In an era of change, the survival and adaptability of ecosystems will be tested. An optimal ecosystem would be both resistant and resilient to negative disturbance but also efficient and redundant in its growth when given positive subsidies. However, initial evidence has suggested that these properties cannot all be maximized at the same time, and so we sought to quantitatively assess whether there are fundamental trade-offs between them at the ecosystem level. To achieve this aim, we used a 250-m resolution NASA MODIS dataset of gross primary productivity (GPP) to monitor 145,871 tidal wetland locations across the conterminous United States every 16 days from March 2000 to December 2020. We quantified the size and duration of the perturbation events in tidal wetland GPP (n = 13,754,386) and modeled their frequency distributions. Event sizes and recurrence intervals were exponentially distributed and event durations were closely modeled by an inverse power law. This scale-free manner through which tidal wetlands dissipated perturbations to their GPP flux provided them with long-term stability across a wide range of geography. We also found that a tidal wetland's positive event responses traded off between properties of efficiency and redundancy, its negative events traded off between resistance and resilience, and that all four properties were orthogonally related to one another. We then constructed a conceptual model to help understand the potential mechanism behind this four-quadrant trade-off. The trade-off appeared to be driven by a feedback between the waiting time and magnitude of positive and negative events, the duration of their effects, and the environmental and physical constraints limiting an ecosystem's growth and productivity. In summary, we detail an emergent pattern of trade-offs and constraints associated with how tidal wetland ecosystems respond to both positive and negative perturbations in carbon flux.

Tidal wetlands are critical carbon sinks, yet their response to ongoing environmental change remains uncertain across the conterminous United States. To address this gap, we quantified long-term trends and interannual variability in tidal wetland gross primary production (GPP; g C m-2 d-1) using a 20-year (2001-2020) satellite-based data set. We also examined regional differences and the relative influence of climate drivers versus vegetation canopy on gross primary productivity (GPP) dynamics. At the continental scale, GPP increased by approximately 6% over two decades, with the strongest gains in the South Atlantic and Gulf of Mexico regions. Gulf wetlands exhibited the highest productivity, while Pacific and northern Atlantic wetlands were substantially lower, reflecting climatic gradients. Decomposition analysis indicates that rising shortwave radiation and air temperature are the primary drivers of productivity increases, outweighing declines in vegetative canopy coverage and apparent greenness. Interannual variability was modest overall but greatest in the Western Gulf, where episodic disturbances such as hurricanes and drought exert strong influence. These findings suggest that recent productivity gains are driven largely by climate forcing rather than vegetation changes, underscoring the need to incorporate climatic drivers into tidal wetland carbon models and management strategies.

Even though surface water intakes in coastal regions are increasingly threatened by saltwater intrusion and river salinization, there are no comprehensive databases of these intakes. Here, using information from state agencies, we identified and characterized in a consistent manner the surface water intakes on the Chesapeake Bay, a large, coastal plain estuary of the Mid-Atlantic region of the United States, for the period 2016–2020. We identified 291 intakes in six use types: 156 irrigation and agriculture; 76 industrial, commercial, and manufacturing; 28 municipal; 19 fossil power; 10 mining; and 2 nuclear power. The nuclear and fossil power intakes accounted for 67.2% and 28.6%, respectively, of the water volume withdrawn (348 m 3 s –1 ); most of the remainder was due to industrial, commercial, and manufacturing (2.5%) and municipal (1.5%), with very small contributions from irrigation and agriculture (0.1%) and mining (0.04%). There are intakes across a wide salinity (S) range, but many occur in the low-salinity waters threatened by saltwater intrusion—specifically tidal fresh (S < 0.5 g kg –1 ) and oligohaline (0.5 g kg –1 < S < 5 g kg –1 ) , which have, respectively, 37% and 21% of the intakes and 11% and 28% of the water volume withdrawal. Our findings suggest a large potential threat of salt contamination to surface water intakes in tidal waters and the need for national databases identifying and characterizing these intakes to facilitate adaptation planning.

