Articles | Volume 22, issue 7
https://doi.org/10.5194/bg-22-1745-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-22-1745-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
09 Apr 2025
Research article |
| 09 Apr 2025
| 09 Apr 2025
Solubility characteristics of soil humic substances as a function of pH: mechanisms and biogeochemical perspectives
Xuemei Yang
School of Earth System Science, Tianjin University, 92 Weijin Road, Tianjin 300072, China
Institute of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing, 100091, China
Jie Zhang
School of Earth System Science, Tianjin University, 92 Weijin Road, Tianjin 300072, China
School of Earth System Science, Tianjin University, 92 Weijin Road, Tianjin 300072, China
Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, Tianjin 300072, China
Mohammad Mohinuzzaman
School of Earth System Science, Tianjin University, 92 Weijin Road, Tianjin 300072, China
Department of Environmental Science and Disaster Management, Noakhali Science and Technology University, Noakhali, Bangladesh
H. Henry Teng
School of Earth System Science, Tianjin University, 92 Weijin Road, Tianjin 300072, China
Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, Tianjin 300072, China
Nicola Senesi
Dip.to di Scienze del Suolo, della Pianta e degli Alimenti, Università degli Studi di Bari “Aldo Moro”, Via G. Amendola 165/A, 70126 Bari, Italy
Giorgio S. Senesi
CNR – Istituto per la Scienza e Tecnologia dei Plasmi (ISTP) – sede di Bari Via Amendola, 122/D, 70126 Bari, Italy
Jie Yuan
College of Resources and Environment, Xingtai University, Quanbei East Road 88, Qiaodong District, Xingtai City, Hebei Province, China
Yu Liu
School of Earth System Science, Tianjin University, 92 Weijin Road, Tianjin 300072, China
Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, Tianjin 300072, China
Si-Liang Li
School of Earth System Science, Tianjin University, 92 Weijin Road, Tianjin 300072, China
Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, Tianjin 300072, China
Xiaodong Li
School of Earth System Science, Tianjin University, 92 Weijin Road, Tianjin 300072, China
Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, Tianjin 300072, China
Baoli Wang
School of Earth System Science, Tianjin University, 92 Weijin Road, Tianjin 300072, China
Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, Tianjin 300072, China
Cong-Qiang Liu
CORRESPONDING AUTHOR
School of Earth System Science, Tianjin University, 92 Weijin Road, Tianjin 300072, China
Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, Tianjin 300072, China
Related authors
No articles found.
Yanyou Wu, Mohamed Aboueldahab, and Congqiang Liu
EGUsphere, https://doi.org/10.5194/egusphere-2025-1764, https://doi.org/10.5194/egusphere-2025-1764, 2025
Preprint archived
Short summary
Short summary
The complex biochemical intricacies of modern photosynthesis may trace back to Earth's primordial geological processes, providing a transformative perspective on the continuum between inorganic and organic evolution. Origins of bicarbonate photolysis in photosynthetic O2 evolution may trace back to early abiotic O2-generating systems.
Zhichao Dong, Subba Rao Devineni, Xiaoli Fu, Zhanjie Xu, Mingyu Li, Pingqing Fu, Cong-Qiang Liu, and Chandra Mouli Pavuluri
EGUsphere, https://doi.org/10.5194/egusphere-2025-899, https://doi.org/10.5194/egusphere-2025-899, 2025
Preprint archived
Short summary
Short summary
We developed new method to detect and measure organosulfates in PM2.5. By synthesizing organosulfates and combining them with commercial standards, we improved detection accuracy. Testing air samples from Tianjin, China, we found wintertime levels of organosulfates were much higher than in other regions. Our results show how human actions directly impact air quality and provide a tool to track pollution sources. This work helps scientists understand and address harmful aerosols in environments.
Yaxin Liu, Yunting Xiao, Lehui Cui, Qinghao Guo, Yiyang Sun, Pingqing Fu, Cong-Qiang Liu, and Jialei Zhu
EGUsphere, https://doi.org/10.5194/egusphere-2025-763, https://doi.org/10.5194/egusphere-2025-763, 2025
Short summary
Short summary
Dust carries iron deposits into the ocean, providing essential nutrients for the growth of marine phytoplankton, influencing their carbon uptake capacity. A model constrained by global datasets on dust iron content, ocean iron solubility, and dissolved iron concentrations was used to assess the contributions of 11 major dust sources to carbon uptake in 8 marine areas, enhancing understanding of the impact of global dust emissions on marine deposition and carbon cycle with decreased uncertainty.
Yu Xu, Tang Liu, Yi-Jia Ma, Qi-Bin Sun, Hong-Wei Xiao, Hao Xiao, Hua-Yun Xiao, and Cong-Qiang Liu
Atmos. Chem. Phys., 24, 10531–10542, https://doi.org/10.5194/acp-24-10531-2024, https://doi.org/10.5194/acp-24-10531-2024, 2024
Short summary
Short summary
This study investigates the characteristics of aminiums and ammonium in PM2.5 on clean and polluted winter days in 11 Chinese cities, highlighting the possibility of the competitive uptake of ammonia versus amines on acidic aerosols or the displacement of aminiums by ammonia under high-ammonia conditions. The overall results deepen the understanding of the spatiotemporal differences in aminium characteristics and formation in China.
Hao Xiao, Qinkai Li, Shiyuan Ding, Wenjing Dai, Gaoyang Cui, and Xiaodong Li
EGUsphere, https://doi.org/10.5194/egusphere-2024-1621, https://doi.org/10.5194/egusphere-2024-1621, 2024
Preprint archived
Short summary
Short summary
This study established a refined isotopic fingerprint of NOx sources in local Tianjin, which included previously uncharacterized sources in China. Results shown that the representative nature and region-specific characteristics of isotopic fingerprints for six categories of NOx sources in Tianjin. A reasonable source-resolved structure of NO3– could obtained by MixSIAR model using the δ15N values of NOx source established in this study, suggest the important of the refined isotopic fingerprint.
Zhichao Dong, Chandra Mouli Pavuluri, Peisen Li, Zhanjie Xu, Junjun Deng, Xueyan Zhao, Xiaomai Zhao, Pingqing Fu, and Cong-Qiang Liu
Atmos. Chem. Phys., 24, 5887–5905, https://doi.org/10.5194/acp-24-5887-2024, https://doi.org/10.5194/acp-24-5887-2024, 2024
Short summary
Short summary
Comprehensive study of optical properties of brown carbon (BrC) in fine aerosols from Tianjin, China, implied that biological emissions are major sources of BrC in summer, whereas fossil fuel combustion and biomass burning emissions are in cold periods. The direct radiation absorption caused by BrC in short wavelengths contributed about 40 % to that caused by BrC in 300–700 nm. Water-insoluble but methanol-soluble BrC contains more protein-like chromophores (PLOM) than that of water-soluble BrC.
