Marcus Schulz

The Influence of Sorption Processes on the Phosphorus Mass Balance in a Eutrophic German Lowland River

Previous studies on sorption processes in running waters lack a quantification of phosphorus sorption in relation to phosphorus mass balances of entire river sections. The present study was designed to investigate the influence of sorption processes on the phosphorus mass balance in a medium-sized lowland river. Riverbed surface sediments were sampled in the lower River Spree in February and in July 2002, and used for sorption shaking experiments. Phosphorus analyses results were evaluated using Langmuir-isotherms. Organic sediments revealed sorption properties that were affected by incubation temperature in a manner opposite to those of clastic sediments. Particulate iron is assumed to be the dominant sorption site of phosphorus in the lower River Spree. Clastic sediments act as phosphorus sinks, especially in summer, when soluble reactive phosphorus (SRP) concentrations in the water body are relatively high. Organic river substrates were found to be a source rather than a sink of phosphorus for the water body, but even in the worst case of a storm event, including complete resuspension of an organic surface layer, the contribution of desorption to the riverine phosphorus load of a eutrophic river was negligible (at maximum 2.5% of SRP load during vegetation period).

A multi-criteria evaluation system for marine litter pollution based on statistical analyses of OSPAR beach litter monitoring time series

During the last decades, marine pollution with anthropogenic litter has become a worldwide major environmental concern. Standardized monitoring of litter since 2001 on 78 beaches selected within the framework of the Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR) has been used to identify temporal trends of marine litter. Based on statistical analyses of this dataset a two-part multi-criteria evaluation system for beach litter pollution of the North-East Atlantic and the North Sea is proposed. Canonical correlation analyses, linear regression analyses, and non-parametric analyses of variance were used to identify different temporal trends. A classification of beaches was derived from cluster analyses and served to define different states of beach quality according to abundances of 17 input variables. The evaluation system is easily applicable and relies on the above-mentioned classification and on significant temporal trends implied by significant rank correlations.

A simple model of phosphorus retention evoked by submerged macrophytes in lowland rivers

This study was designed to quantify and model the effects of macrophytes on phosphorus retention in a lowland river. The seasonal course of phosphorus retention was calculated from the measured difference in TP between beginning and end of a 30-km river course and the estimated lateral P input. The coverage of submersed macrophytes was mapped and coincided with the difference between theoretical water level (without vegetation) and the observed one. Therefore, the increase in water level was used as measure of the macrophytes’ abundance. In years with rare vegetation (1991–1994), P was retained in winter and remobilized in summer. In years with dense stands of macrophytes (1995–2002), net P retention was highest in summer and amounted up to 20% of TP load, and was negative during winter. The annual P budget was close to zero in both periods. The found sinusoidal annual pattern of total phosphorus retention was used to create a retention model for vegetated lowland rivers.

Comparative analysis of time series of marine litter surveyed on beaches and the seafloor in the southeastern North Sea.

The comparative analysis of marine litter in different marine compartments has rarely been attempted. In this study, long-term time series of marine litter abundance on the seafloor and on the coast, both from the southeastern North Sea, were analyzed for temporal trends and correlations. On four beach sections of 100 m length, mean abundances of total beach litter collected four times a year from 2002 to 2008 varied between 105 and 435 items. Mean densities of total inorganic litter on the seafloor amounted to 10.6 ± 9.7 kg km(-2) in the offshore region (2001-2010) and 13.7 ± 12.6 kg km(-2) in the Wadden Sea (1998-2007), respectively. In the offshore region, there was no significant long-term trend, while in the Wadden Sea, densities of marine litter declined significantly. Correlations between time series were weak, indicating different sources and transport processes responsible for compositions of beach litter and litter on the seafloor. Decreases in inputs from fisheries and substantial export due to resuspension are discussed as reasons for the decrease in litter on the seafloor in the Wadden Sea.