Even though surface water intakes in coastal regions are increasingly threatened by saltwater intrusion and river salinization, there are no comprehensive databases of these intakes. Here, using information from state agencies, we identified and characterized in a consistent manner the surface water intakes on the Chesapeake Bay, a large, coastal plain estuary of the Mid-Atlantic region of the United States, for the period 2016–2020. We identified 291 intakes in six use types: 156 irrigation and agriculture; 76 industrial, commercial, and manufacturing; 28 municipal; 19 fossil power; 10 mining; and 2 nuclear power. The nuclear and fossil power intakes accounted for 67.2% and 28.6%, respectively, of the water volume withdrawn (348 m 3 s –1 ); most of the remainder was due to industrial, commercial, and manufacturing (2.5%) and municipal (1.5%), with very small contributions from irrigation and agriculture (0.1%) and mining (0.04%). There are intakes across a wide salinity (S) range, but many occur in the low-salinity waters threatened by saltwater intrusion—specifically tidal fresh (S < 0.5 g kg –1 ) and oligohaline (0.5 g kg –1 < S < 5 g kg –1 ) , which have, respectively, 37% and 21% of the intakes and 11% and 28% of the water withdrawal. Our findings suggest a large potential threat of salt contamination to surface water intakes in tidal waters and the need for national databases identifying and characterizing these intakes to facilitate adaptation planning.

As atmospheric CO2 emissions and the trend of urbanization both increase, the ability to accurately assess the CO2 budget from urban environments becomes more important for effective CO2 mitigation efforts. This task can be difficult for complex areas such as the urban–coastal Mediterranean region near Marseille, France, which contains the second most populous city in France as well as a broad coastline and nearby mountainous terrain. In this study, we establish a CO2 modeling framework for this region for the first time using WRF-Chem and demonstrate its efficacy through comparisons against cavity-ringdown spectrometer measurements recorded at three sites: one 75 km north of the city in a forested area, one in the city center, and one at the urban/coastal border. A seasonal CO2 analysis compares Summertime 2016 and Wintertime 2017, to which Springtime 2017 is also added due to its noticeably larger vegetation uptake values compared to Summertime. We find that there is a large biogenic signal, even in and around Marseille itself, though this may be a consequence of having limited fine-scale information on vegetation parameterization in the region. We further find that simulations without the urban heat island module had total CO2 values 0.46 ppm closer to the measured enhancement value at the coastal Endoume site during the Summertime 2016 period than with the module turned on. This may indicate that the boundary layer on the coast is less sensitive to urban influences than it is to sea-breeze interactions, which is consistent with previous studies of the region. A back-trajectory analysis with the Lagrangian Particle Dispersion Model found 99.83% of emissions above 100 mol km−2 month−1 captured in Summer 2016 by the three measurement towers, providing evidence of the receptors’ ability to constrain the domain. Finally, a case study showcases the model’s ability to capture the rapid change in CO2 when transitioning between land-breeze and sea-breeze conditions as well as the recirculation of air from the industrial Fos region towards the Marseille metroplex. In total, the presented modeling framework should open the door to future CO2 investigations in the region, which can inform policymakers carrying out CO2 mitigation strategies.

Shocked zircon from impactites from the Mien impact structure, Sweden, has been investigated with the aim to date the impact event and correlate the degree of U-Pb age resetting with shock-related microtextures. In situ U-Pb spot isotope analyses of granular and microporous-granular zircon grains from the impact melt rocks give an age of 120.0 +/- 1.0 Ma. This essentially confirms the previous best estimate age of 122.4 +/- 2.3 Ma, while also increasing precision on the Mien impact age. U-Pb isotope mapping shows that radiation damage likely explains the similar U-Pb age reset associated with different shock-related microtextures. Microporous and some of the granular and microporous-granular domains yield higher U concentrations along with younger 238U/206Pb dates. Lower U contents with older 238U/206Pb dates are predominately observed in pristine domains. Due to the U-decay, the zircon lattice is damaged, a process through which Pb can be lost. This would result in younger 238U/206Pb dates, as observed for the high U domains. As the zircon crystal lattices were locally weakened, metamictization possibly facilitated the development of microporous and granular textures during the impact event. Analyses of unshocked Mien zircon confirm that radiation damage already existed before impact. Lead loss from granular domains occurred through recrystallization and from microporous domains through Pb leaching by hydrothermal fluids. In addition, our study demonstrates the utility of combined U-Pb isotope mapping and spot analysis in unraveling the link between U-Pb resetting and shock-related microtextures, the formation of which was in this case likely promoted by pre-existing radiation damage.

