Changes In Water pH Research Articles

Pengaruh Kualitas Air Terhadap Produksi Ikan Lele Dumbo (Clarias gariepinus)

Catfish is the most popular freshwater fish by the community, because of its ease of cultivation and affordable price, so many beginner catfish farmers choose this fish as a mainstay commodity. This research was conducted on a catfish farm in sampali village, kec. Percut sei tuan. on August 15, 2023, the methods used in this research are surveys and interviews. The tools used to conduct the survey were a smartphone used for audio and visual documentation of the results of surveys and interviews taken from the farm where the survey was conducted and a ruler to measure the survey results periodically. Data collection was conducted twice during 2 months. The catfish cultivated in the Sampali CatfishFarm pond is Dumbo catfish. Based on the results of interviews that have been conducted by the author to the owner of the catfish farm, Mr. Agus Suprianto, the author concludes that Mr. Agus Suprianto has experienced obstacles in cultivating Dumbo catfish due to limited tools to measure the pH level of the pond water and can control the water quality of the pond which is used as a cultivation of Dumbo catfish. Pond owners can only estimate changes in water pH from the behavior of fish that often float on the surface of the water. The purpose of this study was to determine the effect of differences in water cleanliness on the development of catfish.

Probing Solubility and pH of CO2 in aqueous solutions: Implications for CO2 injection into oceans

CO2 sequestration is among the most anticipated methods to mitigate the already detrimental concentrations of CO2 in the atmosphere. Among sequestration methods, CO2 injection into oceans is of great significance due to the oceans’ large sequestration capacity. However, there are concerns about the changes in water pH as CO2 is injected into oceans. Previous studies in conditions representative of CCS in the ocean are scarce. In the current study, we experimentally measure the pH and solubility at pressures up to 400 atm, temperatures between 283 and 298 K, and different aqueous solutions in a high-pressure autoclave reactor. The results indicated that increasing pressure increases the solubility of CO2 in aqueous solutions, resulting in lower pH values. In contrast, increasing salinity and temperature lowers the solubility and, as a result, increases the system's pH. Among all the tested aqueous solutions, the synthetic seawater mimicked that of a potential injection point in the South China sea, exhibiting the highest salting-out effect and, therefore, the lowest solubility (i.e., the highest pH). The experimental dataset of this study was fed to a machine learning algorithm, Group modeling data handling(GMDH), to develop an explainable, white-box solubility model. The model could predict the pH as a function of solubility, temperature, pressure, and salinity with an accuracy of 0.87. The pH values from the model were compared to those from previous studies, and a good agreement among the values was found. Lastly, a parameter importance analysis was conducted to shed further light on the model's performance. Pressure and temperature were found to be the most and the least influential factors, respectively. As the implantation of the technology is currently being considered in China, the current study can pave the way to better understand the interactions and mechanisms involved in conditions representative of ocean sequestration before large-scale operations.

ФИЗИКО-ХИМИЧЕСКИЕ УСЛОВИЯ В ВОДОРОСЛЕВЫХ МАТАХ И ИХ ВЛИЯНИЕ НА НЕКОТОРЫЕ ГРУППЫ ГИДРОБИОНТОВ В ГИПЕРСОЛЁНЫХ ВОДОЁМАХ (НА ПРИМЕРЕ ЗАЛИВА СИВАШ, КРЫМ)

The physical and chemical characteristics (salinity, temperature, pH) in algae mats of hypersaline Sivash Bay (Crimea) were studied. They were formed in the coastal waters of the bay and influence alive community condition. A significant tendence of the pH increase in the direction of shore-clear water was noted. This represents an improvement of oxygen conditions in the said direction. Heterotrophic and denitrifying bacteria had been isolated ubiquitously. The presence of a significant negative correlation between pH of th e water and the number of heterotrophic bacteria was noted. A slight negative correlation between pH of the water and the number of denitrifying bacteria was determined. Thus, there was a tendency for the inhibition of these bacteria groups’ growth by high pH. Salinity, in the range of its change (60.8–94.5 ‰), hadn’t a significant effect on the abundance of the studied groups of bacteria. In the detected range of temperature (23 –32 ˚С), it was impossible to assert the presence of a close relationship betwe en these parameters. In algal mats, there was a community of poor diversity. The macrocomponents were represented by Artemia salina (Linnaeus, 1758) and larvae of Chironomidae sp. Salinity in the studied range of values hadn’t affected the abundance and biomass of the components of the macrozoocommunity significantly. At the same time, a positive effect of changes in water pH on the abundance and biomass of A. salina was noted. This phenomenon for the larvae of Chironomidae sp. not fixed.

