Community assembly influences plant trait economic spectra and functional trade-offs at ecosystem scales.

Plant functional traits hold the potential to greatly improve the understanding and prediction of climate impacts on ecosystems and carbon cycle feedback to climate change. Traits are commonly used to place species along a global conservative-acquisitive trade-off, yet how and if functional traits and conservative-acquisitive trade-offs scale up to mediate community and ecosystem fluxes is largely unknown. Here, we combine functional trait datasets and multibiome datasets of forest water and carbon fluxes at the species, community, and ecosystem-levels to quantify the scaling of the tradeoff between maximum flux and sensitivity to vapor pressure deficit. We find a strong conservative-acquisitive trade-off at the species scale, which weakens modestly at the community scale and largely disappears at the ecosystem scale. Functional traits, particularly plant water transport (hydraulic) traits, are strongly associated with the key dimensions of the conservative-acquisitive trade-off at community and ecosystem scales, highlighting that trait composition appears to influence community and ecosystem flux dynamics. Our findings provide a foundation for improving carbon cycle models by revealing i) that plant hydraulic traits are most strongly associated with community- and ecosystem scale flux dynamics and ii) community assembly dynamics likely need to be considered explicitly, as they give rise to ecosystem-level flux dynamics that differ substantially from trade-offs identified at the species-level.

Variations in water economy traits in two Sphagnum species across their distribution boundaries.

PREMISE: We assessed changes in traits associated with water economy across climatic gradients in the ecologically similar peat mosses Sphagnum cuspidatum and Sphagnum lindbergii. These species have parapatric distributions in Europe and have similar niches in bogs. Sphagnum species of bogs are closely related, with a large degree of microhabitat niche overlap between many species that can be functionally very similar. Despite this, ecologically similar species do have different distributional ranges along climatic gradients that partly overlap. These gradients may favor particular Sphagnum traits, especially in relation to water economy, which can be hypothesized to drive species divergence by character displacement. METHODS: We investigated traits relevant for water economy of two parapatric bryophytes (Sphagnum cuspidatum and S. lindbergii) across the border of their distributional limits. We included both shoot traits and canopy traits, i.e., collective traits of the moss surface, quantified by photogrammetry. RESULTS: The two species are ecologically similar and occur at similar positions along the hydrological gradient in bogs. The biggest differences between the species were expressed in the variations of their canopy surfaces, particularly surface roughness and in the responses of important traits such as capitulum mass to climate. We did not find support for character displacement, because traits were not more dissimilar in sympatric than in allopatric populations. CONCLUSIONS: Our results suggest that parapatry within Sphagnum can be understood from just a few climatic variables and that climatic factors are stronger drivers than competition behind trait variation within these species of Sphagnum.

Coupled hydraulics and carbon economy underlie age-related growth decline and revitalisation of sand-fixing shrubs after crown removal.

Crown removal revitalises sand-fixing shrubs that show declining vigour with age in drought-prone environments; however, the underlying mechanisms are poorly understood. Here, we addressed this knowledge gap by comparing the growth performance, xylem hydraulics and plant carbon economy across different plant ages (10, 21 and 33 years) and treatments (control and crown removal) using a representative sand-fixing shrub (Caragana microphylla Lam.) in northern China. We found that growth decline with plant age was accompanied by simultaneous decreases in soil moisture, plant hydraulic efficiency and photosynthetic capacity, suggesting that these interconnected changes in plant water relations and carbon economy were responsible for this decline. Following crown removal, quick resprouting, involving remobilisation of root nonstructural carbohydrate reserves, contributed to the reconstruction of an efficient hydraulic system and improved plant carbon status, but this became less effective in older shrubs. These age-dependent effects of carbon economy and hydraulics on plant growth vigour provide a mechanistic explanation for the age-related decline and revitalisation of sand-fixing shrubs. This understanding is crucial for the development of suitable management strategies for shrub plantations constructed with species having the resprouting ability and contributes to the sustainability of ecological restoration projects in water-limited sandy lands.

Carbon budget at the individual-tree scale: dominant Eucalyptus trees partition less carbon belowground.

