Abstract δ 2 H and δ 18 O values of precipitations follow an empirical linear relationship at the global scale that is called the Global Meteoric Water Line (GMWL) and characterized by a slope of 8. However, Local Meteoric Water Lines (LMWLs) may have different slopes S depending on their geographic situation. Monthly δ 2 H and δ 18 O of precipitation have been compiled from European International Atomic Energy Agency (IAEA) stations. Those data allowed the calculation of the slopes S of the δ 2 H– δ 18 O LMWL determined for each station. S increases with longitude ϕ from c. 5 (Portugal) to c. 9 (Russia) – they are positively correlated with relative humidity (RH), negatively with temperature and positively with the mean intra-annual amplitude of temperatures, which is a proxy of continentality. Slopes of 5–6, recorded in SW Europe, reflect mean RH (70–75%) and sea surface temperatures ( c. 25°C) of the Central Atlantic Ocean where the main flux of moisture is formed before being transported by the westerlies. In addition, falling water droplets within an air column with a high RH (>80%) and low temperature are expected to escape sub-cloud evaporation. Therefore, slopes with values close to 9 are considered to reflect isotopic equilibrium conditions during the condensation of water vapour in clouds.

Abstract In this chapter, we analyse the influence of the Carpathian Mountains on the variability of stable isotopes in precipitation by employing a combination of observed and model data. Overall, the mean value of the stable isotopes in precipitation over the Carpathian Mountains, based on observational data, was −9.8‰ for δ 18 O and −68.6‰ for δ 2 H. The local meteoric line, using all samples from the study sites, was δ 2 H = 7.65 × δ 18 O + 5.82. The simulated δ 18 O, based on the ECHAM5-wiso isotopes enable model, showed good agreement with the observed isotopic data. By comparing all the monthly values of the observed isotopic data from all analysed stations and the corresponding model data, a correlation coefficient of 0.76 ( n = 455, p < 0.001) was obtained. The spatial distribution of the simulated δ 18 O values in precipitation had the lowest values over the Romanian Carpathian Mountains and the highest values over the extra-Carpathian area, with the maximum in southeastern Romania. This pattern was strongly influenced by the Carpathian Mountains orography. Using the simulated δ 18 O data, we show that the spatial distribution of the δ 18 O values increases with temperature and decreases with altitude and latitude (−0.5‰ for δ 18 O per degree of latitude). The continental gradient is characterized by a polynomial trend of the second degree in the form of a large-open ‘U’ shape, and the general pattern of the δ 18 O values follows the spatial distribution of the Carpathian Mountains.

Abstract Water, the vital element of the environment, considered for long time an inexhaustible and renewable resource, can have a limiting or favourable potential in the socioeconomic development of a region. Given that Romania's NE (Eastern Carpathians and the northwestern part of the Moldova Plateau) is undergoing increased competition for water resources, triggered by the intensification of agriculture and industrial development, better knowledge of the hydrological processes and the quality of surface water is required. The main purpose of the present study was to identify the hydrological processes determining the quality of surface waters based on analyses of the stable isotopic composition of water from precipitation, rivers and lakes and its quality parameters. For this, water samples were collected from 29 river sections, two lakes and a precipitation monitoring point over a period of 12 months (January to December 2019). The results show that the changes in the isotopic composition of precipitation and surface water are mainly controlled by air temperature, which, in turn, is influenced by the large-scale atmospheric circulation and other factors (e.g. precipitation amount, season, altitude). At the same time, the chemical analyses indicate that the water resources of the study area are predominantly characterized by a good chemical and ecological state, except for two sampling points with a moderate state and three with a poor ecological state.