Effects of abandoned coal mine on the water quality

ABSTRACT Improving effective strategies to control acid mine drainage (AMD) in abandoned mine areas is a significant challenge because of water quality issues. AMD is a serious water pollution problem. The water in the area where the mine is located acquires an acidic character, the pH level of the environment decreases, the concentration of heavy metals increases with their dissolution in the acidic environment, and can cause serious environmental pollution by creating a toxic effect for all living things. However, acidic characteristics are not observed in the waters at high pH levels; a basic environment is formed; the heavy metal dissolution slows down; and the precipitation of minerals begins. In such an environment, it is not possible to observe AMD formation and heavy metal pollution. If AMD source is characterized, the most effective strategies can be developed to control the acidic effluents. The main aim of this work was to investigate the potential impact of Ovacik abandoned, coal mine (Cankiri, Turkey) on the water quality in the areas around the mine. Water samples were collected along the open pit area (abandoned), dump sites and coal storage area. Effluent characterizations were investigated for the better evaluation of the water contamination level to develop the successful treatment strategies. In the studies conducted in the same field in 2010–2011, it was determined that the water pH changes between 6.64 and 8.13. Similarly, in this study, the results showed that the pH values of water streams in the abandoned mine were measured between 7.28 and 8.94 with no heavy metal contamination. Although the coal deposit exhibits AMD source minerals, the rock formations which have alkaline content prevented AMD in the considered site.

Thiourea-assisted one-step fabrication of a novel nitrogen and sulfur co-doped biochar from nanocellulose as metal-free catalyst for efficient activation of peroxymonosulfate

The N, S co-doped biochar (N, S-BC) with multistage pore structure was successfully synthesized from nanocellulose and thiourea by one-step pyrolysis, which could effectively activate peroxymonosulfate (PMS) to degrade sulfamethoxazole (SMX) in water. Moreover, the removal efficiency of SMX by this oxidation system was 2.3–3.1 times than that of other systems activated by common metal oxides (such as Fe3O4、Fe2O3, and MnO2). More importantly, the mechanism of the N, S-BC/PMS process was deduced by reactive oxygen species (ROS) quenching experiment and electron paramagnetic resonance (EPR) test, which exhibited that surface-bound free radicals and singlet oxygen (1O2) played an essential role in the SMX degradation. Surprisingly, the sulfate radical (SO4•-) and hydroxyl radical (•OH) produced in this system existed in a bound state on the surface of the carbon catalyst to react with SMX, rather than dispersed in the aqueous solution. This particular form of free radicals could resist the influence of background substances and pH changes in water, and maintain excellent SMX degradation efficiency under different water matrices and pH. This study provides a new insight into the application of carbon catalyst in actual water pollution control.

Renovated multifunctional colorimetric/fluorometric sensor for simultaneous detection, imaging of pH variance and antimicrobial therapies

pH is an essential aspect of the intracellular environment and potentially affect virtually all cellular processes. Tracking pH changes in diverse heterogeneous environments thus become so important. Most of studies have reported the development of molecular pH sensors based on different response mechanisms. However, multifunctional pH probes which can integrate pH sensing and other job duties such as illness treatment are rarely reported. In this study, we have created such a sensor NNBDH which is based on conjugation of the norfloxacin and NBD (as the fluorophore) molecules and the subsequent studies indicated that NNBDH can sensitively and selectively sense pH changes in water, live cells and zebrafish via a colorimetric and fluorometric response with good reversibility, stability and cell or animal tissue permeability and compatibility. Even more interesting is that NNBDH can offer concurrent potent antibacterial therapies against the superbug MRSA. This 2-in-1 pH sensor can be very useful in coping with some clinical situations often manifested by rising pH and subsequent bacterial infections such as S. aureus or even fatal MRSA. The current proof-of-study is paying way for developing a new generation of economic, fast-response and multifunctional molecular pH sensors which can do not only sensing but also treating and healing.

