There is currently no reliable geochemical proxy of historical coral bleaching. Here we test the hypothesis that increases in the nitrogen isotopic signature of coral tissue, which is recorded in skeletal-bound organic material (CS-δ15N), can be used to detect coral bleaching events in the past. We measured CS-δ15N in coral colonies that showed high density thermal stress bands associated with the

Benthic stream sediments interact strongly with phosphorus (P) and can buffer dissolved reactive P (DRP) concentrations. The sediment P buffer can be measured with the sediment equilibrium phosphate concentration at net zero sorption (EPC0), which often correlates well with DRP. Yet, it is unclear how much of this P affinity in sediments is attributable to biotic (microbial P demand) or abiotic (sorption)

Coastal waters have strong gradients in dissolved organic matter (DOM) quantity and characteristics, originating from terrestrial inputs and autochthonous production. Enclosed seas with high freshwater input therefore experience high DOM concentrations and gradients from freshwater sources to more saline waters. The brackish Baltic Sea experiences such salinity gradients from east to west and from

Plant litter decomposition is a key ecological process that is mostly studied at the forest floor. However, decomposition generally starts in the canopy. In this study, we evaluated the effect of litter composition and climate on the initial phase of decomposition in the soil and two contrasting types of canopy microsites along an elevational gradient (0–2200 m a.s.l.). To this end, we incubated standard

The aim of this study was to determine the effect of drainage on peat properties, porewater chemistry, and peat decomposition proxies in an ombrogenous peatland in the Hudson Bay Lowland (HBL). We anticipated that drainage would change peatland hydrology, vegetation, and biogeochemistry, leading to an increase in peat decomposition. As indicators of peat biogeochemical change and potential proxies

Potassium presents a conundrum for biogeochemists. Potassium is cycled wastefully at the plant level, but it appears to be conserved in the nutrient budgets of entire ecosystems, where it sometimes limits net primary productivity. An increasing demand for K fertilizer may accompany the expansion of agriculture into highly weathered tropical soils, where limited supplies of K may control the distribution

Tree roots penetrate the soil to several meters depth, but the role of subsoils for the supply of nutrient elements such as phosphorus (P) to the trees is poorly understood. Here, we tested the hypothesis that increased P deficiency in the topsoil results in an increased microbial recycling of P from the forest subsoil. We sampled soils from four German temperate forest sites representing a gradient

As forest ecosystems generally develop on poor and unfertilized soils, nutrient cycles and input/output budgets, notably in the humus compartment, are key to determining forest sustainability. Previous studies generally focused on the ecosystem scale or only on C, N, P in the humus layer. Our objectives in this study are to establish these budgets for principal elements, considering dust inputs and

Bark decomposition is an underexamined component of soil carbon cycling and soil community assembly. Numerous studies have shown faster decomposition of leaf litter in “home” environments (i.e. within soil adjacent to the plant that produced the leaves), suggesting potential legacy effects from previous deposition of similar litter. This is expected to occur through, in part, accumulation of microorganisms

It is uncertain how the predicted further rise of atmospheric carbon dioxide (CO2) concentration will affect plant nutrient availability in the future through indirect effects on the gross rates of nitrogen (N) mineralization (production of ammonium) and depolymerization (production of free amino acids) in soil. The response of soil nutrient availability to increasing atmospheric CO2 is particularly

The potential consequences of global warming for ecosystem carbon stocks are a major concern, particularly in high-latitude regions where soil carbon pools are especially large. Research on soil and plant carbon responses to warming are often based on short-term (< 10 year) warming experiments. Furthermore, carbon budgets from boreal forests, which contain at least 10–20% of the global soil carbon

Soil soluble nitrogen (N) is crucial to the N nutrition and productivity of plants. Consequently, understanding the factors that affect its pool size and composition is of considerable importance. Here, six typical forest types in northeast China were investigated to determine the dynamics of soil soluble N across seasons and plant communities, and the potential drivers. Soil free amino acids, NH4+