Shuai Chen, Jun Zhong, Lishan Ran, Yuanbi Yi, Wanfa Wang, Zelong Yan, Si-liang Li, and Khan M. G. Mostofa
Biogeosciences, 20, 4949–4967, https://doi.org/10.5194/bg-20-4949-2023, https://doi.org/10.5194/bg-20-4949-2023, 2023
Short summary
Short summary
This study found the source of dissolved organic carbon and its optical properties (e.g., aromaticity, humification) are related to human land use and catchment slope in anthropogenically impacted subtropical mountainous rivers. The study highlights that the combination of dual carbon isotopes and optical properties represents a useful tool in tracing the origin of dissolved organic carbon and its in-stream processes.
Zhichao Dong, Chandra Mouli Pavuluri, Zhanjie Xu, Yu Wang, Peisen Li, Pingqing Fu, and Cong-Qiang Liu
Atmos. Chem. Phys., 23, 2119–2143, https://doi.org/10.5194/acp-23-2119-2023, https://doi.org/10.5194/acp-23-2119-2023, 2023
Short summary
Short summary
This study has provided comprehensive baseline data of carbonaceous and inorganic aerosols as well as their isotope ratios in the Tianjin region, North China, found that Tianjin aerosols were derived from coal combustion, biomass burning and photochemical reactions of VOCs, and also implied that the Tianjin aerosols were more aged during long-range atmospheric transport in summer via carbonaceous and isotope data analysis.
Shujun Zhong, Shuang Chen, Junjun Deng, Yanbing Fan, Qiang Zhang, Qiaorong Xie, Yulin Qi, Wei Hu, Libin Wu, Xiaodong Li, Chandra Mouli Pavuluri, Jialei Zhu, Xin Wang, Di Liu, Xiaole Pan, Yele Sun, Zifa Wang, Yisheng Xu, Haijie Tong, Hang Su, Yafang Cheng, Kimitaka Kawamura, and Pingqing Fu
Atmos. Chem. Phys., 23, 2061–2077, https://doi.org/10.5194/acp-23-2061-2023, https://doi.org/10.5194/acp-23-2061-2023, 2023
Short summary
Short summary
This study investigated the role of the secondary organic aerosol (SOA) loading on the molecular composition of wintertime urban aerosols by ultrahigh-resolution mass spectrometry. Results demonstrate that the SOA loading is an important factor associated with the oxidation degree, nitrate group content, and chemodiversity of nitrooxy–organosulfates. Our study also found that the hydrolysis of nitrooxy–organosulfates is a possible pathway for the formation of organosulfates.
Junjun Deng, Hao Ma, Xinfeng Wang, Shujun Zhong, Zhimin Zhang, Jialei Zhu, Yanbing Fan, Wei Hu, Libin Wu, Xiaodong Li, Lujie Ren, Chandra Mouli Pavuluri, Xiaole Pan, Yele Sun, Zifa Wang, Kimitaka Kawamura, and Pingqing Fu
Atmos. Chem. Phys., 22, 6449–6470, https://doi.org/10.5194/acp-22-6449-2022, https://doi.org/10.5194/acp-22-6449-2022, 2022
Short summary
Short summary
Light-absorbing brown carbon (BrC) plays an important role in climate change and atmospheric chemistry. Here we investigated the seasonal and diurnal variations in water-soluble BrC in PM2.5 in the megacity Tianjin in coastal China. Results of the source apportionments from the combination with organic molecular compositions and optical properties of water-soluble BrC reveal a large contribution from primary bioaerosol particles to BrC in the urban atmosphere.
Qiaorong Xie, Sihui Su, Jing Chen, Yuqing Dai, Siyao Yue, Hang Su, Haijie Tong, Wanyu Zhao, Lujie Ren, Yisheng Xu, Dong Cao, Ying Li, Yele Sun, Zifa Wang, Cong-Qiang Liu, Kimitaka Kawamura, Guibin Jiang, Yafang Cheng, and Pingqing Fu
Atmos. Chem. Phys., 21, 11453–11465, https://doi.org/10.5194/acp-21-11453-2021, https://doi.org/10.5194/acp-21-11453-2021, 2021
Short summary
Short summary
This study investigated the role of nighttime chemistry during Chinese New Year's Eve that enhances the formation of nitrooxy organosulfates in the aerosol phase. Results show that anthropogenic precursors, together with biogenic ones, considerably contribute to the formation of low-volatility nitrooxy OSs. Our study provides detailed molecular composition of firework-related aerosols, which gives new insights into the physicochemical properties and potential health effects of urban aerosols.
Cited articles
Aeschbacher, M., Sander, M., and Schwarzenbach, R. P.: Novel electrochemical approach to assess the redox properties of humic substances, Environ. Sci. Technol., 44, 87–93, https://doi.org/10.1021/es902627p, 2010.
Ai, Y., Zhao, C., Sun, L., Wang, X., and Liang, L.: Coagulation mechanisms of humic acid in metal ions solution under different pH conditions: A molecular dynamics simulation, Sci. Total Environ., 702, 135072, https://doi.org/10.1016/j.scitotenv.2019.135072, 2020.
Anastasiou, E., Lorentz, K. O., Stein, G. J., and Mitchell, P. D.: Prehistoric schistosomiasis parasite found in the Middle East, Lancet Infect. Dis., 14, 553–554, https://doi.org/10.1016/S1473-3099(14)70794-7, 2014.
Andersson, C. A. and Bro, R.: The N-way Toolbox for MATLAB, Chemometr. Intell. Lab., 52, 1–4, https://doi.org/10.1016/S0169-7439(00)00071-X, 2000.
Asli, S. and Neumann, P. M.: Rhizosphere humic acid interacts with root cell walls to reduce hydraulic conductivity and plant development, Plant Soil, 336, 313–322, https://doi.org/10.1007/s11104-010-0483-2, 2010.
Avena, M. J. and Wilkinson, K. J.: Disaggregation kinetics of a peat humic acid: Mechanism and pH effects, Environ. Sci. Technol., 36, 5100–5105, https://doi.org/10.1021/es025582u, 2002.
Benes, P.: Radiotracer study of thorium complexation with humic acid at pH 2–11 using free-liquid electrophoresis, Radiochim. Acta, 97, 273–281, https://doi.org/10.1524/ract.2009.1611, 2009.
Boguta, P., D'Orazio, V., Sokołowska, Z., and Senesi, N.: Effects of selected chemical and physicochemical properties of humic acids from peat soils on their interaction mechanisms with copper ions at various pH, J. Geochem. Explor., 168, 119–126, https://doi.org/10.1016/j.gexplo.2016.06.004, 2016.
Boguta, P., D'Orazio, V., Senesi, N., Sokołowska, Z., and Szewczuk-Karpisz, K.: Insight into the interaction mechanism of iron ions with soil humic acids. The effect of the pH and chemical properties of humic acids, J. Environ. Manage., 245, 367–374, https://doi.org/10.1016/j.jenvman.2019.05.098, 2019.
