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1.
The optical properties and spatial distribution of chromophoric dissolved organic matter (CDOM) in Meiliang Bay of Lake Taihu were evaluated and compared to the results in literature. Concentrations of dissolved organic carbon (DOC) ranged from 8.75 to 20.19 mg L?1 with an average of (13.10 ± 3.51) mg L?1. CDOM absorption coefficients a(λ) at 280 nm, 355 nm, and 440 nm were in the range 11.28...33.46 m?1 (average (20.95 ± 5.52) m?1), 2.42...7.90 m?1 (average (4.92 ± 1.29) m?1), and 0.65...2.44 m?1 (average (1.46 ± 0.44) m?1), respectively. In general, CDOM absorption coefficient and DOC concentration were found to decrease away from the river inflow to Meiliang Bay towards the lake center. The values of the DOC‐specific absorption coefficients a*(λ), given as absorption coefficient related to mass concentration of organic carbon (C) ranged from 0.28 to 0.47 L mg?1 m?1 at 355 nm. The determination coefficients between CDOM absorption and DOC concentration decreased with the increase of wavelength from 280 to 550 nm. The linear regression relationship between CDOM absorption at 280 nm and DOC concentration was following: a(280 nm) = 1.507 L mg?1 m?1 · DOC + 1.215 m?1. The spectral slope S values were dependent on the wavelength range used in the regression. The estimated S values decreased with increasing wavelength range used. A significant negative linear relationship was found between CDOM absorption coefficients, DOC‐specific absorption coefficients and estimated S values especially in longer wavelength range. The linear regression relationship between DOC‐specific absorption coefficients at 440 nm and estimated S values during the wavelength range from 280 to 500 nm was following: a*(440 nm) = (–0.021 μm · S + 0.424) L mg?1 m?1.  相似文献   

2.
Carbon Turnover by Respiration in the River Ilm (Thuringia, Germany) In the river Ilm, the organic carbon content of water and sediments was analyzed inclusively the C turnover by CO2-respiration with IR-measurement. A comparison of the unpolluted rhithral (headwater) with the polluted epipotamal (lower course) gives downstream an increase of DOC and CO2-respiration of 50...100 mg/(m3 · h) C. In the headwater region, the respiration of the sediments is dominant, in the underflow the respiration of the water. Permeable sand and gravel beds are important for the degradation of the organic load. The sediments of the river are covered with a biofilm of 1...2 g/m2 Corg. A turnover of the Corg. content from 20...400 days is calculated by the respiration measurements.  相似文献   

3.
A total of 1008 samples were collected from the eight major riverine runoff outlets in the Pearl River Delta (PRD) during 2005-2006 to estimate the fluxes of total organic carbon (TOC) to the coastal ocean off South China. The average dissolved organic carbon (DOC) concentration was 1.67 mg/L with a range of 1.38-2.13 mg/L. Concentrations of particulate organic carbon (POC) ranged from 2.66-4.12% of total suspended particulate matter (SPM). The fluxes of TOC and SPM from the PRD via the eight outlets were 9.2 x 10(5) and 2.5 x 10(7)tons/yr, respectively. Temporal variations in POC and DOC were observed at all outlets due to the large variability in runoff levels because of the seasonality of rainfall, and the riverine discharge amount was an important factor controlling TOC flux. The net contribution of organic carbon from the PRD to the coastal ocean represented approximately 0.1-0.2% of total organic carbon transported by rivers worldwide.  相似文献   