Coastal North Carolina experienced 36 tropical cyclones (TCs), including three floods of historical significance in the past two decades (Hurricanes Floyd-1999, Matthew-2016 and Florence-2018). These events caused catastrophic flooding and major alterations of water quality, fisheries habitat and ecological conditions of the Albemarle-Pamlico Sound (APS), the second largest estuarine complex in the

Microbial extracellular enzymes decompose distinct components of soil organic matter (SOM), thus influencing its stability. However, we lack the knowledge about how the kinetics of individual enzymes vary when multiple substrates change simultaneously. Here we used Japanese knotweed (Polygonum cuspidatum) invasion as a model system to explore how the Michaelis–Menten kinetics (Vmax and km) of microbial

Nutrient losses from Mississippi watersheds degrade downstream water bodies. As forested floodplains intercept agricultural drainage waters, a limiting nutrient like phosphorus (P) could potentially be sequestered in forest soils, reducing P loss to the Gulf of Mexico. Thus far, the role of temperate deciduous floodplain soils for P has not been extensively investigated in the Midwestern United States

Nutrient pollution and greenhouse gas emissions related to crop agriculture and confined animal feeding operations (CAFOs) in the US have changed substantially in recent years, in amounts and forms. This review is intended to provide a broad view of how nutrient inputs—from fertilizer and CAFOs—as well as atmospheric NH3 and greenhouse gas emissions, are changing regionally within the US and how these

Frequency and intensity of precipitation events can alter hydrological conditions of lotic systems and material inflow from the catchment. In this study, interannual changes in food web structure were investigated in a lake–swamp–river system in the semi-arid West Siberian forest-steppe region using carbon and nitrogen stable isotope ratios (δ13C and δ15N). The δ15N signatures of aquatic producers

Eutrophication of natural water bodies is moderated by transformation of nitrate (NO3−) in riparian wetlands, which serve as filters of infiltrating drain water from upland agricultural areas. The present study comprised field observations, laboratory experiments and metagenomic studies to describe NO3− removing transformation pathways and interactions with the cycling of iron (Fe) in a temperate riparian

Ecosystem fires are stochastic and anthropogenic phenomena that affect critical soil processes. Nevertheless, environmental managers, policy-makers, and even scientists have often overlooked the induced transformations that fire does to soil organic matter (SOM), which sustains an ecosystem’s overall health. Here, we investigated the effects of simulated fire conditions on bulk SOM, water-extractable

The effects of anthropogenic pressures in coastal areas are extensively studied in temperate but not in tropical zones, where their impact might be amplified by high water temperatures and upwelling phenomena. Sedimentary features and benthic metabolism were studied during the non upwelling (NUPW) and upwelling (UPW) seasons in Taganga Bay (Colombia). The bay is impacted by a submarine outfall of virtually

Coal is naturally enriched in trace elements, including mercury (Hg) and selenium (Se). Alkaline mine drainage from mountaintop mining valley fill (MTM-VF)—the dominant form of surface coal mining in Appalachia, USA—releases large quantities of Se into streams draining mined catchments, resulting in elevated bioaccumulation of Se in aquatic and riparian organisms. Yet, the release of Hg into these

Decomposing foliar litter organic matter (LOM) in forested watersheds is an essential terrestrial source of dissolved organic matter (DOM) to aquatic ecosystems. To evaluate the relationship of chemical composition between LOM and DOM, we collected freshly fallen leaves of white oak (Quercus alba) and conducted an 80-week field decomposition experiment along a small elevation gradient in a floodplain

The initial online publication contained several typesetting errors. The original article has been corrected.