Behavior of Aluminum Compounds in Soft-Water Lakes Subjected to Experimental Reclamation with Polyaluminum Chloride

The research presented in this work concerns the potential aluminum load of soft-water lake ecosystems as a result of performing chemical reclamation works. On a semitechnical scale, different doses of PAC-type aluminum coagulant (polyaluminum chloride) were tested. The required doses of coagulant (on average, 11 mg Al/L) were determined based on the amount of phosphorus that is bioavailable in the lake ecosystem. The research covered the lake water, near-bottom and interstitial water, and bottom sediments of five lakes with low alkalinity (0.4–2.5 meq/L) and low calcium contents (5–35 mg Ca/L). The experiments were conducted in situ for 2 years using mesocosms with a volume of approximately 20 m3. The effectiveness of the flocculation and sedimentation processes of coagulant flocs was closely related to changes in water pH caused by acidic coagulant application, and the corresponding transformation level ranged from 39.8 to 99.8%. In the waters of these lakes, where the alkalinity did not reach 1 meq/L, the coagulant used in doses adequate for intensive full-scale projects caused high water pollution with dissolved aluminum fractions (from 0.05 ± 0.01 to 4.67 ± 1.32 mg Al/L). In all lakes, the penetration of dissolved aluminum into the interstitial water of the bottom sediment was limited to the first 5-cm layer. After the application of coagulant, the aluminum content in the bottom sediments significantly increased in proportion to the amount of the PAC used (by 12–96% in terms of a 5-cm surface layer of sediment). Within 2 years of the research, solid fractions (flocks) of the coagulant moved to a depth of 5–10 cm below the bottom level. Due to high release rates of aluminum from the applied aluminum treatments, modifications to the treatment protocols are needed in soft-water lakes.

Influence of ultrasound on the concentration of hydrogen ions in water

The paper deals with the physical and chemical effects arising in water under the action of the energy of elastic vibrations of ultrasonic frequency in the cavitation mode. Cavitation state is characterized by the formation of the gas and air cavities - bubbles in the aquatic environment. The theory of occurrence of high temperatures at the moment of collapse of a cavitation bubble in water is given. It is noted that there is a dissimilation of the substance of free active radicals, dissociated and ionized molecules. The kinetics of chemical reactions in the ultrasonic field under the cavitation regime is described. Methods for obtaining ultrasonic cavitation in a liquid medium with a description of the generation of ultrasonic vibrations and a list of transducers and types of emitters are given. A relatively wide spectrum of radiated frequencies and instability of frequency and amplitude of oscillations are considered. The choice of ultrasonic generator is justified due to the necessary frequencies and intensities for the excitation of cavitation in water (f = 18-22 kHz, I = 2.0 W/cm2), technological considerations about the possibility of mounting the transducer in an existing production line, as well as safety and efficiency issues. The relevance, purpose and objectives of the work are formulated. The equipment and methods of experimental research are presented. Laboratory experimental studies on the effect of ultrasonic vibrations in the cavitation mode on the change of water pH were carried out. It is shown that bubbles formed in the ultrasonic field in the studied water collapse and create micro-explosions, shock waves and micro-flows. The results of studies on the change of pH in water are shown and the analysis of experimental data is performed. The experimental studies made it possible to substantiate the conclusions of this work and to formulate a conclusion about the influence of the ultrasonic field in the cavitation mode on the pH of the aqueous medium and its further application in water treatment processes.

Biochar as adsorbent in purification of clear-cut forest runoff water: adsorption rate and adsorption capacity

Forest management practices in boreal peatlands increase nutrient export and suspended solids to watercourses calling for development of new water protection methods. One potential solution could be adsorption-based purification of runoff water using biochar. The aim of this study was to determine the adsorption rate and capacity for Norway spruce and silver birch biochars to design a biochar-filled reactor for a ditch drain. In a 10-day laboratory experiment, biochar was stirred with runoff water from a clear-cut peatland forest, and changes in water pH, total nitrogen, nitrate nitrogen, ammonium nitrogen, phosphorus, and total organic carbon concentrations were measured. Based on the concentration changes, adsorption was quantified and adsorption model containing the adsorption rate and capacity was fitted to the data. Our results indicate that biochar effectively adsorbs both inorganic and organic nitrogen from runoff water. Birch biochar had higher adsorption capacity of nitrogen than spruce biochar. This study demonstrates that the adsorption of nitrogen compounds onto biochar surfaces increases with increasing initial concentrations. Thus, aquatic ecosystems exposed to high nutrient loads from fertile peatlands would particularly benefit from biochar-based water purification.