Abstract For the first time, we present a decadal-scale stable isotope record (δ 18 O, δ 13 C) of 67 speleothem calcite samples coming from an artificial tunnel network located in Graz, Austria. Stable isotope data are interpreted with the help of time series (TS) analysis of mean air temperatures (MAT) and mean annual precipitations (MAP) that have been monitored and recorded in a neighbouring meteorological station. Speleothem records have proved to be very useful in reconstructing changes of environmental conditions. For studied stalagmites, which grew between 1945 and 2018, the δ 18 O values average −18.64‰ and range from −23‰ to −17‰ (VPDB, Vienna Pee Dee Belemnite), suggesting variable climatic conditions. The δ 18 O values of calcite increase along the growth axis and are correlated with high temporal resolution MAT, MAP and weighted mean annual δ 18 O of precipitations. For the same time interval, while the temperature TS show an increasing trend, with a steeper gradient since the 1980s, the precipitation TS presents a weak decreasing tendency. Increase in the δ 13 C values of speleothems from −33‰ to −24‰ (VPDB) is correlated with increasing temperature and drought, associated CO 2 degassing and soil erosion over the tunnel system.

Abstract The stable isotopic composition of pedogenic carbonate forms in equilibrium with environmental parameters and, thus, records palaeoenvironmental signals. The aims of this study are to synthesize available data on the stable isotopic composition of Quaternary pedogenic carbonates in calcareous parent materials of Iran and to decipher paleoenvironmental implications of the isotopic data for the country. Isotopic composition and microfabric of pedogenic carbonates in 18 pedons in both gravelly (calcareous alluvium in central Iran) and non-gravelly deposits (calcareous loess in northeastern Iran) have been investigated. The results indicate that in limestone-derived soils of central Iran in situ weathering of calcareous pebbles is a major source of Ca for genesis of the carbonates, and carbonate features consist of micritic calcite crystals. In the loessic soils of northeastern Iran, pedogenic carbonates show a dominance of nodule morphology and are classified as orthic nodules. Microfabric analysis reveals that most of the carbonates have not been altered by diagenetic processes, especially the Holocene carbonates, and are suitable for isotopic study and palaeoreconstructions. In limestone-derived soils within the arid region of central Iran, the δ 18 O and the δ 13 C values of carbonates indicate their enrichment due to the effects of evaporative water loss, a decline in plant density and the entrance of atmospheric CO 2 into the soils. In semi-arid ecosystems of central and northeastern Iran, most of the Holocene carbonates have formed in equilibrium with the ambient environment and are suitable for palaeoenvironmental reconstructions. The combination of carbon and oxygen isotopic data demonstrates the dominant role of climate in determining the δ 13 C values of carbonates. There is a strong relationship between the δ 13 C values of carbonates and rainfall, and between O isotopes and aridity indices. Stable isotope patterns in Holocene soils appear to provide data for models that can then be used to interpret the many localities where Pleistocene-aged soils and associated carbonate exist.

ABSTRACT This paper summarizes the hydrological variability in eastern California (central Sierra Nevada) for the past 3000 yr based on three distinct paleoclimate proxies, δ 18 O, total inorganic carbon (TIC), and magnetic susceptibility (chi). These proxies, which are recorded in lake sediments of Pyramid Lake and Walker Lake, Nevada, and Mono Lake and Owens Lake, California, indicate lake-level changes that are mostly due to variations in Sierra Nevada snowpack and rainfall. We evaluated lake-level changes in the four Great Basin lake systems with regard to sediment-core locations and lake-basin morphologies, to the extent that these two factors influence the paleoclimate proxy records. We documented the strengths and weaknesses of each proxy and argue that a systematic study of all three proxies together significantly enhances our ability to characterize the regional pattern, chronology, and resolution of hydrological variability. We used paleomagnetic secular variation (PSV) to develop paleomagnetic chronostratigraphies for all four lakes. We previously published PSV records for three of the lakes (Mono, Owens, Pyramid) and developed a new PSV record herein for Walker Lake. We show that our PSV chronostratigraphies are almost identical to previously established radiocarbon-based chronologies, but that there are differences of 20–200 yr in individual age records. In addition, we used eight of the PSV inclination features to provide isochrons that permit exacting correlations between lake records. We also evaluated the temporal resolution of our proxies. Most can document decadal-scale variability over the past 1000 yr, multidecadal-scale variability for the past 2000 yr, and centennial-scale variability between 2000 and 3000 yr ago. Comparisons among our proxies show a strong coherence in the pattern of lake-level variability for all four lakes. Pyramid Lake and Walker Lake have the longest and highest-resolution records. The δ 18 O and TIC records yield the same pattern of lake-level variability; however, TIC may allow a somewhat higher-frequency resolution. It is not clear, however, which proxy best estimates the absolute amplitude of lake-level variability. Chi is the only available proxy that records lake-level variability in all four lakes prior to 2000 yr ago, and it shows consistent evidence of a large multicentennial period of drought. TIC, chi, and δ 18 O are integrative proxies in that they display the cumulative record of hydrologic variability in each lake basin. Tree-ring estimations of hydrological variability, by contrast, are incremental proxies that estimate annual variability. We compared our integrated proxies with tree-ring incremental proxies and found a strong correspondence among the two groups of proxies if the tree-ring proxies are smoothed to decadal or multidecadal averages. Together, these results indicate a common pattern of wet/dry variability in California (Sierra Nevada snowpack/rainfall) extending from a few years (notable only in the tree-ring data) to perhaps 1000 yr. Notable hydrologic variability has occurred at all time scales and should continue into the future.