Grassland degradation, a process of retrogressive succession, is an extensive global threat, especially on the Qinghai-Tibet Plateau. However, the influences of grassland degradation on carbon (C): nitrogen (N): phosphorus (P) ratios of streamwater and biofilms, as well as their implications for nutrient limitation, are not well studied. Assessing nutrient limitation and stoichiometry could facilitate

We report a data set of dissolved organic carbon (DOC) concentration and dissolved organic matter (DOM) composition (stable carbon isotope signatures, absorption and fluorescence properties) obtained from samples collected in Lake Victoria, a large lake in East Africa. Samples were collected in 2018–2019 along a bathymetric gradient (bays to open waters), during three contrasting seasons: long rainy

Accurate description of temperature response and sensitivity of different carbon pools within soil is critical for accurately modelling soil carbon stocks and changes. Inconsistent sampling, incubation and fractionation methods highlights the need for new approaches to this area of study. We developed and tested a new protocol which allowed measurement of the temperature response of two carbon pools

Increased anthropogenic nitrogen (N) inputs can alter the N cycle and affect forest ecosystem functions. The impact of increased N deposition depends among others on the ultimate fate of N in plant and soil N pools. Short-term studies (3–18 months) have shown that the organic soil layer was the dominant sink for N. However, longer time scales are needed to investigate the long-term fate of N. Therefore

Topography is tightly coupled with soil organic carbon (SOC) cycling in sloping landscapes. However, we know little about the spatial variation of SOC accumulation and persistence along a topographic gradient and the controlling processes. Here, we assessed the spatial variation of SOC and its composition along a topographic gradient in a humid mountain forest. The variables associated with environmental

Symbiotic nitrogen- (N) fixing trees can influence multiple biogeochemical cycles by fixing atmospheric N, which drives net primary productivity and soil carbon (C) and N accumulation, as well as by mobilizing soil phosphorus (P) and other nutrients to support growth and metabolism. The soil micronutrient molybdenum (Mo) is essential to N-fixation, yet surprisingly little is known of whether N-fixing

Early forest re-establishment in landforms constructed from materials such as overburden or mine waste is partly determined by nitrogen (N) availability in reclamation covers. Here we examined whether the ecosystem model ecosys which simulates key processes governing N availability such as mineralization, plant N uptake and N return to soil through litterfall could be used to forecast potential N limitations

Nitrogen (N) trace gas emission pulses produced after wetting dry soils may be important pathways of ecosystem N loss. However, the rates and mechanisms controlling these emissions remain unclear. We tested whether changes in microbial community structure and increased rates of atmospheric N deposition could explain N emissions at two desert sites differing in atmospheric N deposition by ~ six fold

Terrestrial carbon (C)-climate feedbacks depend strongly on how soil organic matter (SOM) decomposition responds to temperature. This dependency is often represented in land models by the parameter Q10, which quantifies the relative increase of microbial soil respiration per 10 °C temperature increase. Many studies have conducted paired laboratory soil incubations and inferred “active” and “slow” pool

Floodplains play a crucial role in water quality regulation via denitrification. This biogeochemical process reduces nitrate (NO3−), with aquifer saturation, organic carbon (OC) and N availability as the main drivers. To accurately describe the denitrification in the floodplain, it is necessary to better understand nitrate fluxes that reach these natural bioreactors and the transformation that occurs

Due to the geographical expanse of grasslands with depleted organic matter stocks, there has been growing interest in the management of these ecosystems for C sequestration to help mitigate climate change. It is generally accepted that management practices intending to increase forage production (e.g. decreasing grazing density) result in increased soil C stocks by increasing the return of biomass

The sediment–water interfaces (SWI) of streams serve as important biogeochemical hotspots in watersheds and contribute to whole-catchment reactive nitrogen budgets and water-quality conditions. Recently, the SWI has been identified as an important source of nitrous oxide (N2O) produced in streams, with SWI residence time among the principal controls on its production. Here, we conducted a series of

Atmospheric deposition is an important component of the nutrient cycles of terrestrial ecosystems, but field measurements are especially scarce in tropical regions. In this study we analysed 15 months of precipitation chemistry collected in an old growth tropical forest located in French Guiana. We measured nutrient inputs via bulk precipitation and throughfall and used the canopy budget model to estimate

The seasonally stratified continental shelf seas are highly productive, economically important environments which are under considerable pressure from human activity. Global dissolved oxygen concentrations have shown rapid reductions in response to anthropogenic forcing since at least the middle of the twentieth century. Oxygen consumption is at the same time linked to the cycling of atmospheric carbon

