Replacement Of Water Research Articles

Deficit Irrigation with Ascophyllum nodosum Extract Application as a Strategy to Increase Tomato Yield and Quality

Deficit irrigation is applied to several agricultural crops as a water-saving irrigation strategy. The tomato plant is sensitive to water stress; however, integration with biostimulant applications, based on seaweed extracts, could be a strategy for plants adapting to this abiotic condition. The objective of this study was to evaluate agronomic and quality aspects of tomato cultivated under deficit irrigation combined with Ascophyllum nodosum extract (ANE) application. The experiment was conducted using a completely randomized design with two water replacement levels, 70 and 100% of crop evapotranspiration (ETc), and five doses of ANE (0, 0.1, 0.2, 0.3 and 0.4%) applied via soil drench. The interaction between ANE and ETc was significant (p < 0.05) in terms of plant growth, physiological parameters, fruit yield, yield components and fruit quality. Results indicated that when the tomato plant is under deficit irrigation, a higher ANE dose is required to achieve better development when compared to the 100% ETc condition, where the dose is lower. Under deficit irrigation, the largest fruit yield was obtained with 0.3 and 0.4% ANE, and with 100% ETc, the largest fruit yield was obtained with 0.2% ANE. ANE applications were also effective in increasing plant height, stem diameter, plant biomass, leaf area, chlorophyll and relative water content. In addition, tomato quality was also favored under deficit irrigation and seaweed extract application. We conclude that ANE applications attenuate water deficit effects in tomato plants and provide a strategy to ameliorate tomato yield, tomato quality and water use in agriculture.

Influence of lactic-acid bacteria feed supplementation on free amino acid levels in serum and feces of rainbow trout (Oncorhynchus mykiss, Walbaum 1792)

IntroductionThe influence of intestinal microbiota, particularly lactic-acid bacteria, on digestion and nutrient metabolic activities has been extensively studied. In this research, we investigated the effects of supplementing the feed of rainbow trout (O. mykiss) with P. acidilactici or L. lactis probiotics. A Control group without probiotic supplementation was also included. The study aimed to evaluate growth, feed conversion indices, free amino acid levels in serum and feces, and the relative gene expression of amino acid solute carrier transporters (SLC).MethodsRainbow trout weighing 73.9±10 g were fed with a basal commercial diet supplemented with mono-strains of P. acidilactici or L. lactis at a dosage of 5 x 108 CFU per gram of feed for 60 days. The trout were reared in 100-liter tanks with independent closed recirculation systems, with a water replacement rate of 80% of the total volume daily and a controlled temperature of 15 ± 0.3 °C. The proximate composition of the basal diet consisted of crude protein (49.8%), fat (32.1%), fiber (1.31%), ash (13%), and moisture (8.3%) on a dry matter basis. The diet was provided at a rate of 2% of bodyweight per day.ResultsNo significant differences (p > 0.05) were observed in growth and feed conversion indices between the experimental groups. However, significant differences in free amino acid levels in feces and serum samples (p ≤ 0.05) were observed. The P. acidilactici group exhibited significantly higher levels of glutamate, lysine, proline, and tyrosine in feces samples, and higher levels of arginine, iso/leucine, phenylalanine, proline, serine, threonine, and valine in serum samples compared to the Control group. Additionally, the supplemented probiotic groups showed significant downregulation (p ≤ 0.05) of theslc6a19 and slc7a9 genes, which encode transporters for neutral and cationic amino acids.DiscussionThe autochthonous rainbow trout strain, P. acidilactici, demonstrated more pronounced effects on amino acid levels in feces and serum compared to the non-autochthonous L. lactis strain. However, the increased amino acid levels, particularly in the serum, resulting from P. acidilactici supplementation, did not lead to improved trout growth or feed conversion. Nonetheless, lactic-acid bacteria supplementation induced measurable metabolic effects, as evidenced by elevated levels of specific amino acids in the serum and feces.Future research should focus on evaluating these probiotic effects using specialized diets and considering the observed metabolic effects in this study.

