Effects of catchment characteristics and disturbances on storage and export of dissolved organic carbon in a boreal headwater stream

2004 ◽  
Vol 61 (8) ◽  
pp. 1447-1460 ◽  
Author(s):  
Graham R Hillman ◽  
Joseph C Feng ◽  
Cecilia C Feng ◽  
Yonghe Wang
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Castor Canadensis ◽  
Flood Wave ◽  
Sources And Sinks ◽  
Organic Debris ◽  
Beaver Dam ◽  
Debris Dams ◽  
The Mean ◽  
Mean Concentration

The transportation of large amounts of dissolved organic carbon (DOC) down a stream within a 15.51-km2 catchment in Alberta, Canada, related directly to events, such as high rainfall and beaver (Castor canadensis) dam failures, that created major disturbances. A 2.3-km section of the stream was drastically altered in June 1994 when a flood wave resulting from a breached beaver dam deposited large amounts of debris and sediment within the section. Results from stream DOC-storage analyses, in which a difference method was used, suggest that the organic-debris dams created by the failed dam event served as both sources and sinks for DOC. Discharge and DOC measurements at hydrometric stations located at intervals along the stream indicated that storage of DOC on the catchment was strongly influenced by the presence of wetlands and beaver. In 1994 and 1995, disturbances occurring during periods totalling 17 days and 28 days accounted for 94% (1374 kg·km–2) and 84% (204 kg·km–2), respectively, of the amount of DOC exported from the catchment. DOC concentrations in the stream were greatest (77.0 mg·L–1) near the top of the catchment and decreased progressively downstream to the catchment outlet, where the mean concentration was 23.3 mg·L–1.

scholarly journals Distribution Characteristics and Pollution Assessment of Soil Heavy Metals under Different Land-Use Types in Xuzhou City, China

2019 ◽  
Vol 11 (7) ◽  
pp. 1832 ◽  
Author(s):  
Aman Fang ◽  
Jihong Dong ◽  
Yingli An
Keyword(s):  
Heavy Metals ◽  
Land Use ◽  
Organic Carbon ◽  
Mining Area ◽  
Distribution Characteristics ◽  
Grassland Soils ◽  
Risk Levels ◽  
Land Use Types ◽  
The Mean ◽  
Mean Concentration

Xuzhou, as a mining city in China, has been experiencing 130 years of coal mining and processing. To explore the spatial distribution characteristics and pollution status of soil heavy metals (Cr, Cd, As, Hg, Zn, and Pb) under different land-use types, a total of 2697 topsoil samples were collected in all of the areas (except for water) of Xuzhou in 2016. Overall, the mean concentrations of Cr (70.266 mg/kg), Cd (0.141 mg/kg), As (10.375 mg/kg), Hg (0.036 mg/kg), Zn (64.788 mg/kg), and Pb (24.84 mg/kg) in Xuzhou soils were lower than the environmental quality standard for soils (GB15618-1995). However, the mean concentrations of Cr, Hg, and Pb exceeded their corresponding background values, with the mean concentration of Hg being almost three times its background value. For different land-use types, the highest mean concentration of Cr was concentrated in grassland soils. The mean concentrations of Cd, As, Zn, and Pb in mining area soils were higher than those in the other soils. The mean concentration of Hg was the highest in the built-up area soils. Based on the potential ecological risk assessment, the forestland, garden land, grassland, and others were at low and moderate risk levels, the farmland and mining area were at low, moderate, and high risk levels, and the built-up area was at various risk levels in Xuzhou. There was a significant positive correlation between Cr, Pb, and Hg concentrations and the corresponding organic carbon contents in the farmland, built-up area, garden land, forestland, and other soils ( p < 0.01 ). A high degree of correlation was found between Cr and Hg concentrations, as well as organic carbon contents in grassland soils, with values of p < 0.05 and p < 0.01 , respectively. An obvious correlation could be seen between Hg concentrations and organic carbon contents in mining area soils ( p < 0.01 ).

Colour - mass balances and colour - dissolved organic carbon relationships in lakes and streams in central Ontario

1997 ◽  
Vol 54 (12) ◽  
pp. 2789-2795 ◽  
Author(s):  
Lewis A Molot ◽  
Peter J Dillon
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Upper Bound ◽  
Balance Model ◽  
Strongly Correlated ◽  
Mass Balances ◽  
Loss Coefficients ◽  
The Mean ◽  
Study Sites

