Particulate Organic Matter Research Articles

Seasonal variations in the exchange of particulate organic matter between the East China Sea and the Northwest Pacific Ocean and the influencing factors.

Evolution of soil organic matter pools during Martian regolith terraforming, with a focus on organo-Fe (oxyhydr)oxide interactions.

Synergistic plant-fungal interactions under Phragmites australis - mangrove mixed growth regimes boost particulate organic carbon sequestration in estuarine wetlands.

Long-term organic-inorganic fertilization promoted the microbial necromass carbon accumulation in particulate and mineral-associated organic matter fractions in paddy soil

Sediment amplifies organic matter cycling and nutrients feedback in eutrophic lake zones.

Seasonal dynamics of particulate organic matter sources in arid saline lakes: Insights from stable isotopes and Bayesian mixing models.

Removing macromolecular organic matter from biogas slurry prior to its application reduces organic N leaching and soil N2O emissions.

Unraveling profiles of organic ultraviolet filters in coastal waters of the East China Marginal Seas.

Transformations of particulate organic matter from the surface to the abyssal plain in the North Pacific as inferred from compound-specific stable isotope and microbial community analyses

ABSTRACTSoil organic matter (SOM) is an important component of ecosystem carbon stocks. Generally, SOM found in mineral and organo‐mineral soils can be categorised into two fractions: particulate organic matter (POM) and mineral‐associated‐organic matter (MAOM), both of which contain soil organic carbon (SOC). Understanding the relationship between SOC and SOM fractions provides insight into SOM decomposition and SOC storage potential. Here we show an intriguingly tight relationship between the fraction of SOC in SOM (denoted as fOC), habitat and soil physical properties, as well as SOC stored in POM and MAOM. This opens up new ways to predict spatial variations in the distribution of POC and MAOC using more widely available fOC data as a covariate. By compiling 14 datasets and 9503 measurements from across Europe and globally we analysed fOC across mineral and organic soils, which fell between 0.38 and 0.58, consistent with variation in carbon of major plant components. fOC followed a habitat gradient with lowest median values in Seagrass sediments (0.36 ± 0.09) and Permafrost habitats, followed by croplands (0.47 ± 0.08) and a maximum in semi‐natural habitats (e.g., neutral, acid and calcareous grasslands) (0.56 ± 0.07), with differences between broadleaved (0.50 ± 0.087) and coniferous woodlands (0.53 ± 0.07) which were driven by overall organic matter content. The data show a tight link between vegetation carbon and the contents of SOC and SOM across various habitats, which could be used to inform agricultural soil management, improved land‐use planning (e.g., woodlands), and tracking climate‐related SOC targets.

A rise in atmospheric CO2 concentration can have positive or negative effects on soil organic carbon (SOC) pools, with likely impacts on soil nutrient availability, which can in turn, drive ecosystem-level impacts. Much of the soil nutrients are locked in the more stable mineral-associated organic matter (MAOM) pool compared to the more labile particulate organic matter (POM) pool, but how elevated CO2 (eCO2) affects these pools is unclear. In this study, we examined how 12 years of eCO2 affected the POM and MAOM C, nitrogen (N), and phosphorus (P) pools at two different depths (0-10 and 10-20 cm) in a low P, native Eucalyptus woodland. Across soil depths, we found that 12 years of eCO2 caused significant decreases in MAOM-total C (16%), MAOM-organic N (15%), and MAOM-organic P (16%) compared to ambient CO2 (aCO2), but no effects on C, organic N (Norg), and organic P (Porg) in POM. The MAOM had consistently lower C: Porg and C: Norg ratios (228 and 12.4, respectively) than POM (655 and 24.1, respectively). Our results cannot be explained by eCO2-induced changes in plant inputs but instead suggest that the increased belowground C inputs under eCO2, in combination with low soil P availability, triggered a rhizosphere priming effect on the MAOM pool. Since MAOM was richer in P than POM, microbes may have preferentially mined MAOM for P (and N) to meet their P demand, thereby enhancing the decomposition of MAOM more than POM. While uncertainties remain about the fate of P after microbial death in this ecosystem, this study highlights that the nutrient-rich MAOM pool is vulnerable to rhizosphere priming, thereby restricting the potential for greater SOC accumulation under eCO2 in soils with low P availability.

Corals often form reef ecosystems that support diverse marine life, but they are sensitive to environmental fluctuations that can affect their nutrient acquisition. While coral-associated microbes (e.g., Symbiodiniaceae, bacteria and fungi) may supplement nutrients to coral hosts via metabolite translocation and nutrient recycling, the extent to which these microbial partners contribute to coral autotrophy or heterotrophy remains unclear. Here, we seasonally measure the carbon isotopes of amino acids (δ13CAA) in reef-building coral Pocillopora damicornis and its nutrient sources (e.g., Symbiodiniaceae and particulate organic matter). Regional Bayesian mixing models show that P. damicornis increased autotrophy (from 67.1 to 80.5%), but decreased particulate feeding (from 32.9 to 19.5%) from the cool season to the warm season. Stable essential δ13CAA values (valine, leucine and isoleucine) suggest limited seasonal changes in microbial contributions. Linear discriminant analysis, which combines current and published data from basal organisms (e.g., bacteria and fungi) to coral consumers, also reveals limited bacterial and fungal contributions to coral nutrition. Thus, we advocate that coral nutrition is primarily determined by Symbiodiniaceae translocation and particulate feeding. As these nutritional pathways are highly subject to environmental fluctuations, corals lacking trophic flexibility may suffer more from malnutrition and even population decline under global environmental change.

