Ambiguous Ecological Control by Dissolved Humic Matter (DHM) and Natural Organic Matter (NOM): Trade-offs between Specific and Non-specific EffectsWe dedicate this paper to Prof. Dr. Fritz H. Frimmel on the occasion of his 60th birthday anniversary.

Steinberg, Christian E. W.; Brüggemann, Rainer

doi:10.1002/1521-401x(200112)29:6/7<399::aid-aheh399>3.0.co;2-f

Cited by 7 publications

(4 citation statements)

References 35 publications

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“…DOM provides energy and carbon for microorganisms in aquatic environments. Understanding the controls on the processes of DOM uptake and metabolism enhances our understanding of aquatic food webs 8–10…”

Section: Ecological Requirements For Investigating Dom Cycling Inclumentioning

confidence: 99%

Photochemical degradation of natural organic sulfur compounds (CHOS) from iron‐rich mine pit lake pore waters – an initial understanding from evaluation of single‐elemental formulae using ultra‐high‐resolution mass spectrometry

Herzsprung

Hertkorn

Friese

et al. 2010

Rapid Comm Mass Spectrometry

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In order to better understand the chemical diversity of dissolved organic matter (DOM) in iron-rich mine waters, a variety of sediment pore waters was analysed by means of ultra-high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS). A considerable number of the DOM elemental formulae were found to contain sulfur. In a rather simplified experiment, DOM was exposed to sunlight in the presence of dissolved ferric iron, which is common in the oxygenated acidified epilimnetic waters of mine pit lakes. The photochemical alteration of the CHOS (carbon-, hydrogen-, oxygen- and sulfur-containing) compounds was then categorised by following the changes in signal intensity of mass peaks. Nearly 20,000 elemental compositions were identified and sorted into the following categories: totally degraded, partially degraded, not significantly degraded, minor new photoproducts, and newly formed photoproducts. A large proportion of the CHOS compounds were found to be entirely degraded; the degradation ratios exceeded those of the CHO compounds. The pools of totally degraded compounds and those of newly formed products were contrasted with respect to photochemically relevant mass differences. These results indicate that photochemical loss of sulfur-containing low molecular weight compounds can be considered likely. One feasible explanation is the photodegradation of sulfonic acids within the CHOS pool eventually leading to the release of sulfate.

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Section: Ecological Requirements For Investigating Dom Cycling Inclumentioning

confidence: 99%

Photochemical degradation of natural organic sulfur compounds (CHOS) from iron‐rich mine pit lake pore waters – an initial understanding from evaluation of single‐elemental formulae using ultra‐high‐resolution mass spectrometry

Herzsprung

Hertkorn

Friese

et al. 2010

Rapid Comm Mass Spectrometry

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“…In general, net‐heterotrophy may be caused by the promotion of heterotrophic and/or the suppression of autotrophic, processes. Consequently, the resulting community response is a trade‐off of at least two competing processes (for a mathematical model of this competition, see Steinberg & Brüggemann, 2002). Many, but not all, of the HS isolates tested so far potentially suppressed photosynthetic oxygen release (Pflugmacher et al.…”

Section: Larger‐scale Ecological Significance Of Hs and Some Remaininmentioning

confidence: 99%

Dissolved humic substances – ecological driving forces from the individual to the ecosystem level?

