Cumulative Surface Area Research Articles

Effects of silico-tungstic acid on the pseudo capacitive properties of manganese oxide for electrochemical capacitors applications

In this work manganese oxide (MnO2) is modified with silico-tungstic acid (STA). Three samples are synthesized by the co-precipitation method. The powders obtained after elaboration are characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) imaging coupled to Electron Dispersive Spectroscopy (EDS) analysis and Brunauer-Emmet-Teller (BET) for their surface area determination. The effect of the modification of the manganese oxide with STA on its surface is determined. It is shown that MnO2 modified with STA exhibits better cumulative high specific surface areas and mesoporous volumes areas. For example, the sample fabricates with 10% STA (MnO2 – 10% STA) has a BET surface area of 153.6 ​m2 ​g−1 and volume area 0.92 ​cm3 ​g−1 whereas the sample without STA (MnO2 – 0% STA) has a surface area of 132.57 ​m2 ​g−1 and a mesoporous area of 0.26 ​cm3 ​g−1. The electrochemical performance analysis of the different working electrodes prepared for super-capacitors applications is carried out using cyclic voltammetry (CV)., using a solution of 0.5 M K2SO4 as an electrolyte in potential range of −0.4 and 0.9 ​V at a sweep speed of 10 ​mV/s. The CV results are correlated to those of the BET surface and mesoporous areas values Accordingly, it is shown that samples spiked with STA exhibit higher electrochemical double layer capacitance than those of none modified with STA. These measurements respectively give 38 ​F ​g−1, and 181 ​F ​g−1 for MnO2 without STA (MnO2 – 0% STA), and MnO2 modified with 10% STA (MnO2 – 5% STA).

Looks like home: numerosity, but not spatial frequency guides preference in zebrafish larvae (Danio rerio)

Despite their young age, zebrafish larvae have a well-developed visual system and can distinguish between different visual stimuli. First, we investigated if the first visual surroundings the larvae experience during the first days after hatching shape their habitat preference. Indeed, these animals seem to “imprint” on the first surroundings they see and select visual stimuli accordingly at 7 days post fertilization (dpf). In particular, if zebrafish larvae experience a bar background just after hatching, they later on prefer bars over white stimuli, and vice versa. We then used this acquired preference for bars to investigate innate numerical abilities. We wanted to specifically test if the zebrafish larvae show real numerical abilities or if they rely on a lower-level mechanism—i.e. spatial frequency—to discriminate between two different numerosities. When we matched the spatial frequency in stimuli with different numbers of bars, the larvae reliably selected the higher numerosity. A previous study has ruled out that 7 dpf zebrafish larvae use convex hull, cumulative surface area and density to choose between two numerosities. Therefore, our results indicate that zebrafish larvae rely on real numerical abilities rather than other cues, including spatial frequency, when spontaneously comparing two sets with different numbers of bars.

Implications of Temperature for the Modification of High-Overmature Shale Reservoirs: Experimental and Numerical Analysis

Summary High-temperature pore reconstruction technology is a reservoir reconstruction measure that has emerged in recent years. It is of great significance to study the variation in pore structure characteristics of shale under high temperature for reservoir reconstruction. To study the effect of high temperature on shale pores, scanning electron microscopy (SEM) experiments and fluid injection experiments were used to analyze the variation of pore structure characteristics under high temperature. Studies have shown that temperature has a great influence on the morphology and distribution characteristics of shale pores. In particular, there is a temperature between 300°C and 400°C that is suitable for modifying pores. The distribution characteristics, surface area, and volume of pores vary dramatically under this temperature threshold. The pore morphology and distribution characteristics changed from small and sparse to large and dense. The Brunauer-Emmett-Teller (BET) surface area increased by 95%. The cumulative surface area of Barrett-Joyner-Halenda (BJH) adsorption and desorption increased by 71.7% and 72%, respectively. The pore volume of the 2-nm to 20-nm pore size increased by 63.2%. The pore volume of pore sizes greater than 20 nm increased by 191.6%. The pore variation characteristics were in line with the typing law, and the fitting result R2 ranged from 0.92201 to 0.99882.