Bond-Lamberty, B. and Thomson, A.: Temperature-associated increases in the global soil respiration record, Nature, 464, 579–582, https://doi.org/10.1038/nature08930, 2010.
Brady, C. N. and Weil, R. R.: The Nature and Properties of Soils, 14th edn., 980 pp., ISBN 978-0-13-227938-3, 2008.
Bronick, C. J. and Lal, R.: Soil structure and management: A review, Geoderma, 124, 3–22, https://doi.org/10.1016/j.geoderma.2004.03.005, 2005.
Bryan, N. D., Abrahamsen, L., Evans, N., Warwick, P., Buckau, G., Weng, L., and Van Riemsdijk, W. H.: The effects of humic substances on the transport of radionuclides: Recent improvements in the prediction of behaviour and the understanding of mechanisms, Appl. Geochem., 27, 378–389, https://doi.org/10.1016/j.apgeochem.2011.09.008, 2012.
Canellas, L. P. and Olivares, F. L.: Physiological responses to humic substances as plant growth promoter, Chemical and Biological Technologies in Agriculture, 1, 1–11, https://doi.org/10.1186/2196-5641-1-3, 2014.
Chassapis, K., Roulia, M., and Nika, G.: Fe(III)-humate complexes from Megalopolis peaty lignite: A novel eco-friendly fertilizer, Fuel, 89, 1480–1484, https://doi.org/10.1016/j.fuel.2009.10.005, 2010.
Chen, C., Hall, S. J., Coward, E., and Thompson, A.: Iron-mediated organic matter decomposition in humid soils can counteract protection, Nat. Commun., 11, 1–13, https://doi.org/10.1038/s41467-020-16071-5, 2020.
Chen, H., Abdulla, H. A. N., Sanders, R. L., Myneni, S. C. B., Mopper, K., and Hatcher, P. G.: Production of Black Carbon-like and Aliphatic Molecules from Terrestrial Dissolved Organic Matter in the Presence of Sunlight and Iron, Environ. Sci. Tech. Let., 1, 399–404, https://doi.org/10.1021/ez5002598, 2014.
Chou, P. I., Ng, D. Q., Li, I. C., and Lin, Y. P.: Effects of dissolved oxygen, pH, salinity and humic acid on the release of metal ions from PbS, CuS and ZnS during a simulated storm event, Sci. Total Environ., 624, 1401–1410, https://doi.org/10.1016/j.scitotenv.2017.12.221, 2018.
Christl, I., Metzger, A., Heidmann, I., and Kretzschmar, R.: Effect of humic and fulvic acid concentrations and ionic strength on copper and lead binding, Environ. Sci. Technol., 39, 5319–5326, https://doi.org/10.1021/es050018f, 2005.
Ciceri, D. and Allanore, A.: Microfluidic leaching of soil minerals: Release of K+ from K feldspar, PLoS One, 10, 1–10, https://doi.org/10.1371/journal.pone.0139979, 2015.
Coble, P. G.: Characterization of marine and terrestrial DOM in sea water using excitation-emission matrix spectroscopy, Mar. Chem., 52, 325–346, 1996.
Coble, P. G., Green, S. A., Blough, N. V., and Gagosian, R. B.: Characterization of dissolved organic matter in the Black Sea by fluorescence spectroscopy, Nature, 348, 432–435, 1990.
Cory, R. M. and McKnight, D. M.: Fluorescence spectroscopy reveals ubiquitous presence of oxidized and reduced quinones in dissolved organic matter, Environ. Sci. Technol., 39, 8142–8149, https://doi.org/10.1021/ES0506962, 2005.
Crowther, T. W., Todd-Brown, K. E. O., Rowe, C. W., Wieder, W. R., Carey, J. C., Machmuller, M. B., Snoek, B. L., Fang, S., Zhou, G., Allison, S. D., Blair, J. M., Bridgham, S. D., Burton, A. J., Carrillo, Y., Reich, P. B., Clark, J. S., Classen, A. T., Dijkstra, F. A., Elberling, B., Emmett, B. A., Estiarte, M., Frey, S. D., Guo, J., Harte, J., Jiang, L., Johnson, B. R., Kroël-Dulay, G., Larsen, K. S., Laudon, H., Lavallee, J. M., Luo, Y., Lupascu, M., Ma, L. N., Marhan, S., Michelsen, A., Mohan, J., Niu, S., Pendall, E., Peñuelas, J., Pfeifer-Meister, L., Poll, C., Reinsch, S., Reynolds, L. L., Schmidt, I. K., Sistla, S., Sokol, N. W., Templer, P. H., Treseder, K. K., Welker, J. M., and Bradford, M. A.: Quantifying global soil carbon losses in response to warming, Nature, 540, 104–108, https://doi.org/10.1038/nature20150, 2016.
Curtin, D., Beare, M. H., Chantigny, M. H., and Greenfield, L. G.: Controls on the Extractability of Soil Organic Matter in Water over the 20 to 80 °C Temperature Range, Soil Sci. Soc. Am. J., 75, 1423–1430, https://doi.org/10.2136/sssaj2010.0401, 2011.
Davidson, E. A. and Janssens, I. A.: Temperature sensitivity of soil carbon decomposition and feedbacks to climate change, Nature, 440, 165–173, https://doi.org/10.1038/nature04514, 2006.
De la Rosa, J. M., Faria, S. R., Varela, M. E., Knicker, H., González-Vila, F. J., González-Pérez, J. A., and Keizer, J.: Characterization of wildfire effects on soil organic matter using analytical pyrolysis, Geoderma, 191, 24–30, https://doi.org/10.1016/J.GEODERMA.2012.01.032, 2012.
Demyan, M. S., Rasche, F., Schulz, E., Breulmann, M., Müller, T., and Cadisch, G.: Use of specific peaks obtained by diffuse reflectance Fourier transform mid-infrared spectroscopy to study the composition of organic matter in a Haplic Chernozem, Eur. J. Soil Sci., 63, 189–199, 2012.
dos Santos, J. V., Fregolente, L. G., Mounier, S., Hajjoul, H., Ferreira, O. P., Moreira, A. B., and Bisinoti, M. C.: Fulvic acids from Amazonian anthropogenic soils: Insight into the molecular composition and copper binding properties using fluorescence techniques, Ecotox. Environ. Safe., 205, 111173, https://doi.org/10.1016/j.ecoenv.2020.111173, 2020.
Drake, T. W., Van Oost, K., Barthel, M., Bauters, M., Hoyt, A. M., Podgorski, D. C., Six, J., Boeckx, P., Trumbore, S. E., Cizungu Ntaboba, L., and Spencer, R. G. M.: Mobilization of aged and biolabile soil carbon by tropical deforestation, Nat. Geosci., 12, 541–546, https://doi.org/10.1038/s41561-019-0384-9, 2019.
Dynarski, K. A., Bossio, D. A., and Scow, K. M.: Dynamic Stability of Soil Carbon: Reassessing the “Permanence” of Soil Carbon Sequestration, Front. Environ. Sci., 8, 514701, https://doi.org/10.3389/FENVS.2020.514701, 2020.
