ϱCO2 variations in streamwaters draining an acidic and acid sensitive spruce forested catchment in Mid-Wales

Neal, Colin

doi:10.1016/0048-9697(88)90113-1

Cited by 24 publications

(9 citation statements)

References 15 publications

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“…Alkalinity was analyzed weekly, as part of the long‐term monitoring program, by titration at pH = 4.5 (Standing Committee of Analysts ) and converted to Gran alkalinity by adding 31.6 μ eq HCO 3 L −1 (Neal ). Bicarbonate concentration [HCO 3 ] was multiplied by discharge to calculate the carbon flux.…”

Section: Methodsmentioning

confidence: 99%

Hydrological pulses and burning of dissolved organic carbon by stream respiration

Demars

2018

Limnology & Oceanography

102

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Stream metabolism plays a significant role in the global carbon cycle. Storm events can lower stream metabolic activities by removing standing biomass and river bed stock of organic matter. However, hydrological events could also stimulate stream ecosystem respiration (ER) by providing dissolved organic carbon (DOC) derived from soils. Here, I show how hydrological connectivity between land and water affects fluxes of DOC and daily whole stream bacterial respiration over an annual cycle in streams rich in DOC in north‐west Europe. The novelty of the approach resides in combining continuous whole stream metabolism with hydrological flow paths and water chemistry to quantify the in situ fate of DOC at ecosystem scale, with an estimation of all major stream carbon fluxes (land‐derived CO2, in‐stream biotic CO2, HCO3, and DOC) at catchment scale. An average 23% ± 11% of the annual DOC inputs from the land was respired away by benthic microbial metabolism within about an hour of transit time in small watersheds (about 1 km2). Stream ER was highly related to discharge and was stimulated for as long as the hydrological connectivity between land and water remained, as indicated by soil moisture continuous monitoring. In‐stream heterotrophic respiration represented 16% ± 7% of the annual total carbon fluxes (also including HCO3, land‐derived CO2, and DOC) at the catchment outlet under stable flows. This study suggests that DOC supply (soil carbon loss) will increase with rainfall, stimulating aquatic respiration, and CO2 emissions in streams.

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Section: Methodsmentioning

confidence: 99%

Hydrological pulses and burning of dissolved organic carbon by stream respiration

Demars

2018

Limnology & Oceanography

102

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“…All contribute to anomalies in indirect measurements of epCO 2 (Neal, 1988a, b). Neal (1988b) has suggested the use of alkalimetric titrations as a method for minimizing the affect of low HCO 3 concentrations and organic matter interferences common to lower pH waters.…”

Section: Indirect Determination Of Epcomentioning

confidence: 99%

“…the volume and CO 2 concentration of terrestrial waters entering the stream and the volume and surface water CO 2 concentration already present (Griffiths et al, 2007). Stream temperature, volume, depth, velocity, gradient, turbulence and wind speed then influence CO 2 losses to the atmosphere if epCO 2 values are >1 (Neal, 1988b;Rebsdorf et al, 1991;Dawson et al, 2001b). Allied to this, in particular, at downstream sites less dependent on terrestrial inputs, are the concentration and composition of mineralizable DOC from upstream as well as the activity and establishment of biotic communities (both benthic and in the water-column).…”

Section: Integration Of Processes Controlling Epco 2 Valuesmentioning

confidence: 99%

Seasonality of epCO₂ at different scales along an integrated river continuum within the Dee basin, NE Scotland

Dawson

Soulsby

Hrachowitz

et al. 2009

Hydrological Processes

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Abstract:Spatial and temporal variations of free CO 2 concentrations in surface waters are mainly controlled by dynamic processes encompassing terrestrial inputs and in-stream biotic cycling. Free CO 2 can be expressed as 'excess partial pressure of CO 2 ' (epCO 2 ), indicating supersaturation or under-saturation with respect to atmospheric CO 2 . Seasonal patterns of epCO 2 at sites draining nested upland catchments between 3Ð40 and 1837 km 2 were assessed within the River Dee basin in NE Scotland. EpCO 2 values ranged from 0Ð14 at the lowermost site on the mainstem in autumn to 12Ð7 on a major tributary during spring.A seasonality index was derived to describe contrasting winter/spring maxima and summer/autumn minima as annual mean epCO 2 values could not clearly distinguish between different sites. Seasonal differences tended to increase downstream as progressive changes in physicochemical conditions enhanced the influence of autotrophic communities. However, perturbations to this continuum occurred as CO 2 inputs from high DOC, heterotrophic tributaries and land-use changes between open moorland and forest affected downstream continuity. Major tributaries showed reduced differences between seasons compared to the mainstem. Smaller headwaters indicated a lack of seasonality as high connectivity of responsive, peaty soils enabled continual inputs of terrestrially derived free CO 2 to streams concomitant with limited autotrophic CO 2 removal, maintaining epCO 2 > 1 throughout.Seasonality of epCO 2 was mainly driven by the ability of in-stream biota to consume CO 2 during optimal conditions in summer/autumn. This was confirmed by multiple linear regression analysis, which indicated that, apart from catchment area, baseflow and biotic activity indicators were the best predictors of epCO 2 seasonality characteristics at any particular stage of the river system.

