Assessment of Water Quality in the Elbe River at Low Water Conditions Based on Factor Analysis

An assessment of water quality measurements during a long‐lasting low water period in the Elbe River is presented. Weekly samples were taken from May to December 2003 at a sampling site in the middle part of the Elbe River. For multivariate data analysis, 34 parameters of 46 samplings were considered. As a result of this analysis, 78% of the variance of the data set is explained by five factors. They can be assigned to the following latent variables: season (37.5%) > tributaries (12.7%) > re‐suspension (10.4%) > discharge (9.4%) > complexation (8.5%). For the investigated sampling site, two key processes were identified as dominating factors on the water quality during low water conditions. First, seasonal phytoplankton development caused changes in redox conditions with consequences for re‐solution of pollutants from sediments. Second, tributaries have a higher impact on the main stream, due to changes in mixing processes. Therefore, in addition to flood investigations, monitoring strategies, and management plans should be developed in order to survey changes in water quality during low water conditions.     

The dynamics of phytoplankton, bacteria and heterotrophic flagellates at two Banks near Magdeburg in the River Elbe (Germany)

The main objectives of this study were to describe the seasonal standing stock dynamics of phytoplankton, bacterioplankton and heterotrophic flagellates in the highly eutrophic River Elbe (Germany), and to compare the seasonal patterns observed with other streams. Emphasis was placed on examining and assessing abiotic and biotic controlling factors influencing the structure and dynamics of the riverine plankton. All the physico-chemical and biological parameters determined were within the range or somewhat higher (in the case of phytoplankton abundance and biomass) than reported for other large streams. The underwater light conditions resulting from atypically short phytoplankton growth periods of about 6 months per year and the low phytoplankton carbon to chl a ratio of 23 were identified as a major limiting factor for phytoplankton development in the River Elbe. The seasonal distribution pattern of bacterioplankton indicated probable tight trophodynamical coupling both with phytoplankton and with heterotrophic flagellates, whereas heterotrophic flagellates showed a more trophic link with bacterial densities. Although approximately constant DOC and DON levels throughout the year sustained bacterial growth rates, during the phytoplankton growing season an increase of bacterial standing stocks was observed. Although the left-bank sampling site of the Elbe is strongly influenced by the tributaries Mulde and Saale containing higher concentrations of chloride, nitrogen nutrients, heavy metals and organic pollutants, no clear differences were observed between the two sides of the river concerning the biological parameters measured. Possible reasons and the slightly higher phytoplankton abundance and diversity at the right bank are discussed.     

Chlorinated Hydrocarbons in River Sediments of Mecklenburg-West Pomerania – Patterns,Levels, and Regional Distribution

As a first contribution to the assessment of organic microcontaminants in rivers of Mecklenburg-West Pomerania, the patterns, levels, and regional distribution of chlorinated hydrocarbons (PCB, HCH, DDT, and HCB) in river sediments were investigated. The sediment sampling was carried out at selected stations in rivers of Mecklenburg-West Pomerania (Peene, Uecker, Randow, Zarow, Ziese, Warnow, Elde, and Elbe) in August/September 1996. The chlorinated hydrocarbons were determined by GC/ECD following ultrasonic extraction. Generally, the contents of chlorinated hydrocarbons in the river Warnow and rivers of West Pomerania were at a low level, up to 15 ng/g (given for TOC). In Elde sediments, three to ten times higher contents of CHC were found, due to a higher degree of industrialization in the catchment area. Much higher CHC contents up to a factor of 100 higher than in the river Warnow occurred in Elbe sediments between the towns Dömitz and Boizenburg. A comparison of the CHC contents in river sediments of Mecklenburg-West Pomerania with those in Elbe sediments reflects the difference between rivers with a large and highly industrialized catchment area and much smaller rivers, only affected by agriculture and municipal sewages. The contribution from rivers of Mecklenburg-West Pomerania to the riverine input of organic microcontaminants into the innercoastal waters (boddens, hafts, and sounds) and the adjacent Baltic Sea seems to be low.     

