(Figure 2) Mean discharge per day (total and baseflow part) of the San Francisco River and daily precipitation at station ECPL (Planta), in 2007

We investigated controls on the water chemistry of a South Ecuadorian cloud forest catchment which is partly pristine, and partly converted to extensive pasture. From April 2007 to May 2008 water samples were taken weekly to biweekly at nine different subcatchments, and were screened for differences in electric conductivity, pH, anion, as well as element composition. A principal component analysis was conducted to reduce dimensionality of the data set and define major factors explaining variation in the data. Three main factors were isolated by a subset of 10 elements (Ca2+, Ce, Gd, K+, Mg2+, Na+, Nd, Rb, Sr, Y), explaining around 90% of the data variation. Land-use was the major factor controlling and changing water chemistry of the subcatchments. A second factor was associated with the concentration of rare earth elements in water, presumably highlighting other anthropogenic influences such as gravel excavation or road construction. Around 12% of the variation was explained by the third component, which was defined by the occurrence of Rb and K and represents the influence of vegetation dynamics on element accumulation and wash-out. Comparison of base- and fast flow concentrations led to the assumption that a significant portion of soil water from around 30 cm depth contributes to storm flow, as revealed by increased rare earth element concentrations in fast flow samples. Our findings demonstrate the utility of multi-tracer principal component analysis to study tropical headwater streams, and emphasize the need for effective land management in cloud forest catchments.

(Tables 1-3) Water chemistry of cloud forest streams at baseflow conditions, Rio San Francisco, Ecuador

We investigated controls on the water chemistry of a South Ecuadorian cloud forest catchment which is partly pristine, and partly converted to extensive pasture. From April 2007 to May 2008 water samples were taken weekly to biweekly at nine different subcatchments, and were screened for differences in electric conductivity, pH, anion, as well as element composition. A principal component analysis was conducted to reduce dimensionality of the data set and define major factors explaining variation in the data. Three main factors were isolated by a subset of 10 elements (Ca2+, Ce, Gd, K+, Mg2+, Na+, Nd, Rb, Sr, Y), explaining around 90% of the data variation. Land-use was the major factor controlling and changing water chemistry of the subcatchments. A second factor was associated with the concentration of rare earth elements in water, presumably highlighting other anthropogenic influences such as gravel excavation or road construction. Around 12% of the variation was explained by the third component, which was defined by the occurrence of Rb and K and represents the influence of vegetation dynamics on element accumulation and wash-out. Comparison of base- and fast flow concentrations led to the assumption that a significant portion of soil water from around 30 cm depth contributes to storm flow, as revealed by increased rare earth element concentrations in fast flow samples. Our findings demonstrate the utility of multi-tracer principal component analysis to study tropical headwater streams, and emphasize the need for effective land management in cloud forest catchments.

Atmospheric electric measurement in the troposphere and stratosphere on the Atlantic Ocean during 1965 and 1969

One main point of the air electric investigations at the atlantic 1965 and 1969 was the record of the potential gradient in the troposphere with free and captive balloon ascents. The course of the field vs. altitude above the sea differs from that over land. A remarkable enlargement of the field strength occurs at the altitude of the passat inversion. The electric voltage between ionosphere and earth could be obtained by integrating the potential gradient over the altitude. Such computations have been made by balloon ascents simultaneous over the ocean and at Weissenau (South Germany), From 15 simultaneous measurements the average value of the potential of the ionosphere over the ocean is 214 kV and over South Germany 216 kV, that means very close together. Because of the small differences also between the single values it can be concluded that in generally the ionosphere potential has an equal value over these both places at one moment. From the potential of the ionosphere VI, the field strength E0 and the conductivity lamda o, both measured at the sea surface, the columnar resistance R could be derived to 2.4 x 10**17 Ohm x m**2. By correlation of the single values of the ionosphere potential with the potential gradient measured simultaneously at the surface of the sea a linear proportional relationship exists; it follows from this result, that R is nearly constant. The mean value of the air-earth current density over the ocean could be calculated by using the measured values of the small ion density with respect to the electrode effect prooved at the equator station. The current density was only 0.9 x 10**-12 A/m**2, which means, a three and a half times smaller value than estimated by Carnegie and accepted up to now. Therefore it seems to be necessary to correct the former calculations of the global current balance.

(Table 1) Dissolved organic carbon, water temperature and conductivity in three subarctic ponds near Kilpisjärvi, North Finland

Daphnia was collected from five subarctic ponds which differed greatly in their DOC contents and, consequently, their underwater light (UV) climates. Irrespective of which Daphnia species was present, and contrary to expectations, the ponds with the lowest DOC concentrations (highest UV radiation levels) contained Daphnia with the highest eicosapentaenoic acid (EPA) concentrations. In addition, EPA concentrations in these Daphnia generally decreased in concert with seasonally increasing DOC concentrations. Daphnia from three of the ponds was also tested for its tolerance to solar ultraviolet radiation (UVR) with respect to survival. Daphnia pulex from the clear water pond showed, by far, the best UV-tolerance, followed by D. longispina from the moderately humic and D. longispina from the very humic pond. In addition, we measured sublethal parameters related to UV-damage such as the degree to which the gut of Daphnia appeared green (as a measure of their ability to digest algae), and whether their guts appeared damaged. We developed a simple, noninvasive scoring system to quantify the proportion of the gut in which digestive processes were presumably active. This method allowed repeated measurement of the same animals over the course of the experiment. We demonstrated, for the first time, that sublethal damage of the gut precedes mortality caused by exposure to UVR. In a parallel set of experiments we fed UV-exposed and non-exposed algae to UV-exposed and non-exposed daphnids. UVR pretreatment of algae enhanced the negative effects of exposure to natural solar UV-irradiation in Daphnia. These UV-related effects were generally not specific to the species of Daphnia.

