Mass Input Research Articles

The effects of weathering of coal-bearing stratum on the transport and transformation of DIC in karst watershed

The mining of medium- to high‑sulfur coal in karst areas has led to serious acidification problems in surface water, thus encouraging a re-evaluation of DIC transformation and CO2 source-sink relationships in karst watersheds. The weathering of limestone and sulfide-rich coal measures jointly influence the pH of the Huatan River in karst areas in Southwest China, which is lower in the rainy season and higher in the dry season. Due to CO2 degassing, DIC concentration tends to decrease along the flow direction, while δ13C-DIC gradually becomes heavier. In general, DIC transformation in the Huatan River is controlled by AMD input, CO2 degassing, organic matter (OM) degradation, and the dissolution and precipitation balance of carbonate minerals in different seasons. In spring, the mineralization of OM from terrestrial and domestic sewage gradually enhances and replenishes DIC in the water. As the pH increases in this season, the capacity for buffering CO2 increases. Meanwhile, OM degradation generates a large amount of CO2 in summer, and carbonic acid begins to dissolve limestone. In autumn, the pH decreases due to the enhanced weathering of sulfide-rich coal measures and the mass input of AMD. Thus, the river shows the ability to drive CO2 outgassing. In winter, CO2 degassing gradually weakens, DIC concentration is at its lowest, and δ13C-DIC reaches the heaviest value.

Farm‐scale models in fish aquaculture – An overview of methods and applications

AbstractModels are important tools to address sustainability challenges associated with developing aquaculture at farm, regional and global scales. Farm‐scale models (FSMs), which are integrated mathematical models developed to simulate farm operations, can quantify energy, mass or economic input flows and predict a variety of outputs such as fish biomass, waste and by‐products. The variety of farming systems, equations available to build the models, and objectives of applications and intended users has resulted in the publication of wide range of FSMs. We performed a narrative review of 36 fish FSMs published from 1985–2021 to address several questions: Can the main characteristics of these models be defined? How do the farming system studied and the objectives of the study influence model development? What are the main modelling techniques available to simulate the main processes of a fish farm, and what are their advantages and disadvantages? How can FSMs help address sustainability challenges of aquaculture? This review discusses advances, limitations and future lines of research related to FSMs to help select existing models, or develop new ones, that are suitable for their intended use and users. The article is structured according to the main steps of the modelling process: (i) definition of scope and objectives; (ii) process formulation and model selection at individual, cohort and farm levels; (iii) implementation and evaluation; and (iv) applications (e.g. precision fish farming, IMTA modelling, supporting spatial management, life cycle assessment). At each step, recommendations are provided and research needs are stated.

Validation of a multi-modal blood-based test for the detection of colorectal cancer with sub single molecule sensitivity.

3627 Background: Blood-based colorectal cancer (CRC) screening tests can improve adherence to screening guidelines. Yet, current commercially available options have poor sensitivity and specificity inhibiting incorporation into routine clinical care. Here we report the validation of a blood-based test for the detection of colorectal cancer and advanced neoplasia. Methods: This blood-based test aims to detect colorectal neoplasia by identifying tumor-associated biomarkers including genomic or epigenomic (methylation and fragmentomics) signatures in cell-free DNA (cfDNA). cfDNA is partitioned based on methylation level, enriched for informative genomic regions, and sequenced. This novel workflow enables high-fidelity analysis of multi-modal information in majority of extracted cfDNA molecules. Results are integrated into a binary “detected” versus “not-detected” result using a proprietary bioinformatic pipeline (Guardant Health, USA). The assay was trained on samples obtained from >6,000 unique individuals (2,685 cancer-free and 1,698 with advanced colorectal neoplasia (ACN) for training, 1,072 cancer-free and 551 with ACN for threshold setting). The thresholds were frozen prior to validation targeting a specificity of > 91.5%. Each aspect of the validation study followed Nex-StoCT CLIA working group and CLSI guidelines. Results: Limit of detection (LoD) was established across six dilutions. Even for low cfDNA mass inputs of less than 4ng, the 95% LoD was determined to be less than 1 tumor-derived genomic equivalent (0.5), indicating over at least 10-fold increase in assay sensitivity compared to best-in-class assays for somatic mutation detection. Precision studies in 60 positive and negative replicates from clinical samples yielded >90% average positive and negative percent agreement both within and between batches. Endogenous interference studies yielded > 90% positive and negative percent agreement between reference control and common endogenous substances, including albumin, bilirubin, hemoglobin, triglycerides, and genomic DNA, in clinical positive and negative samples and minimally manipulated samples. The clinical validation of the test was conducted in > 300 cases (biobanked pre-operative cohort for CRC cases and screening cohort for advanced adenoma and negative cases). Conclusions: Here we present the validation of a multi-modal blood-based test for the detection of colorectal cancer. This test is currently being evaluated in a registrational study (ECLIPSE: NCT04136002).