Ellerbrock, R. H., Gerke, H. H., and Deumlich, D.: Soil organic matter composition along a slope in an erosion-affected arable landscape in North East Germany, Soil Till. Res., 156, 209–218, https://doi.org/10.1016/J.STILL.2015.08.014, 2016.
Fang, C., Smith, P., Moncrieff, J. B., and Smith, J. U.: Similar response of labile and resistant soil organic matter pools to changes in temperature, Nature, 433, 57–59, https://doi.org/10.1038/nature03138, 2005.
Firestone, M. K., Killham, K., and McColl, J. G.: Fungal toxicity of mobilized soil aluminum and manganese, Appl. Environ. Microb., 46, 758–761, 1983.
Fulda, B., Voegelin, A., Maurer, F., Christl, I., and Kretzschmar, R.: Copper Redox Transformation and Complexation by Reduced and Oxidized Soil Humic Acid. 1. X-ray Absorption Spectroscopy Study, Environ. Sci. Technol., 47, 10903–10911, 2013.
Gabor, R. S., Burns, M. A., Lee, R. H., Elg, J. B., Kemper, C. J., Barnard, H. R., and McKnight, D. M.: Influence of leaching solution and catchment location on the fluorescence of water-soluble organic matter, Environ. Sci. Technol., 49, 4425–4432, https://doi.org/10.1021/es504881t, 2015.
Gao, J., Lv, J., Wu, H., Dai, Y., and Nasir, M.: Impacts of wheat straw addition on dissolved organic matter characteristics in cadmium-contaminated soils: Insights from fluorescence spectroscopy and environmental implications, Chemosphere, 193, 1027–1035, https://doi.org/10.1016/j.chemosphere.2017.11.112, 2018a.
Gao, L., Zhou, Z., Reyes, A. V., and Guo, L.: Yields and Characterization of Dissolved Organic Matter From Different Aged Soils in Northern Alaska, J. Geophys. Res.-Biogeo., 123, 2035–2052, https://doi.org/10.1029/2018JG004408, 2018b.
Gao, X., Zhang, J., Mostofa, K. M. G., Zheng, W., Liu, C. Q., Senesi, N., Senesi, G. S., Vione, D., Yuan, J, Liu, Y., Mohinuzzaman, M., Li, L., and Li, S. L.: Sulfur-mediated transformation, export and mineral complexation of organic and inorganic C, N, P and Si in dryland soils, Sci. Rep., 15, 9850, https://doi.org/10.1038/s41598-025-94920-3, 2025.
Garcia-Mina, J. M.: Stability, solubility and maximum metal binding capacity in metal-humic complexes involving humic substances extracted from peat and organic compost, Org. Geochem., 37, 1960–1972, https://doi.org/10.1016/j.orggeochem.2006.07.027, 2006.
Gilbert, B., Lu, G., and Kim, C. S.: Stable cluster formation in aqueous suspensions of iron oxyhydroxide nanoparticles, J. Colloid Interf. Sci., 313, 152–159, 2007.
Green, J. K., Seneviratne, S. I., Berg, A. M., Findell, K. L., Hagemann, S., Lawrence, D. M., and Gentine, P.: Large influence of soil moisture on long-term terrestrial carbon uptake, Nature, 565, 476–479, https://doi.org/10.1038/s41586-018-0848-x, 2019.
Haitzer, M., Aiken, G. R., and Ryan, J. N.: Binding of mercury(II) to dissolved organic matter: The role of the mercury-to-DOM concentration ratio, Environ. Sci. Technol., 36, 3564–3570, https://doi.org/10.1021/es025699i, 2002.
Haitzer, M., Aiken, G. R., and Ryan, J. N.: Binding of mercury(II) to aquatic humic substances: Influence of pH and source of humic substances, Environ. Sci. Technol., 37, 2436–2441, https://doi.org/10.1021/es026291o, 2003.
Harden, J. W., Hugelius, G., Ahlström, A., Blankinship, J. C., Bond-Lamberty, B., Lawrence, C. R., Loisel, J., Malhotra, A., Jackson, R. B., Ogle, S., Phillips, C., Ryals, R., Todd-Brown, K., Vargas, R., Vergara, S. E., Cotrufo, M. F., Keiluweit, M., Heckman, K. A., Crow, S. E., Silver, W. L., DeLonge, M., and Nave, L. E.: Networking our science to characterize the state, vulnerabilities, and management opportunities of soil organic matter, Glob. Change Biol., 24, e705–e718, https://doi.org/10.1111/gcb.13896, 2018.
Heckman, D. S., Geiser, D. M., Eidell, B. R., Stauffer, R. L., Kardos, N. L., and Hedges, S. B.: Molecular Evidence for the Early Colonization of Land by Fungi and Plants, Science, 293, 1129–1133, https://doi.org/10.1126/science.1061457, 2001.
Heitmann, T., Goldhammer, T., Beer, J., and Blodau, C.: Electron transfer of dissolved organic matter and its potential significance for anaerobic respiration in a northern bog, Glob. Change Biol., 13, 1771–1785, https://doi.org/10.1111/j.1365-2486.2007.01382.x, 2007.
Helms, J. R., Mao, J., Schmidt-Rohr, K., Abdulla, H., and Mopper, K.: Photochemical flocculation of terrestrial dissolved organic matter and iron, Geochim. Cosmochim. Ac., 121, 398–413, https://doi.org/10.1016/j.gca.2013.07.025, 2013.
Hemingway, J. D., Rothman, D. H., Grant, K. E., Rosengard, S. Z., Eglinton, T. I., Derry, L. A., and Galy, V. V.: Mineral protection regulates long-term global preservation of natural organic carbon, Nature, 570, 228–231, https://doi.org/10.1038/s41586-019-1280-6, 2019.
Hernández, D., Plaza, C., Senesi, N., and Polo, A.: Detection of Copper(II) and zinc(II) binding to humic acids from pig slurry and amended soils by fluorescence spectroscopy, Environ. Pollut., 143, 212–220, https://doi.org/10.1016/j.envpol.2005.11.038, 2006.
Huang, W. and Hall, S. J.: Elevated moisture stimulates carbon loss from mineral soils by releasing protected organic matter, Nat. Commun., 8, 1774, https://doi.org/10.1038/s41467-017-01998-z, 2017.
Jiang, T., Skyllberg, U., Wei, S., Wang, D., Lu, S., Jiang, Z., and Flanagan, D. C.: Modeling of the structure-specific kinetics of abiotic, dark reduction of Hg(II) complexed by O
Jones, K. D. and Tiller, C. L.: Effect of solution chemistry on the extent of binding of phenanthrene by a soil humic acid: A comparison of dissolved and clay bound humic, Environ. Sci. Technol., 33, 580–587, https://doi.org/10.1021/es9803207, 1999.