et al. 2006

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SUMMARY1. This review focuses on direct and indirect interactions between dissolved humic substances (HS) and freshwater organisms and presents novel opinions and hypotheses on their ecological significance. Despite their abundance in freshwaters, the role of HS is still inadequately understood. These substances have been considered too large to be taken up by freshwater organisms. On the contrary, here we present evidence that dissolved HS are indeed taken up and interact directly and/or indirectly with freshwater organisms. 2. We show that dissolved HS exert a mild chemical stress upon aquatic organisms in many ways; they induce molecular chaperones (stress shock proteins), induce and modulate biotransformation enzymes and modulate (mainly inhibiting) the photosynthetic release of oxygen by freshwater plants. Furthermore, they produce an oxidative stress, which may lead to membrane oxidation. HS modulate the multixenobiotic resistance activity and probably other membrane-bound pumps. This property may lead to the increased bioaccumulation of xenobiotic chemicals. Furthermore, they can modulate the numbers of offspring in a nematode and feminise fish and amphibians. The ecological consequences of this potential remain obscure at present. HS also have the potential to act as chemical attractants (as shown with a nematode). 3. In some macrophytes and algae we show that HS interfere with photosynthesis and growth. For instance, the presence of HS suppresses cyanobacteria more than eukaryotic algae. By applying a quantitative structure activity relationship approach, we show that quinones in the HS interfere with photosynthetic electron transport. We show that even Phragmites leachate can act as a kind of phytotoxin. HS also have the potential to suppress fungal growth, as shown with the water mould Saprolegnia parasitica and force the fungus to respond by spore production. 4. In very soft, humic freshwaters, such as the Rio Negro, Brazil, HS stimulate the uptake of essential ions, such as Na and Ca, at extremely low pH (3.5-4.0) and prevent the ionoregulatory disturbance induced by acid waters, thereby enabling fish to survive in these environments. 5. We discuss whether or not HS are directly utilised by aquatic microorganisms or via exoenzymes, which may be washed in from the terrestrial catchment. There is accumulating evidence that the quality of the HS controls microbial growth. In total, netheterotrophy may result from HS-mediated suppression of primary production by the quinone structures and/or from HS-mediated support of microbial growth. As there is also evidence that HS have the potential to support photoautotrophic growth and suppress microbial growth, the opposite community effect could result. Consequently, dissolved organic carbon (DOC) has to be chemically characterised, rather than simply measuring bulk DOC concentration. 6. In sum, dissolved HS interact with freshwater organisms in a variety of ways in unenriched humic lakes. In addition to the well known effects of HS on light regime, for exampl...

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“…However, a promoting effect of It is evident that DOM has modulatory effects on environmental substances and their effects on organisms; however, the direction of modulation is not uniform. In a model analysis, Steinberg and Brüggemann [53] showed that humic substances can react in seemingly opposite ways, depending on their structure and chemical characterization. In fact, the effect of organic matter is a trade-off between promotion and inhibition due to its diverse nature, and this contrasting effect appeared to be intrinsic.…”

Section: Dom Can Modulate the Toxicity Of Epfrsmentioning

confidence: 99%

Biochar Extracts Can Modulate the Toxicity of Persistent Free Radicals in the Nematode Caenorhabditis elegans

Zhang

Saul

Lieke

et al. 2023

Applied Biosciences

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As an effective soil amendment, biochars require a comprehensive ecological evaluation before they can be widely used in agriculture because endogenous contaminants, such as environmentally persistent free radicals (EPFRs), certainly pose an ecological risk to soil invertebrates. In this study, Caenorhabditis elegans (C. elegans) was used as a model organism to investigate the neurotoxicity of two rice straw biochars pyrolyzed at 500 and 700 °C. After 24 h exposure to unwashed biochar, washed biochar, and leaching fluids (supernatants), the neurobehavioral parameters of C. elegans were determined in a liquid toxicity test. The results showed that the washed 700 °C biochar particles significantly impaired locomotion and prolonged the defecation interval at a biochar concentration of 4 g·well−1, while the unwashed biochar and supernatants caused no apparent impairment. Supporting this, electron paramagnetic resonance (EPR) results showed that the intensity of EPFRs in unwashed 700 °C biochar was stronger than that of the corresponding washed particles. This indicates that, in the liquid test, the EPR signal alone is not indicative of particle toxicity. The accessibility and activity of the EPFRs should be considered. Dissolved organic matter (DOM) was observed in the leaching fluids. The neurotoxic activity of the washed biochar was alleviated after the re-addition of leaching fluids to the washed biochar, suggesting that the dissolved organic materials modulate the reactivity of the EPFRs in the liquid phase. This study suggests that the leaching process may increase the risk of biochar when used in the field environment.

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Ambiguous Ecological Control by Dissolved Humic Matter (DHM) and Natural Organic Matter (NOM): Trade-offs between Specific and Non-specific EffectsWe dedicate this paper to Prof. Dr. Fritz H. Frimmel on the occasion of his 60th birthday anniversary.

Cited by 7 publications

References 35 publications

Photochemical degradation of natural organic sulfur compounds (CHOS) from iron‐rich mine pit lake pore waters – an initial understanding from evaluation of single‐elemental formulae using ultra‐high‐resolution mass spectrometry

Photochemical degradation of natural organic sulfur compounds (CHOS) from iron‐rich mine pit lake pore waters – an initial understanding from evaluation of single‐elemental formulae using ultra‐high‐resolution mass spectrometry

Dissolved humic substances – ecological driving forces from the individual to the ecosystem level?

Biochar Extracts Can Modulate the Toxicity of Persistent Free Radicals in the Nematode Caenorhabditis elegans

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