The response of dissolved organic matter in different sedimentary regimes to nitrogen–phosphorus imbalanced input: insights from microcosm experiments

Abstract

Lakes regulate the global carbon cycle, with sediment dissolved organic matter (DOM) playing a pivotal role in organic carbon (OC) sequestration. However, the effects of imbalanced nitrogen (N) and phosphorus (P) inputs on sediment DOM dynamics and carbon sequestration remain unclear. We conducted short-term microcosm experiments using muddy (MS) and sandy (SS) lake sediments under N/P input ratios of 5:1, 15:1, and 45:1. The results revealed that MS sediments were enriched with protein-like (~50%) bioavailable DOM, whereas SS sediments were dominated by aromatic DOM (~90%), exhibiting greater humification and superior carbon retention. Protein-like components responded rapidly to nutrient changes, whereas humic-like substances exhibited greater persistence. Notably, elevated N inputs accelerated the degradation of recalcitrant humic substances (C4) according to MS. Mantel tests revealed that sedimentary organic carbon (SOC) in MS was highly significantly positively correlated with TN (p < 0.001), whereas that in SS was highly significantly positively correlated with TP (p < 0.001). PLS‒SEM analysis further revealed that the N/P input ratio inhibited carbon sequestration in both sediment types through distinct pathways: In muddy sediments, the N/P input ratio primarily altered the DOM composition, whereas in sandy sediments, the N/P input ratio regulated both the DOM properties and nutrient availability. Our results demonstrate that sediment type regulates DOM transformation and early-stage carbon retention under N/P imbalance, with muddy and sandy sediments exhibiting fundamentally different response pathways. These findings highlight the importance of incorporating sediment heterogeneity into assessments of lake carbon cycling and nutrient management under eutrophication pressure.

Graphical abstract

Keywords

Nitrogen and phosphorus imbalance / Dissolved organic matter / Lake sediment / Carbon sequestration

Highlight

	● N/P imbalance accelerates degradation of recalcitrant carbon.
	● Protein-like DOM is a highly reactive indicator of nutrient perturbation.
	● Sandy sediments exhibit superior carbon retention despite lower initial activity.
	● N/P stoichiometry is a more critical driver than absolute nutrient loads.

References

[1] Brodowski S , Amelung W , Haumaier L , Abetz C , Zech W . (2005). Morphological and chemical properties of black carbon in physical soil fractions as revealed by scanning electron micro-scopy and energy-dispersive X-ray spectroscopy. Geoderma, 128(1−2): 116–129

[2] Chen H Z , Guo S Z , Zhang S H , Tang Y S , Zhang T L , Lv X , Wang D J , Zhong J C . (2025). Comprehensive effects of lake dredging on microbial community and dissolved organic matter compositions in surface sediments. Ecological Indicators, 175: 113566

[3] Drake T W , Raymond P A , Spencer R G M . (2018). Terrestrial carbon inputs to inland waters: a current synthesis of estimates and uncertainty. Limnology and Oceanography Letters, 3(3): 132–142

[4] Freeman C , Evans C D , Monteith D T , Reynolds B , Fenner N . (2001). Export of organic carbon from peat soils. Nature, 412(6849): 785–785

[5] He Y , Peng S S , Liu Y W , Li X Y , Wang K , Ciais P , Arain M A , Fang Y Y , Fisher J B , Goll D . et al. (2020). Global vegetation biomass production efficiency constrained by models and observations. Global Change Biology, 26(3): 1474–1484

[6] Heathcote A J , Anderson N J , Prairie Y T , Engstrom D R , del Giorgio P A . (2015). Large increases in carbon burial in northern lakes during the Anthropocene. Nature Communications, 6(1): 10016

[7] Heathcote A J , Downing J A . (2012). Impacts of eutrophication on carbon burial in freshwater lakes in an intensively agricultural landscape. Ecosystems, 15(1): 60–70

[8] Hertkorn N , Harir M , Cawley K M , Schmitt-Kopplin P , Jaffé R . (2016). Molecular characterization of dissolved organic matter from subtropical wetlands: a comparative study through the analysis of optical properties, NMR and FTICR/MS. Biogeosciences, 13(8): 2257–2277

[9] Huguet C, Kim J H, de Lange G J, Sinninghe Damsté J S, Schouten S (2009). Effects of long term oxic degradation on the U37K′, TEX₈₆ and BIT organic proxies. Organic Geochemistry 40(12): 1188–1194

[10] Jiang T , Bravo A G , Skyllberg U , Björn E , Wang D Y , Yan H Y , Green N W . (2018). Influence of dissolved organic matter (DOM) characteristics on dissolved mercury (Hg) species composition in sediment porewater of lakes from southwest China. Water Research, 146: 146–158

[11] Kastowski M , Hinderer M , Vecsei A . (2011). Long-term carbon burial in European lakes: analysis and estimate. Global Biogeochemical Cycles, 25(3): GB3019