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“…This is because the estimate of EpCO 2 is linked to (a) the small difference between Gran alkalinity and 10 6-pH at low pH, which can even lead to unacceptably negative values of EpCO 2 , and (b) the exponential term in pH (Neal, 1988). For this study, only those waters with pH above 6 were used for the analysis, and the results are as follows.…”

Section: Dissolved Carbon Dioxide In the Streams And Groundwatermentioning

confidence: 99%

The water quality of streams draining a plantation forest on gley soils: the Nant Tanllwyth, Plynlimon mid-Wales

Neal

Reynolds

Neal

et al. 2004

Hydrol. Earth Syst. Sci.

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The water quality of the Nant Tanllwyth stream in the Plynlimon region of mid-Wales is related to the key hydrobiogeological controls and the effects of conifer harvesting based on an analysis of rain, cloud, stream and groundwater measurements. The results show the normal patterns of stream water quality response to hydrology. Thus, there is a high damping of atmospheric inputs due to storage in a highly heterogeneous soil and groundwater system. Correspondingly, there is a highly dynamic response for components such as calcium, bicarbonate and aluminium. This response links to the relative inputs of acidic and aluminium-bearing soil waters under high flow conditions and base enriched bicarbonate bearing waters from the groundwater areas under baseflow conditions. The introduction of a deep borehole near the main stem of the river opened up a groundwater flow route to the stream and other parts of the catchment. There were two aspects to this. Firstly, it caused a change to the stream water quality, particularly under baseflow conditions, by increasing the concentrations of calcium and magnesium and by reducing the acidity. The monitoring shows that this change has persisted for over eight years and that there is no sign of reversion to pre-borehole times. Secondly, it caused a change in the groundwater level and chemistry at a borehole on the other side of the river. This feature shows that the fracture system is of hydrogeochemical and hydrogeological complexity. The effects of conifer harvesting are remarkable. At the local scale, felling leads to the expected short term increase in nitrate, ammonium and phosphate from the disturbance of the soil and the reduction in uptake into the vegetation. Correspondingly, there is a reduction in sodium and chloride linked to reduced scavenging of atmospheric inputs from cloud water by the vegetation and also due to increased dilution potential due to reductions in transpiration by the trees. However, within the main stream, virtually no change is observed in stream water quality with felling, except for a decrease rather than an expected increase in nitrate concentration. It seems that the increase in phosphate, for a system that is essentially phosphate limiting, has stimulated biological activity in the stream leading to increased uptake of nitrate and ammonium. However, there is little change in the sodium and chloride in the stream and there are important issues of the representative nature of studying small scale drainage areas. Boreholes, introduced to assess the impacts of the felling programme, show unexpected variations in groundwater chemistry. These variations are associated with the complexity of both flow routing and the chemical reactivity within the groundwater and lower soil zones, rather than changes that can be linked specifically to felling. The implications of the study are discussed in relation to both process understanding and forestry management practices.

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ϱCO2 variations in streamwaters draining an acidic and acid sensitive spruce forested catchment in Mid-Wales

Cited by 24 publications

References 15 publications

Hydrological pulses and burning of dissolved organic carbon by stream respiration

Hydrological pulses and burning of dissolved organic carbon by stream respiration

Seasonality of epCO₂ at different scales along an integrated river continuum within the Dee basin, NE Scotland

The water quality of streams draining a plantation forest on gley soils: the Nant Tanllwyth, Plynlimon mid-Wales

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ϱCO2 variations in streamwaters draining an acidic and acid sensitive spruce forested catchment in Mid-Wales

Cited by 24 publications

References 15 publications

Hydrological pulses and burning of dissolved organic carbon by stream respiration

Hydrological pulses and burning of dissolved organic carbon by stream respiration

Seasonality of epCO2 at different scales along an integrated river continuum within the Dee basin, NE Scotland

The water quality of streams draining a plantation forest on gley soils: the Nant Tanllwyth, Plynlimon mid-Wales

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Seasonality of epCO₂ at different scales along an integrated river continuum within the Dee basin, NE Scotland