Accelerated and Biopredictive In Vitro Release Testing Strategy for Single Agent and Combination Long-Acting Injectables

The purpose of this study was to develop an in vitro release testing (IVRT) strategy to predict the pre-clinical performance of single agent and combination long acting injectable (LAI) suspension products. Two accelerated IVRT methods were developed using USP apparatus 2 to characterize initial, intermediate, and terminal phases of drug release. Initial and intermediate phases were captured using a suspension cup with moderate agitation to ensure a constant, low surface area exposure of the LAI suspension to the release media. The terminal phase was obtained by exposing the LAI suspension to a high initial paddle speed. This resulted in smaller suspension particulates with high cumulative surface area that were dispersed throughout the release media, enabling rapid drug release. The in vitro release profiles obtained with these two methods in 48 h or less were independently time scaled to reflect the in vivo time scale of approximately 1800 h. Level-A in vitro in vivo correlations (IVIVCs) were separately developed for each method and active pharmaceutical ingredient (API) using in vivo absorption profiles obtained by deconvolution of rat plasma concentration-time profiles. The IVIVCs were successfully validated for each API. This work provides a framework for evaluating individual phases of drug release of complex LAIs to ultimately predict their in vivo performance.

The Influence of TiO2 Nanoparticles on the Physico–Mechanical and Structural Characteristics of Cementitious Materials

The urgent need for sustainable construction that corresponds to the three pillars of sustainable development is obvious and continuously requires innovative solutions. Cementitious composites with TiO2 nanoparticles (NT) addition show potential due to their improved durability, physico–mechanical characteristics, and self-cleaning capacity. This study aimed to evaluate the influence of NT on cementitious composites by comparing those with 2%–5% nanoparticles with a similar control sample without nanoparticles, as well as an analysis of cost growth. The experimental results showed an increase in bulk density of the material (4.7%–7.4%), reduction in large pore sizes by min. 12.5%, together with an increase in cumulative volume and cumulative specific surface area of small pore sizes, indicating densification of the material, also supported by SEM, EDS, and XRD analyses indicating acceleration of cement hydration processes with formation of specific products. The changes at microstructural level support the experimental results obtained at macrostructural level, i.e., modest but existent increases in flexural strength (0.6%–7.9%) and compressive strength (0.2%–2.6%) or more significant improvements in abrasion resistance (8.2%–58%) and reduction in water absorption coefficient (37.5%–81.3%). Following the cost–benefit analysis, it was concluded that, for the example case considered of a pedestrian pavement with a surface area of 100 m2, using 100 mm thick slabs, if these slabs were to be made with two layers, the lower layer made of cementitious composite as a reference and the upper layer with a thickness of 10 mm made of cementitious composite with 3% NT or 4% NT, the increase in cost would be acceptable, representing less than 15% compared to the cost for the exclusive use of cementitious composite without NT.

Influence of the gas–liquid non-equilibrium media structure on the mass transfer dynamics in biophysical processes

Multiphase biophysical media are known to be complex structures with continuous high demand to the scientific community for understanding the relationships and ratios between factors affecting the type, dynamics and nature of its structural changes on their impact degree on the media itself. Among the plentiful list of such factors the following do worth mentioning: the lifetime of a particle, turbulence factors and a number of others, each requiring careful analysis, assessment of the contribution degree and, importantly, correct accounting. The present study is focused on such a factor affecting mass transfer intensity change as surface tension through its relationship with the interfacial area: the latter is the site of mass exchange between the gas and liquid phases, and modifications in surface tension values can significantly impact the characteristics of this area, hence altering the rate of mass transfer. By controlling surface tension, one can effectively modulate the size and stability of particles, namely bubbles or droplets, which in turn changes the interfacial area available for mass transfer. The total interfacial area, which is the cumulative surface area of all bubbles, serves as the site for mass transfer. The impact of the surface tension coefficient variation into gas–liquid mass transfer characteristics is analyzed both for the case of water and model liquid. The latter means the potential contribution of surface-active substances was a part of research scope since it was applied to recreate conditions similar to the cultural liquid when microorganisms that produce surfactants are grown. The proposed new methodology assumes calculating interfacial area through the segmentation of images captured by a high-speed camera, thus we can gain a profoundly enhanced understanding of the relationship between surface tension and mass transfer. The precise visual data and subsequent computation of the interfacial area provide deeper insights into the dynamics of bubble formation and the effects of surface tension on bubble size and distribution. As a result, this method has significantly improved our capacity to investigate and optimize mass transfer processes in multiphase biophysical systems. Both analytical approach and results interpretation not only influence affirmatively on deep understanding of natural mechanisms in biophysical media, but also might serve their best for potential application, e.g. in the context of the development of biotechnological industries based on fermentation processes for protein production.