Jovanović, U. D., Marković, M. M., Cupać, S. B., and Tomić, Z. P: Soil humic acid aggregation by dynamic light scattering and laser Doppler electrophoresis, J. Plant Nutr. Soil Sc., 176, 674–679, https://doi.org/10.1002/JPLN.201200346, 2013.
Kallenbach, C., Frey, S., and Grandy, A.: Direct evidence for microbial-derived soil organic matter formation and its ecophysiological controls, Nat. Commun., 7, 13630, https://doi.org/10.1038/ncomms13630, 2016..
Karadirek, Ş., Kanmaz, N., Balta, Z., Demirçivi, P., Üzer, A., Hizal, J., and Apak, R.: Determination of total antioxidant capacity of humic acids using CUPRAC, Folin–Ciocalteu, noble metal nanoparticle- and solid–liquid extraction-based methods, Talanta, 153, 120–129, https://doi.org/10.1016/J.TALANTA.2016.03.006, 2016.
Kelly, B., Carrizo, G. E., Edwards-Hicks, J., Sanin, D. E., Stanczak, M. A., Priesnitz, C., Flachsmann, L. J., Curtis, J. D., Mittler, G., Musa, Y., Becker, T., Buescher, J. M., and Pearce, E. L.: Sulfur sequestration promotes multicellularity during nutrient limitation, Nature, 591, 471–476, https://doi.org/10.1038/s41586-021-03270-3, 2021.
Kirsten, M., Mikutta, R., Vogel, C., Thompson, A., Mueller, C. W., Kimaro, D. N., Bergsma, H. L. T., Feger, K. H., and Kalbitz, K.: Iron oxides and aluminous clays selectively control soil carbon storage and stability in the humid tropics, Sci. Rep., 11, 1–12, https://doi.org/10.1038/s41598-021-84777-7, 2021.
Klapper, L., McKnight, D. M., Fulton, J. R., Blunt-Harris, E. L., Nevin, K. P., Lovley, D. R., and Hatcher, P. G.: Fulvic acid oxidation state detection using fluorescence spectroscopy, Environ. Sci. Technol., 36, 3170–3175, https://doi.org/10.1021/ES0109702, 2002.
Kleber, M., Sollins, P., and Sutton, R.: A conceptual model of organo-mineral interactions in soils: Self-assembly of organic molecular fragments into zonal structures on mineral surfaces, Biogeochemistry, 85, 9–24, https://doi.org/10.1007/s10533-007-9103-5, 2007.
Kleber, M., Bourg, I. C., Coward, E. K., Hansel, C. M., Myneni, S. C. B., and Nunan, N.: Dynamic interactions at the mineral–organic matter interface, Nature Reviews Earth and Environment 6, 402–421, https://doi.org/10.1038/s43017-021-00162-y, 2021.
Klüpfel, L., Piepenbrock, A., Kappler, A., and Sander, M.: Humic substances as fully regenerable electron acceptors in recurrently anoxic environments, Nat. Geosci., 7, 195–200, https://doi.org/10.1038/ngeo2084, 2014.
Kothawala, D. N., Murphy, K. R., Stedmon, C. A., Weyhenmeyer, G. A., and Tranvik, L. J.: Inner filter correction of dissolved organic matter fluorescence, Limnol. Oceanogr.-Meth., 11, 616–630, https://doi.org/10.4319/lom.2013.11.616, 2013.
Kunlanit, B., Vityakon, P., Puttaso, A., Cadisch, G., and Rasche, F.: Mechanisms controlling soil organic carbon composition pertaining to microbial decomposition of biochemically contrasting organic residues: Evidence from midDRIFTS peak area analysis, Soil Biol. Biochem., 76, 100–108, 2014.
Lalonde, K., Mucci, A., Ouellet, A., and Gélinas, Y.: Preservation of organic matter in sediments promoted by iron, Nature, 483, 198–200, https://doi.org/10.1038/nature10855, 2012.
Lange, O. L., Belnap, J., and Reichenberger, H.: Photosynthesis of the cyanobacterial soil-crust lichen Collema tenax from arid lands in southern Utah, USA: Role of water content on light and temperature responses of CO2 exchange, Funct. Ecol., 12, 195–202, 1998.
Leenheer, J. A., Wershaw, R. L., and Reddy, M. M.: Strong-Acid, Cariioxyl-Group Structures in Fulvic Acid from the Suwannee River, Georgia. 2. Major Structures, Environ. Sci. Technol., 29, 399–405, https://doi.org/10.1021/es00002a016, 1995.
Lehmann, J. and Kleber, M.: The contentious nature of soil organic matter, Nature, 528, 60–68, https://doi.org/10.1038/nature16069, 2015.
Levicán, G., Ugalde, J. A., Ehrenfeld, N., Alejandro Maass, A., and Parada, P.: Comparative genomic analysis of carbon and nitrogen assimilation mechanisms in three indigenous bioleaching bacteria: predictions and validations, BMC Genomics, 9, 581, https://doi.org/10.1186/1471-2164-9-581, 2008.
Li, H. and Vaughan, J. C.: Switchable Fluorophores for Single-Molecule Localization Microscopy, Chem. Rev., 118, 9412–9454, https://doi.org/10.1021/acs.chemrev.7b00767, 2018.
Li, Q., Chen, X., Veroustraete, F., Bao, A. M., Liu, T., and Wang, J. L.: Validation of soil moisture retrieval in arid and semi-arid areas, Shuikexue Jinzhan/Advances in Water Science, 21, 201–207, 2010.
Lippold, H., Evans, N. D. M., Warwick, P., and Kupsch, H.: Competitive effect of iron(III) on metal complexation by humic substances: Characterisation of ageing processes, Chemosphere, 67, 1050–1056, https://doi.org/10.1016/j.chemosphere.2006.10.045, 2007.
Liu, J., Mu, Y., Geng, C., Yu, Y., He, H., and Zhang, Y.: Uptake and conversion of carbonyl sulfide in a lawn soil, Atmos. Environ., 41, 5697–5706, https://doi.org/10.1016/j.atmosenv.2007.02.039, 2007.
Lundström, U. S., Van Breemen, N., and Bain, D.: The podzolization process. A review, Geoderma, 94, 91–107, https://doi.org/10.1016/S0016-7061(99)00036-1, 2000.
Lützow, M. V., Kögel-Knabner, I., Ekschmitt, K., Matzner, E., Guggenberger, G., Marschner, B., and Flessa, H.: Stabilization of organic matter in temperate soils: Mechanisms and their relevance under different soil conditions – A review, Eur. J. Soil Sci., 57, 426–445, https://doi.org/10.1111/j.1365-2389.2006.00809.x, 2006.
Ma, H., Mao, P., Imran, S., Raza, T., Gao, R., and Lin, Y.: Rice Planting Increases Biological Nitrogen Fixation in Acidic Soil and the Influence of Light and Flood Layer Thickness, J. Soil Sci. Plant Nut., 21, 341–348, 2021.