Colour and dissolved organic carbon (DOC) concentrations and mass balances were measured for seven unproductive lakes and 20 tributary streams between June 1980 and May 1992. Individual observations of colour, which measures an unknown DOC fraction assumed to be principally humic, were not good predictors of discrete DOC concentrations for any of the study sites. Long-term mean colour was, however, strongly correlated with long-term mean DOC concentrations in streams and lakes. Colour behaved differently from the total DOC pool in lakes. Lake retention and loss coefficients for colour were always higher than corresponding values for the total DOC pool, and the mean annual colour/DOC ratios in lake outflows were always less than the corresponding ratios in lake inputs, indicating that the coloured fraction was preferentially removed or photooxidized. A steady-state mass balance model was used to estimate the upper bound for the average coloured fraction of DOC in each lake. The upper bound for the seven lakes ranged from 34 to 88%, increasing with increasing colour, DOC, and total phosphorus.

scholarly journals REVIEW: DISSOLVED ORGANIC CARBON CONTENT OF BIOCHAR VARYING WITH THE TYPE OF FEEDSTOCK AND THE PYROLYSIS TEMPERATURE

2017 ◽  
Author(s):  
Enrico MANCINELLI ◽  
Edita BALTRĖNAITĖ ◽  
Pranas BALTRĖNAS ◽  
Raimondas GRUBLIAUSKAS ◽  
Giorgio PASSERINI
Keyword(s):  
Linear Regression ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Pyrolysis Temperature ◽  
Organic Carbon Content ◽  
Mean Values ◽  
Slow Pyrolysis ◽  
Different Types ◽  
Production Temperature ◽  
The Mean

The present review aims at investigating the influence of the type of feedstock and the production temperature on the dissolved organic carbon (DOC) content of biochar (BC) from slow pyrolysis. To collect data from the literature, peer reviewed articles in English published in 2007–2016 were considered. The different types of BC were classified depending on the fractions of cellulose and lignin and the type of feedstock. A linear regression (R-squared = 0.5) of the mean values of DOC content (g/kg) of BC was calculated in the range of 350–800 °C with slope (–0.005) and intercept (4.1) significant at p &amp;lt;0.05. Irrespective of the type of feedstock, slow pyrolysis with temperatures above 500 °C would be a proper choice for limiting the mean DOC content of BC to values in the range of 0.28–1.01 g/kg.

scholarly journals The dynamics and export of dissolved organic carbon from subtropical small mountainous rivers during typhoon and non-typhoon periods

2017 ◽  
Author(s):  
Tsung-Yu Lee ◽  
Li-Chin Lee ◽  
Jr-Chuan Huang ◽  
Shih-Hao Jien ◽  
Thomas Hein ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Water Discharge ◽  
Dilution Effect ◽  
Carbon Export ◽  
Doc Concentration ◽  
The Mean ◽  
Doc Flux ◽  
Small Mountainous Rivers

Abstract. Small mountainous rivers (SMRs) are important conveyors of the land-to-ocean organic carbon export. However, relatively few studies have focused on dissolved organic carbon (DOC) compared to particulate organic carbon. In a long-term project (2002 to 2014), stream DOC was monitored in three neighboring subtropical small mountainous rivers of Taiwan. The objective was to relate DOC concentrations to water discharge and to quantify DOC flux during typhoon and non-typhoon periods. Seasonal fluctuations of DOC concentrations were closely correlated with air temperature at all sampling stations. During non-typhoon periods, increasing water discharge led to decreasing DOC concentrations due to a dilution effect. However, during typhoon periods, DOC concentrations increased with some lead time along the hydrograph and reached the annual maximum which likely sources from a significant input of litter and upper soil layers. The mean DOC concentration of the studied systems (

Statistical patterns of carbonates and total organic carbon on soils of Tuber rufum and T. melanosporum (black truffle) brûlés

Soil Research ◽  
2009 ◽  
Vol 47 (2) ◽  
pp. 206 ◽  
Author(s):  
L. G. García-Montero ◽  
I. Valverde-Asenjo ◽  
P. Díaz ◽  
C. Pascual
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Principal Component ◽  
Soil Conditions ◽  
Carbonate Content ◽  
Black Truffle ◽  
Total Carbonate ◽  
The Mean ◽  
New Hypothesis ◽  
Mean Concentration

The ascocarps of several truffle species, such as Tuber rufum, are harvested in T. melanosporum brûlés; these species reduce T. melanosporum production. Some authors argue that this competition might be due to the evolution of organic matter in the soil. However, soil conditions in brûlés have yet to be clarified, and most studies on T. melanosporum fail to supply statistical data. We propose a study of 40 soils to compare the values for total organic carbon (TOC), pH, and carbonates inside the brûlés with the values for the outer edges of the same brûlés, where T. rufum ascocarps are collected. A principal component analysis relates the soils from the inner brûlés with high active carbonate content and soils outside the brûlés with high TOC and total carbonate content. ANOVA analyses indicate that the mean concentration of active carbonate, total CO32–, and % active/total carbonate differ significantly depending on soil location, but there are no significant differences for pH and TOC. These results lead us to propose a new hypothesis: T. melanosporum mycelia may solubilise active carbonate (<50 μm) and the other carbonate fractions (>50 μm) inside the brûlés; however the environmental conditions of the brûlés could favour a secondary carbonate precipitation with a net increase in active carbonate. This increase would counterbalance carbonate losses from leaching, which would in turn favour T. melanosporum mycelia, suggesting a feedback process.

