A conceptual framework for analyzing deltas as coupled social–ecological systems: an example from the Amazon River Delta

At the nexus of watersheds, land, coastal areas, oceans, and human settlements, river delta regions pose specific challenges to environmental governance and sustainability. Using the Amazon Estuary-Delta region (AD) as our focus, we reflect on the challenges created by the high degree of functional interdependencies shaping social–ecological dynamics of delta regions. The article introduces the initial design of a conceptual framework to analyze delta regions as coupled social–ecological systems (SES). The first part of the framework is used to define a delta SES according to a problem and/or collective action dilemma. Five components can be used to define a delta SES: social–economic systems, governance systems, ecosystems-resource systems, topographic-hydrological systems, and oceanic-climate systems. These components are used in association with six types of telecoupling conditions: socio-demographic, economic, governance, ecological, material, and climatic-hydrological. The second part of the framework presents a strategy for the analysis of collective action problems in delta regions, from sub-delta/local to delta to basin levels. This framework is intended to support both case studies and comparative analysis. The article provides illustrative applications of the framework to the AD. First, we apply the framework to define and characterize the AD as coupled SES. We then utilize the framework to diagnose an example of collective action problem related to the impacts of urban growth, and urban and industrial pollution on small-scale fishing resources. We argue that the functional interdependencies characteristic of delta regions require new approaches to understand, diagnose, and evaluate the current and future impacts of social–ecological changes and potential solutions to the sustainability dilemmas of delta regions.     

Sediment contact test with <Emphasis Type="Italic">Potamopyrgus antipodarum</Emphasis> in effect-directed analyses—challenges and opportunities

Background and scope  

Effect-directed analysis is increasingly used for the identification of key toxicants in environmental samples and there is a growing need for in vivo biotests as diagnostic tools. Within this study, we performed an in vivo sediment contact test, applicable on both native field samples and their extracts or fractions, in order to be able to compare the results from both field and laboratory studies.     

Emission and burnt smell characteristics from combustion experiments with defined materials

Typical burnt smell often results from fire accidents or in general from incomplete combustion. Recently, eleven compounds were identified, which are basically responsible for this odour. When analyzing residual materials from different fire accidents, the pattern that means the relative ratios of these compounds among each other varies strongly, although always causing a burnt smelling. Consequently, lab-scale combustion experiments were performed in order to investigate the influence of defined materials from domestic environment on the burnt-smell fingerprints. Furthermore, the occurrence of other polar and higher molecular combustion products was studied. It was found that under good combustion conditions, the burnt smell patterns resulting from the single materials were astonishingly consistent, mostly dominated by methylphenols or naphthalene. No correlation could be found between these ‘fingerprints’ and combustion product groups identified by GC/MS-screenings. LC/MS/MS-measurements especially pointed at the existence of higher molecular weight phenolic and acidic functionalized compounds in the combustion residues.     

Bioremediation of chlorobenzene-contaminated ground water in an in situ reactor mediated by hydrogen peroxide

New in situ reactive barrier technologies were tested nearby a local aquifer in Bitterfeld, Saxonia-Anhalt, Germany, which is polluted mainly by chlorobenzene (CB), in concentrations up to 450 microM. A reactor filled with original aquifer sediment was designed for the microbiological remediation of the ground water by indigenous bacterial communities. Two remediation variants were examined: (a) the degradation of CB under anoxic conditions in the presence of nitrate; (b) the degradation of CB under mixed electron acceptor conditions (oxygen+nitrate) using hydrogen peroxide as the oxygen-releasing compound. Under anoxic conditions, no definite degradation of CB was observed. Adding hydrogen peroxide (2.94 mM) and nitrate (2 mM) led to the disappearance of CB (ca. 150 microM) in the lower part of the reactor, accompanied by a strong increase of the number of cultivable aerobic CB degrading bacteria in reactor water and sediment samples, indicating that CB was degraded mainly by productive bacterial metabolism. Several aerobic CB degrading bacteria, mostly belonging to the genera Pseudomonas and Rhodococcus, were isolated from reactor water and sediments. In laboratory experiments with reactor water, oxygen was rapidly released by hydrogen peroxide, whereas biotic-induced decomposition reactions of hydrogen peroxide were almost four times faster than abiotic-induced decomposition reactions. A clear chemical degradation of CB mediated by hydrogen peroxide was not observed. CB was also completely degraded in the reactor after reducing the hydrogen peroxide concentration to 880 microM. The CB degradation completely collapsed after reducing the hydrogen peroxide concentration to 440 microM. In the following, the hydrogen peroxide concentrations were increased again (to 880 microM, 2.94 mM, and 880 microM, respectively), but the oxygen demand for CB degradation was higher than observed before, indicating a shift in the bacterial population. During the whole experiment, nitrate was uniformly reduced during the flow path in the reactor.