Coping with floods: preparedness,response and recovery of flood-affected residents in Germany in 2002

Abstract

In August 2002, a severe flood event occurred in Central Europe. In the following year, a poll was performed in Germany in which 1697 private households were randomly selected from three regions: (a) the River Elbe area, (b) the Elbe tributaries in Saxony and Saxony-Anhalt, and (c) the Bavarian Danube catchment. Residents were interviewed about flood characteristics, early warning, damage, recovery, preparedness and previously experienced floods. Preparedness, response, financial losses and recovery differed in the three regions under study. This could be attributed mainly to differences in flood experience and flood impact. Knowledge about self-protection, residents' home-ownership and household size influenced the extent and type of private precautions taken, as well as the residents' ability to perform mitigation measures. To further improve preparedness and response during future flood events, flood warnings should include more information about possible protection measures. In addition, different information leaflets with flood mitigation options for specific groups of people, e.g. tenants, homeowners, elderly people or young families, should be developed.     

Trends und Verteilungsmuster in der Schadstoffbelastung von Sedimenten aus östlichen Bundeswasserstraßen

Trends and Patterns in the Contamination of Sediments from Federal Waterways in Eastern Germany The following study presents a concept for a sediment pollution cadastre and the results of systematic investigations of sediment contamination for eight toxic heavy metals and arsenic, as well as for eight classes of organic priority pollutants in all together 21 reaches in the Elbe and Oder waterway systems. Based on data from the years 1991 to 1995; multivariate statistical evaluations were carried out to identify local and temporal trends in the overall contamination. It was possible to differentiate between more non-point and point sources of sediment contamination. Because of the closure of substantial parts of the industry in Eastern Germany and by common sanitation efforts of both the German and the Czech sides since 1990, the situation in the Elbe river system with respect to the heavy metals has improved markedly. For the Oder river system, a comparable trend does not exist yet, and the sediment contamination by heavy metals is stagnant there. As a consequence, the pollution situation in both German parts of the rivers has become similar except for mercury and arsenic. Regarding organic pollutants, the picture is quite different. With the exception of PAHs, Oder sediments are contaminated by organics only to a lower extent and compare better with the ones from unpolluted waters found in parts of Brandenburg and Mecklenburg-Western Pomerania than with those of rivers Elbe, Mulde, and Saale with its tributaries. On the one hand, organic pollution generally also decreased since 1991 in these rivers. On the other hand, due to continuing inputs from plants in the Czech Republic and from old contaminated sites, both in Czechia and Germany, a decreasing trend is not significant or cannot be found at all for such pollutants as HCB, PCBs, or PAHs. The general trends are discussed in detail, e.g., by comparison with quality targets for sediments and suspended matter, and illustrated at the example of individual contaminants being typical for the overall situation.     

Mitochondrial DNA provides evidence of a double origin for the stone crayfish Austropotamobius torrentium in the Elbe basin

The stone crayfish Austropotamobius torrentium is the smallest native European crayfish, restricted to central and southeast Europe. Northeast boundary of its range is located within the Elbe basin but considerable uncertainties existed regarding its status in this area. Until recently, known stone crayfish populations in the Elbe basin were very scattered and human translocations have been implicated in such distribution pattern. Discoveries of additional populations in the Czech Republic and Saxony (east Germany) nevertheless suggest that the species may have been more widespread there. We provide data on genetic variation (based on 181 sequences of the mitochondrial COI gene) of 20 representative populations from the Elbe basin (both from the Czech Republic and Saxony). We tested whether the haplotype variation is consistent with a scenario of natural dispersal or whether long-range transport has been involved. All analysed individuals from the easternmost, geographically isolated Czech stone crayfish population carried a haplotype previously recorded only in Slovenia and its vicinity; it is therefore likely that such population has been introduced by humans. In contrast, all remaining studied populations were dominated by a haplotype widespread in adjacent regions of species’ distribution in Germany, and additional haplotypes differing by point mutations were occasionally detected. This is consistent with a scenario of a postglacial colonization from Bavaria (southeast Germany). Our study provides evidence for a double origin of stone crayfish populations in the upper Elbe basin, with both natural and anthropogenic factors likely affecting the present diversity and distribution of this species.     

Application of Ultrafiltration for Characterization of the DOC of Elbe River Water