Large trees in plantations generally produce more wood per unit of resource use than small trees. Two processes may account for this pattern: greater photosynthetic resource use efficiency or greater partitioning of carbon to wood production. We estimated gross primary production (GPP) at the individual scale by combining transpiration with photosynthetic water-use efficiency of Eucalyptus trees. Aboveground production fluxes were estimated using allometric equations and modeled respiration; total belowground carbon fluxes (TBCF) were estimated by subtracting aboveground fluxes from GPP. Partitioning was estimated by dividing component fluxes by GPP. Dominant trees produced almost three times as much wood as suppressed trees. They used 25 ± 10% (mean ± SD) of their photosynthates for wood production, whereas suppressed trees only used 12 ± 2%. By contrast, dominant trees used 27 ± 19% of their photosynthate belowground, whereas suppressed trees used 58 ± 5%. Intermediate trees lay between these extremes. Photosynthetic water-use efficiency of dominant trees was c. 13% greater than the efficiency of suppressed trees. Suppressed trees used more than twice as much of their photosynthate belowground and less than half as much aboveground compared with dominant trees. Differences in carbon partitioning were much greater than differences in GPP or photosynthetic water-use efficiency.

Assessment of the changes in growth, photosynthetic traits and gene expression in Cynodon dactylon against drought stress.

Drought stress considered a key restrictive factor for a warm-season bermudagrass growth during summers in China. Genotypic variation against drought stress exists among bermudagrass (Cynodon sp.), but the selection of highly drought-tolerant germplasm is important for its growth in limited water regions and for future breeding. Our study aimed to investigate the most tolerant bermudagrass germplasm among thirteen, along latitude and longitudinal gradient under a well-watered and drought stress condition. Current study included high drought-resistant germplasm, "Tianshui" and "Linxiang", and drought-sensitive cultivars; "Zhengzhou" and "Cixian" under drought treatments along longitude and latitudinal gradients, respectively. Under water deficit conditions, the tolerant genotypes showed over-expression of a dehydrin gene cdDHN4, antioxidant genes Cu/ZnSOD and APX which leads to higher antioxidant activities to scavenge the excessive reactive oxygen species and minimizing the membrane damage. It helps in maintenance of cell membrane permeability and osmotic adjustment by producing organic osmolytes. Proline an osmolyte has the ability to keep osmotic water potential and water use efficiency high via stomatal conductance and maintain transpiration rate. It leads to optimum CO2 assimilation rate, high chlorophyll contents for photosynthesis and elongation of leaf mesophyll, palisade and thick spongy cells. Consequently, it results in elongation of leaf length, stolon and internode length; plant height and deep rooting system. The CdDHN4 gene highly expressed in "Tianshui" and "Youxian", Cu/ZnSOD gene in "Tianshui" and "Linxiang" and APX gene in "Shanxian" and "Linxiang". The genotypes "Zhongshan" and "Xiaochang" showed no gene expression under water deficit conditions. Our results indicate that turfgrass show morphological modifications firstly when subjected to drought stress; however the gene expression is directly associated and crucial for drought tolerance in bermudagrass. Hence, current research has provided excellent germplasm of drought tolerant bermudagrass for physiological and molecular study and future breeding.

Combined leaf gas-exchange system for model assessment.

Leaf gas-exchange measurements are useful in assessing plant environmental responses. However, uncertainties in the leaf gas-exchange model potentially limit its application. The main challenge in the model-dependent calculations is to detect violations of assumptions. Here, we developed a system that integrates into one instrument the direct measurement of leaf intercellular CO2 concentration and the standard open-flow (OF) and novel open-diffusion (OD) systems for flux measurement. In the OD system, a gas-permeable membrane between the leaf ambient air and outside air creates CO2 and H2O differentials, rather than the air flow in the OF chamber. We measured hypostomatous and amphistomatous leaves of several species with different photosynthetic capacities [sunflower (Helianthus annuus), grape (Vitis vinifera), lemon (Citrus limon), and cherry (Prunus avium)]. The CO2 and H2O differentials in the OD system strictly depend on the flux measured by the OF system. The lower permeability of the membrane resulted in a larger differential per flux, indicating that the OD system can increase the resolution for a small flux. An analysis of the conductance model along with observations suggested that cuticle and leaf intercellular conductances and the unsaturation of leaf humidity contributed to discrepancies between the direct measurement and standard calculation. The combined system developed here provides an opportunity to address these overlooked concepts in leaf gas exchange.