4.
The extensive blanket peatlands of the UK uplands account for almost half of total national terrestrial carbon storage. However, much of the blanket peat is severely eroded so that the contemporary role of the peatland system in carbon sequestration is compromised by losses of organic carbon in dissolved (DOC) and particulate (POC) form in the fluvial system. This paper presents the first detailed assessment of dissolved and organic carbon losses from a severely eroded headwater peatland (River Ashop, South Pennines, UK). Total annual fluvial organic carbon losses range from 29–106 Mg C km,‐2 decreasing from the headwaters to the main catchment outlet. In contrast to less eroded systems fluvial organic carbon flux is dominated by POC. POC:DOC ratios decrease from values of 4 in the headwaters to close to unity at the catchment outlet. These results demonstrate the importance of eroding headwater sites as sources of POC to the fluvial system. Comparison with a range of catchment characteristics reveals that drainage density is the best predictor of POC:DOC but there is scatter in the relation in the headwaters. Steep declines in specific POC yield from headwater catchments are consistent with storage of POC within the fluvial system. Key to the significance of fluvial carbon flux in greenhouse gas budgets is understanding the fate of fluvial carbon. Further work on the fate of POC and the role of floodplains in fluvial carbon cycling is urgently required. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

5.
Deforestation and mining activities have proven to be very damaging to rivers because these activities disturb the environmental characteristics of rivers. Thus, the concentrations of dissolved organic carbon (DOC), particulate organic carbon (POC), particulate nitrogen (PN), and Chlorophyll‐a (Chl‐a) were measured monthly during 2 hydrological years in the Maroni and Oyapock Rivers to assess the dynamics and fluxes of organic carbon and nitrogen in these 2 Guiana Shield basins, which have been strongly (Maroni) and weakly (Oyapock) impacted by deforestation and mining activities. The 2‐year time series show that DOC, POC, PN, and Chl‐a concentrations vary seasonally with discharge in both rivers, indicating a hydrologically dominated control. Temporal patterns of DOC, POC, and PN indicate that these variables show maximum concentrations in rising waters due to the yield of organic matter and nitrogen accumulated in soils, which are incorporated into the rivers during rainfall. However, the Chl‐a concentrations were at a maximum during low‐water stages. The C/N and C/Chl‐a ratios also showed a seasonal trend, with lower values during the low water periods due to an increase in algal biomass. During high water, the POC in both rivers is the result of terrestrial organic matter, whereas during low‐water autochthonous organic matter can reach up to 34% of the POC. The mean annual fluxes of TOC and PN were higher (4.56 × 105 tonC year?1 and 1.77 × 104 tonN year?1, respectively) in the Maroni River than those (1.84 × 105 tonC year?1 and 0.54 × 104 tonN year?1, respectively) in the Oyapock River. However, the specific fluxes of DOC, POC, and PN from both basins were nearly the same. Although gold mining activities are performed in both basins, there is no conclusive evidence regarding the impact of these activities on the dynamics of organic matter and particulate nitrogen in the Maroni and Oyapock Rivers.  相似文献   

6.
We investigate sources of both dissolved and particulate organic carbon in the St Lawrence River from its source (the Great Lakes outlet) to its estuary, as well as in two of its tributaries. Special attention is given to seasonal interannual patterns by using data collected on a bi‐monthly basis from mid‐1998 to mid‐2003. δ13C measurements in dissolved inorganic carbon, dissolved organic carbon (DOC) and particulate organic carbon (POC), as well as molar C : N in particulate organic matter (POM), are used to bring insight into the dynamic between aquatic versus terrigenous sources. In addition, 14C activities of DOC were measured at the outlet of the St Lawrence River to its estuary to assess a mean age of the DOC exported to the estuary. In the St Lawrence River itself, aquatically produced POC dominates terrestrially derived POC and is depleted in 13C by approximately 12‰ versus dissolved CO2. In the Ottawa River, the St Lawrence River's most important tributary, the present dataset did not allow for convincing deciphering of POC sources. In a small tributary of the St Lawrence River, aquatically produced POC dominates in summer and terrestrially derived POC dominates in winter. DOC seems to be dominated by terrestrially derived organic matter at all sampling sites, with some influence of DOC derived from aquatically produced POC in summer in the St Lawrence River at the outlet of the Great Lakes and in one of its small tributaries. The overall bulk DOC is relatively recent (14C generally exceeding 100% modern carbon) in the St Lawrence River at its outlet to the estuary, suggesting that it derives mainly from recent organic matter from topsoils in the watershed. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

