基于二元模型和贝叶斯混合模型的青海湖表层沉积物有机碳来源解析

doi:10.12118/j.issn.1000-6060.2025.697

摘要/Abstract

摘要：

湖泊沉积物有机碳来源是揭示湖泊碳循环与流域环境演变规律的核心内容之一。目前，关于青海湖沉积物有机碳来源的量化研究仍较为缺乏，且不同溯源指标常得出不一致的结论。基于已发表文献的青海湖表层沉积物有机质碳氮比（C/N）和有机碳同位素值（δ¹³C_org）数据，应用二元模型和贝叶斯混合（MixSIAR）模型，对陆源与内源有机碳的贡献比例进行定量解析。结果表明：（1）青海湖表层沉积物有机碳以陆源输入为主，MixSIAR模型计算的陆源平均贡献率为70.2%；内源部分以刚毛藻属为主要来源（贡献率平均26.0%），沉水植物贡献较低（平均3.8%）。（2）沉积物有机碳来源的组成具有明显的空间异质性，陆源贡献比例与水深呈负相关。（3）基于δ¹³C_org的MixSIAR模型在量化有机碳来源方面的可靠性更高，而基于C/N的二元模型易受端元取值不确定性及早期成岩作用影响。研究揭示了青海湖表层沉积物有机碳的来源组成与空间分布规律，可为高寒咸水湖泊的有机碳埋藏机制提供参考。

关键词: 有机碳来源, 二元模型, 贝叶斯混合模型, 表层沉积物, 青海湖

Abstract:

Determining the sources of organic carbon in lake sediments is key to unraveling carbon cycling in lakes and the evolution of watershed environments. Currently, quantitative studies on sources of organic carbon in sediments from Lake Qinghai remain relatively limited, and disparate source-tracing proxies often yield inconsistent conclusions. Drawing on the published carbon-nitrogen ratio (C/N) of organic matter and organic carbon isotope (δ¹³C_org) data for surface sediments from Lake Qinghai, this study employed the Binary model and Bayesian mixing model to quantitatively resolve the contribution of terrestrial-derived and autochthonous organic carbon to the surface sediments, demonstrating that (1) Organic carbon in the surface sediments of Lake Qinghai is predominantly derived from terrestrial inputs, with an average contribution rate of 70.2%, as estimated using the MixSIAR model; the autochthonous part is mainly from the genus Cladophora (with an average contribution rate of 26.0%), and the contribution of submerged plants is relatively low (with a mean value of 3.8%). (2) The composition of organic carbon sources in the sediments displays distinct spatial heterogeneity, where the terrestrial contribution is negatively correlated with the water depth. (3) Comparison of the models indicates that the δ¹³C_org-based MixSIAR model exhibits higher reliability in quantifying sources of organic carbon, whereas the C/N-based Binary model is prone to uncertainties in selecting the end-member value and early diagenesis. This study revealed the source, composition, and spatial distribution patterns of organic carbon in the surface sediments of Lake Qinghai, providing a reference for evaluating the organic carbon burial mechanism in alpine saltwater lakes.

Key words: source of organic carbon, binary model, Bayesian mixing model, surface sediments, Lake Qinghai

陈婉婷, 马育军, 姜传礼, 韩陈晓语. 基于二元模型和贝叶斯混合模型的青海湖表层沉积物有机碳来源解析[J]. 干旱区地理, 2026, 49(9): 1803-1814.

CHEN Wanting, MA Yujun, JIANG Chuanli, HAN Chenxiaoyu. Sources of organic carbon in surface sediments of Lake Qinghai based on Binary model and Bayesian mixing model[J]. Arid Land Geography, 2026, 49(9): 1803-1814.

图/表 9

表1

图1

表2

图2

表3

表4

不同碳源对青海湖表层沉积物有机碳贡献的计算结果"

