Spurenelementgehalt der Saale – ein Vergleich der Analysenergebnisse aus den Jahren 1950 und 1996

Thirty four elements dissolved in water and 33 elements bound in particulate matter were analysed in the small river Saale (Thuringia, Germany, MQ=23 m³/s) in 1996 and the results were compared with those obtained in 1950 (44 elements). Monthly sampling was used to eliminate fluctuations caused by seasons and weather. Comparison of the element contents of a river over a 40-year-time span provides interesting insight into the anthropogenic change in the catchment area of the river with regard to „global change”.Without taking into consideration systematic errors, the analysed elements can be divided into three groups:

(a) Elements whose average annual analytical values in 1996 were lower by >50% than those in 1950: Al, As, Ba, Fe, Pb, Zn (in solution), and As, B, Cr, Li, Mn, Pb, Se, Sn, U (suspended).

(b) Elements whose average annual analytical values in 1996 are in the range of those in 1950, i.e., are within 50–150%: Ca, Co, Cr, F, K, Li, Mn, Na, Si, Sr, Ti, U (in solution), and Hg, Cr, Cu, Sc, Sr, Ti, Zn (suspended).

(c) Elements whose average annual analytical values in 1996 were higher by >150% than those in 1950: B, Cd, Mg, Ni, Rb, Sc (in solution), and Ba, Ni, P, Zr (suspended).

The increases in the element concentrations are not only caused by wastewater. Acid rain and fertilizer affect the pH and the electrolyte status of soils and cause mobilization of elements. This can be a reason for the increase in the alkalies and alkaline earth. For most elements are higher and lower values were found in 1996 and are only partly caused by systematic errors in the methods used in 1950. Taking into consideration of the natural fluctuations some element values 1996 equal or are lower (Tabelle 10 and 12). Because of the 100–200% RSD (12 samples per year), it is almost impossible to decide whether the deviations are due to analytical errors or to natural causes. The bound part of the elements is considered to be the suspended portion (seston=particulate matter) and, for one and the same element the suspended portion is equal or higher than the portion in solution. In the case of natural plant stock in the catchment area, the erosion is small. The increase in farming caused a higher soil erosion in the river. Storm precipitation causes short-term (1–2 h) peaks in the suspended load with values 2–3 orders of magnitude higher. In the case of monthly sampling, such peaks are unlikely to be detected. This produces values of suspended loads that tend to be too small. Increases of the bounded elements together with the elements in solution cause increases of eutrophication in the ocean.The contents of elements transported in solution and in particulate form in the river Saale are not equal to the element contents of the upper earth crust. Weathering and the fluviatil element transport cause a fractionation of the thallassophile (enriched in ocean) and therraphile elements (enriched in continents). Thallassophile elements are Mg, Ca, Sr, B, As, U, Sn, Cd, Zn, Se (transported in solution) and U, Cr, Li, B, Ba, Se, Mn, Cu, P, Sn, Cd, Rb, Pb, S and Zn (transported in seston) and therraphile elements are Cs, Co, Sc, Ni, Ti, Fe, Al, and K. As a result a fractionation in thallassophile and therraphile elements results and influences the geochemical cycles like magmatic differentiations.     

Ein Beitrag zur Bestimmung von partikulärem organischen Kohlenstoff in Wasserproben

The method after Strickland and Parsons is modified for fresh water as follows: filtration on glass-fibre paper, oxidation with K₂Cr₂O₇ in cone. H₂SO₄ for 2 h at 130 °C, dilution to 2.5 times the volume by aqua dest., centrifuging-off of the turbidity and extinction measurement at 445 nm against the blank value, the sample solution being balanced to the transmission of 100% (extinction = 0). Here, the following calibration line holds for the concentration C and the quantity of oxidation solution Ox: C = E_1cmc · 0.162 · Ox, C in mg filter. The oxidation solution contains 4.8 g K₂Cr₂O₇ as dissolved in 20 ml aqua dest. and made up with conc. H₂SO₄ to 11. With 5 ml of this solution one is able to determine 0.05 … 1 mg C/filter. Calibration is performed with 125 mg/l glucose solution. Comparative investigations have shown a good agreement with elementary-analytically obtained measured values. The occurring errors have been determined mainly by sampling. In the range of very small values we have to take into account a blank value of the filter due to the adsorption of dissolved organic substances on the filter.     

A three-dimensional discontinuous Galerkin model applied to the baroclinic simulation of Corpus Christi Bay

In this work, we present results of a numerical study of Corpus Christi Bay, Texas and surrounding regions and compare simulated model results to recorded data. The validation data for the year 2000 include the water elevation, velocity, and salinity at selected locations. The baroclinic computations were performed using the University of Texas Bays and Estuaries 3D (UTBEST3D) simulator based on a discontinuous Galerkin finite element method for unstructured prismatic meshes. We also detail some recent advances in the modeling capabilities of UTBEST3D, such as a novel turbulence scheme and the support for local vertical discretization on parts of the computational domain. All runs were conducted on parallel clusters; an evaluation of parallel performance of UTBEST3D is included.     

Fidelity of the integrated kinetic energy factor as an indicator of storm surge impacts

Natural Hazards - After the devastating hurricane season of 2005, shortcomings with the Saffir–Simpson Hurricane Scale’s (SSHS) ability to characterize a tropical cyclone’s...     

Kohlenstoffumsatz durch Respiration in der Ilm (Thüringen,Deutschland)

Carbon Turnover by Respiration in the River Ilm (Thuringia, Germany) In the river Ilm, the organic carbon content of water and sediments was analyzed inclusively the C turnover by CO₂-respiration with IR-measurement. A comparison of the unpolluted rhithral (headwater) with the polluted epipotamal (lower course) gives downstream an increase of DOC and CO₂-respiration of 50...100 mg/(m³ · h) C. In the headwater region, the respiration of the sediments is dominant, in the underflow the respiration of the water. Permeable sand and gravel beds are important for the degradation of the organic load. The sediments of the river are covered with a biofilm of 1...2 g/m² C_org. A turnover of the C_org. content from 20...400 days is calculated by the respiration measurements.     

Biosilicium (BSi) in Sedimenten Mecklenburger Seen (Deutschland) und das Calciumcarbonat-Biosilicium-Verhältnis als Trophie- und Wasserstandsindikator Biogenic Silica (BSi) in Sediments of the Mecklenburgian Lake District (Germany) and the Calcite-Silica-Relation as Indicator for Trophy and Water Level

The BSi content has been investigated in the surface sediments of lakes of different trophic state in the Mecklenburgian Lake District. The BSi content differs between 1 to 1000 mg BSi/g dry matter. High values were found in deep eutrophic lakes. Litoral sediments and shallow eutrophic lakes have lower contents. BSi content was found to be correlated with lake morphometry, depth, trophic level, sediment composition and especially with calcite. With the CaCO₃/BSi-value, 3 groups of lakes can be characterized:

• CaCO₃/BSi = 0 oligotrophic and dystrophic lakes
• CaCO₃/BSi ≤ 10 mesotrophic and eutrophic deep lakes
• CaCO₃/BSi ≤ 10 eutrophic shallow lakes

The results from the recent sediments have been compared with those from older sediments. Using the CaCO₃/BSi-value, climatic change, trophic state, and sea level can be detected.