Strong decays of excited 2+ charmed mesons

The new charmed resonance $ D_2^*(3000) $ was observed by the LHCb Collaboration in $ B $ decays. In this paper, by assigning it as four possible excited states of the $ 2^+ $ family, we use the instantaneous Bethe-Salpeter method to calculate their Okubo-Zweig-Iizuka-allowed two-body strong decays. The results of $ 1^3F_2 $ and $ 3^3P_2 $ states deviate from the present experimental observation while $ 2^3P_2 $ and $ 2^3F_2 $ are in the error range. Our study also reveals that the widths of these states depend strongly on the masses. Due to the large uncertainties and different mass input, variable models get inconsistent conclusions at the moment. The analysis in this work can provide essential assistance for future measurements and investigations.

Monitoring concept for powder flow monitoring in Laser-Directed Energy Deposition (L-DED) process based on flexible piezoelectric sensors

Background: The quality of powder-blown Laser-Directed Energy Deposition (L-DED) is mainly governed by the energy density per unit of mass employed to melt the material. In most of the previous works, the focus in process monitoring and control was on the control of energy input, by controlling the properties of the melt pool. However, the powder mass input is as important to monitor as the energy input, in order to preserve the equilibrium of the process. Methods: In this paper, the authors present the first test results of the Pyzoflex® sensor for powder flow monitoring in L-DED using real powder feeding system in the robot-based laser-processing cell. The sensor was tested against the powder projected from the powder feeder under typical flow regimes and the real-time measurements were taken using a specifically designed software tool. Results: The graphical representation of the registered sensor signals are clearly correlated with the powder flow values set at the powder feeder, which demonstrates that the piezoelectric sensors can detect the powder flow with elevated precision in real time. Conclusions: The first laboratory tests of flexible printed piezoelectric sensors demonstrate that they are fast and precise in the powder flow measurement, but that more effort must be invested in the robustness of the measurement setup as well as in clearing and stabilization of the registered signal.

Spatial distribution and mass transport of Perfluoroalkyl Substances (PFAS) in surface water: A statewide evaluation of PFAS occurrence and fate in Alabama

Per- and polyfluoroalkyl substances (PFAS) have been previously detected near suspected sources in Alabama, but the overall extent of contamination across the state is unknown. This study evaluated the spatial distribution of 17 PFAS within the ten major river basins in Alabama and provided insights into their transport and fate through a mass flux analysis. Six PFAS were identified in 65 out of the 74 riverine samples, with mean ∑6PFAS levels of 35.2 ng L−1. The highest ∑6PFAS concentration of 237 ng L−1 was detected in the Coosa River, a transboundary river that receives discharges from multiple sources in Alabama and Georgia. PFAS distribution was not observed to be uniform across the state: while the Coosa, Alabama, and Chattahoochee rivers presented relatively high mean ∑6PFAS concentrations of 191, 100 and 28.8 ng L−1, respectively, PFAS were not detected in the Conecuh, Escatawpa, and Yellow rivers. Remaining river systems presented mean ∑6PFAS concentrations between 7.94 and 24.7 ng L−1. Although the short-chain perfluoropentanoic acid (PFPeA) was the most detected analyte (88%), perfluorobutanesulfonic acid (PFBS) was the substance with the highest individual concentration of 79.4 ng L−1. Consistent increases in the mass fluxes of PFAS were observed as the rivers flowed through Alabama, reaching up to 63.3 mg s−1, indicating the presence of numerous sources across the state. Most of the mass inputs would not have been captured if only aqueous concentrations were evaluated, since concentration is usually heavily impacted by environmental conditions. Results of this study demonstrate that mass flux is a simple and powerful complementary approach that can be used to broadly understand trends in the transport and fate of PFAS in large river systems.