Makiel, M., Skiba, M., Kisiel, M., Maj-Szeliga, K., Błachowski, A., Szymański, W., and Salata, D.: Formation of iron oxyhydroxides as a result of glauconite weathering in soils of temperate climate, Geoderma, 416, 115780, https://doi.org/10.1016/J.GEODERMA.2022.115780, 2022.
Malik, A. A., Puissant, J., Buckeridge, K. M., Goodall, T., Jehmlich, N., Chowdhury, S., Gweon, H. S., Peyton, J. M., Mason, K. E., van Agtmaal, M., Blaud, A., Clark, I. M., Whitaker, J., Pywell, R. F., Ostle, N., Gleixner, G., and Griffiths, R. I.: Land use driven change in soil pH affects microbial carbon cycling processes, Nat. Commun., 9, 3591, https://doi.org/10.1038/s41467-018-05980-1, 2018.
Marschner, B., Brodowski, S., Dreves, A., Gleixner, G., Gude, A., Grootes, P. M., Hamer, U., Heim, A., Jandl, G., Ji, R., Kaiser, K., Kalbitz, K., Kramer, C., Leinweber, P., Rethemeyer, J., Schäffer, A., Schmidt, M. W. I., Schwark, L., and Wiesenberg, G. L. B.: How relevant is recalcitrance for the stabilization of organic matter in soils?, J. Plant Nutr. Soil Sc., 171, 91–110, https://doi.org/10.1002/jpln.200700049, 2008.
Masaki, Y., Ozawa, R., Kageyama, K., and Katayama, Y.: Degradation and emission of carbonyl sulfide, an atmospheric trace gas, by fungi isolated from forest soil, FEMS Microbiol. Lett., 363, 3–5, https://doi.org/10.1093/femsle/fnw197, 2016.
Min, K., Lehmeier, C. A., Ballantyne, F., Tatarko, A., and Billings, S. A.: Differential effects of pH on temperature sensitivity of organic carbon and nitrogen decay, Soil Biol. Biochem., 76, 193–200, https://doi.org/10.1016/J.SOILBIO.2014.05.021, 2014.
Mohinuzzaman, M., Yuan, J., Yang, X., Senesi, N., Li, S. L., Ellam, R. M., Mostofa, K. M. G., and Liu, C. Q.: Insights into solubility of soil humic substances and their fluorescence characterisation in three characteristic soils, Sci. Total Environ., 720, 1–38, https://doi.org/10.1016/j.scitotenv.2020.137395, 2020.
Mora, V., Baigorri, R., Bacaicoa, E., Zamarreño, A. M., and García-Mina, J. M.: The humic acid-induced changes in the root concentration of nitric oxide, IAA and ethylene do not explain the changes in root architecture caused by humic acid in cucumber, Environ. Exp. Bot., 76, 24–32, https://doi.org/10.1016/j.envexpbot.2011.10.001, 2012.
Mostofa, K. M. G., Yoshioka, T., Mottaleb, M. A., and Vione, D.: Photobiogeochemistry of Organic Matter: Principles and Practices in Water Environments, Springer, Berlin, Germany, https://doi.org/10.1007/978-3-642-32223-5, 2013.
Mostofa, K. M. G., Li, W., Wu, F., Liu, C. Q., Liao, H., Zeng, L., and Xiao, M.: Environmental characteristics and changes of sediment pore water dissolved organic matter in four Chinese lakes, Environ. Sci. Pollut. R., 25, 2783–2804, https://doi.org/10.1007/s11356-017-0545-6, 2018.
Mostofa, K. M. G., Jie, Y., Sakugawa, H., and Liu, C. Q.: Equal Treatment of Different EEM Data on PARAFAC Modeling Produces Artifact Fluorescent Components That Have Misleading Biogeochemical Consequences, Environ. Sci. Technol., 53, 561–563, https://doi.org/10.1021/acs.est.8b06647, 2019.
Noy, A., Vezenov, D., and Lieber, C.: Chemical force microscopy Annu. Rev. Mater. Sci., 27, 381–421, https://doi.org/10.1146/annurev.matsci.27.1.381, 1997.
Nurmi, J. T. and Tratnyek, P. G.: Electrochemical properties of natural organic matter (NOM), fractions of NOM, and model biogeochemical electron shuttles, Environ. Sci. Technol., 36, 617–624, https://doi.org/10.1021/ES0110731, 2002.
Paul, E. A.: The nature and dynamics of soil organic matter: Plant inputs, microbial transformations, and organic matter stabilization, Soil Biol. Biochem., 98, 109–126, 2016.
Peinemann, N., Guggenberger, G., and Zech, W.: Soil organic matter and its lignin component in surface horizons of salt-affected soils of the Argentinian Pampa, Catena, 60, 113–128, https://doi.org/10.1016/J.CATENA.2004.11.008, 2005.
Pietikäinen, J., Pettersson, M., and Bååth, E.: Comparison of temperature effects on soil respiration and bacterial and fungal growth rates, FEMS Microbiol. Ecol., 52, 49–58, https://doi.org/10.1016/j.femsec.2004.10.002, 2005.
Ritchie, J. D. and Michael Perdue, E.: Proton-binding study of standard and reference fulvic acids, humic acids, and natural organic matter, Geochim. Cosmochim. Ac., 67, 85–96, https://doi.org/10.1016/S0016-7037(02)01044-X, 2003.
Robarge, W. P.: Precipitation/dissolution reactions in soils, in: Soil Physical Chemistry, 2nd edn., edited by: Sparks, D. L., CRC Press, Boca Raton, 193–238, https://doi.org/10.1201/9780203739280, 2018.
Ronchi, B., Clymans, W., Barão, A. L. P., Vandevenne, F., Struyf, E., Batelaan, O., Dassargues, A., and Govers, G.: Transport of Dissolved Si from Soil to River: A Conceptual Mechanistic Model, Silicon-Neth, 5, 115–133, https://doi.org/10.1007/s12633-012-9138-7, 2013.
Rousk, J., Brookes, P. C., and Bååth, E.: Contrasting soil pH effects on fungal and bacterial growth suggest functional redundancy in carbon mineralization, Appl. Environ. Microb., 75, 1589–1596, https://doi.org/10.1128/AEM.02775-08, 2009.
Saito, T., Nagasaki, S., and Tanaka, S.: Molecular fluorescence spectroscopy and mixture analysis for the evaluation of the complexation between humic acid and
Schad, P., van Huyssteen, C., and Michéli, E.: World Reference Base for Soil Resources 2014, Organización de las Naciones Unidas para la Alimentación y la Agricultura (FAO), Update 2015, ISBN 978-92-5-108369-7, 978-92-5-108370-3, http://www.fao.org/3/i3794en/I3794en.pdf (last access: 30 March 2025), 2015.
Schmidt, W., Santi, S., Pinton, R., and Varanini, Z.: Water-extractable humic substances alter root development and epidermal cell pattern in Arabidopsis, Plant Soil, 300, 259–267, https://doi.org/10.1007/s11104-007-9411-5, 2007.