An ultrafiltration methodology and the results of its application on Elbe river water are presented. Compared with other methods, Ultrafiltration allows fractionation of the molecular-weight fractions of DOC for higher volumes of solution in a shorter time. To characterize the molecular-weight fractions, the sum parameter DOC (β(DOC)) and the absorption coefficient at 254 nm a₂₅₄ were measured, together with determination of a₂₅₄/ β(DOC) for further characterization of the DOC fractions and to provide information about changes in parts of the UV-active substances of the total dissolved organic material. In the period May 1992 to November 1994, the DOC molecular-weight composition of 65 samples of Elbe river water were determined. At two sampling locations (Torgau-East and Meissen), the DOC content β(DOC) was approximately 6 mg/L. The high-molecular weight fraction (> 10000 g/mol) gave a mean of 13% of the total DOC content β₀(DOC). The measurements showed that the molecular composition of DOC in the Elbe does not greatly differ. There was also no clear seasonal influence on the molecular-weight composition of the DOC content. During the period of investigation, the percentage part of β(DOC) and a₂₅₄/β(DOC) of the high-molecular weight fraction of the total dissolved organic material increased, while the a₂₅₄/β(DOC) values of the middle molecular-weight fraction remained fairly constant. The dependence of β(DOC) on discharge of the Elbe river is low. Changes in molecularweight composition of DOC were only observed during the steepest increase in river discharge during a flood event, with another spectrum of substances responsible for the increase in β(DOC) when compared with the β(DOC) for low or middle water level.     

Assessment of Water Quality in the Elbe River at Flood Water Conditions Based on Cluster Analysis,Principle Components Analysis,and Source Apportionment

An assessment of water quality measurements during a spring flood in the Elbe River is presented. Daily samples were taken at a site in the middle Elbe, which is part of the network of the International Commission for the Protection of the Elbe River (IKSE/MKOL). Cluster analysis (CA), principal components analysis (PCA), and source apportionment (APCS apportioning) were used to assess the flood‐dependent matter transport. As a result, three main components could be extracted as important to the matter transport in the Elbe River basin during flood events: (i) re‐suspended contaminated sediments, which led to temporarily increased concentrations of suspended matter and of most of the investigated heavy metals; (ii) water discharge related concentrations of pedogenic dissolved organic matter (DOM) as well as preliminary diluted concentrations of uranium and chloride, parameters with stable pollution background in the river basin; and (iii) abandoned mines, i.e., their dewatering systems, with particular influence on nickel, manganese, and zinc concentrations.     

Reaction of fish larvae to the water of the River Elbe at Hamburg harbour

The River Elbe is one of the biggest streams carrying pollutants of all kinds into the North Sea. However, investigations of direct effects of the Elbe water on river life are not numerous. Early life stages of common whitefish and carp were reared under comparable conditions in water of the River Elbe, and in tap water, respectively. No direct effects on the viability of the fry could be found by observing mortality and growth rates in both treatments. Whitefish larvae were severely infested by parasitic ciliates which were able to build up a dense population in the river water. In these experiments life conditions for the protozoa seemed to be much better than in tap water. Mortality rates of early larvae of common whitefish were lower in the Elbe water than in tap water. Mortality, growth rate and starvation resistance of carp fry was equal in river and tap water.     

Shifts in the Processes of Oxygen and Nutrient Balances in the River Elbe since the Transformation of the Economic Structure

The reduction of pollution in the river Elbe since 1990 has resulted in changes in the processes taking place in the river. The heterotrophic degradation which dominated until 1990 was accompanied by a lack of oxygen, floating masses of sewage fungi, and sludge formation in the areas of still water. Since the early 1990s, autotrophic processes have come to dominate, with an increase in pH fluctuations and the oxygen production potential, but evidently not the chlorophyll level during the growing season. The degradable organic pollution of the Elbe is determined by algae production. The high levels of ammonium previously encountered in the Elbe were attributable to not only dischargers but also in particular the lack of oxygen in the water. Via heterotrophic nitrate assimilation, nitrate served as an oxygen reserve, resulting in high levels of nitrite. At present, when the oxygen contents are sufficient, the concentration reductions of nitrate and nitrite along the reach of the Elbe are approximately parallel, which in view of the lack of ammonium indicates the denitrification of microzones low in oxygen. The relative proportion of structurally bound substance turnover will become increasingly important for the Elbeπs material budget.     

Formaldehyde in the Elbe Estuary: Distribution and Processes

From 1989 to 1992, the concentration of formaldehyde was measured along the Elbe estuary as well as at anchor stations. In mesocosm experiments, the turnover of formaldehyde could be investigated avoiding the variability caused by tidal advection of different water bodies. Formaldehyde concentrations in the Elbe estuary ranged from 0.5… 180 μg/L. As sources, a release by algae and microbial processes were identified. Three areas with different dominance of formaldehyde turnover processes were found in the estuary. In the limnic part of the estuary, a release of formaldehyde by algae was dominant. In the mixohaline zone and the turbidity maximum, bacterial degradation of organic matter increased the formaldehyde concentration. In the mouth of the estuary, the adjacent Wadden sea areas influenced the concentration due to formaldehyde-rich runoff from the tidal mud flats. In the other parts of the estuary, a fast degradation of formaldehyde kept the formaldehyde concentration at a low level. In sediment cores from the Elbe and a mesocosm, the formaldehyde concentrations were in the same range as in the water column. Mesocosms with and without sediment showed no significant differences in concentration levels which were similar to those measured in the Elbe at the same time. During the investigated period, no anthropogenic impacts of formaldehyde into the Elbe estuary could be detected.     