Analysis of bacterial biotyping datasets with a mass-based phylonumerics approach.

A mass tree, phylonumerics approach, is implemented for the first time with expressed protein mass data acquired in biotyping applications. It is shown, for two separate and diverse bacterial datasets, that the MassTree algorithm can be used to build phylogenetic trees in a single step that mirror those output by biotyping analysis software in the form of a main spectral profile (MSP) dendrogram or alike. Adapted for these applications to accommodate higher mass inputs and large mass error tolerances for pairwise matching, the mass tree algorithm and approach offers an alternative to commercial biotyping platforms by utilizing datasets acquired from any mass spectrometer without the need for specialized and expensive software.

The Contribution of Convection to the Stratospheric Water Vapor: The First Budget Using a Global Storm‐Resolving Model

AbstractThe deepest convection on Earth injects water in the tropical stratosphere, but its contribution to the global stratospheric water budget remains uncertain. The Global Storm‐Resolving Model ICOsahedral Non‐hydrostatic is used to simulate the moistening of the lower stratosphere for 40 days during boreal summer. The decomposition of the water vapor budget in the tropical lower stratosphere (TLS, 10°S–30°N, and 17–20 km altitude) indicates that the average moistening (+21 Tg) over the simulated 40‐day period is the result of the combined effect of the vertical water vapor transport from the troposphere (+27 Tg), microphysical phase changes and subgrid‐scale transport (+2 Tg), partly compensated by horizontal water vapor export (−8 Tg). The very deep convective systems, explicitly represented thanks to the employed 2.5 km grid spacing of the model, are identified using the very low Outgoing Longwave Radiation of their cold cloud tops. The water vapor budget reveals that the vertical transport, the sublimation and the subgrid‐scale transport at their top contribute together to 11% of the water vapor mass input into the TLS.

Influence of Meteorological Conditions on Artificial Ice Reservoir (Icestupa) Evolution

Since 2014, mountain communities in Ladakh, India have been constructing dozens of Artificial Ice Reservoirs (AIRs) by spraying water through fountain systems every winter. The meltwater from these structures is crucial to meet irrigation water demands during spring. However, there is a large variability associated with this water supply due to the local weather influences at the chosen location. This study compared the ice volume evolution of an AIR built in Ladakh, India with two others built in Guttannen, Switzerland using a surface energy balance model. Model input consisted of meteorological data in conjunction with fountain discharge rate (mass input of an AIR). Model calibration and validation were completed using ice volume and surface area measurements taken from several drone surveys. The model was successful in estimating the observed ice volume evolution with a root mean square error within 18% of the maximum ice volume for all the AIRs. The location in Ladakh had a maximum ice volume four times larger compared to the Guttannen site. However, the corresponding water losses for all the AIRs were more than three-quarters of the total fountain discharge due to high fountain wastewater. Drier and colder locations in relatively cloud-free regions are expected to produce long-lasting AIRs with higher maximum ice volumes. This is a promising result for dry mountain regions, where AIR technology could provide a relatively affordable and sustainable strategy to mitigate climate change induced water stress.

Relating snowfall observations to Greenland ice sheet mass changes: an atmospheric circulation perspective

Abstract. Snowfall is the major source of mass for the Greenland ice sheet (GrIS) but the spatial and temporal variability of snowfall and the connections between snowfall and mass balance have so far been inadequately quantified. By characterizing local atmospheric circulation and utilizing CloudSat spaceborne radar observations of snowfall, we provide a detailed spatial analysis of snowfall variability and its relationship to Greenland mass balance, presenting first-of-their-kind maps of daily spatial variability in snowfall from observations across Greenland. For identified regional atmospheric circulation patterns, we show that the spatial distribution and net mass input of snowfall vary significantly with the position and strength of surface cyclones. Cyclones west of Greenland driving southerly flow contribute significantly more snowfall than any other circulation regime, with each daily occurrence of the most extreme southerly circulation pattern contributing an average of 1.66 Gt of snow to the Greenland ice sheet. While cyclones east of Greenland, patterns with the least snowfall, contribute as little as 0.58 Gt each day. Above 2 km on the ice sheet where snowfall is inconsistent, extreme southerly patterns are the most significant mass contributors, with up to 1.20 Gt of snowfall above this elevation. This analysis demonstrates that snowfall over the interior of Greenland varies by up to a factor of 5 depending on regional circulation conditions. Using independent observations of mass changes made by the Gravity Recovery and Climate Experiment (GRACE), we verify that the largest mass increases are tied to the southerly regime with cyclones west of Greenland. For occurrences of the strongest southerly pattern, GRACE indicates a net mass increase of 1.29 Gt in the ice sheet accumulation zone (above 2 km elevation) compared to the 1.20 Gt of snowfall observed by CloudSat. This overall agreement suggests that the analytical approach presented here can be used to directly quantify snowfall mass contributions and their most significant drivers spatially across the GrIS. While previous research has implicated this same southerly regime in ablation processes during summer, this paper shows that ablation mass loss in this circulation regime is nearly an order of magnitude larger than the mass gain from associated snowfall. For daily occurrences of the southerly circulation regime, a mass loss of approximately 11 Gt is observed across the ice sheet despite snowfall mass input exceeding 1 Gt. By analyzing the spatial variability of snowfall and mass changes, this research provides new insight into connections between regional atmospheric circulation and GrIS mass balance.