Type B trichothecenes in cakes and their interaction with matrix components

The study evaluated the detectable type B trichothecenes (TCTB) in cakes with different formulations in order to analyse their interaction with matrix components and the impact of daily exposure to these mycotoxins by cake consumption. A central composite design was carried out with the variables type of wheat flour (wholemeal and white flour) and ratios of milk, water and sugar. The TCTB reductions were correlated with the matrix components by principal component analysis (PCA) and the daily exposure was estimated in the condition that promoted the higher TCTB mitigation. The natural contamination of wheat flour, the ingredients dilution effect and the partial replacement of water by milk affected the TCTB levels in wholemeal cake (<1500 μg/kg) and white cake (<320 μg/kg). The PCA showed that the resistant starch was correlated with the TCTB detectable. The ingredients combination that promoted TCTB reductions of 68.9% in the white cake and 78.8% in the wholemeal cake, was the formulation that used 70 g of sugar and partial substitution of water by milk (20:20, mL/mL) in relation to 100 g of wheat flour. The daily exposure estimated by consumption of wholemeal cake was 3.5 times higher in comparison to white cake. The use of ingredients that lead to high resistant starch formation is a promising mitigation strategy.

Analysis of Principal Components for the Assessment of Silage Corn Hybrid Performance under Water Deficit

Corn is an important crop for animal production systems. Owing to climate change, it is important to understand the behavior of commercial corn hybrids under low soil water availability. The objective of this study was to evaluate the morphogenic characteristics and yields of silage corn hybrids subjected to different water conditions using univariate and multivariate analyses. The experimental design was randomized blocks in a 5 × 2 factorial scheme with four replications. Corn hybrids (AGRI104, AGRI320, AGRI330, AGRI340, and AGRI360) and water replacement levels (50% and 100% replacement of crop evapotranspiration—ETc) were considered as factors. A water replacement level of 50% ETc was defined as a severe water deficit that persisted for 46 days from V7 until harvesting (R3). Plant height, stem diameter, leaf area, chlorophyll index, water productivity, fresh and dry mass, and dry matter of the shoot and root systems were evaluated. An analysis of variance and a mean test of isolated variables were carried out, and a multivariate perspective, through principal components was performed. In general, the replacement of 50% ETc changed the morphophysiological characteristics of the plants; however, it was only possible to classify the hybrids through a principal components analysis. The best performing hybrids, regardless of the water replacement levels, were AGRI340 and AGRI360.

Effect of using wastewater from the ready-mixed concrete plant on the performance of one-part alkali-activated GBFS/FA composites: Fresh, mechanical and durability properties

Water scarcity is the world's most pressing issue, as concrete batching facilities and concrete mixer trucks produce massive amounts of wash water every day. Recycling waste water from ready-mix concrete factories' concrete washing water is critical for conserving hundreds of millions of tons of water and preventing water and soil contamination. This study examined the impact of waste washing water on the microstructural, durability, fresh, and mechanical characteristics of one-part alkali-activated ground blast furnace slag (GBFS)/fly as (FA) composites (AAC) containing partial and complete replacement of tap water under ambient conditions. GBFS was used as the main binder in the production of AAC. FA was also used as a binder at 0%, 25%, and 50% instead of GBFS. Sodium metasilicate (MS) was used as a one-part activator at two dosages 7.5% and 15% of the total binder. The fresh properties (setting time and flowability), physical properties, compressive and flexural strength (3, 7, 28, 90, and 180 days) and durability (high-temperature resistance, freeze, and thaw resistance, drying shrinkage, sorptivity, HCl and MgSO4 resistances, NaCl effect and alkali-silica reaction) and microstructure analysis were investigated. The findings showed that the use of wastewater (WW) instead of tap water (TW) contributed positively or had no serious negative effect on the mechanical and durability properties of AAC. Compressive strength of 72.37 MPa and 81.67 MPa was gained with the inclusion of 50%WW at 7.5 and 15 %MS content respectively. The findings showed that WW improved the workability of fresh ACC containing FA, reduced dry shrinkage and sorptivity of ACC with 15%MS content, and refined the pores of hardened ACC. The results also supported that WW contributed to the decrease in expansion due to ASR and sulfate expansion. Using WW improved the high temperature and F-T resistance of ACC mixtures containing 15%MS content.