Daily Cyclic Changes in Water pH of Flooded Rice in the Mississippi Delta and Black Belt

Daily Cyclic Changes in Water pH of Flooded Rice in the Mississippi Delta and Black Belt

A simple and green methodology to assemble poly(4-vinylpyridine) and a sulfonated azo-dye for obtaining stable polymeric nanoparticles

A new green and simple method of synthesis of polymeric nanoparticles comprising a pH-responsive polymer and a sulfonated dye, without needing the use of any organic solvent or cross-linker, is shown. It is based on the complexation between weak basic aromatic polyelectrolytes and a strong acidic dye by means of aromatic-aromatic interactions in water at acidic pH, and subsequent fast pH change, which triggers a controlled collapse of the system in the form of nanoparticles. Poly(4-vinylpyridine) and the tetrasulfonated azo dye 4,4'-((1E,1′E)-(3,3′-dimethyl-[1,1′ biphenyl]-4,4′diyl)bis(diazen-2,1-diyl))bis(3-hidroxynaphtalen-2,7-disulfonate) form complexes at pH 3–5, undergoing short-range aromatic-aromatic interactions, as seen by 1H NMR. Subsequent and fast pH adjustment to 9–10 leads to the system collapse with faster kinetics than those for the hydration and release of the hydrophilic negatively charged dye, so that polymeric nanoparticles are formed that include the dye, which acts as stabilizer. The monomodal distributed nanoparticles showed 50–200 nm of hydrodynamic diameter, with PDI ranging between 0.1 and 0.4, and zeta potential values in the range −40 to −60 mV, resulting stable for at least 14 days. The synthesized nanoparticles have been included in calcium alginate beads, showing colorimetric sensitivity to pH changes in water. We envisage that our findings could be also applied in other hydrophilic-aromatic polymers to create stable and functional materials by using this simple and green methodology.

Research on hydrophobicity treatment of aluminum nitride powder and the fabrication and characterization of AlN/PTFE composite substrates

A study on fabrication and characterization of different filler ratios AlN/ PTFE composite substrates was described. Phenyltrimethoxysilane (Z6124) was used to modify AlN ceramic powder. The contents of Z6124 were 0.8, 1.0, 1.2, 1.4, 1.6 wt%, respectively. The infrared spectroscopy, microstructure, contact angle and the pH changes in water of AlN ceramic powder were investigated in detail. The results revealed that 1.0 wt% Z6124 modified AlN ceramic powder exhibited the largest contact angle (θ = 148.4°), obvious coupling agent characteristic peak, and excellent water resistance. Next, 1.0 wt% Z6124 modified AlN powders were used to manufacture AlN/PTFE composites, and the contents of AlN ceramic filler were 25, 30, 35, 40, 45, 50 and 55 wt%, respectively. The effects of AlN ceramic content on the microwave dielectric properties, water absorption and thermal conductivity of AlN/PTFE composite substrates were systematically investigated. When the content of filler was 45 wt%, composite substrates exhibited reliable dielectric constant (er = 3.38), acceptable dielectric loss (tan δ = 0.006) and excellent temperature coefficient of dielectric constant (− 32.6 ppm/°C), lower water absorption (0.056%) and high thermal conductivity (0.957 W/m K).