Thermal conductivity at DSDP Leg 60 Holes

A total of 1547 thermal conductivity values were determined by both the NP (needle probe method) and the QTM (quick thermal conductivity meter) on 1319 samples recovered during DSDP Leg 60. The NP method is primarily for the measurement of soft sedimentary samples, and the result is free from the effect of porewater evaporation. Measurement by the QTM method is faster and is applicable to all types of samples-namely, sediments (soft, semilithified, and lithified) and basement rocks. Data from the deep holes at Sites 453, 458, and 459 show that the thermal conductivity increases with depth, the rate of increase ranging from (0.18 mcal/cm s °C)/100 m at Site 459 to (0.72 mcal/cm s °C)/100 m at Site 456. A positive correlation between the sedimentary accumulation rate and the rate of thermal conductivity increase with depth indicates that both compaction and lithification are important factors. Drilled pillow basalts show nearly uniform thermal conductivity. At She 454 the thermal conductivity of one basaltic flow unit was higher near the center of the unit and lower toward the margin, reflecting variable vesicularity. Hydrothermally altered basalts at Site 456 showed higher thermal conductivity than fresh basalt because secondary calcite, quartz, and pyrite are generally more thermally conductive than fresh basalt. The average thermal conductivity in the top 50 meters of sediments correlates inversely with water depth because of dissolution of calcite, a mineral with high thermal conductivity, from the sediments as the water depth exceeds the lysocline and the carbonate compensation depth. Differences between the Mariana Trench data and the Mariana Basin and Trough data may reflect different abundances of terrigenous material in the sediment. There are remarkable correlations between thermal conductivity and other physical properties. The relationship between thermal conductivity and compressional wave velocity can be used to infer the ocean crustal thermal conductivity from the seismic velocity structure.

(Table 2) Atmospheric electric measurements during the Atlantic Expedition 1965 of METEOR

During the Atlantic expedition potential gradient, small ion density and space charge density have been recorded. Laborious efforts have been taken for receiving an exact estimation of the reduction factor for the field measurements. The mean value of the potential gradient on the free Atlantic Ocean was 105 V/m. The mean daily course is in very good agreement with the results of the Carnegie Institution. Even records taken on individual days near the quator show this course. For the first time it has been attempted to correlate the potential gradient at sea and the voltage between ionosphere and earth measured over land. A narrow relation has been found in 10 cases of balloon ascents with radiosondes. A further remarkable result is, that the short periodical fluctuations of the air electric field at sea with periods of 2 to 20 minutes have amplitudes of the magnitude of the mean field strength and exist all over the oceans. Recordings of the space charge density show, that positively charged air parcels drift in the first hectometer of the air near the sea surface and produce the fluctuation of the potential gradient. A period analysis did not indicate a recognizable relation to the wind velocity up to now, although an effect of air turbulence must be involved. The concentration of small ions also has been measured occasionally. With this and mean values of the potential gradient the air earth curent density has been computed. With n+ = 310 cm**-3, n- = 220 cm**-3 the air conductivity would be Lambda = 1,14 * 10**-14 Ohm**-1 m**-1. These values are smaller than values of other authors by a factor of 2 or 3. Therefore the computed air earth current density is also smaller. The discrepancy could not be explained yet.

Susceptibility, conductivity and porosity along a GEM-SHARK profile

The coastal systems, are often subjected to high anthropogenic pressure, which makes it necessary to develop new techniques to assess the environmental impacts caused by such human activity. This paper presents the first results obtained during the development and implementation of a new equipment of submarine geophysics survey oriented to integrated coastal zone management (ICZM). It is based on the drag of a submarine in contact with the sea-bottom. The submarine is equipped with an electromagnetic sensor which allows the measurement of the magnetic susceptibility and electrical conductivity of the surface sediments continuously and to a depth of sediment of 40 cm. This system, once improved, will allow us to obtain valuable information for monitoring the environmental quality of coastal areas.

CTD measurement at station GeoB12761-1 in the area of the Coral Patch seamount (NE Atlantic)

To gain information on the physical parameters of the water masses in the area of the Coral Patch seamount (NE Atlantic), one CTD measurement was accomplished in close vicinity to the seamount (station GeoB 12761: 34°31.210'N, 11°08.510'W, 4430m water depth). CTD measurement were conducted during R/V PELAGIA expedition 64PE284 in spring 2008 (Hebbeln and cruise participants, 2008, urn:nbn:de:gbv:46-ep000103738). The CTD measurement of the water column down to a maximum water depth of 2500m was conducted using a SEABIRD "SBE 9 plus" underwater unit and a SEABIRD "SBE 11 plus" deck unit. The vertical profile over the water column provided standard data for conductivity, temperature and pressure. Additionally, the CTD was equipped with sensors for optical backscatter (turbidity), fluorescence (chlorophyll) and dissolved oxygen. Conductivity and temperature data were used to compute salinity.