scholarly journals Interactive comment on “Dissolved Organic Carbon Driven by Rainfall Events from a Semi-arid Catchment during Concentrated Rainfall Season in the Loess Plateau, China” by Linhua Wang et al.

2019 ◽  
Author(s):  
Anonymous
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Loess Plateau ◽  
The Loess Plateau ◽  
Rainfall Events ◽  
Rainfall Season ◽  
Semi Arid

scholarly journals Dissolved Organic Carbon Driven by Rainfall Events from a Semi-arid Catchment during Concentrated Rainfall Season in the Loess Plateau, China

2019 ◽  
Author(s):  
Linhua Wang ◽  
Haw Yen ◽  
Xinhui E ◽  
Liding Chen ◽  
Yafeng Wang
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
The Loess Plateau ◽  
Rainfall Season ◽  
Doc Export ◽  
Doc Concentration ◽  
Doc Flux ◽  
Event Based ◽  
Runoff Discharge ◽  
Semi Arid

Abstract. Dissolved organic carbon (DOC) transported by surface runoff has been identified as an important role of the global carbon cycle. Despite there being many studies on DOC concentration and flux, but little information is available in semi-arid catchments of the Loess Plateau Region (LPR). The primary goal of this study was to quantify DOC exported from a sequence of runoff events during the concentrated rainfall season. In addition, factors that affect DOC export from a small headwater catchment will be investigated accordingly. Runoff discharge and DOC concentration were monitored at the outlet of the Yangjuangou catchment in Yanan, Shaanxi Province, China. The results showed that DOC concentration was highly variable (1.91–34.70 mg L−1), with event-based DOC concentrations ranging from 4.08 to 15.66 mg L−1. The mean monthly DOC flux loading from the catchment was 94.73–110.17 kg km−2 from June to September, while the event-based DOC flux ranged from 0.08 to 2.81 kg km−2. Intra-events of rainfall amount and runoff discharge led to event-based/monthly differences in DOC concentration and flux. Hysteresis analysis showed a nonlinear relationship between DOC concentration and discharge in the runoff process. Our results highlighted the advantages of high-frequency monitoring for DOC export and indicated that DOC export from a catchment is largely influenced by the interaction of rainfall and antecedent conditions for a rainfall event. Engineering and scientists can take advantage of the derived results to better develop advanced field monitoring work. In addition, release of DOC runoff can take quantified during hydrological and biogeochemical processes within catchments in LPR.

scholarly journals Dissolved organic carbon driven by rainfall events from a semi-arid catchment during concentrated rainfall season in the Loess Plateau, China

2019 ◽  
Vol 23 (7) ◽  
pp. 3141-3153 ◽  
Author(s):  
Linhua Wang ◽  
Haw Yen ◽  
Xinhui E ◽  
Liding Chen ◽  
Yafeng Wang
Keyword(s):  
Organic Carbon ◽  
The Loess Plateau ◽  
Rainfall Events ◽  
Rainfall Season ◽  
Doc Export ◽  
Doc Concentration ◽  
Doc Flux ◽  
Event Based ◽  
Runoff Discharge ◽  
Semi Arid

