Cardiovascular diseases risk factors during the first year of life

The pattern of change in cardiovascular risk factors, blood pressure (SBP and DBP) and plasma total cholesterol (TC), over time, their tracking and their relation to anthropometric measurements during the first year of life were investigated. Also, the effect of breast feeding on TC and the relationship of blood pressure measurements and family history of CVD risk factors were examined. One hundred five newborn term, healthy infants who were seen at a pediatric clinic in The Woodlands, Texas were followed longitudinally from 2 weeks to 1 year of age. TC, blood pressure, weight and length of the infants were measured at age 2 weeks, and again at 2, 4, 6, 9 and 12 months. In addition, family history, maternal and paternal, of CVD risk factors was obtained. Data analyses included only 40 infants who completed one year of follow up.^ At 2 weeks of age, the median value for TC was 23 mg/dl higher for females than for males. This difference disappeared as infants got older. For males, most of the increase in TC median levels, from 114 to 137 mg/dl, occurred between the ages of 2 weeks and 2 months, whereas for the female group, TC levels increased moderately, about 10 mg/dl, between 9 and 12 months of age. Tracking of TC was examined by using Spearman's correlation analysis. There were strong correlations between measurements taken as early as 2 weeks of age with later measurements. These correlations were stronger and more significant for males than for females (for males, r varied between 0.51 to 0.70, whereas for females, r varied between 0.11 to 0.70). The association of body measurements with TC is no more than modest and is closer for female infants than for male infants. Analysis, also, showed that infants who received breast milk had a TC mean value 47 mg/dl higher than that for infants who received formula milk only during the period of breast feeding and this difference disappeared by age 12 months.^ In both genders, most of the increase in blood pressure (about 10-15 mmHg in both SBP and DBP) occurred during the first 4 months of life. Most of the increase for male infants occurred during the first 2 months of life, while for females, the increase in SBP and DBP was between the age of 2 and 4 months. Neither SBP nor DBP track well during the first year of life and most of the correlations between measurements at different ages were not significant for either gender. The cross-sectional relationship of blood pressure measurements and selected body measurements was assessed. For females, only at age of 12 months did DBP have positive and significant correlations with weight, length and Quetelet index (r = 0.57, 0.60 and 0.57, respectively). There were no significant correlations between blood pressure and body measurements for males. Finally, analysis showed that maternal history of CV risk factors was significantly related to SBP in the female infant group, but not for males. For DBP, neither maternal nor paternal history was related. ^

Iron (Fe) concentrations and fluxes in TALDICE ice core 0.6 to 314 ky BP

Atmospheric fluxes of iron (Fe) over the past 200 kyr are reported for the coastal Antarctic Talos Dome ice core, based on acid leachable Fe concentrations. Fluxes of Fe to Talos Dome were consistently greater than those at Dome C, with the greatest difference observed during interglacial climates. We observe different Fe flux trends at Dome C and Talos Dome during the deglaciation and early Holocene, attributed to a combination of deglacial activation of dust sources local to Talos Dome and the reorganisation of atmospheric transport pathways with the retreat of the Ross Sea ice shelf. This supports similar findings based on dust particle sizes and fluxes and Rare Earth Element fluxes. We show that Ca and Fe should not be used as quantitative proxies for mineral dust, as they all demonstrate different deglacial trends at Talos Dome and Dome C. Considering that a 20 ppmv decrease in atmospheric CO2 at the coldest part of the last glacial maximum occurs contemporaneously with the period of greatest Fe and dust flux to Antarctica, we confirm that the maximum contribution of aeolian dust deposition to Southern Ocean sequestration of atmospheric CO2 is approximately 20 ppmv.

Environmental observations from Station Ssagastyr during the first International Polar Year 1882/83 (digitized tables)

Vorliegender Band enthält die für alle internationalen Polarstationen obligatorischen meteorologischen Beobachtungen der russischen Polarstation an der Lenamündung für den Zeitraum vom 1. September 1882 bis 31. August 1883 und vom 1. September 1883 bis zum 6. Juli 1884.