渭河干流与其秦岭北麓典型支流浮游动物群落结构及影响因素

浮游动物作为食物链中重要的初级消费者,其群落结构特征是水生态系统健康评价的重要指标之一.本研究于2017年秋季和2018年春季对渭河干流及秦岭北麓五条典型支流开展了系统的水环境及浮游动物群落调查.结果表明,渭河干流营养盐浓度整体高于秦岭北麓支流,干流浊度远高于支流.两次调查共鉴定出浮游动物种类数136种(原生动物65种,轮虫44种,枝角类15种,桡足类12种),其中2017年秋季渭河干流浮游动物种类数、密度和生物量分别为14种、9.02 ind./L和0.0051 mg/L,秦岭北麓支流为37种、42.78 ind./L和0.0229 mg/L;2018年春季渭河干流浮游动物种类数、密度和生物量分别为52种、292.89 ind./L和0.1734 mg/L,秦岭北麓支流为68种、70.15 ind./L和0.0508 mg/L.秋季渭河干流下游浮游动物种类数、密度和生物量最低,而春季随上、中、下游三者均依次增大;秋季秦岭支流中罗敷河浮游动物密度和生物量最高,而春季灞河最高.春、秋两季干支流间浮游动物优势种差异较小,但秋季优势种种类数少于春季.秋季渭河干流中游Shannon-Wiene...     

Spatial patterns in macroinvertebrate assemblages in surface-flowing waters of a glacially-influenced floodplain

We examined the spatial structure of macroinvertebrate assemblages in surface-flowing waters of a glacially-influenced floodplain. The floodplain main-channel responded longitudinally to changes in hydrology with evident coarse-scale zones of upwelling and downwelling; the lower floodplain main channel fell dry in late winter. Physico-chemical attributes differed among tributaries and the main channel. The main channel had lower values of conductivity, alkalinity and nitrate–N than tributaries, with right-side (east-facing) tributaries having the highest values. Left-side (west-facing) tributaries flowing over an exposed rock-face had warmer water temperatures than the main channel and right-side tributaries. The biomass of benthic organic matter and periphyton was highest in right-side tributaries, followed by main channel sites then left-side tributaries. Similarly, macroinvertebrate density and richness were higher in right-side tributaries, intermediate in main channel sites, and lowest in left-side tributaries. Macroinvertebrate assemblages clearly differed between main channel sites, right-side tributaries, and left side tributaries based on an NMDS analysis. Minor differences were observed among main channel sites, although most upstream sites showed some structural differences from downstream sites. Ephemeropterans and plecopterans were most common in main channel sites and right-side tributaries, whereas chironomids and trichopterans also were common in right-side tributaries. Although the main channel changed longitudinally in physico-chemical characteristics, no real patterns of zonation were evident in macroinvertebrate assemblages. Coarse spatial patterns in macroinvertebrate assemblages in the floodplain were reflected in the physico-chemical differences between the main channel and tributaries, and between left-side and right-side tributaries. We conclude that coarse-scale floodplain properties enhance the overall diversity of lotic macroinvertebrates. Consequently, floodplain alterations that reduce surface water heterogeneity/connectivity limits the potential macroinvertebrate diversity of floodplains.     

Methods to calculate sedimentation rates of floodplain soils in the middle region of the Elbe River

This study presents different methods to quantify the historic and recent sedimentation of floodplain soils along the Elbe River. These methods include the comparison of surface elevations, the quantification of sedimentation with the aid of anthropogenic and geogenic tracers, sediment trap studies, and the calculation of load balances. Selected results from sites at the lower section of the middle Elbe River are presented and verified. The results show that several methods are suitable. In future work it should be possible, depending on the available soil and sediment data, to calculate sedimentation in Elbe River floodplain and the loss of retention volume for larger areas.     