Comparative dynamic optimization study of batch hydrothermal liquefaction of two microalgal strains for economic bio-oil production.

This work presents dynamic optimization strategies of batch hydrothermal liquefaction of two microalgal species, Aurantiochytrium sp. KRS101 and Nannochloropsis sp. to optimize the reactor temperature profiles. Three dynamic optimization problems are solved to maximize the endpoint biocrude yield, minimize the final time, and minimize the reactor thermal energy. The biocrude maximization and time minimization problems demonstrated 11% and 6.18% increment in the optimal biocrude yields and reduction of 78.2% and 61.66% in batch times compared to the base cases for the microalgae with higher lipid and protein fractions, respectively. The energy minimization problem revealed a significant reduction in the reactor thermal energies to generate the targeted biocrude yields compared to the biocrude maximization. Therefore, the identified optimal temperature trajectories outperformed the conventional fixed temperature profiles and could improve the overall economics of the batch bio-oil production from the algal-based biorefineries by significantly enhancing the reactor performance.

A Quantitative Re-Assessment of Microencapsulation in (Pre-Treated) Yeast.

Most hydrophobes easily diffuse into yeast cells, where they experience reduced evaporation and protection from oxidation, thus allowing inherently biocompatible encapsulation processes. Despite a long-standing industrial interest, the effect of parameters such as how is yeast pre-treated (extraction with ethanol, plasmolysis with hypertonic NaCl, depletion to cell walls), the polarity of the hydrophobes and the process conditions are still not fully understood. Here, we have developed thorough analytical protocols to assess how the effects of the above on S. cerevisiae's morphology, permeability, and encapsulation efficiency, using three differently polar hydrophobes (linalool, 1,6-dihydrocarvone, limonene) and three separate processes (hydrophobes as pure 'oils', water dispersions, or acetone solutions). The harsher the pre-treatment (depleted > plasmolyzed/extracted > untreated cells), the easier the diffusion into yeast became, and the lower both encapsulation efficiency and protection from evaporation, possibly due to denaturation/removal of lipid-associated (membrane) proteins. More hydrophobic terpenes performed worst in encapsulation as pure 'oils' or in water dispersion, but much less of a difference existed in acetone. This indicates the specific advantage of solvents/dispersants for 'difficult' compounds, which was confirmed by principal component analysis; furthering this concept, we have used combinations of hydrophobes (e.g., linalool and α-tocopherol), with one acting as solvent/enhancer for the other. Our results thus indicate advantages in using untreated yeast and-if necessary-processes based on solvents/secondary hydrophobes.

Human Health Risk Assessment due to the Incidence of Heavy Metals in Different Commercial Feeds Used for the Culturing of Biofloc Fish (Nile tilapia: Oreochromis niloticus).

Fish meat is a major and rich source of white protein; its quality is determined by the fish feed. However, the low-quality feed may contribute to a source of contamination if it does not fulfill the standard protocol. Biofloc is considered one of the most efficient, successful aquacultures, but this system is still under investigation for its efficiency and safety. Thus, current study focused on the heavy metal contamination in biofloc fish fed on different commercial feeds and human health risk analysis. Samples of extensively used three feeds (Supreme™, Hitech™, and MH-Aqua™), tanks water, and biofloc fish (gills, liver muscle) were collected for heavy metals (Cu, Cd, Pb, and Cr) analysis using atomic absorption spectrometry. An experiment was designed by dividing the fish into three groups: group 1 (Supreme™), group 2 (Hitech™), and group 3 (MH-Aqua™). A bioaccumulation factor and human health risk assessment have been calculated to measure fish and human health. Results revealed that most of the heavy metal concentration was higher (P < 0.05) in MH-Aqua™ feed compared to others. Similarly, heavy metal concentration was higher (P < 0.05) in the water of group 3, where fish was cultured on MH-Aqua™ feed. However, in the fish gills, liver, and muscle, the heavy metal concentration was significantly greater in group 3 fed on MH-Aqua™ feed, followed by group 1. Heavy metals in all feeds were positively correlated to the heavy metal concentration of the fish muscles. The bioaccumulation factor for Cu and Pb was higher in the fish liver, Cd and Cr in the case of fish gills, and least in the fish muscle. EDI and THQ values vary in all the groups, while the HI value was found lower than 1 in group 1 and group 2 but higher in group 3 fed on MH-Aqua™ feed. Strict checks and balances in formulating a diet will be helpful to progressively lower the amount of dangerous heavy metals.

