Spatiotemporal characteristics of carbon dioxide and methane in cascade reservoirs in the Nanpanjiang-Hongshui River Basin

doi:10.3969/j.issn.1000-5641.2026.03.001

Abstract

Abstract:

In order to understand the spatiotemporal characteristics and key regulatory factors of greenhouse gas emissions from karst cascade reservoirs, four dammed reservoirs with different hydrological regulation characteristics in the Nanpanjiang-Hongshui River Basin were studied. The results show significant regional characteristics of the carbon dioxide (CO₂) and methane (CH₄) concentrations and emission fluxes from the reservoirs. The diffusive fluxes of CO₂ and CH₄ in the watershed were 4.98~260.11 mmol·m⁻²·d⁻¹ and 0.01~0.27 mmol·m⁻²·d⁻¹, respectively, of which the CO₂ fluxes were higher than the average level of reservoirs in China. Estimation of the greenhouse gas emissions from the reservoirs indicated that the total greenhouse gas emissions of the basin system have clear spatial differences. Hydraulic load is the key factor regulating the greenhouse gas emission of karst dammed rivers in the Nanpanjiang-Hongshui River Basin. The CO₂ emission flux of reservoirs was found to decrease first and then increase with the increase of hydraulic load, and there is a correlation between hydraulic load and methane concentration in the reservoirs. This study is of great significance for a comprehensive understanding of the greenhouse gas emission law and control mechanism of karst dammed rivers and can provide theoretical support and data reference for carbon emission assessment as well as carbon reduction in the karst reservoirs.

Key words: karst basin, cascade reservoir, carbon dioxide, methane, hydraulic load

CLC Number:

X142

Rongrong YANG, Ziyan CHEN, Yi WU, Lijun HOU, Xia LIANG. Spatiotemporal characteristics of carbon dioxide and methane in cascade reservoirs in the Nanpanjiang-Hongshui River Basin[J]. J* E* C* N* U* N* S*, 2026, 2026(3): 1-16.

Figures/Tables 12

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水库名称	运行年份	流域面积^#/ km²	水库面积/ km²	水库长度/ km	水库容量^#/ (10⁸ m³)	水力停留时间^#/d	最大水深^#/ m	入库流量^#/ (m³· s^–1)	泄流量^#/ (m³· s^–1)	水力负荷/ (m·d^–1)	调节类型
柴石滩	2002	4556	9.11	38	4.37	104.25	60	31.5	48.4	0.39	年调节
龙滩	2009	98500	41.83	72	272.70	192.53	140	1777.8	1639.4	0.48	年调节
岩滩	1995	106580	55.09	55	33.50	22.03	55	1464.6	1760.0	1.54	月调节
大化	1986	112200	4.62	20	9.64	5.61	25	1796.8	1990.0	7.84	日调节

关键参数	参数值	数值范围	n
WT/℃	22.00±3.57	13.28, 29.54	80
DO 浓度/(mg·L⁻¹)	6.88±2.92	0.02, 18.25	80
Chl-a 含量/(μg·L⁻¹)	7.44±12.45	2.13, 71.98	66
DOC 浓度/(mg·L⁻¹)	1.71±0.92	0.93, 4.48	80
Ca²⁺浓度/(mg·L⁻¹)	50.94±7.25	30.92, 63.64	80
TP浓度/(mg·L⁻¹)	0.03±0.02	0.01, 0.14	80
TN浓度/(mg·L⁻¹)	2.70±1.56	0.97, 7.40	80
CO₂浓度/(μmol·L⁻¹)	179.79±178.74	28.48, 776.77	64
CH₄浓度/(μmol·L⁻¹)	0.88±6.12	0.01, 54.05	79
CO₂扩散通量/(mmol·m⁻²·d⁻¹)	61.08±65.51	4.98, 260.11	28
CH₄扩散通量/(mmol·m⁻²·d⁻¹)	0.05±0.05	0.01, 0.27	37

水文地质状态	水库名称	CO₂/(10³ t·a⁻¹)	CH₄/(t·a⁻¹)	CO_2eq/(10³ t·a⁻¹)
筑坝前	柴石滩	4.98	5.30	5.11
	龙滩	24.70	21.63	25.24
	岩滩	33.68	11.83	33.97
	大化	1.69	0.62	1.70
筑坝后	柴石滩	3.82	2.53	3.88
	龙滩	55.27	12.37	55.58
	岩滩	23.08	15.82	23.48
	大化	4.71	0.38	4.72
碳排放增量	柴石滩	–1.16	–2.77	–1.23
	龙滩	30.57	–9.26	30.34
	岩滩	–10.60	3.99	–10.49
	大化	3.02	–0.24	3.02

参数	回归模型	r²	p值	dƒ
CO₂浓度	y =1138.842−22.095 DO−15.676 c	0.384	DO: p=0.001; c: p<0.001	62
CH₄浓度	y = −0.118 + 0.011 WT−0.011 H	0.203	WT: p=0.006; H: p=0.011	62

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