表层沉积物	采样区域	水深/m	TOC/%	TN/%	C/N	贡献比例/%
表层沉积物	采样区域	水深/m	TOC/%	TN/%	C/N	陆源	内源
QHH-1^*	西北湖区	20.1	3.5	0.42	8.33	56.7	43.3
QHH-2^*	西北湖区	26.6	4.8	0.70	6.86	38.4	61.6
QHH-3^*	北深水区	28.0	3.4	0.32	10.63	75.0	25.0
QHH-4^*	北深水区	27.5	3.5	0.48	7.29	44.5	55.5
QHH-5^*	北深水区	26.7	4.6	0.55	8.36	57.0	43.0
QHH-6^*	东北湖区	26.3	2.1	0.19	11.05	77.6	22.4
QHH-8^*	北深水区	27.3	2.6	0.39	6.67	35.4	64.6
QHH-9^*	北深水区	28.0	4.1	0.53	7.74	50.1	49.9
QHH-10^*	北深水区	27.4	2.7	0.37	7.30	44.6	55.4
QHH-11^*	布哈河口区	12.0	1.7	0.21	8.10	54.2	45.8
QHH-12^*	西南湖区	18.6	1.6	0.20	8.00	53.1	46.9
QHH-13^*	西南湖区	24.7	2.7	0.48	5.63	15.7	84.3
QHH-14^*	湖心区	27.8	3.3	0.50	6.60	34.3	65.7
QHH-15^*	南深水区	28.0	4.3	0.72	5.97	23.1	76.9
QHH-16^*	南深水区	27.7	3.3	0.40	8.25	55.8	44.2
QHH-17^*	南深水区	26.6	1.4	0.14	10.00	70.8	29.2
QHH-18^*	南深水区	25.1	4.7	0.53	8.87	61.8	38.2
QHH-19^*	西南湖区	21.9	3.5	0.56	6.25	28.3	71.7
QHH-20^*	东南湖区	24.5	1.9	0.33	5.76	18.6	81.4
QHH-21^*	东南湖区	26.5	3.1	0.38	8.16	54.8	45.2
QHH-22^*	东南湖区	25.2	1.9	0.28	6.79	37.3	62.7
QHH-23^*	东南湖区	27.0	3.5	0.48	7.29	44.5	55.5
QHH-24^*	南深水区	27.5	3.9	0.56	6.96	40.0	60.0
QHH-25^*	南深水区	27.0	4.0	0.55	7.27	44.3	55.7
QHH-26^*	东南湖区	23.5	1.8	0.22	8.18	55.1	44.9
QHH-27^*	东南湖区	26.0	3.3	0.50	6.60	34.3	65.7
1^#**	151码头	22.0	2.6	0.25	10.54	74.5	25.5
3^#**	湖心区	25.0	2.7	0.25	11.18	78.3	21.7
4^#**	江西沟码头	25.0	2.71	0.25	10.92	76.8	23.2
5^#**	布哈河口区	11.9	1.47	0.15	10.15	71.9	28.1
6^#**	布哈河口区	9.2	2.60	0.23	11.42	79.6	20.4
7^#**	西北湖区	24.5	2.70	0.25	10.64	75.1	24.9
8^#**	青海湖农场	15.0	1.77	0.17	10.25	72.6	27.4
9^#**	沙柳河口区	10.0	1.73	0.16	11.09	77.8	22.2
10^#**	泉吉河口区	5.0	1.14	0.10	11.28	78.9	21.1
11^#**	黑马河口区	8.6	0.89	0.09	9.53	67.3	32.7
1^***	西南湖区	-	1.77	0.25	7.20	43.3	56.7
2^***	南深水区	-	2.20	0.30	7.25	44.0	56.0
3^***	东南湖区	-	2.16	0.31	7.07	41.5	58.5
5^***	东北湖区	-	1.03	0.19	5.40	10.5	89.5
6^***	西北湖区	-	2.26	0.30	7.53	47.6	52.4
7^***	北深水区	-	1.38	0.21	6.71	36.1	63.9
8^***	北深水区	-	2.40	0.34	7.09	41.7	58.3
9^***	东南湖区	-	2.11	0.31	6.84	38.2	61.8
10^***	西南湖区	-	1.95	0.27	7.33	45.1	54.9
11^***	西南湖区	-	2.00	0.28	7.03	40.8	59.2
12^***	南深水区	-	1.90	0.25	7.49	47.1	52.9
15^***	东北湖区	-	1.59	0.21	7.71	49.8	50.2
16^***	西北湖区	-	1.90	0.23	8.11	54.3	45.7
17^***	湖心区	-	1.97	0.27	7.26	44.1	55.9
18^***	布哈河口区	-	1.62	0.23	7.09	41.8	58.2

表4

图3

表5

图4

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端元C/N变化	陆源有机碳贡献率变化量/%
端元C/N变化	平均变化量	最大变化量
R_e=17±1	±0.65	±1.35
R_e=17±2	±1.29	±2.98
R_e=17±3	±1.96	±4.97
R_i=5±0.1	±0.73	±1.41
R_i=5±0.2	±1.43	±2.84
R_i=5±0.3	±2.13	±4.30

表层沉积物	样品水深/m	δ¹³C_org/‰	陆源贡献比例/%		沉水植物贡献比例/%		刚毛藻属贡献比例/%
表层沉积物	样品水深/m	δ¹³C_org/‰	平均值	标准差	平均值	标准差	平均值	标准差
S01	26.5	-27.5	69.2	0.205	3.5	0.046	27.3	0.186
S02	26.0	-28.0	65.7	0.218	3.3	0.043	31.0	0.203
S03	26.0	-27.6	68.3	0.211	3.6	0.050	28.1	0.190
S04	26.0	-27.6	68.3	0.203	3.6	0.047	28.1	0.185
S05	26.0	-27.8	67.9	0.210	3.4	0.046	28.7	0.193
S06	25.5	-27.6	68.8	0.211	3.6	0.050	27.5	0.190
S07	25.0	-27.4	69.9	0.199	3.6	0.047	26.5	0.179
S08	25.0	-27.3	70.5	0.200	3.8	0.051	25.7	0.178
S09	25.0	-28.1	65.1	0.218	3.4	0.046	31.5	0.202
S10	24.0	-28.6	61.3	0.223	3.2	0.042	35.4	0.207
S11	24.0	-27.1	71.6	0.195	3.8	0.052	24.6	0.171
S12	24.0	-27.7	68.5	0.212	3.4	0.046	28.1	0.194
S13	24.0	-27.6	68.1	0.214	3.7	0.049	28.2	0.194
S14	24.0	-26.6	74.0	0.188	4.0	0.057	22.0	0.163
S15	24.0	-28.0	66.1	0.217	3.5	0.047	30.4	0.198
S16	24.0	-27.8	67.6	0.212	3.4	0.046	29.0	0.195
S17	24.0	-27.3	69.9	0.207	3.7	0.049	26.4	0.187
S18	22.0	-27.0	72.1	0.195	3.7	0.049	24.2	0.175
S19	20.4	-26.8	72.7	0.198	3.9	0.054	23.4	0.173
S20	18.5	-27.0	72.1	0.197	3.9	0.053	24.0	0.174
S21	18.0	-26.9	72.5	0.196	3.9	0.055	23.6	0.172
S22	13.8	-26.1	76.5	0.180	4.2	0.062	19.3	0.149
S23	11.5	-26.5	74.6	0.187	4.1	0.058	21.2	0.160
S24	10.0	-23.7	81.2	0.178	7.0	0.108	11.8	0.099
1F-1	24.7	-28.2	73.0	0.112	2.8	0.024	24.2	0.097