Effects Of Seawater Temperature Research Articles

Effect of seawater temperature and pH on the sperm motility of the European eel.

The current climate change situation could bring critical effects for marine species, especially those already considered endangered. Although some species can adapt fast to the environmental changes, it is necessary to get into the worst scenario and develop tools to anticipatedly assess the physiological effects of such environmental change. With this purpose, our study aims to determine the effect of a range of seawater temperatures and pHs on sperm motility in the European eel (Anguilla anguilla). Low seawater pH (6.5-7.4) decreased the eel sperm motility in comparison to the control (pH = 8.2). We also studied the combined effect of the pH of the artificial seminal plasma (the plasma where the sperm cells are suspended) with the pH of Artificial Sea Water (ASW, pH 7.8 or and 8.2). We did not find statistical differences in sperm motility and kinetic parameters caused by the artificial seminal plasma pH. However, seawater pH induced significantly higher values of total sperm motility, and the percentage of fast spermatozoa with a pH of 8.2 in comparison with a pH of 7.8. In contrast, the seawater temperature did not affect sperm motility parameters or sperm longevity. To study the effect of the interaction between seawater temperature and pH on sperm motility, two temperatures: 4 and 24°C, and two pHs 7.8 and 8.2, were tested. There were significant differences between temperature and pH in several kinetic parameters and, in general, the lowest values were observed in the samples activated at low temperature and low pH (4°C, pH 7.8). This work suggest that eel sperm motility and kinetics will not be affected by the expected changes in pH or temperature due to the climate change.

Effect of seawater temperature on the corrosion and cavitation erosion-corrosion resistance of Al10Cr28Co28Ni34 high-entropy alloy coating

The influence of temperature on the corrosion and cavitation erosion-corrosion (CE-C) behavior of Al10Cr28Co28Ni34 high-entropy alloy (HEA) coating in seawater was investigated. Interestingly, the corrosion resistance of the coating progressively diminished with an increase in seawater temperature, but the CE-C resistance demonstrated a trend of initial increase followed by a decrease. At higher seawater temperature, the resistance of the coating surface and the destructive force of the bubbles were respectively enhanced and weakened due to the increase in oxide film thickness, maximum bubble size, and collapse time, together leading to a reduction in the damage degree to the coating.

Effects of seawater temperature and irradiance on the growth of sporelings of Amphiroa cf. zonata and Corallina berteroi (Corallinales, Rhodophyta) in Japan

ABSTRACTGeniculate coralline algae in temperate waters form dense, carpet-like turfs and are prevalent in intertidal rocky habitats or as understory beneath canopy-forming seaweeds in shallow subtidal zones. Using laboratory cultures, we determined the optimum and vital growth conditions for sporelings of two geniculate species, Amphiroa cf. zonata and Corallina berteroi, which are dominant in temperate waters around Japan. Samples were genetically identified as matching those two species as known from the coasts of Japan and worldwide, respectively. The optimum water temperature range and the upper critical water temperatures for sporeling growth were similar for the two coralline species. The optimum growth temperatures of A. cf. zonata (25–30°C) and C. berteroi (20–25°C) were comparable to those for temperate seaweeds commonly found in the same temperate region of Japan as the study sites. However, the upper critical temperatures for growth (33°C in A. cf. zonata and 32°C in C. berteroi) were higher than what is known for temperate kelps, though similar to those for other macroalgae. Amphiroa cf. zonata in the upper subtidal zone exhibited photoinhibition in conditions of less than 400 µmol photons m–2 s–1, whereas C. berteroi in the intertidal zone did not show such photoinhibition. The difference in irradiance effects upon growth was inferred to be related to the species distributions in their local environments of the coastal zone.