Caddisfly larvae (Trichoptera) are aquatic invertebrates that contribute to the decomposition of coarse particulate organic matter, such as plant litter in streams. Artificial light at night (ALAN) can interfere with their behaviour, particularly in the presence of a predation threat. We investigated the effects of various types of ALAN on Lepidostoma hirtum, a common caddisfly species in running waters. We tested its behaviour (activity and tendency to hide) under different light conditions: in darkness, in white warm LED light, and in HPS (sodium lamp) light (at 2 lux), with and without the presence of a predation threat (crushed conspecifics). We found that in darkness caddisflies did not change their behaviour in the presence of a predation threat. When exposed to ALAN alone, they exhibited decreased activity compared to dark-night conditions, across all light types. The presence of both a predation threat and ALAN enhanced defensive behaviour in caddisflies, especially under LED light. They not only reduced their activity, but also spent more time in shelter, compared to other treatments. This study highlights that impact of ALAN on the behaviour of nocturnal aquatic invertebrates may vary depending on the spectral composition of light and may be intensified in the presence of a predation threat.

Abstract. Heterotrophic bacteria process nearly half of the organic matter produced by phytoplankton in the surface ocean. Much of this organic matter consists of high-molecular-weight (HMW) biopolymers such as polysaccharides and proteins, which must initially be hydrolyzed to smaller sizes by structurally specific extracellular enzymes. Few previous studies, however, have investigated the structural complexity of polysaccharides among regions and depths. To simultaneously investigate substrate structure and microbial community composition and function, we concurrently determined carbohydrate abundance and structural complexity, bacterial community composition, and peptidase and polysaccharide hydrolase activities across depth gradients from surface to bottom water at four distinct stations in the western North Atlantic Ocean. Although the monosaccharide constituents of particulate organic matter (POM) were similar among stations, the structural complexity of POM-derived polysaccharides varied by depth and station, as demonstrated by polysaccharide-specific antibody probing. Bacterial community composition and polysaccharide hydrolase activities also varied substantially by depth, suggesting that the structure and function of bacterial communities may be related to substrate structural complexity. Thus, the extent to which bacteria can transform organic matter in the ocean is dependent on both the structural complexity of the organic matter and their enzymatic capabilities in different depths and regions of the ocean.

Redistribution of aggregate-associated calcium and soil organic carbon and their synergistic relationship in saline‒sodic soil two decades after a single application of flue gas desulfurization gypsum.

Most dissolved organic contaminants readily react with sulfate radicals (SO4•-) formed when persulfate is activated by thermolysis or base addition during in situ chemical oxidation (ISCO). However, under conditions encountered in the subsurface, hydrophobic contaminants associate with particles. To determine the potential of solids to protect contaminants from oxidation, we measured the stoichiometric efficiency (i.e., moles of contaminant transformed per mole of SO4•-) for a homologous series of chlorinated benzenes using solid-to-water ratios approaching subsurface conditions. Sorption to inorganic surfaces (i.e., sand and clays) reduced the stoichiometric efficiency by 3 orders of magnitude relative to contaminants in solution. At low initial oxidant concentrations (i.e., 10 mM), adsorbed contaminants were oxidized after desorbing to reestablish equilibrium. At higher oxidant concentrations (i.e., 500 mM), contaminant loss was attributable to SO4•- that reacted at the particle surface. Absorption by particulate organic matter (i.e., Pahokee peat) offered greater protection. For the most hydrophobic compounds (i.e., tetra-, penta-, and hexachlorobenzene), 1.5% organic matter by mass reduced the stoichiometric efficiency by an additional order of magnitude. The effect of sorption on the efficacy of persulfate ISCO can be predicted using contaminant hydrophobicity (i.e., the octanol-water partition coefficient, Kow), persulfate dosage, and particulate organic matter content.

Interactive effects of urbanness and land cover types on soil carbon and nitrogen pools in green spaces.

Environmental drivers of food material and calorie content variability of particulate organic matter in four distinct Korean Peninsula Seas

Abstract Field experiments enable researchers to investigate the impacts of both natural and anthropogenic crop production factors on soil respiration (SR), the largest contributor of CO2 emissions from terrestrial ecosystems to the atmosphere. The hypothesis of this study was that the influence of two key anthropogenic factors — applied fertilizers and cultivated crops — on the respiration rate of arable soils could be separated in a field experiment. The objective was therefore to quantify the influence of these factors on SR and assess its dependence on soil characteristics. The study was conducted on the territory of the long-term field experiment at the Timiryazev Academy (Moscow, Russia), where use of plots of crop rotation involving rye, barley, potatoes, and fallow, with liming and various fertilizer types applied, was considered. Measurements were taken using the closed chamber technique and a portable infrared gas analyzer from May 2023 to November 2024. During the vegetation periods SR varied significantly and was not statistically different for most plots (0.063‒0.276 g C/(m2·h)), except for the NPK+manure variant (0.371‒0.430 g C/(m2·h)). During the bare soil period SR was similar between fertilizer variants and 10‒20 times lower under snow cover than during the vegetation period (0.006‒0.018 g C/(m2·h)). A direct dependence of respiration on soil organic carbon and particulate organic matter content was observed (R=0.552‒0.650). Two-way PERMANOVA revealed significant effects of fertilizers (17.2‒24.0% of the variance) and crops (6.5‒7.1%) on SR, although their interaction was insignificant. Our research could form the basis for developing carbon sequestration compensation measures in response to specific fertilizer doses.

Combining organic amendments with enhanced rock weathering shifts soil carbon storage in croplands.