[12] Kellerman A M , Dittmar T , Kothawala D N , Tranvik L J . (2014). Chemodiversity of dissolved organic matter in lakes driven by climate and hydrology. Nature Communications, 5(1): 3804

[13] Kim H N , Park J H . (2024). Monitoring of soil EC for the prediction of soil nutrient regime under different soil water and organic matter contents. Applied Biological Chemistry, 67(1): 1

[14] Li J Y , Han G X , Wang G M , Liu X L , Zhang Q Q , Chen Y W , Song W M , Qu W D , Chu X J , Li P G . (2022). Imbalanced nitrogen–phosphorus input alters soil organic carbon storage and mineralisation in a salt marsh. CATENA, 208: 105720

[15] Li K , Zhao B , Han L L , Ge T T , Wang N , Yao P . (2024). Sediment porewaters serve as a transient organic carbon pool at the land-ocean interface. Water Research, 263: 122151

[16] Li W , Jia X X , Li M , Wu H M . (2019). Insight into the vertical characteristics of dissolved organic matter in 5-m soil profiles under different land-use types on the Loess Plateau. Science of the Total Environment, 692: 613–621

[17] Li W T , Chen S Y , Xu Z X , Li Y , Shuang C D , Li A M . (2014). Characterization of dissolved organic matter in municipal wastewater using fluorescence PARAFAC analysis and chromatography multi-excitation/emission scan: a comparative study. Environmental Science & Technology, 48(5): 2603–2609

[18] Liu B Q , Wu R J , Xue B , Gao R L , An H , Liu L C , Ndzana G M , Du L T , Kamran M . (2024a). Effects of nutrient addition on the composition and chemical characteristics of soil dissolved organic matter in a desert steppe in northern China. Land Degradation & Development, 35(4): 1365–1380

[19] Liu C , Shen Q S , Gu X Z , Zhang L , Han C , Wang Z D . (2023). Burial or mineralization: origins and fates of organic matter in the water–suspended particulate matter–sediment of macrophyte- and algae-dominated areas in Lake Taihu. Water Research, 243: 120414

[20] Liu D , Shi K , Chen P , Yan N X , Ran L S , Kutser T , Tyler A N , Spyrakos E , Woolway R I , Zhang Y L . et al. (2024b). Substantial increase of organic carbon storage in Chinese lakes. Nature Communications, 15(1): 8049

[21] Liu S L , Deng Y Q , Jiang Z J , Wu Y C , Huang X P , Macreadie P I . (2020). Nutrient loading diminishes the dissolved organic carbon drawdown capacity of seagrass ecosystems. Science of the Total Environment, 740: 140185

[22] Mahowald N , Jickells T D , Baker A R , Artaxo P , Benitez-Nelson C R , Bergametti G , Bond T C , Chen Y , Cohen D D , Herut B . et al. (2008). Global distribution of atmospheric phosphorus sources, concentrations and deposition rates, and anthropogenic impacts. Global Biogeochemical Cycles, 22(4): GB4026

[23] Maie N , Parish K J , Watanabe A , Knicker H , Benner R , Abe T , Kaiser K , Jaffé R . (2006). Chemical characteristics of dissolved organic nitrogen in an oligotrophic subtropical coastal ecosystem. Geochimica et Cosmochimica Acta, 70(17): 4491–4506

[24] Mao R, Zhang X H, Li S Y, Song C C (2017). Long-term phosphorus addition enhances the biodegradability of dissolved organic carbon in a nitrogen-limited temperate freshwater wetland. Science of the Total Environment, 605–606: 332–336

[25] Mendonça R , Müller R A , Clow D , Verpoorter C , Raymond P , Tranvik L J , Sobek S . (2017). Organic carbon burial in global lakes and reservoirs. Nature Communications, 8(1): 1694

[26] Meyer N , Welp G , Rodionov A , Borchard N , Martius C , Amelung W . (2018). Nitrogen and phosphorus supply controls soil organic carbon mineralization in tropical topsoil and subsoil. Soil Biology and Biochemistry, 119: 152–161

[27] Mitchell P J , Simpson A J , Soong R , Simpson M J . (2015). Shifts in microbial community and water-extractable organic matter composition with biochar amendment in a temperate forest soil. Soil Biology and Biochemistry, 81: 244–254

[28] Peng S , Wang F P , Wei D B , Wang C P , Ma H J , Du Y G . (2025). Application of FTIR two-dimensional correlation spectroscopy (2D-COS) analysis in characterizing environmental behaviors of microplastics: a systematic review. Journal of Environmental Sciences, 147: 200–216

[29] Peng Y F , Peng Z P , Zeng X T , Houx III J H . (2019). Effects of nitrogen-phosphorus imbalance on plant biomass production: a global perspective. Plant and Soil, 436(1−2): 245–252

[30] Peñuelas J , Poulter B , Sardans J , Ciais P , van der Velde M , Bopp L , Boucher O , Godderis Y , Hinsinger P , Llusia J . et al. (2013). Human-induced nitrogen–phosphorus imbalances alter natural and managed ecosystems across the globe. Nature Commu-nications, 4(1): 2934