Emission reduction agents: A solution to inhibit the emission of harmful volatile organic compounds from crumb rubber modified bitumen

Volatile organic compounds (VOCs) in bitumen fumes pose health risks to workers. Adding end-of-life tire crumb rubber (CR) to bitumen increases VOC emissions. To promote cleaner asphalt production, recycled materials like cementitious materials, activated carbon, zeolite, and geopolymers were incorporated into crumb rubber modified bitumen and explored as emission reduction agents (ERAs). Proton-transfer-reaction time-of-flight mass spectrometry was used to compare VOC emissions across blends. ERAs reduced emissions by at least 33%, with Portland cement, activated carbon, and geopolymer-based fly ash achieving up to 58%, 49%, and 48% reduction, respectively. Multivariable regression analyses showed that the BET surface area, BJH adsorption cumulative surface area, BJH desorption cumulative surface area, and average pore diameter of the ERAs were the predominant factors contributing to the reduction of VOC emissions.

Fractal characteristics of artificially matured lacustrine shales from Ordos Basin, West China

Nanometer scaled pores are critical to studying gas shale reservoirs. In order to obtain the information of the evolution mechanism of nanoscale pore within lacustrine organic-rich shales, artificially matured shale samples from the Ordos Basin were treated using hydrous pyrolysis experiment. Low-temperature nitrogen adsorption, inductively coupled plasma atomic emission spectrometry (ICP-AES), and field emission scanning electron microscopy (FE-SEM) experiments were used to investigate the nanopore evolution with migration and precipitation of materials. The results show that the pore sizes were distributed from 1.1 to 500 nm, and the overall porosity tends to increase first and then decrease. The micropores and fine mesopores (< 10 nm) increased gradually from the 250 to the 350 °C, calcite appeared dissolution following a small peak of feldspar dissolution at this stage, and the CO2 reaches a partial pressure peak at 350 °C. The micropores, mesopores and macropores increased steeply from the 370 °C to the 450 °C. Organic pores were not developed until 350 °C, and well developed at 370 and 400 °C. Organic pores, intergranular pores of clay and intragranular pores of pyrite were well developed at 370 °C. The cumulative specific surface areas increased at 400 °C caused by the dehydration and transformation reaction of clay minerals. This study could provide a reference for the exploration of shale gas in lacustrine shales with different thermal maturities.

A theory of perceptual number encoding.

There has long been interest in how the mind represents numerical magnitude, particularly in the absence of symbols. For humans and nonhuman animals, number represents a core dimension of perceptual experience by which objects in the physical world are delineated. The physical world is also well characterized by other dimensions, many of which covary with number. Yet, the general consensus is that number is perceived independently of other magnitudes that co-occur with it. Here, we present evidence against the independence of number perception. In particular, we use evidence from neuroimaging, computational modeling, visual illusions, and psychophysics to introduce a novel theory of visual number encoding, wherein nonnumerical magnitude information such as cumulative surface area is encoded along with number and sustained throughout visual perception. Moreover, we propose that the experience of number per se reflects the readout of a multidimensional (i.e., integral) representation vis-à-vis selective attention, not the independent encoding of number. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

The efficacy of different implant surface decontamination methods using spectrophotometric analysis: an in vitro study.