Reuse of textile mill ETP sludge in environmental friendly bricks – effect of gamma radiation

Textile mill is the largest industry in Bangladesh facing problem of sludge disposal. In this study, gamma irradiated (15 kGy) textile mill ETP sludge was used to make environmental friendly eco-bricks. According to the percentage (%) of sludge and soil content in brick samples, bricks were graded as E (50% sludge+50% soil), F (25% sludge + 75% soil), G (25% sludge+ 70% soil + 5% sand), X (10% sludge+ 90% soil) and Y (100% soil). A 100% soil content normal commercial brick (N) was also compared with these bricks. All the bricks were fired at 450 °C for 24 h. Physico-chemical analysis of both sludge and soil were studied. Parameters such as density, weight loss (%), firing shrinkage (%), bending strength (BS), bending modulus (BM), impact strength (IS), water uptake (%) and electrical resistivity were investigated. Density, weight loss, firing shrinkage, electrical resistivity reduces as sludge content (%) in bricks increases whereas BS, BM, IS and water uptake (%) increases. The change of density of all bricks has been experienced during the ageing tests in water, acid, alkali and salt. Morphological analysis of the brick samples were done by Inverted Microscope. Finally, change of water pH has been studied during the ageing period.

Abnormal pH elevation in the Chaobai River, a reclaimed water intake area.

The pH is a primary index reflecting water quality in rivers. The Jian River and Chaobai River are two reclaimed water intake areas which have elevated pH. This elevated pH has a marked effect on both the phytoplankton, species in water and vegetation on the shore. Understanding the main reasons causing pH elevation in river water has important implications for river ecosystem management and the improvement of water quality and can provide a theoretical basis for the direction of water quality improvement. For this reason, each biogeochemical and physical process influencing pH changes in water was quantified along the flow direction in the Wenyu to Chaobai reclaimed water diversion project, in which proton consumption and production by such processes were monitored and calculated at five monitoring sections. The calculations indicated that photosynthesis and denitrification were the primary reasons for the increase of pH in the Jian River and Chaobai River. Oppositely, carbonate precipitation and sediment decomposition restricted the increase of pH in both rivers. In addition, CO2 emission to the air also promoted a increase of pH in the Jian River, while CO2 absorption from the air restricted the increase of pH in the Chaobai River. NO3- nitrogen in reclaimed water was not efficiently removed and the reclaimed water flow condition in the intake area created favorable conditions for photosynthesis of algae breeding and denitrification by microorganisms. Therefore, biogeochemical and physical processes that promoted the increase of pH were greater than inhibiting processes and the pH gradually increased along the flow direction. The contribution rates of photosynthesis and denitrification for the increase of pH were 55.48 and 27.09%, respectively, in the Jian River and 78.08 and 21.92%, respectively, in the Chaobai River. In addition, CO2 emission contributed 17.43% of the increase in pH in the Jian River.

Metabolism and antioxidant defense in the larval chironomid Tanytarsus minutipalpus: adjustments to diel variations in the extreme conditions of Lake Magadi.

ABSTRACTInsect larvae are reported to be a major component of the simple but highly productive trophic web found in Lake Magadi (Kenya, Africa), which is considered to be one of the most extreme aquatic environments on Earth. Previous studies show that fish must display biochemical and physiological adjustments to thrive under the extreme conditions of the lake. However, information for invertebrates is lacking. In the present study, the occurrence of the larval chironomid Tanytarsus minutipalpus is reported in Lake Magadi for the first time. Additionally, changes in larval metabolism and antioxidant defense correlated with diel variations in the extremely hostile environmental conditions of the lake are described. Wide variations in water temperature (20.2-29.3°C) and dissolved oxygen content (3.2-18.6 mg O2 l−1) were observed at different times of day, without significant change in water pH (10.0±0.03). Temperature and dissolved oxygen were higher at 13:00 h (29.3±0.4°C and 18.6±1.0 mg O2 l−1) and 19:00 h (29.3±0.8°C and 16.2±1.6 mg O2 l−1) and lower at 01:00 h (21.1±0.1°C and 10.7±0.03 mg O2 l−1) and 07:00 h (20.2±0.4°C and 3.2±0.7 mg O2 l−1). Significant and parallel increases in parameters related to metabolism (cholinesterase, glucose, cholesterol, urea, creatinine and hemoglobin) and the antioxidant system (SOD, GPx, GR, GSH and GSSG) were observed in larvae collected at 13:00 h. In contrast, no significant changes were observed in pro-oxidants (ROS and NO), TOSC and oxidative damage parameters (LPO and DNA damage). Therefore, the observed increases in temperature and dissolved O2 content in Lake Magadi were associated with changes in the antioxidant system of T. minutipalpus larvae. Adjustments performed by the chironomid larvae were efficient in maintaining body homeostasis, as well as protecting biomolecules against oxidative damage, so that oxidative stress did not occur. GSH-GSSG and GPx-GR systems appeared to play an essential role in the adjustments displayed by the chironomid larvae during the diel changes in the extreme conditions of Lake Magadi.