Effects of seawater temperature and acute Vibriosp. challenge on the haemolymph immune and metabolic responses of adult mussels (Perna canaliculus)

The New Zealand Greenshell™ mussel (Perna canaliculus) is an endemic bivalve species with cultural importance, that is harvested recreationally and commercially. However, production is currently hampered by increasing incidences of summer mortality in farmed and wild populations. While the causative factors for these mortality events are still unknown, it is believed that increasing seawater temperatures and pathogen loads are potentially at play. To improve our understanding of these processes, challenge experiments were conducted to investigate the combined effects of increased seawater temperature and Vibrio infection on the immune and metabolic responses of adult mussels. Biomarkers that measure the physiological response of mussels to multiple-stressors can be utilised to study resilience in a changing environment, and support efforts to strengthen biosecurity management. Mussels acclimated to two temperatures (16 °C and 24 °C) were injected with either autoclaved, filtered seawater (control) or Vibriosp. DO1 (infected). Then, haemolymph was sampled 24 h post-injection and analysed to quantify haemocyte immune responses (via flow-cytometry), antioxidant capacity (measured electrochemically) and metabolic responses (via gas chromatography-mass spectrometry) to bacterial infection. Both seawater temperature and injection type significantly influenced the immune and metabolite status of mussels. A lack of interaction effects between temperature and injection type indicated that the effects of Vibrio sp. 24 h post-infection were similar between seawater temperatures. Infected mussels had a higher proportion of dead haemocytes and lower overall haemocyte counts than uninfected controls. The proportion of haemocytes showing evidence of apoptosis was higher in mussels held at 24 °C compared with those held at 16 °C. The proportion of haemocytes producing reactive oxygen species did not differ between temperatures or injection treatments. Mussels held at 24 °C exhibited elevated levels of metabolites linked to the glycolysis pathway to support energy production. The saccharopin-lysine pathway metabolites were also increased in these mussels, indicating the role of lysine metabolism. A decrease in metabolic activity (decreases in BCAAs, GABA, urea cycle metabolites, oxidative stress metabolites) was largely seen in mussels injected with Vibrio sp. Itaconate increased as seen in previous studies, suggesting that antimicrobial activity may have been activated in infected mussels. This study highlights the complex nature of immune and metabolic responses in mussels exposed to multiple stressors and gives an insight into Vibrio sp. infection mechanisms at different seawater temperatures.

Effects of Seawater Temperature and Salinity on Physiological Performances of Swimming Shelled Pteropod Creseis acicula During a Bloom Period

Creseis acicula is a swimming shelled pteropod species, widely distributed in the world’s oceans. In 2020, an unprecedented bloom of C. acicula was observed in Daya Bay, and lasted from June to July. To date, there is very limited information on the physiological characteristics of this species, which is essential to understand bloom dynamics. In the present study, the physiological performances of C. acicula in response to temperature (17–35°C) and salinity (18–38 ppt) were investigated. The oxygen consumption (OCR) and calcification rates (CR) of C. acicula peaked at 32 and 26°C, respectively, while ammonia excretion rate (AER) significantly increased with increasing temperature. The thermal coefficient Q10 (respiration) of C. acicula dropped to a minimum value between 32 and 35°C, suggesting that they were in a stressful status. The O:N ratio ranged from 3.24 to 5.13, indicating that protein was the major catabolism substrate. Temperature exerted a stronger effect on the OCR and AER of C. acicula. Salinity has a more influence on CR. The preferable temperature for C. acicula ranges from 29 to 32°C, and the preferable salinity ranges from 28 to 33 ppt. Based on a comprehensive consideration, we presumed that the warmer seawater temperature around the thermal discharge area of Daya Bay nuclear power plant is a possible cause for the bloom of C. acicula.