Various methods have been proposed to achieve the nearly complete decontamination of the surface of implants affected by peri-implantitis. We investigated the in vitro debridement efficiency of multiple decontamination methods (Gracey curettes [GC], glycine air-polishing [G-Air], erythritol air-polishing [E-Air] and titanium brushes [TiB]) using a novel spectrophotometric ink-model in 3 different bone defect settings (30°, 60°, and 90°). Forty-five dental implants were stained with indelible ink and mounted in resin models, which simulated standardised peri-implantitis defects with different bone defect angulations (30°, 60°, and 90°). After each run of instrumentation, the implants were removed from the resin model, and the ink was dissolved in ethanol (97%). A spectrophotometric analysis was performed to detect colour remnants in order to measure the cumulative uncleaned surface area of the implants. Scanning electron microscopy images were taken to assess micromorphological surface changes. Generally, the 60° bone defects were the easiest to debride, and the 30° defects were the most difficult (ink absorption peak: 0.26±0.04 for 60° defects; 0.32±0.06 for 30° defects; 0.27±0.04 for 90° defects). The most effective debridement method was TiB, independently of the bone defect type (TiB vs. GC: P<0.0001; TiB vs. G-Air: P=0.0017; TiB vs. GE-Air: P=0.0007). GE-Air appeared to be the least efficient method for biofilm debridement. T-brushes seem to be a promising decontamination method compared to the other techniques, whereas G-Air was less aggressive on the implant surface. The use of a spectrophotometric model was shown to be a novel but promising assessment method for in vitro ink studies.

Spatiotemporal Dynamics of Landscape Transformation in Western Balkans’ Metropolitan Areas

Human-caused landscape transformation represents a danger to conserving the Earth’s natural habitats. Landscape fragmentation (LF) caused by transportation infrastructure and urban development poses a threat to human and environmental health by increasing traffic noise and pollution, reducing the size and viability of wildlife populations, facilitating the spread of invasive species, and reducing the recreational qualities of the landscape. It is especially noticeable in the metropolitan areas of developing countries due to rapid and unsupervised urban sprawl. In this context, this study aims to protect natural landscapes and biodiversity, promoting forms of sustainable development. To exemplify our aim, we bring a spatio-temporal analysis of landscape change comparing three metropolitan areas in the Western Balkans (WB). First, we compare the land use land cover (LULC) changes in Tirana (Albania), Skopje (North Macedonia), and Sarajevo (Bosnia and Herzegovina). The comparison was based on the Urban Atlas (UA) data of 2012 and 2018. The analysis was performed on two levels, at the metropolitan and urban spatial scales. Apart from descriptive statistics about the changes in surface area and patch counts, we used effective mesh size (meff) as a landscape metric to quantify the LF level. Our results show that each city has faced significant LULC change between 2012 and 2018, with a dominant increase in artificial surfaces. Furthermore, the cumulative natural surface area reduction is followed by increased landscape patch counts, indicating an increased LF at both levels. This study enhances public awareness about the landscape transformation trends in the developing metropolitan regions of WB. The respective administrative bodies at both local and central levels are invited to consider our results and adopt proper measurements to reduce the adverse consequences of subsequent spatial development decisions.

Microscopic Reservoir Characteristics of the Lacustrine Calcareous Shale: An Example from the Es4 s Shale of the Paleogene Shahejie Formation in Boxing Sag, Dongying Depression.

The Es4s shale is taken as the main research object to understand and describe the reservoir characteristics in Boxing Sag, Dongying Depression. Through core observation, X-ray diffraction, thin section observation, field-emission scanning electron microscopy analysis, and low-pressure nitrogen gas adsorption experiment, the reservoir space of the Es4s shale including pore types, pore size, and pore structure characteristics was elucidated. The study shows that the shale in the Boxing Sag has the following characteristics: (1) the reservoir space in the study area is diverse, with the development of inorganic pores, organic pores, and microfractures. The higher the content of calcite and organic matter, the more favorable the development of intergranular pores, dissolution pores, and organic matter pores and (2) complex pore structure. The average Barrett–Joyner–Halenda pore size of calcareous shale is 6.5–22.8 nm, and the Brunauer–Emmett–Teller cumulative specific surface area is 0.7588–4.744 m2/g. According to the morphological analysis of the adsorption and desorption curve, it is found that the shale samples in the target interval are mainly ink-bottle-shaped, cylindrical, and slit-shaped pores. The shale samples with relatively well-laminated intervals are mainly composed of ink-bottle-shaped and cylindrical pores, while the samples with relatively unlaminated intervals and high clay mineral content are mainly composed of slit-shaped pores. The contents of clay minerals and calcite are correlated with pore volume, specific surface area, and pore size, which further indicates the controlling effect of clay minerals and carbonate mineral components on pore structure parameters. This study not only helps us to understand the distribution of various micropores/nanopores in the lacustrine shale but also acts as a guiding note for the characterization of the shale oil reservoir, which ultimately offers a theoretical foundation for lacustrine shale oil exploration and development.