Simulation Study on the Impact of Water Flow Regulation Based on the MIKE 21 Model in a River Water Environment

Inadequate hydrodynamics can cause deterioration of the water environment within rivers. Regulating water conservancy projects can effectively improve the state of the water environment of rivers and promote sustainable regional development. The river plain in Zhejiang Province, China, suffers from severe hydrodynamic deficiencies, which have a significant impact on the state of the regional water environment. To investigate the changing state of the water environment of the river plain under water conservancy project control, in this study we constructed a two-dimensional hydrodynamic–water quality model based on the AD and ECOLAB modules in MIKE 21 software 2014 Edition. Combined with conservative tracers, the changes in the water displacement rate, flow rate, and water environment quality of the river plain were simulated under different regulation schemes over 7 days. A quantitative analysis of the effects of improving the state of the water environment in the river plain was carried out using a cluster analysis and a cloud model. (1) The water replacement rate of the outer river reached 90% after 3 days and approached 100% after 7 days. The water replacement rates of the inner pond were 51.2, 49.6, and 55.8%. This indicated that the engineering control measures effectively improved the replacement capacity of the river. (2) The contents of DO and BOD5 in the river have increased from class V to above class 3. The overall water quality is in the range of classes 2 to 3, and in some parts it can reach class 1. This indicates that the regulatory plan played a certain role in improving the river water environment. (3) The water pollution in the study area showed a fluctuating and decreasing trend over 7 days. There was a positive correlation between the flow velocity, water replacement rate, DO, and BOD5.

In-situ evaluation of chitosan-based materials containing fertilizer by time-domain reflectometry (TDR) technique

Population growth and resource reduction have created tremendous pressure on the current world scenario to meet the increasing food demands. To face this challenge, strategies are needed to promote the rational use of natural resources since overusing agricultural inputs such as chemical fertilizers may lead to severe environmental problems. In the present work, we evaluated (i) the nutrient release profile of macrospheres, microspheres, and microcapsules based on chitosan, montmorillonite clay, and KNO3 by TDR technique and (ii) the influence of controlled water replacement on the nutrient release in soil. TDR probes inserted in containers with sandy soil evaluated the nutrient release from materials, with and without tracking of field capacity, obtaining results for soil moisture and electrical conductivity. The nutrient release was dependent on soil water management, improving fertilization oversight. Microcapsules released the nutrient slower and for longer periods (higher than 46 days). Also, the water content corroborated the swell ability of materials, which affected and controlled the release of nutrients. These findings validate that chitosan-based materials matched the requirements for a more efficient and sustainable fertilizer, and the TDR technique effectively determined the release of nutrients.

Study on evaporation rate of steel slag pervious concrete based on CT scanning

Pervious concrete can reduce the surface temperature and improve the outdoor environment through its own evaporation capacity. The unique pore structure makes pervious concrete different from ordinary concrete and has a great impact on its macro performance, such as mechanical, penetration, fatigue, durability, noise reduction performance. In this study, the correlation between water evaporation rate and pore structure parameters of steel slag pervious concrete (SPC) was analyzed, and an empirical model formula was proposed to characterize the water evaporation rate at different evaporation time. Evaporation experiments at different temperatures and different specimen heights were designed, and the evaporation of each specimen was obtained. The porosity and surface porosity of each specimen were determined by water replacement method and computed tomography (CT) scanning. The results show that the evaporation and initial evaporation rate of SPC increase with the increase of specimen height and temperature. The relationship between evaporation rate and evaporation time conforms to the exponential function distribution, showing a rapid decline stage and a gentle decline stage, with obvious inflection points. The pore size distribution and sphericity of SPC were analyzed, and its influence on evaporation rate was negligible. With the increase of height ratio, the tortuosity of SPC increases relatively, while the surface porosity decreases. The evaporation rate model of SPC considering the influence of specimen height, temperature, tortuosity and surface porosity is constructed. The research is helpful to improve the ecological design of SPC pavement and promote the application of SPC materials.