Conversion of landscapes to large-scale agriculture has substantially increased the loading of bioavailable nitrogen (N) to stream networks through extensive artificial drainage and fertilizer application. Floodplain restoration may enhance N cycling in agricultural stream systems by increasing residence time of floodwaters in contact with bioreactive surfaces that retain or remove excess N. Microbially-mediated

We tested the hypothesis that benthic fluxes will increase spatially in a coastal deltaic floodplain as sediment organic matter increases in response to developing hydrogeomorphic zones along a chronosequence of the active Mississippi River Delta. A continuous flow-through core system was used to incubate intact sediment cores from three hydrogeomorphic zones along a chronosequence in the emerging

Molybdenum (Mo) is an essential trace metal that plays a central role in biological nitrogen fixation (BNF) as the cofactor in the conventional form of the nitrogenase enzyme. The low availability of Mo in soils often constrains BNF in many terrestrial ecosystems. Atmospheric sources may supply a critical source of exogenous Mo to regions with highly weathered soils likely low in Mo, particularly in

Dissolved organic carbon (DOC) derived from plant litter plays an important role in the ecosystem carbon balance and soil biogeochemistry. However, in boreal coniferous forests no integrated understanding exists of how understory vegetation contributes to litter leaching of DOC, nitrogen (N) and phosphorus (P) with different bioavailability at the forest stand level. We characterized water extractable

Sulphur (S) is a key macronutrient for all organisms, with similar cellular requirements to that of phosphorus (P). Studies of S cycling have often focused on the inorganic fraction, however, there is strong evidence to suggest that freshwater microorganisms may also access dissolved organic S (DOS) compounds (e.g. S-containing amino acids). The aim of this study was to compare the relative concentration

Biological nitrogen fixation (BNF), a key reaction of the nitrogen cycle, is catalyzed by the enzyme nitrogenase. The best studied isoform of this metalloenzyme requires molybdenum (Mo) at its active center to reduce atmospheric dinitrogen (N2) into bioavailable ammonium. The Mo-dependent nitrogenase is found in all diazotrophs and is the only nitrogenase reported in diazotrophs that form N2-fixing

Dissolved organic carbon (DOC) flux is an important mechanism to convey soil carbon (C) from aboveground organic debris (litter) to deeper soil horizons and can influence the formation of stable soil organic C compounds. The magnitude of this flux depends on both infiltration and DOC production rates which are functions of the climatic, soil, topographic and ecological characteristics of a region.

We present the application of dual stable isotope analyses of NO3 (δ15N-NO3 and δ18O-NO3) to provide a comprehensive assessment of the provenance, partitioning, and conversion of nitrate across the Day River Basin (DRB), Vietnam, which is heavily impacted by agriculture and urbanization. Stable isotope compositions of river water δ18O-H2O, in addition to their δ15N-NO3 and δ18O-NO3 signatures, were

Fluorescence spectroscopy is a common tool to assess optical dissolved organic matter (DOM) and a number of characteristics, including DOM biodegradability, have been inferred from these analyses. However, recent findings on soil and DOM dynamics emphasize the importance of ecosystem-scale factors, such as physical separation of substrate from soil microbial communities and soil physiochemical cycles

Salt marsh biogeochemical processes are regulated by ecosystem structure (e.g. plant community composition). However, plant-specific responses to stressors such as elevated nutrient inputs can have differing impacts on nitrogen (N) removal and carbon (C) sequestration. We conducted a field manipulation to investigate the impact of elevated nutrient loading on ecosystem C dynamics and nitrate reduction

Over the last century, anthropogenic activities have increased nitrogen (N) deposition considerably, which significantly affects ecosystem processes and has the potential to induce N saturation in the future. The continuous increase in N deposition may cause a non-linear response in soil respiration (Rs), an important component of carbon (C) cycling. However, little is known about N saturation threshold