The malleable impact of non-numeric features in visual number perception

Non-numeric stimulus features frequently influence observers' number judgments: when judging the number of items in a display, we will often (mis)perceive the set with a larger cumulative surface area as more numerous. These “congruency effects” are often used as evidence for how vision extracts numeric information and have been invoked in arguments surrounding whether non-numeric cues (e.g., cumulative area, density, etc.) are combined for number perception. We test whether congruency effects for one such cue – cumulative area – provide evidence that it is necessarily used and integrated in number perception, or if its influence on number is malleable. In Experiment 1, we replicate and extend prior work showing that the presence of feedback eliminates congruency effects between number and cumulative area, suggesting that the role of cumulative area in number perception is malleable rather than obligatory. In Experiment 2, we test whether this malleable influence is because of use of prior experiences about how number naturalistically correlates with cumulative area, or the result of response competition, with number and cumulative area actively competing for the same behavioral decision. We preserve cumulative area as a visual cue but eliminate response competition with number by replacing one side of the dot array with its corresponding Hindu-Arabic numeral. Independent of the presence or absence of feedback, we do not observe congruency effects in Experiment 2. These experiments suggest that cumulative area is not necessarily integrated in number perception nor a reflection of a rational use of naturalistic correlations, but rather congruency effects between cumulative area and number emerge as a consequence of response competition. Our findings help to elucidate the mechanism through which non-numeric cues and number interact, and provide an explanation for why congruency effects are only sometimes observed across studies.

No intrinsic number bias: Evaluating the role of perceptual discriminability in magnitude categorization.

Accumulating evidence suggests that there is a spontaneous preference for numerical, compared to non-numerical (e.g., cumulative surface area), information. However, given a paucity of research on the perception of non-numerical magnitudes, it is unclear whether this preference reflects a specific bias towards number, or a general bias towards the more perceptually discriminable dimension (i.e., number). Here, we found that when the number and area of visual dot displays were matched in mathematical ratio, number was more perceptually discriminable than area in both adults and children. Moreover, both adults and children preferentially categorized these ratio-matched stimuli based on number, consistent with previous work. However, when number and area were matched in perceptual discriminability, a different pattern of results emerged. In particular, children preferentially categorized stimuli based on area, suggesting that children's previously observed number bias may be due to a mismatch in the perceptual discriminability of number and area, not an intrinsic salience of number. Interestingly, adults continued to categorize the displays on the basis of number. Altogether, these findings suggest a dominant role for area during childhood, refuting the claim that number is inherently and uniquely salient. Yet they also reveal an increased salience of number that emerges over development. Potential explanations for this developmental shift are discussed. RESEARCH HIGHLIGHTS: Previous work found that children and adults spontaneously categorized dot array stimuli by number, over other magnitudes (e.g., area), suggesting number is uniquely salient. However, here we found that when number and area were matched by ratio, as in prior work, number was significantly more perceptually discriminable than area. When number and area were made equally discriminable ('perceptually-matched'), children, contra adults, spontaneously categorized stimuli by area over number (and other non-numerical magnitudes). These findings suggest that area may be uniquely salient early in childhood, with the previously-observed number bias not emerging until later in development.