Effects of seawater temperature and seasonal irradiance on growth, reproduction, and survival of the endemic Antarctic brown alga Desmarestia menziesii (Phaeophyceae)

Endemic Antarctic macroalgae are especially adapted to live in extreme Antarctic conditions. Their potential biogeographic distribution niche is primarily controlled by the photoperiodic regime and seawater temperatures, since these parameters regulate growth, reproduction, and survival during the entire life cycle. Here we analyzed the upper survival temperature (UST) of juvenile sporophytes and the temperature range for sporophyte formation from gametophytes of Desmarestia menziesii, one of the dominant endemic Antarctic brown algal species. This process is a missing link to better evaluate the full biogeographical niche of this species. Two laboratory experiments were conducted. First, growth and maximum quantum yield of juvenile sporophytes were analyzed under a temperature gradient (0, 5, 10, 12, 13, 14, 15, and 16 °C) in a 16:8 h light:dark (LD) regime (Antarctic spring condition) for 2 weeks. Second, the formation of sporophytes from gametophytes (as a proxy of gametophyte reproduction) was evaluated during a 7 weeks period under a temperature gradient (0, 4, 8, 12, and 16 °C), and two different photoperiods: 6:18 h LD regime simulating winter conditions and a light regime simulating the Antarctic shift from winter to spring by gradually increasing the light period from 7.5:16.5 h LD (late winter) to 18.5:5.5 h LD (late spring). Sporophytes of D. menziesii were able to grow and survive up to 14 °C for 2 weeks without visible signs of morphological damage. Thus, this species shows the highest UST of all endemic Antarctic Desmarestiales species. In turn, gametophyte reproduction solely took place at 0 °C but not at 4–8 °C. The number of emerging sporophytes was six times higher under the light regime simulating the transition from winter to spring than under constant short day winter conditions. There was a negative relationship between the number of sporophytes formed and the gametophyte density at the beginning of the experiment, which provides evidence that gametophyte density exerts some control upon reproduction in D. menziesii. Results strongly indicate that although sporophytes and gametophytes may survive in warmer temperatures, the northernmost distribution limit of D. menziesii in South Georgia Islands is set by the low temperature requirements for gametophyte reproduction. Hence, global warming could have an impact on the distribution of this and other Antarctic species, by influencing their growth and reproduction.

Effects of seawater temperature and NaCl concentration on interlaminar shear behavior of CFRP laminates

The aim of this paper is to study the interlaminar shear behavior of CFRP in critical service conditions. The specimens were immersed in the prepared artificial seawater for 7 months to investigate the ageing time, ambient temperature and salt concentration effects. Analytical balance was used to weight the samples for analyzing the dynamic moisture absorption behavior. Short beam shear tests were carried out to evaluate the interlaminar shear properties. Scanning electron microscopy (SEM) was used to observe the ageing damage and failure morphology. The results show that moisture absorption behavior of composites follows Fickian diffusion law. Moisture absorption rate and the maximum absorption content are mainly affected by ambient temperature but not by NaCl concentration. Compared with ageing time and NaCl concentration, the shear stiffness and shear strength are more sensitive to aging environmental temperature. After exposed in 3.5%–70 °C seawater environment for 7 months, the retention rate of shear strength is only 68.8% and the failure displacement decreases by 20.5%. The shear strength increases first and then decreases with the increase of the maximum moisture absorption, which is mainly related to the release of curing shrinking stress and the damage of interface properties. The shear properties degradation after aging is mainly related to the damage of materials induced by environment (delamination, fiber/matrix interface debonding and matrix cracking).

Herbarium macroalgae specimens reveal a rapid reduction of thallus size and reproductive effort related with climate change

Understanding and forecasting the effects of climate changes on vulnerable species are leading concerns for ecologists and conservation biologists. Herbaria are invaluable for use in long-term data series, and one of the few available methods for quantifying biodiversity changes over large periods of time. Gelidium canariense is an endemic and habitat-forming macroalga of the Canary Islands that coexists with two other habitat-forming Gelidiales: G. arbuscula and Pterocladiella capillacea. This study assesses long-term changes in thallus size and reproductive effort of all specimens deposited in the Herbarium of Universidad de La Laguna of these three Gelidiales species. Also assessed were the effects of seawater temperature and increased incident light on net primary production (NPP), and the effects of extreme desiccation conditions on the relative water content and NPP of the three Gelidiales species. The length of the thallus of the endemic species G. canariense was halved during the past 40 years. The shortening of the thallus coincided with a significant decrease in the number of reproductive structures in both Gelidium species. These morphological changes coincide with a significant increase of the sea surface temperature, air temperature above sea surface and ultraviolet radiation in the studied area. The experiments have revealed the deleterious effects of extreme desiccation and extreme irradiance on all three species. Hence, these results suggest that air temperature and irradiance are related with these morphological changes over time in the habitat-forming Gelidium species and that are most likely compromising the survival of their populations which are already declining.