Soil carbon in the Jena Experiment (all blocks Main Experiment up to 30cm depth, year 2006)

This data set contains soil carbon measurements (Organic carbon, inorganic carbon, and total carbon; all measured in dried soil samples) from the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. Soil sampling and analysis: Stratified soil sampling was performed in April 2006 to a depth of 30 cm. Three samples per plot were taken using a split tube sampler with an inner diameter of 4.8 cm (Eijkelkamp Agrisearch Equipment, Giesbeek, the Netherlands). Sampling locations were less than 30 cm apart from sampling locations in 2002. Soil samples were segmented into 5 cm depth segments in the field (resulting in six depth layers) and made into composite samples per depth. Subsequently, samples were dried at 40°C. All soil samples were passed through a sieve with a mesh size of 2 mm. Because of much higher proportions of roots in the soil, samples in years after 2002 were further sieved to 1 mm according to common root removal methods. No additional mineral particles were removed by this procedure. Total carbon concentration was analyzed on ball-milled subsamples (time 4 min, frequency 30 s**-1) by an elemental analyzer at 1150°C (Elementaranalysator vario Max CN; Elementar Analysensysteme GmbH, Hanau, Germany). We measured inorganic carbon concentration by elemental analysis at 1150°C after removal of organic carbon for 16 h at 450°C in a muffle furnace. Organic carbon concentration was calculated as the difference between both measurements of total and inorganic carbon.

Dissolved organic carbon in soil solution of the Jena Experiment (Main Experiment, year 2002)

This data set contains measurements of dissolved organic carbon in samples of soil water collected from the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. In April 2002 glass suction plates with a diameter of 12 cm, 1 cm thickness and a pore size of 1-1.6 mm (UMS GmbH, Munich, Germany) were installed in depths of 10, 20, 30 and 60 cm to collect soil solution. The sampling bottles were continuously evacuated to a negative pressure between 50 and 350 mbar, such that the suction pressure was about 50 mbar above the actual soil water tension. Thus, only the soil leachate was collected. Cumulative soil solution was sampled biweekly and analyzed for dissolved organic carbon concentration by a high TOC elemental analyzer (Elementar Analysensysteme GmbH, Hanau, Germany). Samples were analyzed as soon as possible and stored at 4°C if necessary. Often in summer, no free soil solution was available for collection, especially in the upper soil layers. Annual mean values of measured biweekly concentrations of dissolved organic carbon are provided.

Dissolved organic carbon in soil solution of the Jena Experiment (Main Experiment, year 2005)

This data set contains measurements of dissolved organic carbon in samples of soil water collected from the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. In April 2002 glass suction plates with a diameter of 12 cm, 1 cm thickness and a pore size of 1-1.6 mm (UMS GmbH, Munich, Germany) were installed in depths of 10, 20, 30 and 60 cm to collect soil solution. The sampling bottles were continuously evacuated to a negative pressure between 50 and 350 mbar, such that the suction pressure was about 50 mbar above the actual soil water tension. Thus, only the soil leachate was collected. Cumulative soil solution was sampled biweekly and analyzed for dissolved organic carbon concentration by a high TOC elemental analyzer (Elementar Analysensysteme GmbH, Hanau, Germany). Samples were analyzed as soon as possible and stored at 4°C if necessary. Often in summer, no free soil solution was available for collection, especially in the upper soil layers. Annual mean values of measured biweekly concentrations of dissolved organic carbon are provided.