Markov State Model of Solvent Features Reveals Water Dynamics in Protein-Peptide Binding.

In this work, we investigate the role of solvent in the binding reaction of the p53 transactivation domain (TAD) peptide to its receptor MDM2. Previously, our group generated 831 µs of explicit-solvent aggregate molecular simulation trajectory data for the MDM2-p53 peptide binding reaction using large-scale distributed computing and subsequently built a Markov State Model (MSM) of the binding reaction (Zhou et al. 2017). Here, we perform a tICA analysis and construct an MSM with similar hyperparameters while using only solvent-based structural features. We find a remarkably similar landscape but accelerated implied timescales for the slowest motions. The solvent shells contributing most to the first tICA eigenvector are those centered on Lys24 and Thr18 of the p53 TAD peptide in the range of 3-6 Å. Important solvent shells were visualized to reveal solvation and desolvation transitions along the peptide-protein binding trajectories. Our results provide a solvent-centric view of the hydrophobic effect in action for a realistic peptide-protein binding scenario.

Assessment of textile industry effluent (untreated and microbially treated) induced genotoxic, haematological, biochemical, histopathological and ultrastructural alterations in fresh water fish Channa punctata.

The unregulated expulsion of untreated textile water into water bodies is a major hazard to aquatic ecosystems. The present investigation was contrived to estimate the impact of textile dye bath effluent (untreated and microbially treated) on fish Channa punctata. Untreated effluent-exposed fish showed extremely altered behaviour (air gulping, erratic and speedy movements, increased opercular activity) and morphology (deposition of dyes on skin and scales, high pigmentation, mucus exudation). Significantly increased micronuclei (1.61-, 1.28-, 1.38-fold) and aberrant cell frequency (1.37-, 1.45-, 1.28-fold) was observed in untreated group as compared to treated group after 15, 30, and 45 days of exposure. Tail length, % tail intensity, tail moment and olive tail moment were also enhanced in all the exposed tissues. However, maximum damage was noticed in gill tissues showing 1.19-, 1.37-, 1.34- and 1.50-fold increased TL, %TI, TM and OTM in untreated group as compared to treated group after 45 days of exposure. On comparing untreated and treated groups, increased blood parameters and significantly reduced white blood cell count (WBC) were noticed in treated group. Significantly enhanced alterations in biochemical parameters were also analysed in untreated group. Reduced alterations in enzymological levels of fishes exposed to treated effluent indicate lesser toxic nature of the degraded metabolites of dye. Histological analysis in fishes exposed to untreated effluent showed several deformities in liver (necrosis, congestion, fusion of cells and melanomacrophage infiltration) and gill tissues (necrosis, bending of lamellae and severe aneurysm). Scanning electron microscopy (SEM) analysis further reaffirmed the pathologies observed in histological analysis. Fewer structural alterations were noticed in treated effluent fishes. The results concluded that untreated effluent inflicted toxicity potential on morphology as well as physiological defects in fish, and the severity increased with increasing duration of exposure, whereas reduction in toxicity in microbially treated groups can be analysed for aquacultural purposes owing to their lesser toxic nature.

Bioavailability assessment of difenoconazole to earthworms (Eisenia fetida) in soil by oleic acid-embedded cellulose acetate membrane.

