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 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 carbon deposition in a semi-arid catchment at Loess Plateau, China

2018 ◽  
Author(s):  
Linhua Wang ◽  
Haw Yen ◽  
Liding Chen ◽  
Xinhui E ◽  
Yafeng Wang
Keyword(s):  
Carbon Cycle ◽  
Loess Plateau ◽  
Large Scale ◽  
Carbon Deposition ◽  
Deposition Process ◽  
Global Carbon Cycle ◽  
Deposition Flux ◽  
Dust Deposition ◽  
Global Carbon ◽  
Semi Arid

Abstract. Wet carbon deposition is a critical node of the global carbon cycle, but little is known about dissolved organic and inorganic carbon (DOC and DIC) variation and flux in semi arid area of the Loess Plateau Region (LPR). In this study, concentration of DOC and DIC in rainfall was monitored in the period of July to September 2015 at Yangjuangou catchment in the LPR. Results showed that the Volume-Weighted Mean (VWM) concentration of DOC and DIC were 24.62 and 4.30 (July), 3.58 and 10.52 (August), 1.01 and 5.89 (September) mg C L−1. VWM concentrations of DOC and DIC for the concentrated rainy season (July–September) in the studied region were 7.06 and 7.00 mg C L−1, respectively. In addition, the monthly deposition flux 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. The estimated annual wet carbon depositions were 1.91, 1.89 g C m−2 yr−1 for DOC and DIC, which were higher than those of other sites and lower than those in the tropical and sub-tropical sites. Furthermore, the loess dust deposition process provides soil parental material in soil formation process and might be another source of carbon at the LPR. Therefore, the given results reflect characteristics of wet carbon deposition process during concentrated rainfall season in a semi-arid catchment of the LPR. Our preliminary results suggest that further investigation is needed on carbon source and deposition flux from atmosphere at long term temporal and large scale for revealing the global carbon cycle.

scholarly journals Evolutional Characteristics of Regional Meteorological Drought and Their Linkages with Southern Oscillation Index across the Loess Plateau of China during 1962–2017

2020 ◽  
Vol 12 (18) ◽  
pp. 7237
Author(s):  
Ming Li ◽  
Fuqiang Cao ◽  
Guiwen Wang ◽  
Xurong Chai ◽  
Lianzhi Zhang
Keyword(s):  
Loess Plateau ◽  
Southern Oscillation Index ◽  
Temporal Evolution ◽  
Southern Oscillation ◽  
Arid Area ◽  
The Loess Plateau ◽  
Drought Period ◽  
Humid Area ◽  
Semi Arid ◽  
Meteorological Droughts

The Loess Plateau of China (CLP) is located in the transition zone from a semi-humid climate zone to semi-arid and arid climate zones. It is influenced by the westerly circulation, plateau monsoon, and East Asian monsoon circulation, and the drought disasters across the CLP have obvious regional characteristics. In this study, climate regionalization was performed by a spatial hierarchical cluster approach based on the gridded datasets of monthly precipitation across the CLP from 1961 to 2017. Then, the standardized precipitation index (SPI) was used to explore the temporal evolution of regional meteorological droughts. Finally, wavelet methods were used to investigate the drought cycles in each homogeneous subregion and the linkages between SPI and the Southern Oscillation Index (SOI). The results show that: (1) Spatially, the CLP can be divided into four homogeneous regions, namely, Ordos Plateau semi-arid area (Region I), Northern Shanxi hilly semi-humid area (Region II), Longzhong plateau cold-arid area (Region III), and Fenwei Plain and Shaanxi-Shanxi hilly semi-humid area (Region IV). (2) There are apparent differences in the temporal evolution of meteorological droughts in different subregions, but two wet periods from the 1960s to 1980s and 2010s, and a drought period in the 1990s, can be found in each subregion. (3) There is a significant drought cycle of 3–8 years in the four subregions, and the first main cycles of drought variation are not completely consistent. (4) The linkages between SPI and SOI are time- and space-dependent and the phase differences are dominated by in-phase. The strongest correlations between the two time series occur in the 1980s in the four subregions. The results of this research have important implications for the establishment of drought monitoring programs in homogeneous climate regions, and informed decision making in water resource management.

scholarly journals Hydrologic feasibility of artificial forestation in the semi-arid Loess Plateau of China

2011 ◽  
Vol 15 (8) ◽  
pp. 2519-2530 ◽  
Author(s):  
T. T. Jin ◽  
B. J. Fu ◽  
G. H. Liu ◽  
Z. Wang
Keyword(s):  
Loess Plateau ◽  
Large Scale ◽  
Regional Scale ◽  
Negative Relationship ◽  
Northern Region ◽  
Shaanxi Province ◽  
Stand Age ◽  
Mean Annual Precipitation ◽  
The Loess Plateau ◽  
Semi Arid

Abstract. Hydrologic viability, in terms of moisture availability, is fundamental to ecosystem sustainability in arid and semi-arid regions. In this study, we examine the spatial distribution and after-planting variations of soil moisture content (SMC) in black locust tree (Robinia pseudoacacia L.) plantings in the Loess Plateau of China at a regional scale. Thirty sites (5 to 45 yr old) were selected, spanning an area of 300 km by 190 km in the northern region of the Shaanxi Province. The SMC was measured to a depth of 100 cm at intervals of 10 cm. Geographical, topographic and vegetation information was recorded, and soil organic matter was evaluated. The results show that, at the regional scale, SMC spatial variability was most highly correlated with rainfall. The negative relationship between the SMC at a depth of 20–50 cm and the stand age was stronger than at other depths, although this relationship was not significant at a 5 % level. Watershed analysis shows that the after-planting SMC variation differed depending upon precipitation. The SMC of plantings in areas receiving sufficient precipitation (e.g., mean annual precipitation (MAP) of 617 mm) may increase with stand age due to improvements in soil water-holding capacity and water-retention abilities after planting. For areas experiencing water shortages (e.g., MAP = 509 mm), evapotranspiration may cause planting soils to dry within the first 20 yr of growth. It is expected that, as arid and semi-arid plantings age, evapotranspiration will decrease, and the soil profile may gradually recover. In extremely dry areas (e.g., MAP = 352 mm), the variation in after-planting SMC with stand age was found to be negligible. The MAP can be used as an index to divide the study area into different ecological regions. Afforestation may sequentially exert positive, negative and negligible effects on SMCs with a decrease in the MAP. Therefore, future restoration measures should correspond to the local climate conditions, and the MAP should be a major consideration for the Loess Plateau. Large-scale and long-term research on the effects of restoration projects on SMCs is needed to support more effective restoration policies. The interaction between afforestation and local environmental conditions, particularly water availability to plants, should be taken into account in afforestation campaigns in arid and semi-arid areas.

An integrated simulation model for a semi-arid agroecosystem in the Loess Plateau of northwestern China

1996 ◽  
Vol 52 (1) ◽  
pp. 83-111 ◽  
Author(s):  
Hsin-i Wu ◽  
W.Michael Childress ◽  
Yang Li ◽  
Richard D. Spence ◽  
Jizhou Ren
Keyword(s):  
Simulation Model ◽  
Loess Plateau ◽  
Northwestern China ◽  
The Loess Plateau ◽  
Integrated Simulation ◽  
Semi Arid
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