deforestation and land disturbance, thus increasing lake sediment accumulation rates. These findings are broadly consistent with the interpretation of the Lake District Post-glacial sediment sequence presented in studies by Mackereth, (1966a), and Pennington, (1981), demonstrating a uniformity of lake and catchment development within the Lake District. A prominent minerogenic layer present in the Buttermere and Crummock Water sediment sequence however broadly correlates with similar horizons deposited in other Lake District lakes from circa 7,400 - 5,000 B.P. These have been previously interpreted as composed of topsoil-derived material derived from human actions, (Pennington 1973, 1981). In the Buttermere and Crummock Water sediments, this layer is best interpreted as derived from glaciogenic sediment') reworked from within the lake basins, probably following lowered lake water levels during the period circa 7,300 - 5,300 B.P. Thus it is suggested that a reinterpretation of similar Lake District lacustrine sediments using the methods employed in this study would be appropriate.