Abstract. Dissolved organic carbon (DOC) transported by runoff has been identified as an important role in the global carbon cycle. Despite there being many studies on DOC concentration and flux, little information is available for the semi-arid catchments of the Loess Plateau region (LPR). The primary goal of this study was to quantify DOC exported and driven by a sequence of rainfall events during the concentrated rainfall season. In addition, factors that affect DOC export from a small headwater catchment will be investigated accordingly. Runoff discharge and DOC concentration were monitored at the outlet of the Yangjuangou catchment in Yanan, Shaanxi Province, China. The results showed that DOC concentration was highly variable, with event-based DOC concentrations ranging from 5.14 to 13.14 mg L−1. Hysteresis analysis showed a nonlinear relationship between DOC concentration and flow rate in the hydrological process. The monthly DOC flux loading from the catchment was varied from 94.73 to 110.17 kg km−2, while the event-based DOC flux ranged from 0.18 to 2.84 kg km−2 in the period of June to September. Variations of event-driven DOC concentration contributed slightly to a difference in DOC flux, whereas intra-events of rainfall amount and runoff discharge led to evident differences in DOC export. In conclusion, our case results highlighted the advantages of high-frequency monitoring for DOC export and indicated that event-driven DOC export is largely influenced by the interaction of catchment hydrology and antecedent condition within a catchment. Engineers and scientists can take advantage of the derived results to better develop advanced field monitoring work. In addition, more studies are needed to investigate the magnitude of terrestrial DOC export in response to projected climate change at larger spatio-temporal scales, which may have implications for the carbon balance and carbon cycle model from an ecologically restored catchment in the LPR.

scholarly journals Characteristics of wet dissolved carbon deposition in a semi-arid catchment at the Loess Plateau, China

2018 ◽  
Vol 15 (11) ◽  
pp. 3345-3356
Author(s):  
Linhua Wang ◽  
Haw Yen ◽  
Liding Chen ◽  
Xinhui E ◽  
Yafeng Wang
Keyword(s):  
Loess Plateau ◽  
Carbon Deposition ◽  
Terrestrial Ecosystems ◽  
External Input ◽  
The Loess Plateau ◽  
Dissolved Carbon ◽  
Rainfall Season ◽  
Event Based ◽  
Global Carbon ◽  
Semi Arid

Abstract. Wet dissolved carbon deposition is a critical node of the global carbon cycle, but little is known about dissolved organic and inorganic carbon (DOC and DIC) concentrations and fluxes in the semi-arid areas of the Loess Plateau Region (LPR). In this study, we measured variations in DOC and DIC concentrations in rainfalls at Yangjuangou Ecological Restoration and Soil and Water Observatory. Rainwater samples were collected in 16 rainfall events from July to September and the event-based, monthly concentrations and fluxes of DOC and DIC were quantified. The results showed that the event-based concentrations and fluxes of DOC and DIC were highly variable, ranging from 0.56 to 28.71 mg C L−1 and from 3.47 to 17.49 mg C L−1, respectively. The corresponding event-based fluxes ranged from 0.21–258.36 mg C m−2 and from 4.12 to 42.32 mg C m−2. The monthly concentrations of DOC and DIC were 24.62 and 4.30 (July), 3.58 and 10.52 (August), and 1.01 and 5.89 (September) mg C L−1, respectively. Thus, the monthly deposition fluxes of DOC and DIC were 541.64/94.60, 131.03/385.03, and 44.44/259.16 mg C m−2 for July, August, and September, respectively. In addition, the concentrations of DOC and DIC for the concentrated rainfall season (July–September) in the studied catchment were 7.06 and 7.00 mg C L−1, respectively. The estimated annual wet dissolved carbon depositions were 1.91 and 1.89 g C m−2 yr−1 for DOC and DIC, respectively. The results of this study suggest the variation in concentrations and fluxes of DOC and DIC and explore that these variation may be related to the dissolved carbon source and the rainfall characteristics during the concentrated rainfall season in the semi-arid catchment of the LPR. Furthermore, these results also suggest that dissolved carbon may be an important external input of carbon into terrestrial ecosystems.

scholarly journals Soil carbon fractions and enzyme activities under different vegetation types on the Loess Plateau of China

2016 ◽  
Author(s):  
Haixin Zhang ◽  
Quanchao Zeng ◽  
Shaoshan An ◽  
Yanghong Dong ◽  
Frédéric Darboux
Keyword(s):  
Alkaline Phosphatase ◽  
Organic Carbon ◽  
Loess Plateau ◽  
Enzyme Activities ◽  
Soil Layer ◽  
Shaanxi Province ◽  
The Loess Plateau ◽  
Sucrase Activity ◽  
Carbon Fractions ◽  
Carbon Fraction