Dissolved organic carbon in soil solution of the Jena Experiment (Main Experiment, year 2006)

This data set contains measurements of dissolved organic carbon in samples of soil water collected from the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. In April 2002 glass suction plates with a diameter of 12 cm, 1 cm thickness and a pore size of 1-1.6 mm (UMS GmbH, Munich, Germany) were installed in depths of 10, 20, 30 and 60 cm to collect soil solution. The sampling bottles were continuously evacuated to a negative pressure between 50 and 350 mbar, such that the suction pressure was about 50 mbar above the actual soil water tension. Thus, only the soil leachate was collected. Cumulative soil solution was sampled biweekly and analyzed for dissolved organic carbon concentration by a high TOC elemental analyzer (Elementar Analysensysteme GmbH, Hanau, Germany). Samples were analyzed as soon as possible and stored at 4°C if necessary. Often in summer, no free soil solution was available for collection, especially in the upper soil layers. Annual mean values of measured biweekly concentrations of dissolved organic carbon are provided.

Simulated change in atmospheric CO2 and D14C around 14.6 kyr BP, at the onset of the northern hemispheric warming into the Bølling/Allerød

One of the most abrupt and yet unexplained past rises in atmospheric CO2 (10 p.p.m.v. in two centuries) occurred in quasi-synchrony with abrupt northern hemispheric warming into the Bølling/Allerød, 14,600 years ago. Here we use a U/Th-dated record of atmospheric D14C from Tahiti corals to provide an independent and precise age control for this CO2 rise. We also use model simulations to show that the release of old (nearly 14C-free) carbon can explain these changes in CO2 and D14C. The D14C record provides an independent constraint on the amount of carbon released (125 Pg C). We suggest, in line with observations of atmospheric CH4 and terrigenous biomarkers, that thawing permafrost in high northern latitudes could have been the source of carbon, possibly with contribution from flooding of the Siberian continental shelf during meltwater pulse 1A. Our findings highlight the potential of the permafrost carbon reservoir to modulate abrupt climate changes via greenhouse-gas feedbacks.

Seasonally aggregated values of dissolved inorganic phosphorus in soil solution of the Jena Experiment (Main Experiment, year 2006)

This data set contains measurements of inorganic phosphorus in samples of soil solution collected in 2006 from the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below) that have been aggregated to seasonal values. In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. Glass suction plates with a diameter of 12 cm, 1 cm thickness and a pore size of 1-1.6 µm (UMS GmbH, Munich, Germany) were installed in April 2002 in depths of 10, 20, 30 and 60 cm to collect soil solution. Manual soil matric potential measurements were used to regulate the vacuum system. Manual soil matric potential measurements were used to regulate the vacuum system. The sampling bottles were continuously evacuated to a negative pressure between 50 and 350 mbar, such that the suction pressure was about 50 mbar above the actual soil water tension. Thus, only the soil leachate was collected. Cumulative soil solution was sampled biweekly and analyzed for dissolved inorganic P (PO4P). Here volume-weighted mean values are provided as aggregated seasonal values (spring = March to May, summer = June to August, fall = September to November, winter = December to February) for 2006 in spring. To calculate these values, the sampled volume of soil solution is used as weight for P concentrations of the respective sampling date. Inorganic phosphorus concentrations in the soil solution were measured photometrically with a continuous flow analyzer (CFA Autoanalyzer [Bran&Luebbe, Norderstedt, Germany]). Ammonium molybdate catalyzed by antimony tartrate reacts in an acidic medium with phosphate and forms a phospho-molybdic acid complex. Ascorbic acid reduces this complex to an intensely blue-colored complex. As the molybdic complex forms under strongly acidic conditions, we could not exclude the hydrolysis of labile organic P compounds in our samples. Furthermore, the molybdate reaction is not sensitive for condensed phosphates. The detection limits of both TDP and PO4P were 0.04 mg P l-1 (Autoanalyzer, Bran&Luebbe).