7.
在博斯腾湖选取了13个点位,于2012年5、8、10月测定表层和底层水体中的颗粒有机碳、溶解有机碳、颗粒有机氮和叶绿素a含量.结果显示颗粒和溶解有机碳在表层水体中的浓度与底层相近.博斯腾湖水体中颗粒有机碳的季节变化十分明显,其平均浓度从春季(0.64 mg/L)到夏季(0.71 mg/L)变化不大,但在秋季变化十分显著(浓度达1.58 mg/L).其中西北湖区和湖心区颗粒有机碳的季节变化最明显,东部湖区颗粒有机碳的季节变化相对较小.博斯腾湖水体的颗粒有机碳在春、秋两季主要来自外源输入,在夏季受水体中浮游生物的影响较大.博斯腾湖水体中溶解有机碳也具有一定的季节变化,夏季浓度(平均为9.3 mg/L)略低于春、秋两季(平均为10.3 mg/L).溶解有机碳在河口区的季节变化最强,其夏季浓度明显偏低,主要是由于开都河河水的稀释作用.总体上,博斯腾湖水体中溶解有机碳浓度的变化主要受外部因素的影响.  相似文献   

8.
Effective biodegradation of organic compounds is one of the major objectives while optimizing biological drinking water treatment processes. Enhancing the biological activated carbon (BAC) filter performance with nutrient addition was studied using chemically pre-treated and ozonated lake water. Three parallel pilot-scale biofilters were operated: one with phosphorus addition, one with a mixture of inorganic nutrients addition, and one as a reference. The addition of nutrients had no statistically significant influence on the natural organic matter (NOM) removal when monitored by total organic carbon (TOC), UV absorbance, and assimilable organic carbon (AOC). However, the addition of nutrients significantly increased the heterotrophic plate count (HPC) bacteria of the filter effluent, while the adenosine triphosphate (ATP) analysis of the attached bacteria did not show any increase in BAC filters. It seemed that in BAC filters the bacterial growth was limited by phosphorus, but the increased bacteria could not attach themselves during the relatively short acclimatization period.  相似文献   

9.
Carbon transported by rivers is an important component of the global carbon cycle. Here, we report on organic carbon transport along the third largest river in China, the Songhua River, and its major tributaries. Water samples were collected seasonally or more frequently to determine dissolved organic carbon (DOC) and particulate organic carbon (POC) concentrations and C/N and stable carbon isotopic ratios. Principal component analysis and multiple regression analysis of these data, in combination with hydrological records for the past 50 years, were used to determine the major factors influencing the riverine carbon fluxes. Results indicate that the organic carbon in the Songhua River basin is derived mainly from terrestrial sources. In the 2008–2009 hydrological year, the mean concentrations of DOC and POC were 5.87 and 2.36 mg/L, and the estimated fluxes of the DOC and POC were 0.30 and 0.14 t·km?2·year?1, respectively. The riverine POC and DOC concentrations were higher in subcatchments with more cropland, but the area‐specific fluxes were lower, owing to decreased discharge. We found that hydrological characteristics and land‐use type (whether forest or cropland) were the most important factors influencing carbon transport in this system. Agricultural activity, particularly irrigation, is the principal cause of changes in water discharge and carbon export. Over the last 50 years, the conversion of forest to cropland has reduced riverine carbon exports mainly through an associated decrease in discharge following increased extraction of water for irrigation.  相似文献   