[31] Peñuelas J , Sardans J . (2022). The global nitrogen-phosphorus imbalance. Science, 375(6578): 266–267

[32] Peñuelas J , Sardans J , Rivas-Ubach A , Janssens I A . (2012). The human-induced imbalance between C, N and P in Earth’s life system. Global Change Biology, 18(1): 3–6

[33] Qian W T , Ma B , Li X Y , Zhang Q , Peng Y Z . (2019). Long-term effect of pH on denitrification: high pH benefits achieving partial-denitrification. Bioresource Technology, 278: 444–449

[34] Redfield A C . (1958). The biological control of chemical factors in the environment. American Scientist, 46: 205–221

[35] Regnier P , Resplandy L , Najjar R G , Ciais P . (2022). The land-to-ocean loops of the global carbon cycle. Nature, 603(7901): 401–410

[36] Ren H Y , Wang G X , Ding W C , Li H , Shen X , Shen D B , Jiang X , Qadeer A . (2023). Response of dissolved organic matter (DOM) and microbial community to submerged macrophytes restoration in lakes: a review. Environmental Research, 231: 116185

[37] Sistla S A , Schimel J P . (2012). Stoichiometric flexibility as a regulator of carbon and nutrient cycling in terrestrial ecosystems under change. New Phytologist, 196(1): 68–78

[38] Sobek S , Durisch-Kaiser E , Zurbrügg R , Wongfun N , Wessels M , Pasche N , Wehrli B . (2009). Organic carbon burial efficiency in lake sediments controlled by oxygen exposure time and sediment source. Limnology and Oceanography, 54(6): 2243–2254

[39] Stedmon C A , Bro R . (2008). Characterizing dissolved organic matter fluorescence with parallel factor analysis: a tutorial. Limnology and Oceanography: Methods, 6(11): 572–579

[40] Tranvik L J, Downing J A, Cotner J B, Loiselle S A, Striegl R G, Ballatore T J, Dillon P, Finlay K, Fortino K, Knoll L B, et al. (2009). Lakes and reservoirs as regulators of carbon cycling and climate. Limnology and Oceanography, 54(6, part2): 2298–2314

[41] Wologo E , Shakil S , Zolkos S , Textor S , Ewing S , Klassen J , Spencer R G M , Podgorski D C , Tank S E , Baker M A . et al. (2021). Stream dissolved organic matter in permafrost regions shows surprising compositional similarities but negative priming and nutrient effects. Global Biogeochemical Cycles, 35(1): e2020GB006719

[42] Xing J F, Zhou Y P, He D, Guo F, Li P H, Zhang Y, Lv R, Xue R Z, Liu C Q, Xiao Y H (2025). Sediment amplifies organic matter cycling and nutrients feedback in eutrophic lake zones. Water Research 286: 124164

[43] Yang L Y , Cheng Q , Zhuang W E , Wang H , Chen W . (2019). Seasonal changes in the chemical composition and reactivity of dissolved organic matter at the land-ocean interface of a subtropical river. Environmental Science and Pollution Research, 26(24): 24595–24608

[44] Yang Z J , Liu D F , Ji D B , Xiao S B , Huang Y L , Ma J . (2013). An eco-environmental friendly operation: an effective method to mitigate the harmful blooms in the tributary bays of Three Gorges Reservoir. Science China Technological Sciences, 56(6): 1458–1470

[45] Zark M , Dittmar T . (2018). Universal molecular structures in natural dissolved organic matter. Nature Communications, 9(1): 3178

[46] Zhang D X , Chen X Y , Fu G J , Yang Z , Song J , Tong X G . (2022). Dissimilar evolution of soil dissolved organic matter chemical properties during revegetation with arbor and shrub in desertified land of the Mu Us Desert. Science of the Total Environment, 815: 152904

[47] Zhang R Q , Huang Q Q , Yan T Y , Yang J F , Zheng Y , Li H K , Li M . (2019). Effects of intercropping mulch on the content and composition of soil dissolved organic matter in apple orchard on the loess plateau. Journal of Environmental Management, 250: 109531

[48] Zhang X , Liu S L , Wu Y C , Luo H X , Ren Y Z , Liang J N , Huang X P , Macreadie P I . (2025a). Nutrient loading accelerates breakdown of refractory dissolved organic carbon in seagrass ecosystem waters. Water Research, 273: 123017

[49] Zhang Y X , Zhang H Z , Song J X , Cheng D D . (2025b). More sensitive signatures of DOM are stimulated by socioeconomic-related anthropogenic influences in a typical loess watershed. Journal of Hydrology, 657: 133106

[50] Zhao B , Yao P , Bianchi T S , Arellano A R , Wang X C , Yang J B , Su R G , Wang J P , Xu Y H , Huang X Y . et al. (2018). The remineralization of sedimentary organic carbon in different sedimentary regimes of the Yellow and East China Seas. Chemical Geology, 495: 104–117

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