Passive sampling technology is widely used to evaluate the bioavailability of pollutants. However, relatively few studies have used passive sampling membranes (PSMs) to evaluate the environmental risks of pollutants in soil, particularly pesticides. Here, the bioavailability of difenoconazole to earthworms (Eisenia fetida) was evaluated using an oleic acid-embedded cellulose acetate membrane (OECAM) for the first time. Difenoconazole reached 94 % equilibrium (T94%) within 1 d in OECAM. For soil pore water, the freely dissolved concentration (Cfree) of difenoconazole was determined using OECAM (R2 = 0.969). In the soil system, a strong linear correlation between the difenoconazole concentration in OECAM and earthworms was observed (R2 = 0.913). The bioavailability of difenoconazole was affected by the soil type and biochar content. The higher the content of soil organic matter and biochar, the lower the concentration of difenoconazole in earthworms, OECAM, and soil pore water. The concentrations of difenoconazole in pore water, earthworms, and OECAM decreased by 65.3, 42.0, and 41.6 %, respectively, when 0.5 % biochar was added. Difenoconazole mainly enters OECAM and earthworms through passive diffusion with similar uptake pathways. Therefore, the bioavailability of difenoconazole to earthworms in different soils can be evaluated using the OECAM.

Rethinking economic theories of plant water use.

A central assumption in plant ecophysiology is that carbon is the primary currency for plant fitness. To this end, plants are thought to maximize carbon gain and any deviations from maximum carbon gain are ascribed to resource limitations (e.g., temperature, drought), biophysical limitations (e.g., biophysical limits on cell size), or variation in plant life history that may prioritize future carbon gain over current carbon gain (i.e., applying an economic discount rate to carbon). Compared to living in water, living on land made accessing CO2 substantially easier: CO2 diffuses approximately 10,000 times faster in air than in water. However, because this CO2 must diffuse into the aqueous environment of the living mesophyll cells where photosynthetic metabolism occurs (The´roux-Rancourt et al. 2021), the greater CO2 supply of the terrestrial lifestyle also comes with a cost: losing approximately 200-400 molecules of water by transpiration for every molecule of CO2 fixed by photosynthesis (Nobel et al. 2005). Water, therefore, is considered a valuable resource to be conserved and not wasted. As such, much of the field of plant ecophysiology posits carbon as the central currency for which water is traded.

Multiclass determination of drug residues in water and fish for bioaccumulation potential assessment.

In this work, a wide-scope liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantitative determination of environmental levels of multiclass drugs and their metabolites in water and fish samples was developed. The method allowed the reliable determination of 44 drugs, covering a rather wide range of chemistries and physicochemical characteristics. In order to obtain a reliable and robust analytical protocol, different combinations of extraction and cleanup techniques were systematically examined. Aqueous samples were extracted using a simple Oasis HLB SPE enrichment protocol with pH-optimized sample percolation (pH 3). The extraction of cryo-homogenized biota samples was performed using double extraction with MeOH basified with 0.5% NH3, which allowed high extraction recoveries for all target analytes. The problem of the coextracted lipid matrix, which is known to be the key obstacle for reliable biota analysis, was systematically examined in a series of model cleanup experiments. A combination of cryo-precipitation, filtration, and HLB SPE cleanup was proposed as a protocol, which allowed reliable and robust analysis of all target compounds at low ng/g levels. At the final conditions, the method which was validated at three concentration levels showed high extraction recoveries (68-97%), acceptable matrix effects (12 to -32%), accuracies (81-129%), and reproducibilities (3-32%) for all analytes. The developed method was used to determine drug concentrations in river water and in feral freshwater fish, including whole fish and muscle tissue, from the Sava River (Croatia), in order to estimate their corresponding bioaccumulation potential. With respect to bioaccumulation potential in whole fish and fish muscle, the most relevant drugs were lisinopril, sertraline, terbinafine, torsemide, diazepam, desloratadine, and loratadine with estimated bioaccumulation factors ranging from 20 to 838 and from 1 to 431, respectively.