Behaviour of Different Molecular-weight Fractions of DOC of Elbe River Water during River Bank Infiltration

This paper reports changes in dissolved organic carbon concentration β(DOC) and the relation between UV-active and non-UV-active components determined for Elbe river water and river bank infiltrate in the Torgau river basin between 1992 and 1994. Using an ultrafiltration method, the fractionation of the DOC content was obtained for the fractions > 10 000 g/mol, 1 000…10 000 g/mol, and < 1 000 g/mol. The spectral absorption coefficient at 254 nm a₂₅₄ of the molecular-weight fractions was also measured. The mean total DOC concentration of Elbe river water decreased from 6.0 mg/L to below 3.9 mg/L along two investigated flowpaths. Two thirds of the decrease occurred within the first few metres of the river bed and one third along the 350 m length of the groundwater flowpaths. The a₂₅₄ values showed a significant decrease from 14.8 1/m in Elbe river water to 7.8 1/m in the aquifer. Along a flowpath, the proportion of low-molecular weight fraction of DOC increased, the proportion of high-molecular weight fraction decreased, and the proportion of the 1 000…10 000 g/mol molecular-weight fraction remained relatively stable. The Elbe river water contained the main portion of UV-active compounds in the fraction 1 000…10 000 g/mol, and this was also the case for samples of river infiltrate. For the high-molecular weight fraction, mainly non-UV-active compounds were attenuated in the river bed sediment.     

STATISTICAL RELATIONS BETWEEN GEOMORPHIC PARAMETERS- A CASE STUDY OF THE YUNNAN REACH OF THE LANCANGJIANG RIVER IN SOUTHWESTERN CHINA

The properties of rivers and their catchments can be expressed by statistical relationships between geomorphic parameters. These statistical relationships may reveal some inherent differences in geomorphic evolution for different reaches or different order tributaries of a river basin. A case study was undertaken of the Yunnan reach of the Langcangjiang River. The catchment area, channel length and gradient of the first-, second- and third-order tributaries all with catchment areas larger than 100 km2 in the Yunnan reach were the main geomorphic parameters evaluated. The correlation between catchment area and channel length as well as between catchment area and channel gradient with respect to the total tributaries, different reach tributaries, and different order tributaries were revealed using statistical methods. In general, the channel length as a function of catchment area, was best expressed by a quadratic function where channel length increases with increasing catchment area (half parabola), while the channel gradient as a function of catchment area is best expressed by an exponential decay function. Comparison of the best-fit formulas revealed the following phenomena: the lower Yunnan reach tributaries and the first-order tributaries have a dominant effect on geomorphic parameters of the total tributaries. In addition, the statistical relationships indicate that the river geomorphic system in the upper and lower Yunnan reaches evolved differently. This study method used to differentiate river characteristics by determining statistical relationships between geomorphic parameters may be extended to other rivers and their catchments.     

Interaction of tides and storm surges at the Elbe River mouth

The main regularities in the interaction of tides and storm surges at river mouths are discussed. A study of the Elbe River mouth area is used to describe the processes of interaction of the eustatic sea level rise, tides, surges, and river flow and special features of formation of maximum water levels. As shown, the intensification of cyclonic activity over the Northern Atlantic in the second half of the XX century resulted in more frequent extremely high storm surges at the Elbe River mouth. An assessment is given for possible changes in the regime of tides and surges at the Elbe River mouth in the XXI century, which may be caused by the acceleration of the eustatic sea level rise. The impact of local hydraulic engineering works (diking, dredging, and channel straightening) on maximum water levels within the town of Hamburg is analyzed.     

Comparison between measured and calculated tidal ellipses in the German Bight

Using a three-dimensional non-linear shelf model, the elliptical properties (ellipticity, inclination of the ellipse, major and minor semi-axis and phase) of the M₂ tide in the German Bight were calculated and compared with CODAR measurements. A series of barotropic and baroclinic calculations were carried out to investigate the influence of geometry, stratification and particularly inputs of freshwater on these parameters. The elliptical properties undergo stronger changes in zones of influence of embayments and in the deepening of the old Elbe Valley. Friction effects in the shallow areas are responsible for robust vertical variations of the ellipticity. The island of Helgoland induces wakes on its western and eastern sides. The discharge of freshwater of the rivers Elbe, Weser and Ems induced in general negative ellipticity. Although primarily determined by geography, baroclinic effects significantly modified the inclination of the ellipses. The calculated ellipses pattern of anticlockwise and clockwise tidal current rotation agrees quite well with CODAR measurements. The elliptical properties give a general idea of the interaction of tidal waves with coastal geometries.Responsible Editor: Hans Burchard