Dynamic simulation of once-through multistage flash (MSF-OT) desalination process: Effect of seawater temperature on the fouling mechanism in the heat exchangers

Scale formation of carbonates and sulphates is one of the most well-known types of crystallization fouling in heat exchangers. Tackling crystallization fouling in Once-Through Multistage Flash Desalination (MSF-OT) is one of the most challenging tasks in the desalination industry. In this paper, a fouling model is developed and then incorporated into a MSF model to investigate the fouling behaviour under variable seawater temperature. The proposed dynamic model investigates the crystallization of calcium carbonate and magnesium hydroxide at the inside tube surface areas by considering the attachment and removal mechanisms. The results show that the fouling rate is higher at high constant seawater temperature. Overall, the fouling rate is lower at the seasonal variation of the seawater temperature, resulting in a higher performance ratio (PR). The results also show that although the brine heater duty increases in winter due to low seawater temperature, the drop of fouling rate in cold months may save some energy.

Pengaruh Suhu daPengaruh Suhu dan Kedalaman Terhadap Hasil Tangkapan Yellowfin Tuna di Perairan Samudera Indonesia Selatan Pulau Jawa n Kedalaman Terhadap Hasil Tangkapan Tuna Long Line di Perairan Samudera Indonesia, Selatan Pulau Jawa

Penelitian ini dilaksanakan di PPS. Cilacap dengan daerah penangkapan Samudera Indonesia pada bulan Maret sampai dengan Mei 2020 yang bertujuan untuk menmgetahui pengaruh suhu air laut dan kedlaman pancing terhadap hasil tangkapan yellowfin tuna. Pengumpulan data primer dilakukan dengan pengamatan langsung mengikuti operasi penangkapan long line selama 1 (satu) trip dengan KM. Trans Bahari 3, meliputi data waktu setting dan hauling, panjang main line, jumlah pancing, hasil tangkapan, daerah penangkapan (fishing ground), serta data suhu dan kedalaman perairan. Sedangkan pengumpulan data sekunder dilakukan melalui wawancara dan data Pelabuhan Perikanan Samudera Cilacap. Analisa data dilakukan dengan menghitung nilai hook rate, kedalaman mata pancing, serta pengaruh suhu dan kedalaman pancing terhadap hasil tangkapan yellowfin tuna melalui metode uji t. Dari hasil Analisa data diperoleh nilai total hook rate sebesar 1,33, kedalaman mata pancing berada antara 90,2 m – 181,4 m, dengan kisaran suhu vertikal antara 12,5⁰ C – 25,0⁰ C. Pengaruh suhu dan kedalaman terhadap hasil tangkapan yellow tuna berpengaruh nyata (significant) antara kedalaman A dengan C, sedangkan antara kedalaman A dengan B, dan kedalaman B dengan C masing-masing tidak memberikan perbedaan yang nyata (non significant).