Understanding the interior structure of gaseous giant exoplanets with machine learning techniques

Context. Characterizing the interiors of gaseous giant exoplanets is currently one of the main objectives in exoplanetary sciences. In particular, the planetary heavy-element mass provides a critical constraint on planet formation from exoplanetary systems. However, gas giant exoplanets show large diversities in thermal states and their interior properties vary across a wide magnitude range. Forward modeling of their interiors exhibits a larger degeneracy with respect to rocky exoplanets. Aims. We applied machine learning techniques based on mixture density networks (MDNs) to investigate the interiors of gaseous giant exoplanets. We aim to provide a well-trained MDN for quick and efficient predictions. Methods. Based on our current knowledge of gas giants in the Solar System, we discussed an effect of model uncertainties on planetary interiors and presented a data set for gas giants with masses between 0.1 and 10 Jupiter masses using two-layer interior models. Then, MDNs were constructed to train the generated data set and their performance was evaluated in order to achieve a well-trained one. Results. The MDN using planetary mass and radius as inputs exhibits the well-known degeneracy of interior models. The surface temperature of a planet bears constraints on the thermal state of planetary interiors, and adding it as additional input considerably breaks the degeneracy of possible interior structures. The MDN with inputs of mass, radius, and surface temperature is found to show excellent performance in predicting the interior properties of gaseous giant exoplanets, although these interior properties span over a very wide range. We also applied the well-trained MDN to four gas giants in the Solar System and beyond. The MDN predictions are in good agreement with the interior model solutions within the observational and systematic uncertainties. Conclusions. We offer a convenient and powerful tool available online providing knowledge of the interiors of gaseous giant exoplanets in addition to rocky exoplanets, which could be helpful for our understanding of planet formation in diverse protoplanetary environments.

Chemical production process portfolio optimization considering resource integration

Environmental concerns and depleting resources motivate economies to become more circular and encourage engineers to re-consider plant design by enhancing internal integration. This can be achieved by designing an eco-industrial park (EIP), in which a cluster of plants are synergistically integrated for mass and energy resources. Deciding which plants to include in the cluster determines its overall performance. In terms of economic performance, this is especially challenging as raw materials, products, and utility prices continuously fluctuate on the market, which results in the overall profit of a cluster becoming variable and imposes an investment risk to consider in decision making. In this study, Modern Portfolio Theory (MPT) is adopted to guide the selection of plants to be included in a process investment portfolio, considering both integrated (clusters) and non-integrated process plants or clusters. While integrated clusters typically enable improved returns through savings of energy and mass inputs over individual, stand-alone plants, their coupling may affect variability, and therefore, the risk dimension of portfolio construction. An MPT approach is proposed, which extends a recently presented MPT approach for stand-alone plant portfolio selection to consider optimally integrated clusters of plants, which are synthesized using an optimal design method that simultaneously considers all energy and material resources of a cluster. The MPT approach determines the process plant portfolios that are most attractive for investment from a risk-return perspective and the optimum capital distribution among portfolio constituents. A case study of six plants is presented to illustrate the MPT approach. The findings show that optimal risk-return portfolios do not consist of only integrated clusters of plants (EIPs) but are often complemented by stand-alone plants contributing to portfolio stability.