Study region: Chesapeake Bay Watershed Study focus: Climate plays a critical role in regulating N loading from terrestrial ecosystems to coastal waters and further affecting the health and functioning of coastal ecosystems. However, the sensitivities of riverine exports of different N species to climate change have rarely been investigated. This study examines the response of riverine exports of ammonia (NH4+), nitrate (NO3-), dissolved organic nitrogen (DON), and particulate organic nitrogen (PON) to future changes in precipitation and temperature. A suite of climate forcings was used to drive a processbased terrestrial-aquatic model, DLEM (Dynamic Land Ecosystem Model), to project changes in N loading to the Chesapeake Bay in the mid-21st century, relative to the 1990s. New hydrological insights for the region: Our simulations show that, despite a relatively small average change in freshwater discharge driven by future climate change, annual average NH4+, NO3-, DON, PON, and total nitrogen exports are likely to change by -12 %, +13 %, +2 %, -9 %, and +9 %, respectively. Driven by rising temperature, NH4+ decreases as a result of enhanced volatilization and nitrification, but NO3 - export may increase due to high mineralization and nitrification. The change in DON export is mainly regulated by discharge, and the PON change is highly uncertain due to its high sensitivity to extreme precipitation events. This study highlights the importance of considering different responses of N species to climate change when designing nutrient reduction strategies to mitigate estuarine hypoxia.

Continuous measurements of dissolved oxygen (DO) are useful for quantifying ecosystem metabolism, which is critical for understanding estuarine biogeochemistry and ecology, but current methods applied to these data may lead to estimates that are physically impossible and poorly constrained errors. Here, we present a new approach for estimating estuarine metabolism: Estuarine BAyesian Single-station Estimation (EBASE). EBASE applies a Bayesian framework to a simple process-based model and DO observations, allowing the estimation of critical model parameters, specifically light efficiency and respiration, as informed by a set of prior distributions. EBASE improves upon the stream-based model from which it was derived by accommodating missing DO data and allowing the user to set the time period over which parameters are estimated. We demonstrate that EBASE can recover known metabolic parameters from a synthetic time series, even in the presence of noise (e.g., due to tidal advection) and when prior distributions are uninformed. Optimization periods of 7 and 30 d are more preferable than 1 d. A comparison with the more-conventional method of Odum reveals the ability of EBASE to avoid unphysical results (such as negative photosynthesis and respiration) and improves when the DO data are detided. EBASE is available using open-source software (R) and can be readily applied to multiple years of long-term monitoring data that are available in many estuaries. Overall, EBASE provides an accessible method to parameterize a simple metabolic model appropriate for estuarine systems and will provide additional understanding of processes that influence ecosystem status and condition.

Climate-induced changes in hypoxia are among the most serious threats facing estuaries, which are among the most productive ecosystems on Earth. Future projections of estuarine hypoxia typically involve long-term multi-decadal continuous simulations or more computationally efficient time slice and delta methods that are restricted to short historical and future periods. We make a first comparison of these three methods by applying a linked terrestrial-estuarine model to the Chesapeake Bay, a large coastal-plain estuary in the eastern United States. Results show that the time slice approach accurately captures the behavior of the continuous approach, indicating a minimal impact of model memory. However, increases in mean annual hypoxic volume by the mid-twenty-first century simulated by the delta approach (+ 19%) are approximately twice as large as the time slice and continuous experiments (+ 9% and + 11%, respectively), indicating an important impact of changes in climate variability. Our findings suggest that system memory and projected changes in climate variability, as well as simulation length and natural variability of system hypoxia, should be considered when deciding to apply the more computationally efficient delta and time slice methods.

Multiple climate-driven stressors, including warming and increased nutrientdelivery, are exacerbating hypoxia in coastal marine environments. Withincoastal watersheds, environmental managers are particularly interested inclimate impacts on terrestrial processes, which may undermine the efficacyof management actions designed to reduce eutrophication and consequentlow-oxygen conditions in receiving coastal waters. However, substantialuncertainty accompanies the application of Earth system model (ESM)projections to a regional modeling framework when quantifying future changesto estuarine hypoxia due to climate change. In this study, two downscalingmethods are applied to multiple ESMs and used to force two independentwatershed models for Chesapeake Bay, a large coastal-plain estuary of theeastern United States. The projected watershed changes are then used toforce a coupled 3-D hydrodynamic-biogeochemical estuarine model to projectclimate impacts on hypoxia, with particular emphasis on projectionuncertainties. Results indicate that all three factors (ESM, downscalingmethod, and watershed model) are found to contribute substantially to theuncertainty associated with future hypoxia, with the choice of ESM being thelargest contributor. Overall, in the absence of management actions, there isa high likelihood that climate change impacts on the watershed will expandlow-oxygen conditions by 2050 relative to a 1990s baseline period; however,the projected increase in hypoxia is quite small (4 %) because onlyclimate-induced changes in watershed inputs are considered and not those onthe estuary itself. Results also demonstrate that the attainment ofestablished nutrient reduction targets will reduce annual hypoxia by about 50 % compared to the 1990s. Given these estimates, it is virtually certainthat fully implemented management actions reducing excess nutrient loadingswill outweigh hypoxia increases driven by climate-induced changes interrestrial runoff.