10.
为深入理解纳木错湖水及入湖河流中溶解有机碳（DOC）和总氮（TN）浓度的季节变化特征及其影响因素,于2012-2013年不同季节对纳木错2个站点及流域内21条主要入湖河流进行采样及分析,采用统计学方法初步探讨纳木错水体和21条河流DOC和TN浓度季节变化特征.结果表明,河流DOC平均浓度范围为0.763~1.537 mg/L,TN平均浓度范围为0.179~0.387 mg/L.21条入湖河流DOC浓度在春末夏初和夏季达到高值,冬季为低值,TN浓度季节变化趋势大体上与DOC浓度相反.湖泊水体DOC和TN浓度范围分别为2.42~8.08和0.237~0.517 mg/L,明显分别高于河水中的浓度.湖泊DOC浓度季节变化趋势与河流一致,而TN浓度无明显的季节性变化.河水DOC浓度的季节变化和空间差异受控于河流的补给方式,湖水DOC浓度受湖泊内部藻类等水生植物活动和河流外源输入的影响.DOC等有机质的分解是影响纳木错流域湖水和河水TN浓度的重要原因.  相似文献   

11.
Total organic carbon fluxes of the Red River system (Vietnam)   总被引：1，自引：0，他引：1       下载免费PDF全文
Riverine transport of organic carbon from terrestrial ecosystems to the oceans plays an important role in the global carbon cycle. The Red River is located in Southeast Asia where river discharge, sediment loads and fluxes of elements (carbon, nitrogen and phosphorus) associated with suspended solids have been dramatically altered over past decades as a result of reservoir impoundment and land use, population, and climate change. Dissolved organic carbon (DOC) and particulate organic carbon (POC) concentrations were measured monthly at four stations of the Red River system from January 2008 to December 2010. The results reveal that POC changed synchronically with total suspended solids (TSS) concentration and with the river discharge, whereas no clear trend was observed for DOC concentration. The mean value of total organic carbon (TOC = DOC + POC) flux in the delta of the Red River was 31.5 × 1013 ± 4.0 × 1013 MgC.yr?1 (range 27.9–35.8 × 1013 MgC.yr?1 which leads to a specific TOC flux of 2012 ± 255 kgC.km?2.yr?1 during this 2008–2010 period. About 80% of the TOC flux was transferred to the estuary during the rainy season as a consequence of the higher river water discharge. The high mean value of the POC:Chl‐a ratio (1585 ± 870 mgC.mgChl‐a?1) and the moderate C:N ratio (7.3 ± 0.1) in the water column system suggest that organic carbon in the Red River system is mainly derived from erosion and soil leaching in the basin. The effect of two new dam impoundments in the Red River was also observable with lower TOC fluxes in 2010 compared with 2008. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

12.
To establish the influence of phytoplankton blooms on the dynamics and sources of dissolved organic carbon (DOC) in Lake Taihu, the concentrations and stable carbon isotope values (δ13C) of DOC and particulate organic carbon (POC) were analyzed, along with environmental factors, including water temperature, chlorophyll a (Chl a) concentration, phytoplankton community and total bacterial abundance, from March to August 2013 at five sites in Lake Taihu. Significant differences were observed in the DOC concentrations and δ13CDOC values at the sampling sites. On average, the proportion of DOC in the total organic carbon (TOC) pool ranged from 30% ± 10% to 81% ± 7%. POC was positively associated with both Chl a concentration and cyanobacteria biomass, suggesting that cyanobacteria blooms contribute to the POC pool in Lake Taihu. Depleted 13C in DOC relative to POC was observed in August, indicating that DOC was partially derived from POC in August. However, Chl a explained only 40% of the variation in DOC in the entirety of Lake Taihu, and at two sites far from the estuary, the contribution of allochthonous carbon was less than 50% in August. These results suggested a greater influence of allochthonous sources on the DOC pool. Moreover, the biodegradability of DOC was further determined by the total dissolved carbohydrates to DOC ratio (TCHO/DOC), specific UV absorbance (SUVA254), and the concentrations of bioavailable DOC (BDOC). On average, 17% of the variation in DOC was attributable to the BDOC pool, and the BDOC concentration correlated positively with Chl a, cyanobacteria biomass, and total bacterial abundance, suggesting that cyanobacteria–derived DOC is biodegradable and is preferentially utilized by bacteria.  相似文献   