Revisiting Ice Flux and Mass Balance of the Lambert Glacier–Amery Ice Shelf System Using Multi-Remote-Sensing Datasets, East Antarctica

Due to rapid global warming, the relationship between the mass loss of the Antarctic ice sheet and rising sea levels are attracting widespread attention. The Lambert–Amery glacial system is the largest drainage system in East Antarctica, and its mass balance has an important influence on the stability of the Antarctic ice sheet. In this paper, the recent ice flux in the Lambert Glacier of the Lambert–Amery system was systematically analyzed based on recently updated remote sensing data. According to Landsat-8 ice velocity data from 2018 to April 2019 and the updated Bedmachine v2 ice thickness dataset in 2021, the contribution of ice flux approximately 140 km downstream from Dome A in the Lambert Glacier area to downstream from the glacier is 8.5 ± 1.9 Gt·a−1, and the ice flux in the middle of the convergence region is 18.9 ± 2.9 Gt·a−1. The ice mass input into the Amery ice shelf through the grounding line of the whole glacier is 19.9 ± 1.3 Gt·a−1. The ice flux output from the mainstream area of the grounding line is 19.3 ± 1.0 Gt·a−1. Using the annual SMB data of the regional atmospheric climate model (RACMO v2.3) as the quality input, the mass balance of the upper, middle, and lower reaches of the Lambert Glacier was analyzed. The results show that recent positive accumulation appears in the middle region of the glacier (about 74–78°S, 67–85°E) and the net accumulation of the whole glacier is 2.4 ± 3.5 Gt·a−1. Although the mass balance of the Lambert Glacier continues to show a positive accumulation, and the positive value in the region is decreasing compared with values obtained in early 2000.

Biocatalytic Production of 2-α-d-Glucosyl-glycerol for Functional Ingredient Use: Integrated Process Design and Techno-Economic Assessment.

Advanced biomanufacturing builds on production processes that are both profitable and sustainable. Integrated design of process unit operations, geared to output efficiency and waste minimization and guided by a rigorous techno-economic assessment, is essential for development aligned to these central aims. Here, we demonstrate such a development for the biocatalytic production of the biological extremolyte 2-O-α-d-glucosyl-glycerol (2-GG) for functional ingredient application. The process was aligned in scale over all steps (∼180 g product; ∼2.5 L reaction mixture) and involved continuous enzymatic synthesis from sucrose and glycerol interlinked with reactive extraction and nanofiltration for product isolation (purity of ∼80 wt %) and side stream recovery. Glycerol used in ∼6-fold excess over sucrose was recycled, and hydrothermal conversion into 5-(hydroxymethyl)furfural was evaluated for the fructose by-product released from sucrose. Based on a process mass intensity (total mass input/mass product) of 146, ∼80% of the total mass input was utilized and an E-factor (mass waste/mass product) of 28 was obtained. EcoScale analysis revealed a penalty point score of 44, suggesting an acceptable process from a sustainability point of view. Process simulation for an annual production of 10 tons 2-GG was used for the techno-economic assessment with discounted cash flow analysis. The calculated operating costs involved 35 and 47% contributions from materials and labor, respectively. About 91% of the material costs were due to chemicals for the reactive extraction-acidic stripping step, emphasizing the importance of material reuse at this step. Glycerol recycling involved a trade-off between waste reduction and energy use for the removal of water. Collectively, the study identifies options and boundaries of a profitable 2-GG process. The minimum selling price for 2-GG was calculated as ∼240 € kg–1 or smaller. The framework of the methodology presented can be generally important in applied bio-catalysis: it facilitates closing of the gap between process design and implementation for accelerated development.

ИЗМЕНЕНИЕ МИНЕРАЛЬНОГО И ХИМИЧЕСКОГО СОСТАВА СИЛЛОВ ПРИ ВНЕДРЕНИИ В ОСАДОЧНЫЙ ПОКРОВ, ВПАДИНА ГУАЙМАС, КАЛИФОРНИЙСКИЙ ЗАЛИВ (СКВАЖИНЫ DSDP 477, 477А, 478, 481/481А)