Methane is produced microbially in vast quantities in sediments throughout the world’s oceans. However, anaerobic oxidation of methane (AOM) provides a near-quantitative sink for the produced methane and is primarily responsible for preventing methane emissions from the oceans to the atmosphere. AOM is a complex microbial process that involves several different microbial groups and metabolic pathways

Streambank legacy sediments may be important sources of sediment and nutrients from Mid-Atlantic watersheds. However, little is known about the nutrient processing roles of microorganisms that inhabit legacy sediments, let alone their composition, diversity, and distributions. In this study, we sampled 15 streambanks at multiple depths throughout four watersheds in the Mid-Atlantic Region of the USA

Chronic elevated nitrogen deposition has increased nitrogen availability in many forest ecosystems globally, and this phenomenon has been suggested to increase soil nitrification. Although it is believed that increased nitrogen availability would also increase nitrous oxide (N2O) emissions from forest ecosystems, its impact on N2O flux is poorly known. In this study, 3-years monitoring of N2O emissions

Soil stores over 2500 Pg carbon (C), with the majority of C stored in deep soil layers (> 30 cm). Soil C can be lost to the atmosphere when organic compounds are mineralized to carbon dioxide (CO2, via oxidative decay or respiration) and moved upward through the soil profile (via diffusion). Soil moisture status can influence the balance between respiration and diffusion, thereby altering the soil

The Walker and Syers model predict that phosphorus (P) availability decreases with time leading to a final stage known as retrogression. We tested the validity of the Walker and Syers model in the Canary Islands, a soil chronosequence ranging from 300 years to 11 million years under recurrent episodes of atmospheric dust-containing P inputs. In particular, we compared our results with those from the

Northern lakes are a source of greenhouse gases to the atmosphere and contribute substantially to the global carbon budget. However, the sources of methane (CH4) to northern lakes are poorly constrained limiting our ability to the assess impacts of future Arctic change. Here we present measurements of the natural groundwater tracer, radon, and CH4 in a shallow lake on the Yukon-Kuskokwim Delta, AK

The frequently observed discrepancy between estimations of N2O emissions at regional or global scale based either on field data or inventories (bottom-up) or on direct atmospheric observations (top-down) suggests that riparian areas and river surfaces play a significant role as hot spots of emission. We developed a modeling procedure to assess N2O emissions occurring during the transfer of water masses

Peatlands have accumulated vast quantities of organic carbon over thousands of years but it is unclear how these sensitive ecosystems will respond to future climate change. If emissions of methane from peatlands increase, then they may contribute increasingly towards climatic warming due to the higher greenhouse warming potential of this gas. We investigated the radiocarbon concentration of methane

Precise assessment of soil organic carbon (OC) storage requires understanding of soil type and depth specific differences in organic matter (OM) stabilization. Therefore, we aimed to analyze OC dynamics down the soil profile and to clarify the effect of depth on the importance of aggregate formation and mineral adsorption for OC storage in mature beech forest soils developed from different parent materials

Large uncertainties in estimates of methane (CH4) emissions from tropical inland waters reflect the paucity of information at appropriate temporal and spatial scales. CH4 concentrations, diffusive and ebullitive fluxes, and environmental parameters in contrasting aquatic habitats of Lake Janauacá, an Amazon floodplain lake, measured for two years revealed patterns in temporal and spatial variability

We studied in 2013 and 2014 the spring carbon dynamics in a Boreal landscape consisting of a lake and 15 inflowing streams and an outlet. The first year had weather and a hydrological regime typical of past years with a distinct spring freshet connected with the thaw of the average snowpack. The latter year had higher air temperatures which did not permit snow accumulation, despite similar winter precipitation

Ge/Si ratios of plant phytoliths have been widely used to trace biogeochemical cycling of Si. However, until recently, information on how much of the Ge and Si transferred from soil to plants is actually stored in phytoliths was lacking. The aim of the present study is to (i) compare the uptake of Si and Ge in three grass species, (ii) localize Ge and Si stored in above-ground plant parts and (iii)