Environmental assessment and durability performance of cement mortar incorporating sugarcane vinasse in replacement of water.

Sugarcane vinasse wastewater (SVW) is one of the most voluminous waste generated in the ethanol industry and usually applied in fertigation. It is characterized by presenting high COD and BOD; thus, continued disposal of vinasse results in negative environmental impacts. In this paper, we investigated the potential of SVW in replacement of water in mortar, rethinking about reuse of effluent, reduction of pollutants in the environment, and water consumption in civil construction. Mortar composites with 0, 20, 40, 60, 80, and 100% of water replaced by SVW were studied in order to determine the optimum content. Mortars with 60 to 100% of SVW result in improved workability and reduction in water demand. The mortars with 20, 40, and 60% SVW resulted in satisfactory mechanical properties, i.e., similar to the control mortar. However, XRD analysis of cement pastes showed that the SVW causes a delay in CH formation, reaching mechanical strength after 28days. Durability tests results showed that SVW contributes to the mortar becoming more impermeable; therefore, less susceptible to weathering. This study provides an important evaluation of the potential of SVW for application in civil construction, indicating relevant results for replacement of water by liquid wastes in cementitious composites and reduction the use of natural resources.

Impact of Irrigation on the Yield, Total Cost, and Its Influence on Hydraulic Conductivity in a Soil Under Vinasse Application

This study had the objective to evaluate the effect of irrigation and fertigation (N) in the crop yield and its impact on the total cost, in addition to its influence on the conductivity hydraulic capacity and logarithmic hydraulic conductivity in an Oxisol under vinasse application cultivated with sugarcane (second year), in state of Goiás, Brazil. The experimental design comprised randomized blocks in a 5 × 2 factorial scheme, with four replications. Treatments consisted of five levels of water replacement (100, 75, 50, 25 and 0%), with and without fertirrigation (N). The planting of sugarcane, cultivar RB85-5453, was performed in a double row (W-shaped), 8 m long, with 1.80 m spacing between the double rows, the distance between the crops in the double row was 0.40 m, with a total area of 52.8 m2 in each paddock. For treatments with water, replacement (WR) a drip tube was placed in the ground at a depth of 0.20 m among the furrows of the double row. The drip tube (DRIPNET PC 16150) comprised a thin wall, 1.0 bar pressure, nominal discharge 1.0 L h-1, and 0.50 m spacing between drippers. Nitrogen was applied by fertirrigation at a dose of 100 Kg ha-1, at 30-day intervals, with 10 applications throughout the development of the sugarcane culture. Potassium fertilization was fully realized at planting. The total cost with irrigation did not increase significantly with fertirrigation (&lt; 3%) in an Oxisol under vinasse application.

Structural transformation and magnetic properties of Co(II) coordination polymers with pyrazole-3,5-dicarboxylate and pyrazine

A two-dimensional (2D) Co(II) coordination polymer with rectangular channel, namely {[Co2(Hpzdc)2(pyz)(CH3OH)(H2O)2]⋅3H2O}n (1) was synthesized under the solvothermal condition (Hpzdc = pyrazole-3,5-dicarboxylate and pyz = pyrazine). Both Co(II) centers exhibit octahedral geometry. The coordinated methanol and all water molecules in 1 can be removed by heating to give rise to the amorphous phase of desolvated 1 (1a). After 1a was immersed in the mixture of water and methanol, a new isostructural {[Co2(Hpzdc)2(pyz)(H2O)3]⋅3H2O}n (2) was obtained. The replacement of water for methanol in 1 leads to an alteration in the intermolecular packing, which gives rise to the color variations. The single-crystal to amorphous to single-crystal transformations accompanied by the color changes were confirmed by single crystal X-ray structure analysis, XRPD, TGA, elemental analysis, and spectroscopic techniques. The magnetic properties of 1 and 2 exhibit the antiferromagnetic interaction and spin–orbit coupling of octahedral high-spin Co(II) ion.