Membrane desalination of ballast water using thermoelectric energy from waste heat

Ballast water management and treatment is an on-going issue for marine industry including small and bulk carriers, cruise ships, passenger ships and cargo vessels. Several regulations are implemented at regional, national and international levels to minimise the environmental impacts related to improper disposal of contaminated ballast water at ports. In this study, an environmentally benign approach for managing the ballast water on marine vessels is proposed. Thermoelectric energy harvested from main engine’s waste heat is considered as a primary source of energy for a reverse osmosis desalination process, which recovers the ballast water in the form of clean water to provide for fresh water supplies in ships. A case study is presented to elaborate the proposed scheme. The effects of seawater temperatures and energy recovery schemes on the freshwater production rates are also discussed. The proposed scheme provides a promising approach to ballast water management while allowing to provide in situ treatment for its beneficial use in shipping operations.

Hydrodynamic connectivity, water temperature, and salinity are major drivers of piscirickettsiosis prevalence and transmission among salmonid farms in Chile

Piscirickettsiosis is one of the most important diseases affecting farmed salmonid in Chile. Several studies have demonstrated the survival of Piscirickettsia salmonis in seawater and the horizontal transmission from infected to non-infected fish; however, the extent of waterborne transmission between farms has not been quantified. In this study, we used a stochastic hydrodynamic connectivity-based disease spread model to determine the role of hydrodynamic connectivity and the effect of seawater temperature and salinity on the dynamics of piscirickettsiosis in the Los Lagos region of Chile. Results demonstrate that environmental dynamics play a major role in disease prevalence. The strongest determinants of piscirickettsiosis prevalence were the number of infected farms in upstream waters and the extent of disease outbreaks in upstream waters (total mortality), followed by seawater salinity and temperature. In farms downstream from infected farms, observed disease prevalence 25 wk into the farming cycle was close to 100%, while in farms with little or no exposure to upstream, infected farms, prevalence reached only ~10% by the end of the farming cycle (Week 56). No previous studies have quantified the scales of connectivity associated with piscirickettsiosis or provided risk metrics of waterborne transmission of the disease among farms; these are a novel aspect of this research. The above knowledge regarding the use of the epidemiological model will allow industry and regulators to better target disease control strategies for more effective control of piscirickettsiosis in the study area.

Performance Analysis of a Large-Scale Steam Condenser Used in a Steam Power Plant

This paper summarizes performance analysis of large-scale seawater-cooled box type condenser in a 660 MW steam power plant. Effect of seawater temperature and steam mass flow rate are investigated on the key performance parameters of steam condenser. Results indicated that improvement in the cooling water temperature generally is found favorable on the performance indicators of condenser. On the other hand, in the case of steam flow rate changing, effectiveness and overall heat transfer coefficient almost remain constant. Effectiveness of condenser isn’t found as a function of steam flow variation. Moreover, steam power plant heat rate is investigated as a function of cooling water of condenser and thus it is seen to be decreased in the result of improvement of cooling water temperature. Conversely, power plant overall thermal efficiency decreases due to reduction of power generation.

Physiological performance of three calcifying green macroalgae Halimeda species in response to altered seawater temperatures

The effects of seawater temperature on the physiological performance of three Halimeda species were studied for a period of 28 d. Five treatments were established for Halimeda cylindracea, Halimeda opuntia and Halimeda lacunalis, in triplicate aquaria representing a factorial temperature with 24°C, 28°C, 32°C, 34°C and 36°C, respectively. The average Fv/Fm of these species ranged from 0.732 to 0.756 between 24°C and 32°C but declined sharply between 34°C (0.457±0.035) and 36°C (0.122±0.014). Calcification was highest at 28°C, with net calcification rates (Gnet) of (20.082±2.482) mg/(g•d), (12.825±1.623) mg/(g•d) and (6.411±1.029) mg/(g•d) for H. cylindracea, H. opuntia and H. lacunalis, respectively. Between 24°C and 32°C, the specific growth rate (SGR) of H. lacunalis (0.079%–0.110% d–1) was lower than that of H. cylindracea (0.652%–1.644% d–1) and H. opuntia (0.360%–1.527% d–1). Three Halimeda species gradually bleached at 36°C during the study period. Malondialdehyde (MDA) and proline levels in tissues of the three Halimeda were higher in 34–36°C than those in 24–32°C. The results indicate that seawater temperature with range of 24–32°C could benefit the growth and calcification of these Halimeda species, however, extreme temperatures above 34°C have negative impacts. The measured physiological parameters also revealed that H. cylindracea and H. opuntia displayed broader temperature tolerance than H. lacunalis.