Directional assessment of the skin barrier function in vivo.

INTRODUCTION: The fundamental function of the epidermis is to provide an inside-out barrier to water loss and an outside-in barrier to penetration of external irritants. Transepidermal water loss (TEWL) has been extensively used as a method of estimating the skin barrier quality, typically without any consideration of directionality. The validity of TEWL as an estimate of skin permeability to external substances has been controversial in vitro and in vivo. The aim of this work was to assess the relationship between TEWL and the penetration of a topically applied external marker (caffeine) in healthy skin in vivo before and following a challenge to the barrier. METHODS: The skin barrier was challenged by application of aqueous solutions of mild cleanser products under occlusion for 3 h on the forearms of nine human participants. Skin barrier quality was evaluated before and after the challenge by measuring the TEWL rate and the permeated amount of topically applied caffeine using in vivo confocal Raman microspectroscopy. RESULTS: No skin irritation was observed following the skin barrier challenge. TEWL rates and the caffeine penetrated amount in the stratum corneum after the challenge were not correlated. A weak correlation was observed when the changes were corrected to water-only treatment. TEWL values can be influenced by environmental conditions as well as the skin temperature and water content. CONCLUSIONS: Measuring TEWL rates is not always representative of the outside-in barrier. TEWL may be useful in differentiating large changes in skin barrier function (e.g., between healthy and compromised skin) but is less sensitive to small variations following topical application of mild cleansers.

Acute metabolic responses of two marine brachyuran crabs to dilute seawater: The aerobic cost of hyper regulation.

Hepatus pudibundus ("flecked box crab") is a stenohaline osmoconfomer, and restricted to marine habitats. Callinectes danae ("swimming crab Dana") lives in coastal/estuarine waters and is a weak hyper regulator. There is no consensus on which strategy is more expensive metabolically face salinity challenges: conformation with higher dependence on cell volume regulation, or hyper regulation, alleviating the need for intense cell volume regulation. Crabs were probed for their acute response to dilute seawater through exposures to salinities 35‰, 30‰, 25‰, and 20‰ for 2, 4, and 6 h. Hemolymph osmolality, lactate, and ions (chloride, sodium, magnesium, potassium) were assayed, as well as muscle water content. Water dissolved oxygen, ammonia, and pH levels were also measured. H. pudibundus conformed for osmolality and displayed increase in muscle hydration along the decrease in salinity down to 25‰, while C. danae efficiently maintained hemolymph osmo ionic stability, consumed more oxygen, acidified more the water, and released more ammonia. In 25‰, both species spent energy: H. pudibundus putatively controlling cell volume, and C. danae regulating hemolymph concentrations. In 20‰, H. pudibundus closed itself, avoiding the contact of the interface epithelia with the external environment and producing much lactate, whereas C. danae spent more energy (aerobic) in extracellular osmo ionic stability. Under these conditions, anisosmotic extracellular regulation (together with additional cell volume regulation) is more oxygen consuming than osmoconformation with a putatively more intense challenge to cell volume. The exposure to hyposalinity limits the occupation of estuarine environments by H. pudibundus in short and middle term.

Yield, quality and physiological variation of strawberry in response to irrigation regimes and exogenous proline with a cost benefit analysis.

Strawberry (Fragaria × ananassa Duch.) production is a major aspect of the agricultural economy in Turkey's Mediterranean region, offering high rates of employment and farm revenue. The effects of treatment of the exogenous amino acid on yield, quality, and physiological diversity for strawberry production was analyzed considering the economic aspects. To achieve this, 4 different irrigation regimes (IR (irrigation) 125, IR100, IR75, IR50) with proline treatment was tested. The total berry yield, photosynthesis and leaf water potential (LWP) significantly decreased as irrigation application rates declined. The IR125 treatment with proline (PIR125) produced the highest overall berry production. The use of proline significantly increased berry production by 23%. Exogenous proline generated 3.5 kg/1 m3 greater yields than control in terms of irrigation water use efficiency (IWUE). Under the IR50 conditions, the treatment of proline yielded a 32% higher than the control. Moreover, proline significantly increased fruit soluble solids content (SSC) by 6.4%. The production system achieves the highest cost-benefit ratio (CBR) under PIR125 whereas the lowest cost-benefit ratio under IR50. When each scenario was considered at individually, it was evident that the more water used the more efficient high tunnel strawberry production. The fact that proline generated an increase in CBR in all four irrigation regimes proves this amino acid's economic effectiveness. As a result, PIR125 is recommended for the highest efficiency and CBR in Mediterranean environment. However, it has been discovered that using proline to alleviate this problem in areas where water is limited could be quite helpful.