Dissolved phosphorus in soil solution of the Jena Experiment (Main Experiment, year 2003)

This data set contains measurements of dissolved phosphorus (total dissolved nitrogen: TDP, dissolved inorganic phosphorus: PO4P and dissolved organic phosphorus: DOP) in samples of soil water collected in 2003 from the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. Glass suction plates with a diameter of 12 cm, 1 cm thickness and a pore size of 1-1.6 mm (UMS GmbH, Munich, Germany) were installed in April 2002 in depths of 10, 20, 30 and 60 cm to collect soil solution. Manual soil matric potential measurements were used to regulate the vacuum system. The sampling bottles were continuously evacuated to a negative pressure between 50 and 350 mbar, such that the suction pressure was about 50 mbar above the actual soil water tension. Thus, only the soil leachate was collected. Cumulative soil solution was sampled bi-weekly, in 2003 at the 07.03.2003; 24.03.2003; 07.04.2003; 22.04.2003; 07.05.2003; 20.05.2003; 03.06.2003; 28.07.2003; 12.09.2003; 22.09.2003; 07.10.2003; and 21.10.2003, and analyzed for dissolved inorganic P (PO4P) and total dissolved phosphorus (TDP). Inorganic phosphorus concentrations in the soil solution were measured photometrically with a continuous flow analyzer (CFA SAN++, Skalar [Breda, The Netherlands]). Ammonium molybdate catalyzed by antimony tartrate reacts in an acidic medium with phosphate and forms a phospho-molybdic acid complex. Ascorbic acid reduces this complex to an intensely blue-colored complex. Total dissolved P in soil solution was analyzed by irradiation with UV and oxidation with K2S2O8 followed by reaction with ammonium molybdate (Skalar catnr. 503-553w/r). As the molybdic complex forms under strongly acidic conditions, we could not exclude the hydrolysis of labile organic P compounds in our samples. Furthermore, the molybdate reaction is not sensitive for condensed phosphates. The detection limits of both TDP and PO4P were 0.02 mg P l-1 (CFA, Skalar). Dissolved organic P (DOP) in soil solution was calculated as the difference between TDP and PO4P. In a low number of samples, TDP was equal to or smaller than PO4P; in these cases, DOP was assumed to be zero.

Dissolved phosphorus in soil solution of the Jena Experiment (Main Experiment, year 2004)

This data set contains measurements of dissolved phosphorus (total dissolved nitrogen: TDP, dissolved inorganic phosphorus: PO4P and dissolved organic phosphorus: DOP) in samples of soil water collected in 2004 from the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. Glass suction plates with a diameter of 12 cm, 1 cm thickness and a pore size of 1-1.6 µm (UMS GmbH, Munich, Germany) were installed in April 2002 in depths of 10, 20, 30 and 60 cm to collect soil solution. Manual soil matric potential measurements were used to regulate the vacuum system. The sampling bottles were continuously evacuated to a negative pressure between 50 and 350 mbar, such that the suction pressure was about 50 mbar above the actual soil water tension. Thus, only the soil leachate was collected. Cumulative soil solution was sampled bi-weekly, in 2004 at the 15.01.2004; 30.01.2004; 12.02.2004; 27.02.2004; 09.03.2004; 25.03.2004; 21.04.2004; 07.05.2004; and 24.05.2004, and analyzed for dissolved inorganic P (PO4P) and total dissolved phosphorus (TDP). Inorganic phosphorus concentrations in the soil solution were measured photometrically with a continuous flow analyzer (for samples collected until spring 2004: CFA SAN++, Skalar [Breda, The Netherlands]; for samples collected later: CFA Autoanalyzer [Bran&Luebbe, Norderstedt, Germany]). Ammonium molybdate catalyzed by antimony tartrate reacts in an acidic medium with phosphate and forms a phospho-molybdic acid complex. Ascorbic acid reduces this complex to an intensely blue-colored complex. Total dissolved P in soil solution was analyzed by irradiation with UV and oxidation with K2S2O8 followed by reaction with ammonium molybdate (Skalar catnr. 503-553w/r). As the molybdic complex forms under strongly acidic conditions, we could not exclude the hydrolysis of labile organic P compounds in our samples. Furthermore, the molybdate reaction is not sensitive for condensed phosphates. The detection limits of both TDP and PO4P were 0.02 mg P l-1 (CFA, Skalar) and 0.04 mg P l-1 (Autoanalyzer, Bran&Luebbe). Dissolved organic P (DOP) in soil solution was calculated as the difference between TDP and PO4P. In a low number of samples, TDP was equal to or smaller than PO4P; in these cases, DOP was assumed to be zero.