Hydrothermal co-carbonization of sewage sludge and whey: Enhancement of product properties and potential application in agriculture

The impacts of operating conditions on hydrothermal carbonization of sewage sludge (SS) in water media were investigated in this study. Hydrothermal co-carbonization (co-HTC) of SS and cheese whey was also carried out under selected conditions (T = 250 °C, t = 5 h), to investigate the effects of replacing water with whey on product properties. Besides, the potential application was also tested of HTC products for agricultural use.The HTC treatment increased the content of nutrients (P, Ca, and Mg) in hydrochars compared to untreated SS, but fuel properties were not improved. Increasing the operating temperature and time increased the contents of nitrogen and volatile fatty acids in the process liquids. The replacement of water with whey resulted in remarkable improvement of the fuel properties of hydrochar, as the hydrochar yield increased from 57.10 to 64.14 wt%, the calorific value from 14.75 to 18.29 MJ/kg, and carbon content from 36.89 to 45.24 wt%. The ash content decreased from 46.55 to 40.06 wt%. The content of N, P, Ca, Mg and K increased significantly. SEM-EDS, FTIR and thermogravimetric analysis revealed the strong influence of the co-carbonization on the thermogravimetric behaviour of the hydrochars and their chemical properties. The HTC products proved efficient as fertiliser in a germination test with plants. Process liquids can be used as an N fertiliser, while hydrochars as a P fertiliser. Undiluted process liquids were toxic to the freshwater organisms Daphnia magna.

Economic attractiveness of domestic rainwater harvesting in Brazilian cities

Brazil is the fifth largest country by area in the world, with a variety of climates in its territory. This work assesses the economic attractiveness of domestic rainwater harvesting direct feed systems, for the replacement of non-drinking water, in 148 locations of the Brazilian territory considering hourly rainfall data for the 14-year period between 2008 and 2021. The water tariff and consumption data for each location were also considered along with estimated hourly and monthly consumption patterns. With annual operating expenses at 1% of the capital expenditure and an annual discount rate of 8%, the net present value for the 14-year period is positive in only 15 locations, which are among those with the highest water tariffs in the country. The results of these base case simulations discourage the installation of domestic RWH systems in most of the Brazilian locations considered. However, the results also show that, depending on house occupancy, filtration equipment cost, water tariff, and catchment area, outcomes more favorable to the installation of RWH systems are obtained, especially in cities of Brazil’s southern and southeastern regions.

Study on the Treatment of Simulated Recirculating Mariculture Wastewater by Thiosulfate-Based Autotrophic Denitrification

In this study, a sulfur-based autotrophic denitrifying filter (SADF) was developed for the purpose of removing nitrate from simulated recirculating mariculture wastewater. Results showed that over 90% of the nitrate could be effectively eliminated by utilizing thiosulfate as the electron donor, with a molar ratio of thiosulfate-S to nitrate molar ratio of 2:1 or greater. Additional batch tests confirmed that thiosulfate was a suitable sulfur source for nitrate removal even without prior accumulation of the biomass to nitrite. Excess thiosulfate had a minor impact on N-removal efficiency, so an external sulfur source was not required for nitrate removal, however, it could still help to reduce nitrate accumulation and water replacement to some extent. High-throughput sequencing results illustrated that Thiomicrospira and Thioalkalivibrio were the dominant autotrophic denitrifying genera in the SADF, while Thiomicrospira was more significantly affected in the case of insufficient sulfur sources. As the issue of nitrate accumulation in the mariculture recirculating system has been resolved, only a small amount of water needs to be added to the system daily. Therefore, the thiosulfate-based SADF process has the potential to be implemented for nitrate removal in mariculture systems, which could present a promising sustainable solution to the nitrate pollution issue.

Unraveling the Molecular Mechanisms of Trehalose-Mediated Protection and Stabilization of Escherichia coli Lipid Membrane during Desiccation.

