Michael Matthies

Dynamics and functional relevance of ammonia-oxidizing archaea in two agricultural soils.

Crucial steps in geochemical cycles are in many cases performed by more than one group of microorganisms, but the significance of this functional redundancy with respect to ecosystem functioning is poorly understood. Ammonia-oxidizing archaea (AOA) and their bacterial counterparts (AOB) are a perfect system to address this question: although performing the same transformation step, they belong to well-separated phylogenetic groups. Using pig manure amended with different concentrations of sulfadiazine (SDZ), an antibiotic that is frequently used in veterinary medicine, it was possible to affect AOB and AOA to different degrees. Addition of manure stimulated growth of AOB in both soils and, interestingly, also growth of AOA was considerably stimulated in one of the soils. The antibiotic treatments decreased the manure effect notably on AOB, whereas AOA were affected to a lower extent. Model calculations concerning the respective proportions of AOA and AOB in ammonia oxidation indicate a substantial contribution of AOA in one of the soils that further increased under the influence of SDZ, hence indicating functional redundancy between AOA and AOB.

Environmental decision support systems: Current issues, methods and tools

Abstract Development of environmental decision support systems (EDSS) is rapidly progressing. The sustainable management of natural resources has a growing research focus as the awareness of the complexity of interactions between socio-cultural, economical and biophysical system components is increasingly acknowledged. As better data and methods become available, the complexity of the system representation is augmenting. At the same time realism and relevance are increasing and allowing direct support for management and policy development. This article gives the background of recent developments in EDSS and summarises a selected set of papers that were presented at the 2nd Biennial Conference of the International Society of Environmental Modelling and Software (IEMSS 2004). Recent developments show a continuum between integrated assessment modelling and EDSS with varying levels of stakeholder participation in both EDSS development and application. There is a general tendency towards better utilisation of interdisciplinary data, integration and visualisation of temporal and spatial results. Future developments appear directed towards better representation of reality in models, improving user-friendliness and use in a negotiation or group discussion context.

Generic one-compartment model for uptake of organic chemicals by foliar vegetation

A differential mass-balance equation for the uptake of organic chemicals into the aerial plant compartment from soil and air is derived. Processes considered are uptake from soil, gaseous deposition, volatilization from leaves, transformation and degradation, and growth. An analytical solution is developed. Chemical data needed are K Ow , K AW , and reaction rate constants. Constant average values for environmental parameters are assumed. Plant properties are typical for grass and green fodder. Calculations for 2,3,7,8-TCDD, and the comparison to a recently tested numerical four-compartment model shows the applicability of the mass-balance approach. The equation could be incorporated into existing multimedia and soil transport models and may be useful for the hazard assessment of contaminated soils.

Development of a geography-referenced regional exposure assessment tool for European rivers - great-er contribution to great-er #1

Abstract The objective of the GREAT-ER project is to develop and validate a powerful and accurate aquatic chemical exposure prediction tool for use within the EU environmental risk assessment schemes. Current techniques to estimate regional predicted environmental concentrations (PECs) use a generic multimedia ‘unit world’ approach and do not account for spatial and temporal variability in landscape characteristics, river flows and/or chemical emissions. Hence, the results are merely applicable on a generic screening level since these models do not offer a realistic prediction of actual steady-state background concentrations. A software system will be developed to calculate the distribution of predicted environmental concentrations (PECs) of down-the-drain chemicals in European surface waters on both a river and catchment area level. Data on dissolved oxygen, biological oxygen demand and ammonia will also be used to assess water quality and to provide data for calibration and verification. The system will use a Geographic Information System (GIS) for data storage and visualization, combined with simple mathematical models for the prediction of chemical fate. Hydrological databases and models will be used to determine river flows. This refined exposure assessment tool should significantly enhance the accuracy of current local and regional exposure estimation methods. The new exposure assessment methodology will integrate specific environmental information and be worked out in a geographically-referenced framework, ultimately on a pan-European scale. The initial data collection, collation and model application will be applied to two pilot study areas, representative of different hydrological and climatological situations in Europe. A blueprint of the methodology will be developed and applied to these pilot study areas, which will allow refining, optimization and verification of the system.The ultimate objective is to implement GREAT-ER for the entire European Union.This work will be performed in the second phase of the project, after the initial three years which are limited to the development of the methodology and verification in the pilot study areas.

Are marine plastic particles transport vectors for organic pollutants to the Arctic

Plastic litter accounts for 50-80% of waste items stranded on beaches, floating on the ocean surface and lodged in the seabed. Organic pollutants can be absorbed onto plastic particles from sea water, attached to their surfaces or included in the plastic matrix as additives. Such chemicals may be transported to remote regions by buoyant plastics and ocean currents. We have estimated mass fluxes of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and perfluorooctanoic acid (PFOA) to the Arctic via the main ocean currents and compared them to those in the dissolved state and in air. Substance fluxes with atmospheric or sea water currents account for several tons per year, whereas those mediated by plastics are four to six orders of magnitude smaller. However, the significance of various pollutant transport routes does not depend only on absolute mass fluxes but also on bioaccumulation in marine food chains.