Morphodynamik am Mehrerauer Seeufer (Bodensee)

Abstract The shore west of the town Bregenz situated at Lake Constance (Mehrerauer Seeufer) offers habitats for relictic floristic elements, such as the Lake Constance forget-me-not ( Myosotis rehsteineri , Wartm .). During the last decades, several-meter-high gravely bars developed at the beach, and moved into landward direction. Sedimentological investigations were carried out in the littoral region, at the beach, and in the periodically flooded lagoons, in order to display the reasons for the sediments movements. Regular surveys of the bars exhibited them to move episodically. The translocation probably occurred at high water stages, especially during storm events. Extended well sorted, gravely beds were classified as tempestites, whereas poorly sorted, coarse gravely plasters seaward of the bars were characteristic of long-term erosion of fines. One reason for the observed morphodynamical processes probably were deep hollows in the littoral region, which had been the results of sand and gravel mining: Storm waves were moving towards the beach with low friction, and therefore were barely decelerated. In addition, the artificial progradation of the mouth of the River Bregenzer Aach, and the deepening of its riverbed evoked a reduction in inputs of fine particulate matter from the River Bregenzer Aach, which in turn caused a decrease in substitution of losses of the fine-grained binding agent due to erosion. The morphodynamics at the shore of Mehrerau are based on an interaction between anthropogenic reasons and natural storm events.

OSPAR standard method and software for statistical analysis of beach litter data

The aim of this study is to develop standard statistical methods and software for the analysis of beach litter data. The optimal ensemble of statistical methods comprises the Mann-Kendall trend test, the Theil-Sen slope estimation, the Wilcoxon step trend test and basic descriptive statistics. The application of Litter Analyst, a tailor-made software for analysing the results of beach litter surveys, to OSPAR beach litter data from seven beaches bordering on the south-eastern North Sea, revealed 23 significant trends in the abundances of beach litter types for the period 2009-2014. Litter Analyst revealed a large variation in the abundance of litter types between beaches. To reduce the effects of spatial variation, trend analysis of beach litter data can most effectively be performed at the beach or national level. Spatial aggregation of beach litter data within a region is possible, but resulted in a considerable reduction in the number of significant trends.

Artificial neural networks for modeling time series of beach litter in the southern North Sea.

In European marine waters, existing monitoring programs of beach litter need to be improved concerning litter items used as indicators of pollution levels, efficiency, and effectiveness. In order to ease and focus future monitoring of beach litter on few important litter items, feed-forward neural networks consisting of three layers were developed to relate single litter items to general categories of marine litter. The neural networks developed were applied to seven beaches in the southern North Sea and modeled time series of five general categories of marine litter, such as litter from fishing, shipping, and tourism. Results of regression analyses show that general categories were predicted significantly moderately to well. Measured and modeled data were in the same order of magnitude, and minima and maxima overlapped well. Neural networks were found to be eligible tools to deliver reliable predictions of marine litter with low computational effort and little input of information.

Modeling Arsenic and Oil Contamination After High Water Events in the Town and Floodplain of Bitterfeld (Germany)

Applying the two-dimensional model system Telemac2D, the transport of arsenic and oil during extreme flood events was modeled for the region Bitterfeld (Germany). Telemac2D includes sub-routines that describe hydrodynamics, transport and first-order partitioning of soluble and particle-bound pollutants. Oil spills were numerically treated as particulate pollutants with zero settling velocity. Simulations of the inundation of a small region after a dam-break revealed distinct small-scale contamination patterns and partly exhibited severe contamination. Comparison with measurements from the Mulde flood in August 2002 gives reasonable agreement. The model will be calibrated and validated by several measurements with sediment traps during flood events.

An empirical regression model of soluble phosphorus retention for small pristine streams evaluating tracer experiments

Abstract.Models of in-stream phosphorus retention either lack high spatial and temporal resolution, or need a high number of input parameters.We provide a simple new approach that deals with these deficits. Soluble reactive phosphorus (SRP) tracer studies based on the nutrient spiralling concept were evaluated to derive a simple model that explains SRP retention. SRP uptake length (SRP-Sw) was considered to be a measure of transient SRP storage and was transformed to load-weighted retention (R) using an exponential relationship. Stream order (so) and flow velocity (u) were considered as input parameters to explain SRP uptake length. Model validation showed significant correlation with measured uptake lengths. The model explained 46% of SRP retention, and simulated and measured retention were in the same order of magnitude. Our model may act in concert with emission models to account for lateral SRP sources within the catchment. Although our empirical model does not describe biological processes and is not a substitute for detailed biogeochemical studies, it provides an efficient tool to predict load-weighted soluble nutrient retention and nutrient transport to downstream systems and is applicable in most small pristine streams.