Senesi, N.: Molecular and quantitative aspects of the chemistry of fulvic acid and its interactions with metal ions and organic chemicals. Part II. The fluorescence spectroscopy approach, Anal. Chim. Acta, 232, 77–106, https://doi.org/10.1016/S0003-2670(00)81226-X, 1990a.
Senesi, N.: Molecular and quantitative aspects of the chemistry of fulvic acid and its interactions with metal ions and organic chemicals. Part I. The electron spin resonance approach, Anal. Chim. Acta, 232, 51–75, https://doi.org/10.1016/S0003-2670(00)81225-8, 1990b.
Senesi, N. and Loffredo, E.: The Chemistry of Soil Organic Matter in Soil Physical Chemistry, 2nd edn., https://doi.org/10.1201/9780203739280, 1999.
Senesi, N. and Plaza, C.: Role of humification processes in recycling organic wastes of various nature and sources as soil amendments, Clean-Soil Air Water, 35, 26–41, https://doi.org/10.1002/clen.200600018, 2007.
Senesi, N., D'Orazio, V., and Ricca, G.: Humic acids in the first generation of EUROSOILS, Geoderma, 116, 325–344, https://doi.org/10.1016/S0016-7061(03)00107-1, 2003.
Shammi, M., Pan, X., Mostofa, K. M. G., Zhang, D., Liu, C. Q.: Photo-flocculation of algal biofilm extracellular polymeric substances and its transformation into transparent exopolymer particles. Chemical and spectroscopic evidences, Sci. Rep, 7, 9074, https://doi.org/10.1038/s41598-017-09066-8, 2017.
Singh, R. P., Shukla, M. K., Mishra, A., Kumari, P., Reddy, C. R. K., and Jha, B.: Isolation and characterization of exopolysaccharides from seaweed associated bacteria Bacillus licheniformis, Carbohyd. Polym., 84, 1019–1026, 2011.
Six, J., Conant, R. T., Paul, E. A., and Paustian, K.: Stabilization mechanisms of soil organic matter: Implications for C-saturation of soils, Plant Soil, 241, 155–176, 2002.
Sollins, P., Homann, P., and Caldwell, B. A.: Stabilization and destabilization of soil organic matter: mechanisms and controls Phillip, Geoderma, 74, 65–105, 1996.
Song, Z., McGrouther, K., and Wang, H.: Occurrence, turnover and carbon sequestration potential of phytoliths in terrestrial ecosystems, Earth-Sci. Rev., 158, 19–30, https://doi.org/10.1016/j.earscirev.2016.04.007, 2016.
Soti, P. G., Jayachandran, K., Koptur, S., and Volin, J. C.: Effect of soil pH on growth, nutrient uptake, and mycorrhizal colonization in exotic invasive Lygodium microphyllum, Plant Ecol., 216, 989–998, 2015.
Spence, A. and Kelleher, B. P.: Photodegradation of major soil microbial biomolecules is comparable to biodegradation: Insights from infrared and diffusion editing NMR spectroscopies, J. Mol. Struct., 1107, 7–13, https://doi.org/10.1016/j.molstruc.2015.11.025, 2016.
Stedmon, C. A., Markager, S., and Bro, R.: Tracing dissolved organic matter in aquatic environments using a new approach to fluorescence spectroscopy, Mar. Chem., 82, 239–254, https://doi.org/10.1016/S0304-4203(03)00072-0, 2003.
Steinmuller, H. E. and Chambers, L. G.: Characterization of coastal wetland soil organic matter: Implications for wetland submergence, Sci. Total Environ., 677, 648–659, https://doi.org/10.1016/J.SCITOTENV.2019.04.405, 2019.
Stolpe, B., Guo, L., and Shiller, A. M.: Binding and transport of rare earth elements by organic and iron-rich nanocolloids in alaskan rivers, as revealed by field-flow fractionation and ICP-MS, Geochim. Cosmochim. Ac., 106, 446–462, https://doi.org/10.1016/j.gca.2012.12.033, 2013.
Szulczewski, M. D., Helmke, P. A., and Bleam, W. F.: XANES spectroscopy studies of Cr(VI) reduction by thiols in organosulfur compounds and humic substances, Environ. Sci. Technol., 35, 1134–1141, https://doi.org/10.1021/es001301b, 2001.
Tadini, A. M., Nicolodelli, G., Senesi, G. S., Ishida, D. A., Montes, C. R., Lucas, Y., Mounier, S., Guimarães, F. E. G., and Milori, D. M. B. P.: Soil organic matter in podzol horizons of the Amazon region: Humification, recalcitrance, and dating, Sci. Total Environ., 613–614, 160–167, https://doi.org/10.1016/j.scitotenv.2017.09.068, 2018.
Tadini, A. M., Mounier, S., and Milori, D. M. B. P.: Modeling the quenching of fluorescence from organic matter in Amazonian soils, Sci. Total Environ., 698, 134067, https://doi.org/10.1016/j.scitotenv.2019.134067, 2020.
Tremblay, L., Kohl, S. D., Rice, J. A., and Gagné, J. P.: Effects of temperature, salinity, and dissolved humic substances on the sorption of polycyclic aromatic hydrocarbons to estuarine particles, Mar. Chem., 96, 21–34, https://doi.org/10.1016/j.marchem.2004.10.004, 2005.
Trevisan, S., Pizzeghello, D., Ruperti, B., Francioso, O., Sassi, A., Palme, K., Quaggiotti, S., and Nardi, S.: Humic substances induce lateral root formation and expression of the early auxin-responsive IAA19 gene and DR5 synthetic element in Arabidopsis, Plant Biol., 12, 604–614, https://doi.org/10.1111/j.1438-8677.2009.00248.x, 2010.
Underwood, T. R., Bourg, I. C., and Rosso, K. M.: Mineral-associated organic matter is heterogeneous and structured by hydrophobic, charged, and polar interactions, P. Natl. Acad. Sci. USA, 121, e2413216121, https://doi.org/10.1073/pnas.2413216121, 2024.
Varghese, E. M., Kour, B., Ramya, S., Krishna, P. D., Nazla, K. A., Sudheer, K., Anith, K. N., Jisha, M. S., and Ramakrishnan, B.: Rice in acid sulphate soils: Role of microbial interactions in crop and soil health management, Appl. Soil Ecol., 196, 105309, https://doi.org/10.1016/j.apsoil.2024.105309, 2024.
Vezenov, D. V., Noy, A., Rozsnyai, L. F., and Lieber, C. M.: Force titrations and ionization state sensitive imaging of functional groups in aqueous solutions by chemical force microscopy, J. Am. Chem. Soc., 119, 2006–2015, https://doi.org/10.1021/ja963375m, 1997.