Trehalose, a disaccharide renowned for its ability to stabilize biomolecular architectures under strenuous conditions, finds extensive use in the cryopreservation of probiotics. A profound comprehension of its molecular-level interactions is of great significance. It is notable that current research in the realm of lipid-sugar interactions primarily employs single-component lipid bilayers, which are far from being representative of real cell membranes. Our investigation, however, utilizes molecular dynamics simulations to delve into the specifics of a realistic Escherichia coli membrane that encompasses a diverse array of lipid types, comprising fourteen distinct species, subject to varying hydration levels. The results of our study showcase that the reduction of hydration levels induces lipid ordering and the formation of gel phases, yet trehalose, by forming hydrogen bonds with lipid headgroups, serves to uphold fluidity and supplant the role of water. Moreover, our findings evince that augmented trehalose concentrations lead to a slowdown in lipid motion and contribute to the maintenance of fluidity by way of endowing a viscous matrix. It is noteworthy that our conclusions lend support to the notion that water replacement and vitrification, despite their seemingly disparate nature, need not be considered mutually exclusive in a real bacterial membrane.

Thermo-kinetic analysis of pyrolysis of thermally pre-treated sewage sludge from the food industry

Due to the specific characteristics of sewage sludge from the food industry, including its high fat content, its treatment is quite complex. Therefore, in this study, the effect of the pre-treatment processes torrefaction (T) and hydrothermal carbonization (HTC) on the pyrolysis of industrial sewage sludge (SS) from the vegetable oil industry was investigated by thermogravimetric analysis. Kinetic and thermodynamic analysis was performed using the Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), and Friedman (FRI) iso-conversional kinetic models. In addition, the influence of water replacement by whey in the hydrothermal carbonization process was investigated on the subsequent pyrolysis kinetics.The activation energy (Eα) values for pyrolysis of industrial sewage sludge ranged from 49 to 372 kJ/mol. Pre-treatment (torrefaction, hydrothermal carbonization) of sewage sludge increases the activation energy significantly: the Eα values for torrefied (T-SS) and hydrothermally treated (HTC-SS) samples ranged from 177 to 689 kJ/mol and from 161 to 486 kJ/mol, respectively. The variations in activation energy and the generally lower activation energies for the HTC-SSW sample (158–445 kJ/mol) indicate that the use of whey in the HTC process affects the hydrochar properties and subsequent pyrolysis kinetics significantly. According to the results, the pre-treatment of the samples is reflected in better thermochemical properties and stability of the treated samples, as well as in the thermodynamic parameters of pyrolysis, since the pre-treated samples (especially the torrefied sample, T-SS) exhibited higher entropies and enthalpies and lower Gibbs free energies.

Rock acoustics of CO2 storage in basalt

SUMMARY We simulate variations in the P- and S-wave velocities due to CO2 injection in basalt, caused by water replacement and mineralization in the form of carbonate cements. Carbonization can be monitored with seismic data on the basis of changes in velocity. We consider basalts composed of (Fe, Ca and Mg) minerals mainly, and the pore space is assumed to be initially saturated with water. The mineralization is based on a model that estimates the volume of precipitated cement and resulting porosity loss, and the velocities as a function of injection time are calculated with a patchy cement model. In the example, there are two stages: 1 week of CO2 injection and 29 weeks of frame cementation. After 1 week, water has been replaced by CO2, where density and P-wave velocity decrease, and cementation implies an increase in bulk density, P-wave velocity, whereas porosity and surface area are reduced. To our knowledge there are no models relating the effects of carbon mineralization on seismic properties. The present model can be applied to other rocks, where CO2 injection induces mineralization and storage.

Эффективность использования солевого раствора при искусственном осеменении икры радужной форели Oncorhynchus mykiss (Waibaum, 1972) и ладожской палии Salvelinus alpinus lepechini (Gmelin, 1788)

In order to increase the level of fertilization of eggs, the effect of buffer solution on sperm activity and the effectiveness of its use as a medium for insemination eggs of rainbow trout which was grown in conditions of flowing water and in recirculation aquaculture system (RAS), as well as Ladoga palia, were tested. In male trout and palia, the number of motile spermatozoa and their activity were higher in solution than in water. In trout which was grown in running water, the percentage of eggs fertilization increased significantly when use solution only in cases when the eggs were contaminated with the contents of burst eggs. In fish grown in the RAS, the replacement of water with a buffer solution increased the level of fertilization in all test variants, regardless of the presence or absence of contamination of the eggs. In Ladoga palia, the result of insemination was the same in water and in solution.

