The mineralisation of dissolved organic matter recovered from temperate waterbodies during summer

Stutter, Marc; Cains, Jonathan

doi:10.1007/s00027-015-0446-z

Cited by 10 publications

(7 citation statements)

References 49 publications

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“…DOC samples (30 mL) were immediately acidified with 100 µL of either 25 % H 3 PO 4 (March expedition) or 50 % H 2 SO 4 (all other samples) to pH < 2.0. CDOM samples (30 mL) were preserved with 150 µL of 10 g L −1 NaN 3 following Tilstone et al (2002). DOC and CDOM samples were stored in amber borosilicate vials with PTFE-lined septa at +4 • C until analysis (within 1.5 months of collection), although some river samples in September froze for 1-2 days due to a refrigerator malfunction in the field.…”

Section: Study Region and Sample Collectionmentioning

confidence: 99%

Distribution and cycling of terrigenous dissolved organic carbon in peatland-draining rivers and coastal waters of Sarawak, Borneo

et al. 2018

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Abstract. South-East Asia is home to one of the world's largest stores of tropical peatland and accounts for roughly 10 % of the global land-to-sea dissolved organic carbon (DOC) flux. We present the first ever seasonally resolved measurements of DOC concentration and chromophoric dissolved organic matter (CDOM) spectra for six peatland-draining rivers and coastal waters in Sarawak, north-western Borneo. The rivers differed substantially in DOC concentration, ranging from 120–250 µmol L−1 (Rajang River) to 3100–4400 µmol L−1 (Maludam River). All rivers carried high CDOM concentrations, with a350 in the four blackwater rivers between 70 and 210 m−1 and 4 and 12 m−1 in the other two rivers. DOC and CDOM showed conservative mixing with seawater except in the largest river (the Rajang), where DOC concentrations in the estuary were elevated, most likely due to inputs from the extensive peatlands within the Rajang Delta. Seasonal variation was moderate and inconsistent between rivers. However, during the rainier north-east monsoon, all marine stations in the western part of our study area had higher DOC concentrations and lower CDOM spectral slopes, indicating a greater proportion of terrigenous DOM in coastal waters. Photodegradation experiments revealed that riverine DOC and CDOM in Sarawak are photolabile: up to 25 % of riverine DOC was lost within 5 days of exposure to natural sunlight, and the spectral slopes of photo-bleached CDOM resembled those of our marine samples. We conclude that coastal waters of Sarawak receive large inputs of terrigenous DOC that is only minimally altered during estuarine transport and that any biogeochemical processing must therefore occur mostly at sea. It is likely that photodegradation plays an important role in the degradation of terrigenous DOC in these waters.

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Section: Study Region and Sample Collectionmentioning

confidence: 99%

Distribution and cycling of terrigenous dissolved organic carbon in peatland-draining rivers and coastal waters of Sarawak, Borneo

et al. 2018

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“…However, relatively few studies have addressed PEs in larger rivers. Stutter & Cains (2015) found both positive and negative PE when incubating river sediment with glucose, fulvic acids and dissolved organic matter (DOM) sources from different aquatic ecosystems. Hotchkiss et al (2014) tested PE in a river-water context using bioassays containing mixes of river DOM, soil leachates, commercial humate, algal exudates and glucose in different combinations and employing a Bayesian modelling approach to separate the degradation of the different C pools.…”

Section: Streams and Riversmentioning

confidence: 99%

Interactive effects on organic matter processing from soils to the ocean: are priming effects relevant in aquatic ecosystems?

2018

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Organic matter (OM) is degraded during transport from soils to oceans. However, there are spatial and temporal variabilities along the aquatic continuum, which hamper the development of carbon cycling models. One concept that has been applied in this context is the priming effect (PE), describing nonadditive effects on OM degradation after mixing sources of contrasting bioavailability. Studies on the aquatic PE report divergent results from positive (increased OM degradation rates) to neutral, to negative (decreased OM degradation rates) effects upon mixing. Here, we aim to condense the outcomes of these studies on aquatic PE. Based on a literature review, we discuss differences in the reported PEs across freshwater and marine ecosystems, identifying system-specific features that could favour non-additive effects on OM degradation. Using a quantitative meta-analysis approach, we evaluated the occurrence, direction (positive vs. negative) and magnitude of aquatic PE. The meta-analysis revealed a mean PE of 12.6%, which was not significantly different from zero across studies. Hence, mixing of contrasting OM sources in aquatic ecosystems does not necessarily result in a change in OM degradation rates. Therefore, we suggest to focus on molecular and microbial diversity and function, which could provide a better mechanistic understanding of processes driving OM interactions.

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“…Dissolved organic matter (DOM) represents a key source of nutrients and energy for plants and microorganisms living in pristine low nutrient status waters (Gardner et al, 1989;Lindell et al, 1996;Bernot et al, 2010;Durand et al, 2011;Stutter and Cains, 2015). Conversely, DOM can also be seen as undesirable in freshwaters due to its potential to make pollutants more bioavailable, its ability to affect the hormone balance of freshwater organisms, its ability to generate significant reductions in dissolved oxygen concentrations owing to its uptake by microbial populations, and its potential to lead to the formation of carcinogens during chlorination of drinking water (Steinberg et al, 2008;Durand et al, 2011;McIntyre and Gueguen, 2013).…”

Section: Introductionmentioning

confidence: 99%

Microbial use of low molecular weight DOM in filtered and unfiltered freshwater: Role of ultra-small microorganisms and implications for water quality monitoring

Brailsford

Glanville

Marshall

et al. 2017

Science of The Total Environment

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Dissolved organic matter (DOM) plays a central role in regulating productivity and nutrient cycling in freshwaters. It is therefore vital that we can representatively sample and preserve DOM in freshwaters for subsequent analysis. Here we investigated the effect of filtration, temperature (5 and 25°C) and acidification (HCl) on the persistence of low molecular weight (MW) dissolved organic carbon (DOC), nitrogen (DON) and orthophosphate in oligotrophic and eutrophic freshwater environments. Our results showed the rapid loss of isotopically-labelled glucose and amino acids from both filtered (0.22 and 0.45μm) and unfiltered waters. We ascribe this substrate depletion in filtered samples to the activity of ultra-small (<0.45μm) microorganisms (bacteria and archaea) present in the water. As expected, the rate of C, N and P loss was much greater at higher temperatures and was repressed by the addition of HCl. Based on our results and an evaluation of the protocols used in recently published studies, we conclude that current techniques used to sample water for low MW DOM characterisation are frequently inadequate and lack proper validation. In contrast to the high degree of analytical precision and rigorous statistical analysis of most studies, we argue that insufficient consideration is still given to the presence of ultra-small microorganisms and potential changes that can occur in the low MW fraction of DOM prior to analysis.

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The mineralisation of dissolved organic matter recovered from temperate waterbodies during summer

Cited by 10 publications

References 49 publications

Distribution and cycling of terrigenous dissolved organic carbon in peatland-draining rivers and coastal waters of Sarawak, Borneo

Distribution and cycling of terrigenous dissolved organic carbon in peatland-draining rivers and coastal waters of Sarawak, Borneo

Interactive effects on organic matter processing from soils to the ocean: are priming effects relevant in aquatic ecosystems?

Microbial use of low molecular weight DOM in filtered and unfiltered freshwater: Role of ultra-small microorganisms and implications for water quality monitoring

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