13.
Arctic glaciers are rapidly responding to global warming by releasing organic carbon (OC) to downstream ecosystems. The glacier surface is arguably the most biologically active and biodiverse glacial habitat and therefore the site of important OC transformation and storage, although rates and magnitudes are poorly constrained. In this paper, we present measurements of OC fluxes associated with atmospheric deposition, ice melt, biological growth, fluvial transport and storage (in superimposed ice and cryoconite debris) for a supraglacial catchment on Foxfonna glacier, Svalbard (Norway), across two consecutive years. We found that in general atmospheric OC input (averaging 0.63 ± 0.25 Mg a-1 total organic carbon, i.e. TOC, and 0.40 ± 0.22 Mg a-1 dissolved organic carbon, i.e. DOC) exceeded fluvial OC export (0.46 ± 0.04 Mg a-1 TOC and 0.36 ± 0.03 Mg a-1 DOC). Early in the summer, OC was mobilised in snowmelt but its release was delayed by temporary storage in superimposed ice on the glacier surface. This delayed the export of 28.5% of the TOC in runoff. Biological production in cryoconite deposits was a negligible potential source of OC to runoff, while englacial ice melt was far more important on account of the glacier's negative ice mass balance (–0.89 and –0.42 m a-1 in 2011 and 2012, respectively). However, construction of a detailed OC budget using these fluxes shows an excess of inputs over outputs, resulting in a net retention of OC on the glacier surface at a rate that would require c. 3 years to account for the OC stored as cryoconite debris. © 2018 John Wiley & Sons, Ltd.  相似文献   

14.
The rapid development of instrumental analysis during the last few years simplified organic carbon analyses to such a degree that it can be extensively used in ecological researches. Particularly gas chromatography techniques as well as non-dispersive infra-red gas analyzers (IRGA) greatly improved the organic carbon analysis. The increase of sensitivity of analytical methods to a submicro-level causes the initial steps of collecting and preparing the given material as well as the grade in which the sampling is representative to be the decisive elements for the correctness of the obtained information. In the DOC and POC analyses the important problem consists of the choice of the technique and the materials that are to separate these two fractions. POC concentration changes in lake waters indicate a close relation of this fraction to the eutrophication degree of the separate lakes as well as a dependence of the seasonal changeability and the vertical stratification of POC on the productivity and the biomass of the phytoplankton. DOC concentrations, on the other hand, in the lakes under investigation ranged from 5 to 50 mg/1, being as a rule slightly higher in the inshore parts, covered with macrophytes, than in the open waters. In the summer season the DOC concentration became significantly lower as compared with the remaining seasons. The DOC/POC ratio oscillated between 2 and 20, mostly amounting to 7.  相似文献   

15.
Peatlands cover a very small area of the Earth, but store globally significant quantities of carbon and export disproportionate quantities of fluvial organic carbon, especially when the peatlands are degraded or disturbed. Peatland headwater catchments with high concentrations of dissolved and particulate organic carbon (DOC and POC) provide an opportunity to investigate the possibility of competing effects that could lead to enhanced or diminished turnover of DOC in the presence of POC. Both POC and DOC can be degraded by light and microbes, producing smaller molecules and releasing CO2 and CH4 to the atmosphere, and POC can inhibit light penetration, stabilize DOC by providing adsorption sites and providing surfaces for microbes to interact with DOC. However, the majority of peatland fluvial carbon studies are conducted using filtered water samples, and measure only the DOC concentration, so the impact of the particulate organic matter (POM) on in-stream processing of organic carbon is relatively unknown. It is therefore possible that studies have underestimated carbon transformations in rivers as they have not considered the interaction of the particulate material on the dissolved concentrations; there could be higher losses than previously estimated, increasing the contribution of peatland headwaters to GHG emissions. In this study, we assessed if the current approach of DOC degradation studies accurately represent the impact of POM on DOC degradation, by quantifying DOC production from POM, and therefore POC, over time in water with manipulated POM concentrations. Both filtered and unfiltered water lost 60% of the DOC over 70 hours, whereas the treatment with additional POM lost only 35%. The results showed that filtering does not significantly impact the DOC degradation rates; however, when the POC concentration was doubled, there was a significant reduction in DOC degradation, suggesting that filtering would still be necessary to get accurate rates of DOC transformations in waters with high POC concentrations.  相似文献   

