Reservoirs and radiocarbon: ¹⁴C dating problems in Myvatnssveit, Northern Iceland

This paper examines 2 potential sources of the radiocarbon offset between human and terrestrial mammal (horse) bones recovered from Norse (~AD 870–1000) pagan graves in Mývatnssveit, north Iceland. These are the marine and freshwater 14C reservoir effects that may be incorporated into human bones from dietary sources. The size of the marine 14C reservoir effect (MRE) during the Norse period was investigated by measurement of multiple paired samples (terrestrial mammal and marine mollusk shell) at 2 archaeological sites in Mývatnssveit and 1 site on the north Icelandic coast. These produced 3 new ΔR values for the north coast of Iceland, indicating a ΔR of 106 ± 10 14C yr at AD 868–985, and of 144 ± 28 14C yr at AD 1280–1400. These values are statistically comparable and give an overall weighted mean ΔR of 111 ± 10 14C yr. The freshwater reservoir effect was similarly quantified using freshwater fish bones from a site in Mývatnssveit. These show an offset of between 1285 and 1830 14C yr, where the fish are depleted in 14C relative to the terrestrial mammals. This is attributed to the input of geothermally derived CO2 into the groundwater and subsequently into Lake Mývatn. We conclude the following: i) some of the Norse inhabitants of Mývatnssveit incorporated non-terrestrial resources into their diet that may be identified from the stable isotope composition of their bone collagen; ii) the MRE off the north Icelandic coast during the Norse period fits a spatial gradient of wider North Atlantic MRE values with increasing values to the northwest; and iii) it is important to consider the effect that geothermal activity could have on the 14C activity of samples influenced by groundwater at Icelandic archaeological sites

Temporal and spatial variations in freshwater 14C reservoir effects: Lake Myvatn, Northern Iceland

Lake Mývatn is an interior highland lake in northern Iceland that forms a unique ecosystem of international scientific importance and is surrounded by a landscape rich in archaeological and palaeoenvironmental sites. A significant Freshwater 14C Reservoir Effect (FRE) has been identified in carbon from the lake at some Norse (c.870-1000 AD) archaeological sites in the wider region (Mývatnssveit). Previous AMS measurements indicated this FRE was ~1500-1900 14C years. Here we present the results of a study using stable isotope and 14C measurements to quantify the Mývatn FRE for both the Norse and modern periods. This work has identified a temporally variable FRE that is greatly in excess of previous assessments. New, paired samples of contemporaneous bone from terrestrial herbivores and omnivores (including humans) from Norse sites demonstrate at least some omnivore diets incorporated sufficient freshwater resources to result in a herbivore-omnivore age offset of up to 400 14C yrs. Modern samples of benthic detritus, aquatic plants, zooplankton, invertebrates and freshwater fish indicate an FRE in excess of 5000 14C yrs in some species. Likely geothermal mechanisms for this large FRE are discussed, along with implications for both chronological reconstruction and integrated investigation of stable and radioactive isotop

Psychopathological consequences related to problematic Instagram use among adolescents: the mediating role of body image dissatisfaction and moderating role of gender

In a minority of cases, problematic use of technology can negatively impact on adolescents and impair some aspects of their social, emotional, and psychological development. The purpose of the present study was to examine the direct and indirect effects of problematic Instagram use (PIU) on different psychopathological outcomes including loneliness, depression, anxiety, and social anxiety via body image dissatisfaction (BID). Additionally, moderating role of gender on the relationships among variables was investigated. A total of 491 adolescents (Mage = 15.92 years, SDage = 1.07; range = 14 to 19 years) were recruited for the study to complete a questionnaire that included the relevant assessment tools for the aforementioned variables. Mediation and moderation analyses showed that among male adolescents, PIU was directly associated with loneliness, depression, general anxiety, and social anxiety and BID partially mediated these associations. Among females, PIU was directly associated with depression and indirectly with general anxiety and social anxiety via BID. Gender significantly moderated the direct relationships of PIU with loneliness, general anxiety, and social anxiety. PIU was directly associated with loneliness, general anxiety, and social anxiety among males only, whereas among females, PIU was indirectly associated with general and social anxiety via BID but was not related to loneliness. Results of this study indicate that PIU has different negative psychological effects on male and female adolescents and that BID appears to be one explanatory factor for these impairments especially among females

Reservoirs and radiocarbon: C-14 dating problems in Myvatnssveit, northern Iceland

This paper examines 2 potential sources of the radiocarbon offset between human and terrestrial mammal (horse) bones recovered from Norse (similar to AD 870-1000) pagan graves in Myvatnssveit, north Iceland. These are the marine and freshwater C-14 reservoir effects that may be incorporated into human bones from dietary sources. The size of the marine C-14 reservoir effect (MRE) during the Norse period was investigated by measurement of multiple paired samples (terrestrial mammal and marine mollusk shell) at 2 archaeological sites in Myvatnssveit and 1 site on the north Icelandic coast. These produced 3 new Delta R values for the north coast of Iceland, indicating a Delta R of 106 +/- 10 C-14 yr at AD 868-985, and of 144 +/- 28 C-14 yr at AD 1280-1400. These values are statistically comparable and give an overall weighted mean Delta R of 111 +/- 10 C-14 yr. The freshwater reservoir effect was similarly quantified using freshwater fish bones from a site in Myvatnssveit. These show an offset of between 1285 and 1830 C-14 yr, where the fish are depleted in C-14 relative to the terrestrial mammals. This is attributed to the input of geothermally derived CO2 into the groundwater and subsequently into Lake Myvatn. We conclude the following: i) some of the Norse inhabitants of Myvatnssveit incorporated non-terrestrial resources into their diet that may be identified from the stable isotope composition of their bone collagen; ii) the MRE off the north Icelandic coast during the Norse period fits a spatial gradient of wider North Atlantic MRE values with increasing values to the northwest; and iii) it is important to consider the effect that geothermal activity could have on the C-14 activity of samples influenced by groundwater at Icelandic archaeological sites.</p

Successful aging as management of resources: The role of selection, optimization, and compensation

One of the central tenets of life-span psychology is that the process of development entails gains and losses that occur over the entire life span. Thus, Paul and Margret Baltes (1990) conceptualized successful aging as a lifelong process of maximizing gains and minimizing losses by means of three processes: selection, optimization, and compensation (SOC). This article reviews empirical studies that have investigated the use of SOC during adulthood with different methodological approaches and have found evidence for the importance of SOC for successfully managing one's resources. The article highlights the importance of prioritizing goals (selection) according to their importance for increasing gains (optimization) and avoiding losses (compensation) in consideration of currently available resources. Age-related changes in resource availability and time perspective can also result in a shift in goal orientation towards gains or losses and in goal focus on the process or the outcome of goal pursuit. Taken together, the action-theoretical approach to the SOC framework suggests that selection, optimization, and compensation can be seen as key concepts for understanding successful aging