Relation between Mercury Concentrations in Walleye (Stizostedion vitreum vitreum) and Northern Pike (Esox lucius) in Ontario Lakes and Influence of Environmental Factors

1991 ◽  
Vol 48 (1) ◽  
pp. 132-139 ◽  
Author(s):  
C. D. Wren ◽  
W. A. Scheider ◽  
D. L. Wales ◽  
B. W. Muncaster ◽  
I. M. Gray
Keyword(s):  
Environmental Factors ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Northern Pike ◽  
Esox Lucius ◽  
Stizostedion Vitreum ◽  
Pike Esox Lucius ◽  
The Mean ◽  
Highly Correlated

We examined the relation between mercury levels in walleye (Stizostedion vitreum vitreum) and northern pike (Esox lucius) in Ontario lakes. Walleye and northern pike occurred together in 79 of the 346 study lakes. The length-standardized mercury concentrations in coexisting walleye and northern pike in the 79 lakes were highly correlated (r2 = 0.60). The mean mercury concentrations in walleye and northern pike of standardized length from these lakes were 0.65 and 0.52 μg/g, respectively. Lacustrine characteristics associated with lake dystrophy (dissolved organic carbon and iron) were positively correlated with mercury levels in both species. Variables associated with acidity (pH and alkalinity) and hardness (calcium, conductivity, and magnesium) were negatively correlated with mercury concentrations in northern pike but not walleye.

scholarly journals Short-Term Effects of Changing Soil Management Practices on Soil Quality Indicators and Crop Yields in Greenhouses

Agronomy ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 582
Author(s):  
Jerónimo Salinas ◽  
David Meca ◽  
Fernando del Moral
Keyword(s):  
Organic Carbon ◽  
Soil Quality ◽  
Soil Solution ◽  
Quality Indicators ◽  
Management Practices ◽  
Crop Yields ◽  
Soil Quality Indicators ◽  
Short Term ◽  
The Mean ◽  
Mean Concentration

The short-term responses of soil quality indicators are important for assessing the effects of new management practices and addressing threats to crop yields in greenhouses. The aim of this study was to assess, during three consecutive cropping seasons, the effect of a sustainable management package (CRTMP)—which includes the on-site reuse of greenhouse crop residues and tillage—in comparison with conventional management, based on fertigation only (CMP), on certain biochemical soil quality indicators and crop yields. CRTMP significantly increased (p < 0.05) the values of total organic carbon (TOC), particulate organic carbon (POC), light fraction (LF), water soluble organic carbon (WSOC), and dehydrogenase (DH) and β-glucosidase (GL) activities at a depth of 0–15 cm, as well as the mean concentration of nitrates in the soil solution. In addition, a significant Pearson’s correlation (p < 0.01) found between the indicators suggested a balanced improvement of soil biological activity and nutritional soil state. Nonetheless, the significant (p < 0.05) increases in the mean concentration of chlorides in the soil solution and electrical conductivity (p < 0.05) increased the risk of salinization, which may have affected the concentration of nitrates in the petiole sap and total production in CRTMP, which were significantly lower than in CMP. Nevertheless, the proportion of premium product was significantly higher in CRTMP, while the proportion of non-commercial production decreased.

scholarly journals Long-term stability of marine dissolved organic carbon emerges from a neutral network of compounds and microbes

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
A. Mentges ◽  
C. Feenders ◽  
C. Deutsch ◽  
B. Blasius ◽  
T. Dittmar
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Deep Sea ◽  
Mechanistic Model ◽  
Term Stability ◽  
Long Term Stability ◽  
Heterotrophic Microorganisms ◽  
Wide Range ◽  
The Mean

AbstractDissolved organic carbon (DOC) is the main energy source for marine heterotrophic microorganisms, but a small fraction of DOC resists microbial degradation and accumulates in the ocean. The reason behind this recalcitrance is unknown. We test whether the long-term stability of DOC requires the existence of structurally refractory molecules, using a mechanistic model comprising a diverse network of microbe-substrate interactions. Model experiments reproduce three salient observations, even when all DOC compounds are equally degradable: (i) >15% of an initial DOC pulse resists degradation, but is consumed by microbes if concentrated, (ii) the modelled deep-sea DOC reaches stable concentrations of 30–40 mmolC/m3, and (iii) the mean age of deep-sea DOC is several times the age of deep water with a wide range from <100 to >10,000 years. We conclude that while structurally-recalcitrant molecules exist, they are not required in the model to explain either the amount or longevity of DOC.

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