Global Warming Prediction Model of Fish Migration Based on ArcGIS

Rising global ocean temperatures will disrupt the livelihoods of people who depend on fishing for marine crops. Therefore, we propose fishery migration prediction models to solve the problem. We considered the effects of seawater temperature and salinity, and constructed a fish school migration prediction model based on ArcGIS. On this basis, a thermodynamic map of fish school distribution were made using ArcGIS software and kriging interpolation and nuclear density analysis. Moreover, linear interpolation and fitting are used to obtain the relationship between the annual fish movement distance and the year to predict the fish migration routes in the next 50 years.

Влияние температуры морской воды на развитие гидроида Gonothyraea loveni (Allman) на искусственных субстратах в бухте Севастопольской (Черное море)

The effect of seawater temperature on the subsidence and development of the Gonothyraea loveni (Allman) hydroid at a specific point in the water area was discussed This allows us to trace the connection of seasonal changes in sea temperature with the process of sedimentation of planules and the development of hydroid G. loveni on artificial substrates of various exposures in the Sevastopol bay. Observations were carried out over two periods: from 1979 to 1987. and from 2011 to 2015. The temperature range of 5-10 °C corresponds to the subsidence of planul on plates with a community 10 days aged in the autumn and spring periods. The peak of subsidence was detected at a water temperature of 9 °C. At this time, the greatest number of plates with settled hydroids was detected (22%). The number of hydrotecas in the temperature range of 11-19 °C reaches maximum values due to sedimentation and active growth of colonies, since the frequency of occurrence of plates with hydroids during this period is halved and remains at this level at higher temperatures (17-24 °C). With an increase in the exposure of substrates up to 30 days, the bulk of the plates with hydroid (80%) are concentrated in the temperature range of 6–11 °C. When the temperature of water in the sea is 16-24 °C, plates with hydroids are less than 5%, which is determined in addition to the effect of temperature by the massive subsidence of Botryllys schlosseri (Pallas), which replaces the hydroid. In communities of 2-12 months of age, the hydroid G. loveni develops over a wide range of temperatures, from 5 to 23 °C. Dynamic changes in communities show that the growth of colonies occurs at a temperature of 5-9 °C with a maximum intensity of 10 to 15 °C. At temperatures above 17 °C, the reduction of colonies occurs. Key words: subsidence, development of hydroid Gonothyraea loveni, the temperature of the sea water of the Sevastopol Bay, the Black sea

Hypoxia weakens mussel attachment by interrupting DOPA cross-linking during adhesive plaque curing.

Marine mussels (Mytilus spp.) attach to a wide variety of surfaces underwater using a network of byssal threads, each tipped with a protein-based adhesive plaque that uses the surrounding seawater environment as a curing agent. Plaques undergo environmental post-processing, requiring a basic seawater pH be maintained for up to 8 days for the adhesive to strengthen completely. Given the sensitivity of plaques to local pH conditions long after deposition, we investigated the effect of other aspects of the seawater environment that are known to vary in nearshore habitats on plaque curing. The effect of seawater temperature, salinity and dissolved oxygen concentration were investigated using tensile testing, atomic force microscopy and amino acid compositional analysis. High temperature (30°C) and hyposalinity (1 PSU) had no effect on adhesion strength, while incubation in hypoxia (0.9 mg l-1) caused plaques to have a mottled coloration and prematurely peel from substrates, leading to a 51% decrease in adhesion strength. AFM imaging of the plaque cuticle found that plaques cured in hypoxia had regions of lower stiffness throughout, indicative of reductions in DOPA cross-linking between adhesive proteins. A better understanding of the dynamics of plaque curing could aid in the design of better synthetic adhesives, particularly in medicine where adhesion must take place within wet body cavities.