Dissolved nitrogen in soil solution of the Jena Experiment (Main Experiment, year 2004)

This data set contains measurements of dissolved nitrogen (total dissolved nitrogen: TDN, dissolved organic nitrogen: DON, dissolved ammonium: NH4+, and dissolved nitrate: NO3-) in samples of soil water collected from the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. In April 2002 glass suction plates with a diameter of 12 cm, 1 cm thickness and a pore size of 1-1.6 µm (UMS GmbH, Munich, Germany) were installed in depths of 10, 20, 30 and 60 cm to collect soil solution. The sampling bottles were continuously evacuated to a negative pressure between 50 and 350 mbar, such that the suction pressure was about 50 mbar above the actual soil water tension. Thus, only the soil leachate was collected. Cumulative soil solution was sampled biweekly and analyzed for nitrate (NO3-) and ammonium (NH4+) concentrations with a continuous flow analyzer (CFA, Skalar, Breda, The Netherlands). Nitrate was analyzed photometrically after reduction to NO2- and reaction with sulfanilamide and naphthylethylenediamine-dihydrochloride to an azo-dye. Our NO3- concentrations contained an unknown contribution of NO2- that is expected to be small. Simultaneously to the NO3- analysis, NH4+ was determined photometrically as 5-aminosalicylate after a modified Berthelot reaction. The detection limits of NO3- and NH4+ were 0.02 and 0.03 mg N L-1, respectively. Total dissolved N in soil solution was analyzed by oxidation with K2S2O8 followed by reduction to NO2- as described above for NO3-. Dissolved organic N (DON) concentrations in soil solution were calculated as the difference between TDN and the sum of mineral N (NO3- + NH4+). In 5% of the samples, TDN was equal to or smaller than mineral N. In these cases, DON was assumed to be zero.

Seasonally aggregated values of dissolved inorganic phosphorus in soil solution of the Jena Experiment (Main Experiment, year 2004)

This data set contains measurements of inorganic phosphorus in samples of soil solution collected in 2004 from the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below) that have been aggregated to seasonal values. In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. Glass suction plates with a diameter of 12 cm, 1 cm thickness and a pore size of 1-1.6 µm (UMS GmbH, Munich, Germany) were installed in April 2002 in depths of 10, 20, 30 and 60 cm to collect soil solution. Manual soil matric potential measurements were used to regulate the vacuum system. Manual soil matric potential measurements were used to regulate the vacuum system. The sampling bottles were continuously evacuated to a negative pressure between 50 and 350 mbar, such that the suction pressure was about 50 mbar above the actual soil water tension. Thus, only the soil leachate was collected. Cumulative soil solution was sampled biweekly and analyzed for dissolved inorganic P (PO4P). Here volume-weighted mean values are provided as aggregated seasonal values (spring = March to May, summer = June to August, fall = September to November, winter = December to February) for 2004 in spring, fall, and winter. To calculate these values, the sampled volume of soil solution is used as weight for P concentrations of the respective sampling date. Inorganic phosphorus concentrations in the soil solution were measured photometrically with a continuous flow analyzer (for samples collected until spring 2004: CFA SAN++, Skalar [Breda, The Netherlands]; for samples collected later: CFA Autoanalyzer [Bran&Luebbe, Norderstedt, Germany]). Ammonium molybdate catalyzed by antimony tartrate reacts in an acidic medium with phosphate and forms a phospho-molybdic acid complex. Ascorbic acid reduces this complex to an intensely blue-colored complex. As the molybdic complex forms under strongly acidic conditions, we could not exclude the hydrolysis of labile organic P compounds in our samples. Furthermore, the molybdate reaction is not sensitive for condensed phosphates. The detection limits of both TDP and PO4P were 0.02 mg P l-1 (CFA, Skalar) and 0.04 mg P l-1 (Autoanalyzer, Bran&Luebbe).