In the Guaymas Basin of the Gulf of California, changes in the mineral and chemical composition of sills of different thicknesses were studied in hydrothermal systems, which formed during the intrusion of hot sills into highly porous young (Pleistocene) cold sediments filled with seawater. Holes DSDP 477 and 477A were drilled in the high heat flow area and Holes 478 and 481/481A in the low heat flow area. Thick sills from Holes 477, 477A, and 478 (47 m, 30 m and 112 m, respectively) are fresh or very weakly altered mainly due to the fact that practically no water released from the host Pleistocene sediments during their heating penetrated into the sills. Olivine, whose content is small in these sills (a few percent) is unaltered. In mesostasis, the amount of which is also a few percent, there are clay minerals. The high heat flow in the area of Holes 477 and 477A (1250 mW/m2) did not change the unfavorable situation for changes in the mineral and chemical composition of the thick sills without water entering them. Thin sills with a thickness of 0.1 to 0.65 m and sills with a relatively small thickness of 1.2 to 4.5 m, which were intersected in Holes 478 and 481/481A are altered. They are fractured and therefore favorable for the penetration of water released from the heated sediments. In addition, in these sills a large volume is occupied by mesostasis (mainly from 18 to 45 %, in some samples from 53 to 70 %) replaced to varying degrees by clay minerals. Olivine is often completely replaced by clay minerals. In thin basalt sills, their alteration strongly decreases K contents. In some cases, the content of Mn, Mg, P, Na, and Ti decreases in them insignificantly. The low heat flow measured in the areas where Holes 478 and 481/481A (150 and 165 mW/m2) were drilled indicates that mineral and chemical changes in the thin sills occurred without heat and mass input from the convective long-lived hydrothermal systems.

Identifying hot-spots for microplastic contamination in agricultural soils—a spatial modelling approach for Germany

Microplastic (MP) contamination in agricultural soils has recently gained significant attention in science and society. The continuous plastic waste generation and its low degradation rates indicate a cumulative effect of MP in the environment that calls for more research on the amounts and impacts of this contaminant. The most discussed agricultural sources for MP contamination of cropland are sewage sludge, compost, and plasticulture residues. However, knowledge about how much MP has been emitted into agricultural soils is scarce. Since MP distribution in soils is expected to be highly heterogeneous, its analysis in field samples provides mainly point information. To quantify the various MP sources and pathways within and across ecosystems, data-driven models represent crucial tools to scale these analytic results to a landscape level and to simulate effects of mitigation measures. Some recent modelling studies have estimated MP emissions based on production and consumption statistics at national level, but as of yet, spatially explicit regional quantification of MP emissions into agricultural soils are virtually missing in the scientific literature. Using data on MP analysis results from the literature in combination with national and regional statistics on sewage sludge, compost and organic waste production, as well as speciality cropping areas, we estimated the spatial distributions of cumulative MP mass inputs into agricultural soils in Germany. Although these estimates are based on limited data availability, our results provide first indications about locations where detailed soil analysis could be useful to investigate in situ processes and impacts. The methodology can be applied to other regions and continuously adapted when more knowledge on relevant sources, transport, accumulation, and degradation rates of MP in soils is gained in the future.

Biogeochemical cycling of zinc in soil-cassava cropping system in Thailand

Interminable plant production with negligent management might lead to zinc (Zn) depletion in soils, which could induce a Zn deficit in staple foods and cause human Zn malnutrition in many of the least-developed countries. Knowledge of the Zn pool and balance in soil-cassava systems is unclear and requires a detailed investigation. Herein, we examined Zn mass inputs (weathering and manure) and output (harvest crop) from 34 locations of cassava-grown soils in Thailand. The results revealed that the median available Zn concentration (0.47 mg kg−1) of the studied soils was below the critical Zn requirement for cassava production. The total Zn stock in the soils varied considerably from 9.0 to 633 kg Zn ha−1, only 1% of which was identified as the available pool, and the rest of the fraction was considered as the reserved pool. Strong linear relationships (R2 > 0.61–0.90) of total Zn concentration with clay, organic matter, and total Fe concentration suggested that phyllosilicate, organic matter, and Fe oxyhydroxides were the primary hosts for Zn in the soils. Belowground biomass (70% of the total biomass) was the most abundant biomass fraction, whereas 88% of the total Zn uptake accumulated in the aboveground biomass. The Zn output from the biomass harvest was 61–642 g Zn ha−1 yr−1, corresponding to only 0.10% of the total soil Zn stock. Most locations (91% of the studied sites) received Zn input solely from mineral weathering (0.014–0.975 g Zn ha−1 yr−1) without Zn fertilizer and manure additions, causing net Zn depletions (–642 to –61 g Zn ha−1 yr−1). A few locations had net Zn accumulations (+123 to + 1,971 g Zn ha−1 yr−1) caused by animal manure additions. Without the manure additions, the total Zn stock was estimated to decline by only 1% of the total current Zn stock within the next 10 years, whereas the manure additions would enhance the total Zn stock by 0.26–7.68%. This study highlighted that the Zn input from weathering is meager for cassava production. Combined Zn fertilizer and organic manure are urgently required to resupply and replenish readily available Zn pools and to promote the total Zn stock for sustaining long-term crop production.