Factors influencing the cleaning of plant samples with ultrasonic technology

Effective cleaning of biological samples is a critical step in environmental studies. However, the literature lacks standardized cleaning procedures and protocols and there is little information about how even the most basic conditions may affect cleaning efficiency. Here, leaves of different species were first exposed to the soil naturally containing mercury particles and then washed in an ultrasound water bath under the following conditions: newly cleaned/reused beakers, water temperature, sample immersion/free-floating, sample quantity, and the number of washing cycles. Additionally, the effects of sample pubescence on cleaning efficacy were also assessed. Results indicated that the best cleaning efficacy was recorded when samples were placed in cold water under forced immersion and beakers were cleaned between washing cycles. At least two of these three conditions were needed for adequate washing. The results also indicated that, for the glabrous leaves, a cumulative leaf surface area of ≤10,000 mm2 was efficiently cleaned after 3–5 washing cycles, while as pubescence increased, 9–11 cycles were needed and often the sample quantity had to be reduced (<5,000 mm2). Our experiments reveal that cleaning can be optimized by applying easy procedures and according to individual sample typology, resulting in faster and more effective cleaning. Novelty statement The cleaning of samples is a frequent stage in the analytical processes of phytoremediation studies. This work provides new and valuable information to optimize the cleaning of plant samples by simply applying ultrasonic technology and distilled water. In fact, we have tested the influence of some factors never taken into account previously.

The dangers of reused personal protective equipment: healthcare workers and workstation contamination

BackgroundPersonal protective equipment (PPE) is essential to protect healthcare workers (HCWs). The practice of reusing PPE poses high levels of risk for accidental contamination by HCWs. Scarce medical literature compares practical means or methods for safe reuse of PPE while actively caring for patients.MethodsIn this study, observations were made of 28 experienced clinical participants performing five donning and doffing encounters while performing simulated full evaluations of patients with coronavirus disease 2019. Participants' N95 respirators were coated with a fluorescent dye to evaluate any accidental fomite transfer that occurred during PPE donning and doffing. Participants were evaluated using blacklight after each doffing encounter to evaluate new contamination sites, and were assessed for the cumulative surface area that occurred due to PPE doffing. Additionally, participants' workstations were evaluated for contamination.ResultsAll participants experienced some contamination on their upper extremities, neck and face. The highest cumulative area of fomite transfer risk was associated with the hook and paper bag storage methods, and the least contamination occurred with the tabletop storage method. Storing a reused N95 respirator on a tabletop was found to be a safer alternative than the current recommendation of the US Centers for Disease Control and Prevention to use a paper bag for storage. All participants donning and doffing PPE were contaminated.ConclusionPPE reusage practices pose an unacceptably high level of risk of accidental cross-infection contamination to healthcare workers. The current design of PPE requires complete redesign with improved engineering and usability to protect healthcare workers.

Optimizing the mechanical and surface topography of hydroxyapatite/Gd2O3/graphene oxide nanocomposites for medical applications

A ternary nanocomposite (TNC) was fabricated for introducing multifunctional properties for various biomedical applications. The nanocomposites consist of hydroxyapatite (HAP) combined with/without graphene oxide (GO) and gadolinium oxide (Gd2O3). The lattice constants of HAP were around 9.4285 and 6.7476 Å, while for Gd2O3 was around 10.8441 Å. The morphological investigation detected the nanosheets of GO, and nanorods of HAP/Gd2O3 with length of 27 nm. Moreover, the topological study based on a field emission scanning electron microscope (FESEM) showed that HAP/GO had average roughness (Ra) of 4.8 nm, and the root mean square value (Rq) with a value of 7 nm. Furthermore, the average pore size reached 7.99 nm for the NC of HAP/GO. In addition, the cumulative surface area using the density functional theory (DFT) method was calculated at around 44.61 m2/g for TNC. The cell viability in vitro of osteoblast cell line improved from 95.6 ± 0.6% to 96.7 ± 0.5% which indicates the biocompatibility of the implants to be used in biomedical applications.

