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Dissolved organic matter (DOM) in highly productive intertidal mangroves is an important carbon and nutrient source to the coastal ocean. In highly dynamic mangrove intertidal systems, both tidal pumping or geochemical factors can control DOM characteristics. The influence of groundwater flow on DOM properties and fluxes remains poorly understood. Here, we compared the concentrations, sources, and spectroscopic characteristics of DOM across a recharge‐discharge gradient. We used a three‐dimensional array sampling strategy to reduce spatial biases, groundwater monitoring to quantify tidally driven exchange, and spectrofluoroscopy to quantify DOM fluorescent components. The results showed that tidal hydrology played the key role driving groundwater DOM properties in both horizontal (i.e., from the mangrove to the sea) and vertical directions. Due to the high spatial heterogeneity of dissolved inorganic (DIC) and organic (DOC) carbon concentrations in mangrove groundwater, carbon outwelling showed a high degree of variability at the intertidal scale (54.8–234.8 μmol m−2 d−1 for DIC and 2.5–12.4 μmol m−2 d−1 for DOC). The contribution of terrestrial DOM gradually decreased toward the ocean, but the microbial contributions for recently produced autochthonous DOM increased. Deep groundwater received less terrestrial DOM and experienced anaerobic microbial mineralization, resulting in lower organic carbon than shallow groundwater. Greater variations in spectroscopic characteristics were found in shallow groundwater than in deep groundwater. Overall, tidally driven surface water‐groundwater interactions control the variability in DOM properties and how DOM contributes to carbon budgets and sequestration in mangrove groundwater. Plain Language Summary: Mangroves are carbon‐rich ecosystems producing large amounts of dissolved organic matter (DOM) that can reach the ocean. We conducted detailed groundwater observations to resolve DOM geochemistry along a subtropical mangrove intertidal zone. Tidal flushing of mangrove soils enhanced the exchange between groundwater and surface seawater. Tidal pumping horizontally segmented the intertidal zone into a landward recharge zone of surface water and a seaward discharge zone of groundwater. These zones had contrasting salinity, pH, inorganic carbon, and DOM concentrations and composition. Microbially derived DOM was found in the seaward discharge zone and in deep mangrove groundwater. Deep waters also had higher degree of humification than shallow groundwater. Salinity‐independent humic‐like components were transformed by microbial activity, suggesting external sources. Overall, tidal pumping and the distinct hydrological zones explained DOM chemistry and controlled groundwater‐ocean exchange in mangrove intertidal flats. Key Points: Tidal pumping segmented the intertidal mangrove into a landward recharge zone and a seaward discharge zone3‐D array sampling reveled high spatial heterogeneity of DOM characteristicsHydrological factors explained DOM‐related variables better than geochemical parameters [ABSTRACT FROM AUTHOR]

SCS-KFD08.[10] The main difference was that a hydroxyl group in penicitor A replaced by a methoxyl group ( I i SB H/C sb 3.87/56.0) attached at C-7 ( I i SB C sb 161.5) in B 1 b ,[11] which were confirmed by HMBC correlation (Figure) of H SB 3 sb -14/C-7, and the presence of an additional CH SB 2 sb unit in deduced molecular formula of B 1 b . Crystallographic data of compound B 1 b were measured on a Rigaku XtaLAB PRO single-crystal diffractometer using Cu K I i radiation ( I i = 1.54184 Å). The ECD spectra of different conformers were generated using the program SpecDis 1.6 (University of Würzburg) and Prism 5.0 (GraphPad Software Inc.) with a half-bandwidth of 0.3 eV, according to the Boltzmann-calculated contribution of each conformer after UV correction of +10 nm. Cytotoxicity against MDA-MB-231, C4-2B, MGC803, 143B, and A549 cell lines of compounds 1-10.Figure S3. 1H NMR spectrum of 7-O-methylpenicitor A (1) (DMSO-d6, 700 MHz)Figure S4. 13C NMR and DEPT spectra of 7-O-methylpenicitor A (1) (DMSO-d6, 700 MHz)Figure S5. [Extracted from the article]