Microcosm test for pesticide fate assessment in planted water filters: 13C,15N-labeled glyphosate as an example.

Planted filters are often used to remove pesticides from runoff water. However, the detailed fate of pesticides in the planted filters still remains elusive. This hampers an accurate assessment of environmental risks of the pesticides related to their fate and thereby development of proper mitigation strategies. In addition, a test system for the chemical fate analysis including plants and in particular for planted filters is not well established yet. Therefore, we developed a microcosm test to simulate the fate of pesticide in planted filters, and applied 2-13C,15N-glyphosate as a model pesticide. The fate of 2-13C,15N-glyphosate in the planted microcosms over 31 day-incubation period was balanced and compared with that in the unplanted microcosms. The mass balance of 2-13C,15N-glyphosate turnover included 13C mineralization, degradation products, and the 13C and 15N incorporation into the rhizosphere microbial biomass and plants. We observed high removal of glyphosate (> 88%) from the water mainly due to adsorption on gravel in both microcosms. More glyphosate was degraded in the planted microcosms with 4.1% of 13C being mineralized, 1.5% of 13C and 3.8% of 15N being incorporated into microbial biomass. In the unplanted microcosms, 1.1% of 13C from 2-13C,15N-glyphosate was mineralized, and only 0.2% of 13C and 0.1% of 15N were assimilated into microbial biomass. The total recovery of 13C and 15N was 81% and 85% in planted microcosms, and 91% and 93% in unplanted counterparts, respectively. The microcosm test was thus proven to be feasible for mass balance assessments of the fate of non-volatile chemicals in planted filters. The results of such studies could help better manage and design planted filters for pesticide removal.

Environmental Impacts of Large-Scale Spirulina (Arthrospira platensis) Production in Hellisheidi Geothermal Park Iceland: Life Cycle Assessment.

Spirulina algae (Spirulina platensis) cultivated in geothermally powered photobioreactors is here proposed as a potentially resource efficient, zero-carbon, and nutritious alternative to conventional beef meat. Employing a standard life cycle assessment, environmental impacts of large-scale Spirulina production in this facility are calculated. The production facility is sited in Orka náttúrunnar (ON Power) Geothermal Park, Iceland, and benefits from resource streams accessible through Hellisheiði (Hellisheidi) power station, including renewable electricity for illumination and power usage, hot and cold water streams for thermal management, freshwater for cultivation, and CO2 for biofixation. During cultivation, GHG-intensive ammonia-based fertilizers are replaced with macronutrients sourced from natural open mines. LCA results show that production of 1 kg of wet edible biomass in this facility requires 0.0378 m2 non-arable land, 8.36 m3 fresh water and is carbon neutral with - 0.008 CO2-eq GHG emissions (net zero). Compared with conventionally produced meat from beef cattle, Spirulina algae cultured in the ON Power Geothermal Park, referred to in this study as GeoSpirulina, requires less than 1% land and water and emits less than 1% GHGs. Considering food and nutritional security concerns, cultivation in a controlled environment agriculture system assures consistent nutritional profile year-round. Moreover, GeoSpirulina biomass assessed in this study contains all essential amino acids as well as essential vitamins and minerals. While keeping a balanced nutrition, for every kg beef meat replaced with one kg GeoSpirulina, the average consumer can save ~ 100 kg CO2-eq GHGs. It is concluded that environmental impacts of GeoSpirulina production in the Hellisheidi facility are considerably lower than those of conventionally produced ruminants.