Fig. 6: Firn temperatures at Filchner Station

During the German Antarctic Expedition 1979/80 to the Filchner/Ronne Ice Shelf glaciclogical investigations were carried out at the Filchner station, mainly for determination of snow accumulation. Also meteorological measurements and observations were part of the programme. Similar glaciological work on a smaller seale was done at Atka Ice Port. The report presents the results of the glaciological investigations, In an introductory part some basie eonsiderations, definitions and methods are discussed briefly, completed by a few hints on practical snow pit work. Density measurements, stratigraphie analyses with aid of a throughlight profile and hardness determination are described in more detail. The analyses of the Fi1chner snow profile of January 1980 with suplements of January 1981 reveal 7 complete budget years for 370 cm depth or 53 cm snow accumulation/year, With a mean density of 0.377 g/cm**2 this value corresponds to a water equivalent of 20 g/cm**2. At the Atka site 3 budget years were determined within 210 cm depth of the snow pit or 70 cm of mean annual accumulaticn. With the rat her higher mean density of 0.438 g/cm**2 for this site the corresponding water equivalent amounts here to 30 g/cm**2, In addition to the snow pit studies shallow drillings were made at Filchner Station to a depth of 10.8 m with 128 sampies taken from the core and at Atka to 12.1 m depth with 114 sampies. At the Institute for Radiohydrometry, Neuherberg, the sarnples were analysed with respect to the stable isotope ratios 2H/1H and 18O/16O related to V-SMOW. Also the tritium content was measured. The vartiations of the stable isotope ratios with the depth show quasiperiodic fluctuations which are regarded as annual cycles of the accumulation rate. Counting of the pronounced peaks leads to 20 years for the Filchner core, giving 55 cm annual accumulation or 22 g/cm**2 water equivalent respectively. At Atka 15 years could be found corresponding to 75 cm annual accumulation or 32 g/cm**2 of water. The range of varianon and the mean value of the stable isotope ratios are significantly different for both sites, the agreement of the isotopic anal yses with the pit studies is rat her satisfactory. The tritium content shows for the Filchner core two pronounced peaks which can be related to the 1965 and 1966 winter seasons according to former studies at the South Pole station. These time estimates are consistent with the time scale derived fr orn the stable isotopes distribution. At the Atka site no similar effeet in the tritium values was found. In the drill holes firn temperatures were measured carefully. The 10 m value was determined to be -25 °C at Filchner Station and -17 °C at the Atka position.

Dissolved organic carbon in soil solution of the Jena Experiment (Main Experiment, year 2003)

This data set contains measurements of dissolved organic carbon in samples of soil water collected from the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. In April 2002 glass suction plates with a diameter of 12 cm, 1 cm thickness and a pore size of 1-1.6 mm (UMS GmbH, Munich, Germany) were installed in depths of 10, 20, 30 and 60 cm to collect soil solution. The sampling bottles were continuously evacuated to a negative pressure between 50 and 350 mbar, such that the suction pressure was about 50 mbar above the actual soil water tension. Thus, only the soil leachate was collected. Cumulative soil solution was sampled biweekly and analyzed for dissolved organic carbon concentration by a high TOC elemental analyzer (Elementar Analysensysteme GmbH, Hanau, Germany). Samples were analyzed as soon as possible and stored at 4°C if necessary. Often in summer, no free soil solution was available for collection, especially in the upper soil layers. Annual mean values of measured biweekly concentrations of dissolved organic carbon are provided.