16.
Dissolved organic carbon (DOC) is the smallest amount of organic carbon present in aquifer systems and is typically dwarfed by amounts of particulate organic carbon (POC) and adsorbed organic carbon (AOC). Research conducted over the last half century, however, has shown that these dissolved, particulate, and adsorbed compartments interact dynamically with each other. That suggests the hypothesis that the bioavailability of DOC in groundwater may indicate the bioavailability of the associated POC and AOC compartments as well. If that proves to be the case, it would greatly simplify the process of evaluating the bioavailability of total organic carbon present in groundwater systems. That hypothesis was examined by (1) comparing DOC bioavailability between two aquifers receiving modern atmospheric recharge, but with the recharge passing through POC/AOC sources of substantially different geologic ages, and (2) measuring POC/AOC bioavailability in sediments in from two aquifers before and after injection with bioavailable DOC consisting of dissolved sugars and emulsified vegetable oil. The results of both comparisons are consistent with the hypothesis that DOC bioavailability in groundwater reflects the bioavailability of the associated POC and AOC compartments and vice versa. Thus, DOC bioavailability may be a useful indicator of an aquifer's potential to drive reduction/oxidation processes that affect the chemical quality of groundwater.  相似文献   

17.
Riverine total suspended sediment (TSS) at the lower reach section of the Zengjiang River, a low‐turbidity river in the southern China, was sampled on a 4‐week basis from March 2002 to February 2003. The gross TSS was divided into sedimentary and suspended fractions (SED and SUS) by the sedimentation method. Organic carbon and nitrogen, 14C and 13C were analysed using an elemental analyser and accelerator mass spectrometer respectively. The results show that particulate organic carbon (POC) yield is 0·8 × 106 g km?2 year?1 in the Zengjiang River drainage basin, which is about one‐tenth of that in the Zhujiang (Pearl) River drainage basin. The C/N ratio demonstrates that aquatic biomass is the major contributor to POC in the Zengjiang River. The average share of aquatic biomass in the SUS‐fraction POC and SED‐fraction POC is about 88·89% and 62·76% respectively, with a substantial seasonal variation. δ13C values of SUS‐fraction POC (?26·56 to ? 22·89‰) is slightly lighter than that of SED‐fraction POC (?25·05 to ? 22·20‰), indicating that the contribution of aquatic biomass to δ13C values is more pronounced in the SUS‐fraction POC than in the SED‐fraction POC. The ‘bomb’–14C signature is not detected in the POC of Zengjiang River, and the contribution from geological organic carbon is very little. Δ14C values of the SED‐fraction POC vary from ? 44 to ? 223‰, and the Δ14C values of the SUS‐fraction POC vary from ? 33 to ? 165‰. For most paired samples, the SED‐fraction POC is generally more depleted in 14C than that of its counterpart SUS‐fraction POC. Compared with other small mountainous rivers, the 14C enrichment of POC in the Zengjiang River indicates slight drainage basin erosion. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