Long-Term Evolution of Greenhouse Gas Emissions From Global Reservoirs

The contribution of artificial reservoirs to greenhouse gas (GHG) emissions has been emphasized in previous studies. In the present study, we collected and updated data on GHG emission rates from reservoirs at the global scale, and applied a new classification method based on the hydrobelt concept. Our results showed that CH4 and CO2 emissions were significantly different in the hydrobelt groups (p &amp;lt; 0.01), while no significant difference was found for N2O emissions, possibly due to their limited measurements. We found that annual GHG emissions (calculated as C or N) from global reservoirs amounted to 12.9 Tg CH4-C, 50.8 Tg CO2-C, and 0.04 Tg N2O-N. Furthermore, GHG emissions (calculated as CO2 equivalents) were also estimated for the 1950–2017 period based on the cumulative number and surface area of global reservoirs in the different hydrobelts. The highest increase rate in both the number of reservoirs and their surface area, which occurred from 1950 to the 1980s, led to an increase in GHG emissions from reservoirs. Since then, the increase rate of reservoir construction, and hence GHG emissions, has slowed down. Moreover, we also examined the potential impact of reservoir eutrophication on GHG emissions and found that GHG emissions from reservoirs could increase by 40% under conditions in which total phosphorus would double. In addition, we showed that the characteristics of reservoirs (e.g., geographical location) and their catchments (e.g., surrounding terrestrial net primary production, and precipitation) may influence GHG emissions. Overall, a major finding of our study was to provide an estimate of the impact of large reservoirs during the 1950–2017 period, in terms of GHG emissions. This should help anticipate future GHG emissions from reservoirs considering all reservoirs being planned worldwide. Besides using the classification per hydrobelt and thus reconnecting reservoirs to their watersheds, our study further emphasized the efforts to be made regarding the measurement of GHG emissions in some hydrobelts and in considering the growing number of reservoirs.

Small artificial waterbodies are widespread and persistent emitters of methane and carbon dioxide.

Inland waters play an active role in the global carbon cycle and emit large volumes of the greenhouse gases (GHGs), methane (CH4 ) and carbon dioxide (CO2 ). A considerable body of research has improved emissions estimates from lakes, reservoirs and rivers but recent attention has been drawn to the importance of small, artificial waterbodies as poorly quantified but potentially important emission hotspots. Of particular interest are emissions from drainage ditches and constructed ponds. These waterbody types are prevalent in many landscapes and their cumulative surface areas can be substantial. Furthermore, GHG emissions from constructed waterbodies are anthropogenic in origin and form part of national emissions reporting, whereas emissions from natural waterbodies do not (according to Intergovernmental Panel on Climate Change guidelines). Here, we present GHG data from two complementary studies covering a range of land uses. In the first, we measured emissions from nine ponds and seven ditches over a full year. Annual emissions varied considerably: 0.1-44.3g CH4 m-2 year-1 and -36-4421g CO2 m-2 year-1 . In the second, we measured GHG concentrations in 96 ponds and 64 ditches across seven countries, covering subtropical, temperate and sub-arctic biomes. When CH4 emissions were converted to CO2 equivalents, 93% of waterbodies were GHG sources. In both studies, GHGs were positively related to nutrient status (C, N, P), and pond GHG concentrations were highest in smallest waterbodies. Ditch and pond emissions were larger per unit area when compared to equivalent natural systems (streams, natural ponds). We show that GHG emissions from natural systems should not be used as proxies for those from artificial waterbodies, and that artificial waterbodies have the potential to make a substantial but largely unquantified contribution to emissions from the Agriculture, Forestry and Other Land Use sector, and the global carbon cycle.

Recruitment of Postlarval Abalone Haliotis spp. at Santa Catalina Island: Quantifying Natural Recovery

California abalone Haliotis spp., listed as species of concern, have been slow to recover, after 22 years of fishery closure, or are not recovering at all because of low-density populations and recruitment failure. It is not known if there is successful recruitment in populations in the wild in Southern California. This work examines, for the first time, whether newly settled abalones (<3 mm) are present in the wild at Santa Catalina Island to determine if recruitment is occurring. Natural cobbles with crustose coralline algae cover were sampled for recently settled abalones at two sites and at three depths over the reproductive season of green and pink abalone. A total of 128 abalone recruits (Haliotis spp.) were found over a cumulative rock surface area of 7.47 m2, on 325 cobbles, for a total recruitment density of 17.14 recruits per m2. Abalone recruits ranged in size from 220 to 2,120 µm, with an average recruit size of 490 ± 20 µm (mean ± SE, n = 124). Recruitment was similar across depths (2–4, 6–8, and 10–12 m) but differed between the two study sites, and was highest in June and September. Genetic work is needed to confirm species identification of the new recruits; however, they were most likely green abalone which would be consistent with the signs of green abalone recovery at the island. This work quantifies abalone settlement in Southern California, confirming successful recruitment. These methods can aid future restoration efforts empowering managers and restoration practitioners to monitor and quantify recruitment dynamics for abalones in California.