New generation poly(ε-caprolactone)/gel-derived bioactive glass composites for bone tissue engineering: Part I. Material properties.

Poly(ε-caprolactone) (PCL) based composite films containing 12 and 21vol.% bioactive glass (SBG) microparticles were prepared by solvent casting method. Two gel-derived SBGs of SiO2-CaO-P2O5 system differing in SiO2 and CaO contents were applied (mol%): S2: 80SiO2, 16CaO, 4P2O5 and A2: 40SiO2, 54CaO, 6P2O5. The surfaces of the films in contact with Petri dish and exposed to the gas phase during casting were denoted as GS and AS, respectively. Both surfaces of films were characterised in terms of their morphology, micro- and nano-topography as well as wettability. Also mechanical properties (tensile strength, Young's modulus) and PCL matrix crystallinity (degree of crystallinity, crystal size) were evaluated. Degradation behaviour was examined by incubation of materials in UHQ-water at 37°C for 56weeks. The crystallinity, melting temperature and mass loss of incubated materials and pH changes of water were monitored. Furthermore, proliferation of MG-63 osteoblastic cells by direct contact and cytotoxic effect of obtained materials were investigated. Results showed that opposite surfaces of the same polymer and composite films differ in studied surface parameters. The addition of SBG particles into PCL matrix improves nano- and micro-roughness of both surfaces, enhances the hydrophilicity of GS surfaces (~67° for 21A2-PCL compared to ~78° for pure PCL) and also makes AS surface more hydrophobic (~94° for 21S2-PCL compared to ~86° for pure PCL). The nucleation density of PCL was increased with increasing content of SBG particles, which results in the large number of fine spherulites on composite AS surfaces observed using polarized optical (POM), scanning electron (SEM), and atomic force (AFM) microscopies. Higher content of SBG particles causes a notable increase of Young's modulus (from 0.38GPa for pure PCL, 0.90GPa for 12A2-PCL to 1.31GPa for 21A2-PCL), which also depends on SBG chemical composition. After 56-week degradation test, considerably higher crystallinity increase (Δχc ~148% for 21S2-PCL, ~81% for 21A2-PCL) and weight loss (~17% for both) were found for composite materials, depending on SBG composition, in contrast to value variations for pure PCL film (Δχc ~43%, weight loss ~1.6%). Furthermore, it seems that both SBG could neutralize acidic degradation by-products of PCL at later incubation stages. Obtained SBG-PCL composites show excellent biocompatibility, support cell proliferation also may modulate cell response depending on the glass composition. The results indicate the possibility to use different contents and/or chemical compositions of SBG to obtain composite materials with various, but controlled, surface and mechanical properties as well as degradation kinetics.

Diatom response to Asian monsoon variability during the Late Glacial to Holocene in a small treeline lake, SW China

Analyses of diatoms, grain size, magnetic susceptibility, total organic carbon, and total nitrogen were applied to a 9.26 m long sediment core, spanning the last 12.2 kyr, from a small treeline lake (Tiancai Lake, ~3898 m a.s.l.) in southwest China. Diatom assemblages are dominated by Cyclotella distinguenda, Aulacoseira species, and small fragilarioid taxa, all of which are sensitive to changes in water pH and light conditions that are probably related to vegetation development and runoff processes triggered by variations in the Asian monsoon. High abundances of C. distinguenda and Pseudostaurosira brevistriata reflected cold and dry climates during the Late Glacial (12.2–11.4 kyr BP). In the early Holocene (11.4–9.4 kyr BP), a steep decline in C. distinguenda and a visible increase in Aulacoseira alpigena responded to a strengthening monsoon intensity. The persistent increases in A. alpigena mirrored strong monsoon intensity in the middle Holocene (9.4–4.6 kyr BP). After 4.6 kyr BP, the reduction of A. alpigena was related to weak monsoon intensity in the late Holocene. The main trends of diatom evolution show a general correspondence to variations in solar insolation. Three visible excursions, with an increase in P. brevistriata and a drop in A. alpigena, centered at around 8.4, 2.5, and 0.3 kyr BP, correlate with low sunspot numbers and known cold events in the North Atlantic. Some similarities and correlations between the Holocene diatom data, the North Atlantic record, and solar insolation indicate that variations in the Asian monsoon response to changes in solar forcing and the North Atlantic climate.