Vezenov, D. V., Noy, A., and Ashby, P.: Chemical force microscopy: Probing chemical origin of interfacial forces and adhesion, J. Adhes. Sci. Technol., 19, 313–364, https://doi.org/10.1163/1568561054352702, 2005.
Vidali, R., Remoundaki, E., and Tsezos, M.: Humic acids copper binding following their photochemical alteration by simulated solar light, Aquat. Geochem., 16, 207–218, https://doi.org/10.1007/s10498-009-9080-5, 2010.
Vogel, C., Mueller, C. W., Höschen, C., Buegger, F., Heister, K., Schulz, S., Schloter, M., and Kögel-Knabner, I.: Submicron structures provide preferential spots for carbon and nitrogen sequestration in soils, Nat. Commun., 5, 1–7, https://doi.org/10.1038/ncomms3947, 2014.
Wang, C., Cheng, T., Zhang, D., and Pan, X.: Electrochemical properties of humic acid and its novel applications: A tip of the iceberg, Sci. Total Environ., 863, 160755, https://doi.org/10.1016/J.SCITOTENV.2022.160755, 2023.
Wang, L. F., Wang, L. L., Ye, X. D., Li, W. W., Ren, X. M., Sheng, G. P., Yu, H. Q., and Wang, X. K.: Coagulation kinetics of humic aggregates in mono- and Di-valent electrolyte solutions, Environ. Sci. Technol., 47, 5042–5049, https://doi.org/10.1021/es304993j, 2013.
Ward, N. D., Keil, R. G., Medeiros, P. M., Brito, D. C., Cunha, A. C., Dittmar, T., Yager, P. L., Krusche, A. V., and Richey, J. E.: Degradation of terrestrially derived macromolecules in the Amazon River, Nat. Geosci., 6, 530–533, https://doi.org/10.1038/NGEO1817, 2013.
Whalen, E. D., Grandy, A. S., Geyer, K. M., Morrison, E. W., and Frey, S. D.: Microbial trait multifunctionality drives soil organic matter formation potential, Nat. Commun., 15, 10209, https://doi.org/10.1038/s41467-024-53947-2, 2024.
Whelan, M. E. and Rhew, R. C.: Carbonyl sulfide produced by abiotic thermal and photodegradation of soil organic matter from wheat field substrate, J. Geophys. Res.-Biogeo., 120, 54–62, https://doi.org/10.1002/2014JG002661, 2015.
Wu, F., Cai, Y., Evans, D., and Dillon, P.: Complexation between Hg(II) and Dissolved Organic Matter in Stream Waters: An Application of Fluorescence Spectroscopy, Biogeochemistry, 71, 339–351, 2004a.
Wu, F., Mills, R. B., Evans, R. D., and Dillon, P. J.: Kinetics of Metal–Fulvic Acid Complexation Using a Stopped-Flow Technique and Three-Dimensional Excitation Emission Fluorescence Spectrophotometer, Anal. Chem., 76, 110–113, 2004b.
Xi, M., Zi, Y., Wang, Q., Wang, S., Cui, G., and Kong, F.: Assessment of the content, structure, and source of soil dissolved organic matter in the coastal wetlands of Jiaozhou Bay, China, Phys. Chem. Earth, 103, 35–44, https://doi.org/10.1016/j.pce.2017.03.004, 2018.
Xie, H., Zafiriou, O. C., Cai, W. J., Zepp, R. G., and Wang, Y.: Photooxidation and its effects on the carboxyl content of dissolved organic matter in two coastal rivers in the southeastern United States, Environ. Sci. Technol., 38, 4113–4119, https://doi.org/10.1021/es035407t, 2004.
Yang, X., Yuan, J., Yue, F. J., Li, S. L., Wang, B., Mohinuzzaman, M., Liu, Y., Senesi, N., Lao, X., Li, L., Liu, C. Q., Ellam, R. M., Vione, D., and Mostofa, K. M. G.: New insights into mechanisms of sunlight- and dark-mediated high-temperature accelerated diurnal production-degradation of fluorescent DOM in lake waters, Sci. Total Environ., 760, 143377, https://doi.org/10.1016/j.scitotenv.2020.143377, 2021.
Yang, X., Gao, X., Mostofa, K. M. G., Zheng, W., Senesi, N., Senesi, G. S., Vione, D., Yuan, J., Li, S. L., Li, L., and Liu, C. Q.: Mineral states and sequestration processes involving soil biogenic components in various soils and desert sands of Inner Mongolia, Sci. Rep., 14, 28530, https://doi.org/10.1038/s41598-024-80004-1, 2024.
Yang, Z., Kappler, A., and Jiang, J.: Reducing capacities and distribution of redox-active functional groups in low molecular weight fractions of humic acids, Environ. Sci. Technol., 50, 12105–12113, https://doi.org/10.1021/ACS.EST.6B02645, 2016.
Yu, G. H., Chi, Z. L., Kappler, A., Sun, F. S., Liu, C. Q., Teng, H. H., and Gadd, G. M.: Fungal Nanophase Particles Catalyze Iron Transformation for Oxidative Stress Removal and Iron Acquisition, Curr. Biol., 30, 2943–2950.e4, https://doi.org/10.1016/j.cub.2020.05.058, 2020.
Zhang, D., Pan, X., Mostofa, K. M. G., Chen, X., Mu, G., Wu, F., Liu, J., Song, W., Yang, J., Liu, Y., and Fu, Q.: Complexation between Hg(II) and biofilm extracellular polymeric substances: An application of fluorescence spectroscopy, J. Hazard. Mater., 175, 359–365, https://doi.org/10.1016/j.jhazmat.2009.10.011, 2010.
Zhang, J., Mostofa, K. M. G., Yang, X., Mohinuzzaman, M., Liu, C. Q., Senesi, N., Senesi, G. S., Sparks, D. L., Teng, H. H., Li, L., Yuan, J., and Li, S. L.: Isolation of dissolved organic matter from aqueous solution by precipitation with FeCl3: mechanisms and significance in environmental perspectives, Sci. Rep., 13, 1–15, https://doi.org/10.1038/s41598-023-31831-1, 2023.
Zhu, B. and Ryan, D. K.: Characterizing the interaction between uranyl ion and fulvic acid using regional integration analysis (RIA) and fluorescence quenching, J. Environ. Radioactiv., 153, 97–103, https://doi.org/10.1016/j.jenvrad.2015.12.004, 2016.
Short summary
The solubility characteristics of soil humic acids (HAs), fulvic acids (FAs), and protein-like substances (PLSs) at varying pH levels remain unclear. The key findings include the following: HA solubility increases with increasing pH and decreases with decreasing pH; HApH6 and HApH1 contribute to 39.1–49.2% and 3.1–24.1% of dissolved organic carbon, respectively; and HApH2, FA, and PLSs are highly soluble at acidic pHs and are transported by ambient water. These issues are crucial for sustainable soil management.
The solubility characteristics of soil humic acids (HAs), fulvic acids (FAs), and protein-like...
Altmetrics
Final-revised paper
Preprint