Effects of salinity changes on larval survival, growth, and development of the edible sea cucumber, Holothuria leucospilota (Brandt, 1835) at two developmental stages

For large-scale artificial breeding of sea cucumber (Holothuria leucospilota), it is necessary to understand how environmental parameters affect larval rearing. In this study, the effects of salinity changes on survival, growth, and development of the mid- and late-auricularia of H. leucospilota were estimated within a 7-day culture period. Salinity shock is usually accompanied by water replacement during hatching. To replicate the occurrence of salinity changes in actual larval production, 1/2 of the larval rearing water (initial salinity ∼31.6 ppt) was replaced daily by the experimental waters at different salinity levels (18, 22, 26, 30, 34, 38, and 42 ppt). On day 7, larval survival rates varied with salinity, while the highest survival rates (44.37–46.63% for mid-auricularia; 50.71–53.98% for late-auricularia) were observed in normal salinities (30 and 34 ppt) and the lowest survival rates (15.71–23.96% for mid-auricularia; 24.11–29.57% for late-auricularia) were observed in extreme salinities (18, 22, and 42 ppt). For any sampling event, the body length of mid-auricularia in normal salinities (30 and 34 ppt) were continued to increase during the 7-day culture period. The highest length of late-auricularia was reached on day 3 (880.01 ± 84.38 and 889.06 ± 112.11 µm, respectively), then decreased to 745.31 ± 127.64 and 742.94 ± 98.43 µm on day 7 due to metamorphosis. On day 7, the proportion of mid-auricularia larvae without development potential was the lowest (36.67%) at a salinity level of 34 ppt, and the proportions were increased with both decreasing/increasing salinities. However, this proportion was much lower for the late-auricularia at the same salinity. The decrease in salinity could promote metamorphosis of the late-auricularia, and the highest proportion of doliolaria (24.32%) was observed at salinity level of 26 ppt on day 7. In extreme salinities (18, 22, and 42 ppt), the hyaline spheres (indication of larval competence) in late-auricularia were less obvious than those in other salinities. The ability in resisting salinity shock was increased with larval development, where late-auricularia had better tolerance to salinity shock than mid-auricularia, whereas larvae at both stages were more tolerant to hypertonic than hypotonic conditions. Based on our results, we propose to rear the mid- and late-auricularia at a comparatively high level of salinity (e.g., ∼31 ppt) to promote their survival and performance, while to decrease the salinity (e.g., ∼26 ppt) in the last period of late-auricularia to increase their competence to metamorphose into doliolaria.

Flotation Recovery of Sphalerite in Sea Water: A Feasibility Study

Mining and mineral processing industry adversely affects ecosystems and communities in nearby areas, including high freshwater consumption and scarcity. That is why the emerging global trend is to use sea water in flotation to recover valuable minerals from finely disseminated base metals ores. Recent studies investigate sea water flotation of copper, molybdenum, nickel sulphides and pyrite, while flotation of sphalerite, the main valuable mineral for zinc production, remains uncovered. This paper examines the feasibility of sphalerite flotation by conventional collectors in artificial sea water using a bubble-particles technique and frothless flotation tests. Potassium isopropyl xanthate (PIPX) and sodium isopropyl dithiophosphate (SIDTP) were used as collectors, and copper sulphate was introduced as the activator, while zinc sulphate and sodium sulphide were used as depressants. We examined the most common size fractions of sphalerite: medium (−74 + 44 μm) and fines (−44 μm). The findings showed the feasibility of sphalerite flotation in artificial sea water. We also established correlations between the rate of bubble-particle attachment and the sphalerite flotation recovery resulting in the growth of flotation recovery with the increase of the bubble-particle attachment rate. The results can be used as guidelines in choosing flotation reagents for sphalerite flotation in sea water. Another practical application of the results is the potential for sustainable development of the industrial sector, ecosystems and societies due to the replacement of fresh water by sea water, although further technological and environmental studies are required.