Effect of seawater temperature, pH, and nutrients on the distribution and character of low abundance shallow water benthic foraminifera in the Galápagos.

In order to help predict the effects of anthropogenic stressors on shallow water carbonate environments, it is important to focus research on regions containing natural oceanographic gradients, particularly with respect to interactions between oceanography and ecologically sensitive carbonate producers. The Galápagos Archipelago, an island chain in the eastern equatorial Pacific, spans a natural nutrient, pH, and temperature gradient due to the interaction of several major ocean currents. Further, the region is heavily impacted by the El Niño—Southern Oscillation (ENSO) and the Galápagos exhibited widespread coral bleaching and degradation following the strong ENSO events of 1982–1983 and 1997–1998. These findings are coupled with reports of unusually low abundances of time-averaged benthic foraminiferal assemblages throughout the region. Foraminifera, shelled single-celled protists, are sensitive to environmental change and rapidly respond to alterations to their surrounding environment, making them ideal indicator species for the study of reef water quality and health. Here, statistical models and analyses were used to compare modern shallow water benthic foraminiferal assemblages from 19 samples spanning the Galápagos Archipelago to predominant oceanographic parameters at each collection site. Fisher α diversity indices, Ternary diagrams, Canonical Correspondence Analysis, regression tree analysis and FORAM-Index (FI; a single metric index for evaluating water quality associated with reef development) implied a combined impact from ENSO and upwelling from Equatorial Undercurrent (EUC) waters to primarily impact foraminiferal abundances and drive assemblage patterns throughout the archipelago. For instance, repeated ENSO temperature anomalies might be responsible for low foraminiferal density, while chronically high nutrients and low aragonite saturation and low pH—induced by EUC upwelling and La Niña anomalies—likely inhibited post-ENSO recovery, and caused foraminiferal assemblages to exhibit a heterotrophic dominance in the southern archipelago. What resulted are low FI values in the southern collection sites, indicating environments not conducive to endosymbiont development and/or recovery.

Experimental study of a humidification-dehumidification desalination system with heat pump unit

In this paper, the performance of a humidification-dehumidification (HDH) desalination system with heat pump unit is experimentally investigated. The newly developed HDH system is comprised of humidifier, heat pump unit, 1st stage dehumidifier, plate heat exchanger and 2nd stage dehumidifier. The proposed system takes advantages of heat pump unit, which transfers heat to the seawater through the plate heat exchanger and absorbs heat from air through the 2nd stage dehumidifier in the meantime. Fresh water is accumulated from both the 1st stage dehumidifier and 2nd stage dehumidifier and the productivity of the proposed system is acceptable compared with other reported HDH systems and unaffected by solar radiation. The effects of seawater temperature, air temperature and air flow rate on system productivity are investigated. Seawater temperature has a positive influence on the productivity, while the effect of air temperature is insignificant. As the air flow rate increases, the productivity increases to the maximum value at a certain air flow rate and then decreases as the air flow rate still increases. The maximum productivity of the proposed system and the estimated cost of the fresh water are 22.26 kg/h and 0.051 USD/kg respectively, which are superior compared with other HDH systems.

Discharge and Corrosion Performance of AP65 Magnesium Alloy in Simulated Seawater: Effect of Temperature

The discharge and corrosion performance of AP65 magnesium alloy in simulated seawater with different temperatures is investigated by electrochemical techniques and corrosion morphology observation. The results indicate that AP65 alloy can hardly be activated at a large current density in the 0 °C simulated seawater, whereas the activation time is shortened, and the potential exhibits a significantly negative shift in the 35 °C simulated seawater. However, the increase in temperature promotes the localized corrosion and thus is detrimental to the anode efficiency of AP65 alloy. Moreover, the effect of seawater temperature and current density on the surface morphology of AP65 alloy during the discharge process is also analyzed.