Hypoxia and acidification are commonly coupled in eutrophic aquatic environments because aerobic respiration is usually dominant in bottom waters and can lower dissolved oxygen (DO) and pH simultaneously. However, the degree of coupling, which can be weakened by non-aerobic respiration and CaCO3 cycling, has not been adequately assessed. In this study, we applied a box model to 20 years of water quality monitoring data to explore the relationship between hypoxia and acidification along the mainstem of Chesapeake Bay. In the early summer, dissolved inorganic carbon (DIC) production in mid-bay bottom waters was dominated by aerobic respiration, contributing to DO and pH declines. In contrast, late-summer DIC production was higher than that expected from aerobic respiration, suggesting potential buffering processes, such as calcium carbonate dissolution, which would elevate pH in hypoxic waters. These findings are consistent with contrasting seasonal relationships between riverine nitrogen (N) loads and hypoxic and acidified volumes. The N loads were associated with increased hypoxic and acidified volumes in June, but only increased hypoxic volumes in August, when acidified volume declines instead. Our study reveals that the magnitude of this decoupling varies interannually with watershed nutrient inputs, which has implications for the management of co-stressors in estuarine systems.

— The need for radiation monitoring at coal-mining facilities with the aim of detecting high ionization of gas−dust mixture in the air of mines is demonstrated. An assessment of mining sites by surface dosimetry is proposed in order to identify potential gas leaks in dissintegrating massifs (faults and changes in rock permeability during works). Example applications of surface dosimetry are provided.

Net primary production (NPP) plays an important role in estuarine carbon cycling, which has been increasingly impacted by human activities and global climate change. Spatiotemporal trends of NPP in the open ocean have been well studied using satellite data and standard primary production algorithms such as the Vertically Generalized Production Model (VGPM), but these algorithms are generally not suitable for estuarine and coastal waters. Previous remote sensing studies on estuarine NPP mainly focused on the tuning of the standard VGPM based on extensive local in situ data. Here we make a first attempt to use machine learning algorithms to estimate NPP in an estuarine environment from satellite measurements. Tampa Bay, the largest estuary in Florida (United States), has abundant in situ measurements of NPP, although the spatiotemporal variability of NPP within the bay remains unrevealed. Combining these data with concurrent MODIS/Aqua image data, we developed and evaluated seven machine learning algorithms (support vector regression, random forest, decision tree, bagging, adaptive boosting, gradient tree boosting, and neural network), and applied the one with the least root mean square error (RMSE) and highest correlation coefficient to establish a time-series NPP record for Tampa Bay from 2002 to 2020. Results of the best performing algorithm (Pearson’s r = 0.82, RMSE = 151.0 mgC m−2 d−1) showed substantial improvement over the standard or tuned VGPM (Pearson’s r = 0.51, RMSE = 364.9 mgC m−2 d−1), using the same independent variables for NPP ranging from 157.5 to 1368.8 mgC m−2 d−1. MODIS NPP shows temporal variations that are largely driven by temperature: lowest values in winter, highest values in summer, and an increasing trend from 2003 to 2020, highlighting the impact of global warming on estuarine NPP. The spatial distribution of MODIS NPP shows higher values in Hillsborough Bay, Middle Tampa Bay and Lower Tampa Bay, and relatively lower values in Old Tampa Bay, a pattern that likely reflects differences in river discharge. The long-term NPP product derived from machine learning algorithms and satellite data can complement existing field-based monitoring programs and help to understand estuarine responses to climate changes and human impacts, and design relevant mitigation strategies.

To address the challenges of providing high-performance calorimetry in future hadron collider experiments under conditions of high luminosity and high radiation (FCC-hh environments), we conducted R&D on advanced calorimetry techniques suitable for such operation, based on scintillation and wavelength-shifting technologies and photosensor (SiPM and SiPM-like) technology. In particular, we focused our attention on ultra-compact radiation-hard EM calorimeters based on modular structures (RADiCAL modules) consisting of alternating layers of the very dense absorber and scintillating plates, read out via radiation hard wavelength shifting (WLS) solid fiber or capillary elements to photosensors positioned either proximately or remotely, depending upon their radiation tolerance. RADiCAL modules provide the capability to measure simultaneously and with high precision the position, energy and timing of EM showers. This paper provides an overview of the instrumentation and photosensor R&D associated with the RADiCAL program.