Water pH and metabolic parameters in silver catfish (Rhamdia quelen)

This study evaluated the effects of an acute change in water pH (from pH 7.5 to 4.0, 5.0, 6.0, 7.5, 8.0 or 9.0) on several biochemical parameters in juveniles of the silver catfish, Rhamdia quelen. Ammonia levels decreased in the liver and increased in the muscle with increasing water pH. In the kidney, lower ammonia levels were observed at neutral pH. An increase in water pH decreased the glucose, glycogen and lactate levels in the liver and kidney (except for glycogen levels in the kidney and lactate levels in the liver, which presented lower levels at neutral pH). In muscle, the glucose and glycogen levels decreased with increasing water pH, whereas lactate levels tended to be lower at neutral pH. Gill and kidney Na+/K+-ATPase activities tended to increase in alkaline water, and the highest value was observed in fish exposed to pH 9.0. The optimal levels of the analyzed biochemical parameters occurred at neutral pH. In conclusion, exposure to acidic and alkaline pH changes the metabolic parameters of silver catfish as well as gill Na+/K+-ATPase activity.

A core‐top study of dissolution effect on B/Ca in Globigerinoides sacculifer from the tropical Atlantic: Potential bias for paleo‐reconstruction of seawater carbonate chemistry

AbstractIt has been recently shown that B/Ca in planktonic foraminiferal calcite can be used as a proxy for seawater pH. Based on the study of surface sediments (multi‐cores) retrieved along a depth transect on the Sierra Leone Rise (Eastern Equatorial Atlantic), we document the decrease of B/Ca and Mg/Ca of Globigerinoides sacculifer shells with increasing water depth and dissolution. This effect of dissolution on B/Ca may potentially represent a severe bias for paleo‐pH reconstructions using this species. Samples of G. sacculifer were analyzed independently at two laboratories for B/Ca and Mg/Ca. Both sets of results show a systematic decrease of B/Ca and Mg/Ca along the depth transect, with an overall loss of ~14 µmol/mol (~15%) for B/Ca and of ~0.7 mmol/mol (~21%) for Mg/Ca between the shallowest (2640 m) and the deepest (4950 m) sites. Because of this dissolution effect, surface water pH reconstructed from B/Ca of G. sacculifer decreases by ~0.11 units between the shallowest site and the deepest site, a magnitude similar to the expected glacial/interglacial surface water pH changes.

Sea Water Acidification Affects Osmotic Swelling, Regulatory Volume Decrease and Discharge in Nematocytes of the Jellyfish Pelagia noctiluca

Background: Increased acidification/P_CO2 of sea water is a threat to the environment and affects the homeostasis of marine animals. In this study, the effect of sea water pH changes on the osmotic phase (OP), regulatory volume decrease (RVD) and discharge of the jellyfish Pelagia noctiluca (Cnidaria, Scyphozoa) nematocytes, collected from the Strait of Messina (Italy), was assessed. Methods: Isolated nematocytes, suspended in artificial sea water (ASW) with pH 7.65, 6.5 and 4.5, were exposed to hyposmotic ASW of the same pH values and their osmotic response and RVD measured optically in a special flow through chamber. Nematocyte discharge was analyzed in situ in ASW at all three pH values. Results: At normal pH (7.65), nematocytes subjected to hyposmotic shock first expanded osmotically and then regulated their cell volume within 15 min. Exposure to hyposmotic ASW pH 6.5 and 4.5 compromised the OP and reduced or totally abrogated the ensuing RVD, respectively. Acidic pH also significantly reduced the nematocyte discharge response. Conclusion: Data indicate that the homeostasis and function of Cnidarians may be altered by environmental changes such as sea water acidification, thereby validating their use as novel bioindicators for the quality of the marine environment.