Abstract. Vegetation restoration was effective way of protecting soil erosion and water conservation on the Loess Plateau. Carbon fractions and enzyme activities were sensitive parameters for assessment of soil remediation through revegetation. Forest, forest steppe and grassland soils were collected at 0–5 cm and 5–20 cm soil layers in Yanhe watershed, Shaanxi Province. Urease, sucrase, alkaline phosphatase, soil organic carbon (SOC), microbial biomass carbon (MBC), easily oxidized organic carbon (EOC) and dissolved organic carbon (DOC) were measured. The results showed that carbon fraction contents and enzyme activities in the same soil layer followed the order that forest was higher than others. Carbon fraction contents and enzyme activities appeared that the 0–5 cm was higher than 5–20 cm soil layer. In addition, correlation analysis showed that urease activity was related to SOC, MBC, EOC and DOC at 0–5 cm layer; it was correlated with SOC, MBC and EOC at 5–20 cm layer. Sucrase activity had significant positive relationship with SOC, MBC and EOC. Alkaline phosphatase activity was related to EOC and DOC at 0–5 cm layer; it was correlated with MBC and EOC at 5–20 cm layer. The CCA reflected the relationship between sucrase activity and SOC. The contributions from the various forms of carbon fractions and enzyme activities as evaluated by the canonical coefficient of CV were on the order of SOC > DOC > MBC > EOC; sucrase > urease > alkaline phosphatase. Vegetation type was an important factor influencing the variation of soil enzyme activities and carbon fractions on the Loess Plateau.

scholarly journals Soil organic carbon dynamics following afforestation in the Loess Plateau of China

2013 ◽  
Vol 10 (7) ◽  
pp. 11181-11211 ◽  
Author(s):  
N. Lu ◽  
J. Liski ◽  
R. Y. Chang ◽  
A. Akujärvi ◽  
X. Wu ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Loess Plateau ◽  
Carbon Fixation ◽  
Temporal Dynamics ◽  
Climatic Factors ◽  
Early Stage ◽  
Arable Land ◽  
The Loess Plateau ◽  
Successional Stage

Abstract. Soil organic carbon (SOC) is the largest terrestrial carbon pool and sensitive to land use and cover change; its dynamics is critical for carbon cycling in terrestrial ecosystems and the atmosphere. In this study, we combined a modeling approach and field measurements to examine the temporal dynamics of SOC following afforestation of former arable land at six sites under different climatic conditions in the Loess Plateau during 1980–2010. The results showed that the measured mean SOC increased to levels higher than before afforestation when taking the last measurements (i.e., at age 25 to 30 yr), although it decreased in the first few years at the wetter sites. The accumulation rates of SOC were 1.58 to 6.22% yr–1 in the upper 20 cm and 1.62 to 5.15% yr–1 in the upper 40 cm of soil. The simulations reproduced the basic characteristics of measured SOC dynamics, suggesting that litter input and climatic factors (temperature and precipitation) were the major causes for SOC dynamics and the differences among the sites. They explained 88–96, 48–86 and 57–74% of the variations in annual SOC changes at the soil depths of 0–20, 0–40, and 0–100 cm, respectively. Notably, the simulated SOC decreased during the first few years at all the sites, although the magnitudes of decreases were small at the drier sites. This suggested that the modeling may be advantageous in capturing SOC changes at finer time scale. The discrepancy between the simulation and measurement was a result of uncertainties in model structure, data input, and sampling design. Our findings indicated that afforestation promoted soil carbon sequestration at the study sites, which is favorable for further restoration of the vegetation and environment. Afforestation activities should decrease soil disturbances to reduce carbon release in the early stage. The long-term strategy for carbon fixation capability of the plantations should also consider the climate and site conditions, species adaptability, and successional stage of recovery.

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