Abstract Radon ( 222 Rn) has been highlighted by a number of authors as a significant public health concern. For example, it is the second most significant cause of lung cancer after tobacco smoking ( c. 1000–2000 and 21 000 deaths per year in the UK and USA, respectively), yet a very high proportion of the general public appears to be unaware of the risk. This chapter deals with topical radon issues, such as: radon in the workplace; radon in homes; exposure to radon during leisure activities; radon and water; measurement and monitoring; seasonal correction; remediation; cancer risks; cost–benefit analysis and cost-effectiveness; mapping; future policies; and further research. This assessment of the state of radon research is focused on the UK as an example of a country where radon has been on the governmental agenda since the late 1970s, but also highlights radon issues throughout the world in, for example, the USA, Europe and Asia.

Abstract The majority of radon measurements in the built environment are made over sub-year periods and are then generally seasonally corrected (i.e. scaled by an appropriate seasonal correction factor (SCF)) to estimate the annual average radon concentration. SCFs are statistically derived and assume an underlying annual cycle, reflecting the widely observed seasonal variation in indoor radon concentrations. In the UK, Public Health England has pioneered the calculation and use of a national SCF set using an annual sinusoidal model for variations in radon concentration and averaging across the entire country. To test the validity of that model, a 4 year record of weekly radon data from four houses in Brixworth (Northamptonshire, UK) was analysed in conjunction with corresponding weather data for the period from a nearby weather station. The radon data showed a statistically significant annual cycle comprising both annual sinusoidal and second harmonic (i.e. 6 month period) terms. Two sets of SCFs were calculated: first, using a conventional annual sinusoidal model that explained 21.2% of the variance in the radon data; and, secondly, a second harmonic term was included in the model that explained 24.6% of the variance. This represents an improvement of 3.4 percentage points (15.9%) and, thus, will result in better SCFs.

Abstract Melting of snow and ice contributes a large amount of water to the streamflow in the Satluj River. During the winter season, there is low base flow in the river as compared to spring and summer. Temperature is one of the key factors which directly impacts snow and ice melting throughout the year. A substantial amount of snowmelt only occurs when all the snow in a pack reaches isothermal condition. It is therefore very important to know the duration of impact of temperature on snowmelt runoff. Since the Himalayas have very few stations observing hydrological as well as meteorological conditions, it is difficult to validate the snowmelt models and examine changes in small-scale features in river basins of the region. The present study examines the annual cycle and interannual variability of runoff in the Satluj Basin in the western Himalayas and documents the impact of temperature on snowmelt runoff of Satluj River using daily in situ data for the period 1982–2005. A multivariate regression model using precipitation and surface temperature has been developed to predict the discharge of Satluj River at a daily scale. It is seen that after every warm phase and cold phase of temperature, the impact persists for around one month and affects the snowmelt runoff during January, February and March at lower- and higher-elevation stations such as Bhakra and Kasol, respectively. The effect of a large fall and rise in temperature is noticed on snowmelt runoff measured at all the discharge stations, while a small temperature change does not affect the observed discharge at all the stations. The remote sensing and reanalysis data are consistent with in situ data in the basin, and there is no major change in peak month of discharge or the amplitude during two different periods at Rampur gauge station.