The supplementary material is comprised of three tables (Tables S1-S3) and four figures .Appendix A provides additional details regarding the distribution of watershed organic nitrogen loadings to ChesROMS-ECB.Table S1 describes the USGS Site IDs for the three major rivers used to assess watershed model skill.Table S2 provides a list of locations for the Chesapeake Bay Program monitoring stations used to assess estuarine model skill.Table S3 lists the IDs, names, and KKZ ranks of all Earth System Models (ESMs) used in this study.Figure S1 compares regression metrics of watershed precipitation time periods used to predict annual hypoxic volume.Figure S2 shows the relative changes in watershed precipitation and temperatures for the five MACA and BCSD downscaled ESMs selected using the KKZ methodology.Figure S3 provides a representation of watershed model skill at the three major tributaries for discharge, nitrate, and organic nitrogen loadings.Figure S4 shows the relationship between Phase 6 MACA downscaled ESM estimates of annual hypoxic volume with and without the effects of management conditions.Table S1: USGS Site IDs for major tributaries used to assess watershed model skill after applying WRTDS.

Discordant U–Pb data of zircon are commonly attributed to Pb loss from domains with variable degree of radiation damage that resulted from α-decay of U and Th, which often complicates the correct age interpretation of the sample. Here we present U–Pb zircon data from 23 samples of ca. 1.7–1.9 Ga granitoid rocks in and around the Siljan impact structure in central Sweden. Our results show that zircon from rocks within the structure that form an uplifted central plateau lost significantly less radiogenic Pb compared to zircon grains in rocks outside the plateau. We hypothesize that zircon in rocks within the central plateau remained crystalline through continuous annealing of crystal structure damages induced from decay of U and Th until uplifted to the surface by the impact event ca. 380 Ma ago. In contrast, zircon grains distal to the impact have accumulated radiation damage at shallow and cool conditions since at least 1.26 Ga, making them vulnerable to fluid-induced Pb-loss. Our data are consistent with studies on alpha recoil and fission tracks, showing that annealing in zircon occurs at temperatures as low as 200–250 °C. Zircon grains from these samples are texturally simple, i.e., neither xenocrysts nor metamorphic overgrowths have been observed. Therefore, the lower intercepts obtained from regression of variably discordant zircon data are more likely recording the age of fluid-assisted Pb-loss from radiation-damaged zircon at shallow levels rather than linked to regional magmatic or tectonic events.

The optical characteristics of solutions of crystalline iodine and iodine compounds are studied and the forms of iodine and some associated compounds in solutions are determined. The utility of using direct spectrophotometric methods for the analysis of various forms of iodine and related compounds in water is evaluated.

ABSTRACT Crater-forming events are generally followed by the development of hydrothermal systems due to the rapid heating of the target rock. Such hydrothermal systems are a feature of nearly all large terrestrial impact structures. For the Siljan impact structure in Sweden, there is evidence for such a fossil hydrothermal system, possibly triggered by the impact event ca. 380 Ma. To investigate the thermal regime of the near-surface hydrothermal activity of the Siljan crater, biotite and amphibole grains extracted from samples collected in a transect across the high-pressure regime recorded by the central uplift, as well as from distal localities outside the central uplift of the crater, were dated using the 40Ar/39Ar laser step-heating technique. Our results show that biotite from inside the central uplift, which was strongly altered to chlorite by low-temperature (200–340 °C) hydrothermal reactions, yields strongly disturbed age spectra. The first and second (low laser power) step ages range from ca. 1300 to 190 Ma. In contrast, biotite from outside the central uplift and amphibole, irrespective of location inside or outside of the central uplift, are much less altered, which is reflected in less disturbed, near-flat age spectra. This result indicates that the hydrothermal temperatures inside the central uplift were >200 °C, sufficient to disturb the K-Ar system of biotite during its chloritization, but too low to affect the amphibole (closure temperature of 480–580 °C). In contrast, the temperature of the hydrothermal system outside of the central uplift was <200 °C, as no significant reset of the K-Ar system can be observed in either biotite or amphibole. Our results are consistent with estimated trapping temperatures from fluid inclusion studies, which show a decrease from 327–342 °C within the central uplift to 40–225 °C toward outside the central uplift. We conclude that the near-surface hydrothermal system in the Siljan impact structure was an impact-triggered system. This system was strongly active, with its highest temperature inside the central uplift and decreasing rapidly toward the outlying part of the crater.