Scenario analysis and management options for sustainable river basin management: Application of the Elbe DSS

We developed a decision support system (DSS) for sustainable river basin management in the German Elbe catchment (~100,000km^2), called Elbe-DSS. The system integrates georeferenced simulation models and related data sets with a user friendly interface and includes a library function. Design and content of the DSS have been developed in close cooperation with end users and stakeholders. The user can evaluate effectiveness of management actions like reforestation, improvement of treatment plant technology or the application of buffer strips under the influence of external constraints on climate, demographic and agro-economic changes to meet water management objectives such as water quality standards and discharge control. The paper (i) describes the conceptual design of the Elbe-DSS, (ii) demonstrates the applicability of the integrated catchment model by running three different management options for phosphate discharge reduction (reforestation, erosion control and ecological-farming) under the assumption of regional climate change based on IPCC scenarios, (iii) evaluates the effectiveness of the management options, and (iv) provides some lessons for the DSS-development in similar settings. The georeferenced approach allows the identification of local inputs in sub-catchments and their impact on the overall water quality, which helps the user to prioritize his management actions in terms of spatial distribution and effectiveness.

A conceptual model describing the fate of sulfadiazine and its metabolites observed in manure-amended soils.

Sulfadiazine (SDZ) belongs to the chemical class of sulfonamides, one of the most important groups of antibiotics applied in animal husbandry in Europe. These antibiotics end up in the soil after manure from treated animals is applied as fertilizer. They can inhibit soil microbial functions and enhance the spread of resistance genes among soil microorganisms. In order to assess the exposure of soil microorganisms to SDZ, a conceptual kinetic model for the prediction of temporally resolved antibiotic concentrations in soil was developed. The model includes transformation reactions, reversible sequestration and the formation of non-extractable residues (NER) from SDZ and its main metabolites N(4)-acetyl-sulfadiazine (N-ac-SDZ) and 4-hydroxy-sulfadiazine (OH-SDZ). The optimum model structure and rate constants of SDZ kinetics and its metabolites were determined by fitting different model alternatives to sequential extraction data of a manure-amended Cambisol soil. N-ac-SDZ is degraded to SDZ with a half-life of 4d, whereas OH-SDZ is not. Though, based on the available data, the hydroxylation of SDZ seems to be negligible, it is still included in the model structure since this process has been observed in recent studies. Sequestration into a residual fraction has similar kinetics for SDZ, N-ac-SDZ and OH-SDZ and is one order of magnitude faster than the reverse translocation. The irreversible formation of NER is restricted to SDZ and OH-SDZ. The model shows good agreement when applied to extraction data measured independently for a Luvisol soil. The combination of sequential extraction data and the conceptual kinetic model enables us to gain further insight into the long-term fate and exposure of sulfonamides in soil.

System analysis of water quality management for the Elbe river basin

Abstract A decision support system for integrated river basin management of the German part of the Elbe river basin (Elbe-DSS) is currently under development. It considers water quantity, chemical quality, and ecological status of surface waters. User needs were identified and refined by repeated consultation of water managers. A list of management objectives, measures, and external scenarios emerged, which was taken as the basis for the DSS development. A comprehensive system analysis was carried out to meet the various spatial and temporal scales when dealing with hydrologic, ecologic, economic, and social aspects related to water quantity and quality. System diagrams for the catchments and the river network were constructed. They describe the properties, processes, and data influencing the water flow and substance load. One model for the calculation of the long-term nutrient discharges in 132 sub-catchments from non-point sources, one simulation model for wastewater pathways (point sources) and aquatic fate assessment, and one model for hydrological dynamics were selected for integration into the Elbe-DSS. The interaction of management objectives, external scenarios of climate, agro-economic and demographic change, and selected measures to achieve the desired state of good water quantity and quality is investigated.

Determination of soil biodegradation half-lives from simulation testing under aerobic laboratory conditions: a kinetic model approach.

A kinetic model approach for determination of biodegradation half-lives from soil simulation testing is presented. The model describes transformation of the parent compound to metabolites and formation of bound (non-extractable) residues as well as mineralization in soil under aerobic laboratory conditions. Experimental data for several pesticide compounds from various soil simulation tests are used for fitting kinetic rate constants. Formation of bound residues, either from parent or metabolites or from both, can be described by first-order kinetics for all examined compounds. Correlation of kinetic rate constants of primary degradation and formation of bound residues from parent compound suggests a common mechanism, presumably co-metabolic microbial activity, for both processes. Inverse modelling allows for estimation of primary degradation half-life DegT50 instead of disappearance time DT50. Application of the DegT50 approach in PBT assessment might result in a different persistent classification for which the developed model delivers an appropriate evaluation tool.

Probabilistic uncertainty analysis of the European Union System for the evaluation of substances multimedia regional distribution model

The European Union System for the Evaluation of Substances (EUSES) is a computerized model system to facilitate and harmonize health and environmental risk assessment of previously notified and new substances. For calculation of regional background exposure, a multimedia distribution model is used. In the present study, the uncertainty of this regional model is analyzed. Environmental parameters were collected for North Rhine Westphalia (Germany), which resembles the standard region of EUSES. Probability distribution functions of various types (uniform, triangular, normal, log normal) depending on data availability were derived for environmental input parameters, including geometric parameters. Generic log-normal distribution functions with fixed standard deviations were chosen for solubility in air, water, and n-octanol as well as for degradation half-lives. Monte Carlo simulations were carried out for 10 reference substances having different properties. Contribution of environmental parameter uncertainty to total output uncertainties is higher than that of substance parameters. Range of output uncertainty, defined as the ratio of the logarithms of the 90th and 10th percentiles of the cumulative probability distribution function, shows an increase from air and water to soil. The highest-occurring range is 1.4 orders of magnitude, which means that total uncertainty of the regional model is relatively low and, usually, is lower than the range of measured values. The median of output probability distributions lies above the point estimate. Influence of input parameters was estimated as their rank correlation coefficients to output uncertainty. Substance and environmental parameters contribute differently to output variance depending on individual substance properties and environmental compartment. Hence, the present study underlines the need to perform uncertainty analyses instead of either using a set of simple rules or just looking at certain parameters.