18.
This study provides the first detailed estimate of riverine organic carbon fluxes in British rivers, as well as highlighting major gaps in organic carbon data in national archives. Existing data on organic carbon and suspended solids concentrations collected between 1989 and 1993, during routine monitoring by the River Purification Boards (RPBs) in Scotland and the National River Authorities (NRAs) in England and Wales, were used with annual mean flows to estimate fluxes of dissolved and particulate organic carbon (DOC and POC) in British rivers. Riverine DOC exports during 1993 varied from 7·7–103·5 kg ha−1 year−1, with a median flux of 31·9 kg ha−1 year−1 in the 85 rivers for which data were available. There was a trend for DOC fluxes to increase from the south and east to the north and west. A predictive model based on mean soil carbon storage in 17 catchments, together with regional precipitation totals, explained 94% of the variation in the riverine DOC exports in 1993. This model was used to predict riverine DOC fluxes in regions where no organic carbon data were available. Calculated and predicted fluxes were combined to produce an estimate for exports of DOC to tidal waters in British rivers during 1993 of 0·68±0·07 Mt. Of this total, rivers in Scotland accounted for 53%, England 38% and Wales 9%. Scottish blanket peats would appear to be the largest single source of DOC exports in British rivers. An additional 0·20 Mt of organic carbon were estimated to have been exported in particulate form in 1993, approximately two–thirds of which was contributed by English rivers. It is suggested that riverine losses of organic carbon have the potential to affect the long-term dynamics of terrestrial organic carbon pools in Britain and that rivers may regulate increases in soil carbon pools brought about by climate change. © 1997 by John Wiley & Sons, Ltd.  相似文献   

19.
Peatlands are among the largest long‐term soil carbon stores, but their degradation can lead to significant carbon losses. This study considers the carbon budget of peat‐covered sites after restoration, following degradation by past wildfires. The study measured the carbon budget of eight sites: four restored‐revegetated sites, two unrestored bare soil control sites, and two intact vegetated controls over two years (2006–2008). The study considered the following flux pathways: dissolved organic carbon (DOC); particulate organic carbon (POC); dissolved carbon dioxide (CO2); primary productivity; net ecosystem respiration, and methane (CH4). The study shows that unrestored, bare peat sites can have significant carbon losses as high as 522 ± 3 tonnes C/km2/yr. Most sites showed improved carbon budgets (decreased source and/or increased sink of carbon) after restoration; this improvement was mainly in the form of a reduction in the size of the net carbon source, but for one restored site the measured carbon budget after four years of restoration was greater than observed for vegetated controls. The carbon sequestration benefit of peatland restoration would range between 122 and 833 tonnes C/km2/yr. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

20.
Global peatlands store an unparalleled proportion of total global organic carbon but it is vulnerable to erosion into fluvial systems. Fluvial networks are being recognized as areas of carbon transformation, with eroded particulate organic carbon processed to dissolved organic carbon and CO2. Existing studies indicate biodegradation and photodegradation as key processes controlling the transformation of organic carbon in fluvial systems, with initial concentrations of dissolved organic carbon (DOC) identified as a control on the rate of carbon mineralization. This study manipulates temperature and incident light intensity to investigate carbon mineralization rates in laboratory simulations of peatland sediment transport into fluvial systems. By directly measuring gaseous CO2 emissions from sampled stream water, the relationship of temperature and light intensity with carbon efflux is identified. In simulations where sediment (as particulate organic matter, POM) is absent, temperature is consistently the dominant factor influencing carbon efflux rates. This influence is independent of the initial DOC concentration of the water sample. In simulations where POM was added, representing a peatland river receiving eroded terrestrial sediment, initial DOC concentration predicts 79% of the variation in total gaseous carbon efflux whereas temperature and light intensity predict 12% and 3%, respectively. When sampled stream water's mineralization rates in the presence of added POM are analysed independently, removing DOC as a model variable, the dominant variable affecting CO2 efflux is opposite for each sample. This study presents novel data suggesting peatland erosion introduces further complexity to dynamic stream systems where rates of carbon transformation processes and the influence of specific environmental variables are interdependent. Anthropogenic climate change is identified as a leading risk factor perpetuating peatland erosion; therefore, understanding the fate of terrestrial sediment in rivers and further quantifying the benefits of protecting peatland soils will be of increasing importance to carbon budgeting and ecosystem function studies.  相似文献   

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