Core Ideas: N additions alter soil microbial community composition and reduce forest soil microbial biomass and enzyme activity.Litter decomposition and soil organic matter degradation was slowed by N additions.Reduced decomposition increases soil C, but long‐term effects on forest productivity are unknown. Eastern North American forests receive anthropogenically elevated nitrogen (N) deposition that alters soil processes and forest productivity. We examined N deposition effects on soil carbon (C) and N in temperate, N‐rich forest plots fertilized annually (100 kg N ha−1 y−1) since 1993. After nearly two decades, soil C in O, A, and upper 50 cm of B horizons of N‐addition plots was 17% greater (14.2 ± 0.7 kg C m−2) than control plots. Aboveground tree biomass growth and litterfall were not affected by fertilization. Fine root mass (0–1 mm) was 34% greater in N‐addition plots, but did not explain soil C increases. Rather, reduced decomposition of litter and soil organic matter drove C increases in N‐addition plots. Decomposition rates of black cherry, sugar maple, and mixed leaf litter were 43, 67, and 36%, greater, respectively, in control than N‐addition plots. Light fraction organic matter was greater in N‐addition plots than in control plots, due to either enhanced root production or decreased decomposition of soil organic matter. Soil respiration was reduced, and microbial biomass in O, A, and upper‐B horizons was lower in N‐addition plots than controls. The soil microbial community composition was also altered dramatically with N additions. Recalcitrant organic matter enzyme activity (peroxidase) was reduced in the O‐horizon by N addition. Available Ca, Mg, and K were reduced in O and A horizons by N fertilization. These results suggest that chronic elevated atmospheric N inputs can increase forest soil C storage by decreasing decomposition, however the long‐term stability of this additional C sequestration is unknown. [ABSTRACT FROM AUTHOR]

Fine roots constitute a significant source of plant productivity and litter turnover across terrestrial ecosystems, but less is known about the quantitative and qualitative profile of phenolic compounds within the fine-root architecture, which could regulate the potential contribution of plant roots to the soil organic matter pool., To understand the linkage between traditional macro-elemental and morphological traits of roots and their molecular-level carbon chemistry, we analyzed seasonal variations in monomeric yields of the free, bound, and lignin phenols in fine roots (distal five orders) and leaves of Ardisia quinquegona., Fine roots contained two-fold higher concentrations of bound phenols and three-fold higher concentrations of lignin phenols than leaves. Within fine roots, the concentrations of free and bound phenols decreased with increasing root order, and seasonal variation in the phenolic profile was more evident in lower order than in higher order roots. The morphological and macro-elemental root traits were decoupled from the quantity, composition and tissue association of phenolic compounds, revealing the potential inability of these traditional parameters to capture the molecular identity of phenolic carbon within the fine-root architecture and between fine roots and leaves., Our results highlight the molecular-level heterogeneity in phenolic carbon composition within the fine-root architecture, and imply that traits that capture the molecular identity of the root construct might better predict the decomposition dynamics within fine-root orders. [ABSTRACT FROM AUTHOR]

Microbial fuel cell (MFC) technology has shown great potential for harvesting energy from waste organic materials. Here, we explored the potential of MFC-based electricity generation from forest detritus, a large untapped biomass pool. Electricity generation from in situ MFCs and relevant environmental parameters (i.e., carbon sources and concentrations, temperature, water depth) in a seasonally flooded freshwater cypress-tupelo wetland were monitored intensively for two flooding periods. Current outputs ranged from 0 to 1.27 mA (mean of 0.40 mA for flooding period) and were highly sensitive to environmental changes, showing seasonal and diel dependences. Excluding the influence of heavy storms, drought, or wetland icing, current output was highly temperature-dependent dielly. Seasonally, current output gradually increased in the first 3-4 months (limited by temperature) and decreased slightly during the last 1-2 months (probably limited by carbon and nutrients) of both flooding periods. Litter extract of baldcypress ( Taxodium distictum) with lower C/N ratio and aromatic content showed greater stable current outputs (0.57 mA) based on 50 mg l−1 biological oxygen demand compared to extracts of water tupelo ( Nyssa aquatica) and longleaf pine ( Pinus palustris), suggesting that the current output of in situ MFCs could depend on the vegetation within a wetland. Our study highlights the potential application of MFC in generating green and sustainable electricity from forest biomass for powering remote sensors in wetland ecosystems. [ABSTRACT FROM AUTHOR]