Phosphorus mass balance and input load estimation from the wet and dry periods in tropical semiarid reservoirs.

The dynamics of total phosphorus (TP) in 18 strategic reservoirs of the high-density reservoir network of the Brazilian semiarid was evaluated during the wet and dry periods for the past 12 years. Seasonal overlying concentrations presented no significant differences for about 90% of the reservoirs (p>0.05). This was attributed to a trade-off between the hydrological/limnological processes occurring in the two seasons. Then, a transient complete-mix mass balance model was applied with particular adaptations for the tropical semiarid reservoirs to estimate the TP load for each season. Because of the relatively well-mixed conditions and high hypolimnetic dissolved oxygen concentrations during the wet season, the wet load was assumed to represent the external TP load. On the other hand, because of the absence of reservoir inflow during the dry season, phosphorus release under anoxic sediment conditions and wind-induced resuspension under shallow water depths, the dry load was assumed to reflect the internal TP load. The maximum external loads were related to peak inflows, notably after drought periods. Consistently, the largest internal loads were obtained during the drought periods, when the reservoirs were shallower and more prone to phosphorus release and resuspension. By comparing the impact of the two input load types, the wet period load was predominant in 72% of the reservoirs. The areal phosphorus loads ranged from 0.66 to 7.29 gP m2 year-1, which were consistent with the literature, despite the very high density of reservoirs. Finally, power-law curves including data for all studied reservoirs were adjusted between the dry period load and volume, dry and wet period loads, wet period load and inflow, and total load and catchment area, resulting in satisfactory R2 (0.84-0.98).

Plagioclase population dynamics and zoning in response to changes in temperature and pressure

AbstractZoned plagioclase crystals are often interpreted as proxies for magmatic history because the mineral is present in most silicic magmas and has compositional sensitivity to magmatic conditions (pressure, temperature, and composition) with slow internal diffusion that preserves compositional zones. Changes in growth rates and crystal dissolution present challenges to quantitatively relating time to particular zoning patterns. The numerical model SNGPlag uses Rhyolite MELTS to determine the equilibrium phase assemblage and compositions for a user-defined magma composition experimentally determined instantaneous nucleation and growth rates, and reasonable dissolution rates to examine plagioclase crystallization and population dynamics through time. The model tracks the numbers, sizes, morphologies, and compositional zoning of plagioclase crystals through time in response to changes in pressure, temperature, and volume or mass inputs. Model results show that significant fractions of time are functionally missing from the crystal record because of effectively zero growth rates or erased from the record through dissolution; in some instances, those processes can together remove ≫50% of time from the crystal record. The results show that temperature- (or pressure-) cycling alone will not produce substantial compositional zoning but that the addition of new magma is required to grow complexly zoned phenocrysts. Comparison of the input pressure-temperature-time series with compositional transects shows that the crystal record is biased toward more recent intervals and periods of decreasing temperature (i.e., neither the peak temperatures nor intervals of prolonged, cool storage are favored). Crystallization (or dissolution during heating) acts to return magmas to near-equilibrium crystal fractions within hundreds of days.

Taking a mass-balance approach to assess marine plastics in the South China Sea

The South China Sea (SCS) is recognised as a global hotspot for plastic pollution. We review available field studies and identify a significant lack of data needed to construct a simple mass balance box model for plastic pollution in the SCS. Fundamental information on plastic mass input, transfer and sink terms are simply not available. Also unknown are the rates of accumulation in different environments, the dispersal pathways of plastic particles of different density, the residence times of plastic in the water column and the rate at which macroplastics are transformed into microplastics in different environments. Filling these information gaps is critical for states to determine adequate response measures, including developing and tracking impact of policies to deal with the problem of plastic pollution in the SCS.