Synthesis of NaY zeolite from a submolten depolymerized perlite:Alkalinity effect and crystallization kinetics

NaY zeolites are synthesized using submolten salt depolymerized natural perlite mineral as the main silica and alumina sources in a 0.94 L stirred crystallizer.Effects of alkalinity ranging from 0.38 to 0.55(n(Na_(2)O)/n(SiO_(2)))on the relative crystallinity,textural properties and crystallization kinetics were investigated.The results show that alkalinity exerts a nonmonotonic influence on the relative crystallinity and textural properties,which exhibit a maximum at the alkalinity of 0.43.The nucleation kinetics are studied by fitting the experimental data of relative crystallinity with the Gualtieri model.It is shown that the nucleation rate constant increases with increasing alkalinity,while the duration period of nucleation decreases with increasing alkalinity.For n(Na_(2)O)/n(SiO_(2))ratios ranging from 0.38 to 0.55,the as-synthesized NaY zeolites exhibit narrower crystal size distributions with the increase in alkalinity.The growth rates determined from the variations of average crystal size with time are 51.09,157.50,46.17 and 24.75 nm·h^(-1),respectively.It is found that the larger average crystal sizes at the alkalinity of 0.38 and 0.43 are attributed to the dominant role of crystal growth over nucleation.Furthermore,the combined action of prominent crystal growth and the longer duration periods of nucleation at the alkalinity of 0.38 and 0.43 results in broader crystal size distributions.The findings demonstrate that control of the properties of NaY zeolite and the crystallization kinetics can be achieved by conducting the crystallization process in an appropriate range of alkalinity of the reaction mixture.

Effect of Saline Water on Soil Acidity, Alkalinity and Nutrients Leaching in Sandy Loamy Soil in Rwamagana Bella Flower Farm, Rwanda

The necessity to saline and sodic waters is sometimes used for irrigating agricultural activities under certain circumstances, but it is important to note that the use of these waters comes with specific considerations and limitations. One way to decrease undesirable effects of sodic waters on the physical and chemical properties of soils is to apply organic and chemical amendments within the soil. This study aimed to assess the effectiveness of saline water on soil acidity, alkalinity and nutrients leaching in sandy loamy soil at Bella flower farm, in Rwamagana District, Rwanda. The water used was from the Muhazi Lake which is classified as Class I (Saline water quality). Column leaching experiments using treated soils were then conducted under saturated conditions. The soil under experimental was first analyzed for its textural classification, soil properties and is classified as sandy loamy soil. The t-test was taken at 1%, 5% and 10% levels of statistical significance compared to control soil. The results indicated that the application of saline water to soils caused an increase in some soil nutrients like increase of Phosphorus (P), Potassium (K+), Magnesium (Mg2+), Sulphur (S), CN ratio and Sodium (Na+) and decreased soil texture, physical and chemical properties and remained soil nutrients. Consequently, the intensive addition of saline water leachates to soil in PVC pipes led to decreased of soil EC through leaching and a raiser Soluble Sodium Percentage (SSP). The rate of saline water application affected the increase accumulation of SAR and Na% in the top soil layers. The study indicated that saline water is an inefficient amendment for sandy soil with saline water irrigation. The study recommends further studies with similar topic with saline water irrigation, as it accentuated the alkalinity levels.

Industrial wastes applications for alkalinity regulation in bauxite residue: A comprehensive review

Bauxite residue is a highly alkaline material generated from the production of alumina in which bauxite is dissolved in caustic soda.Approximately 4.4 billion tons of bauxite residues are either stockpiled or landfilled,creating environmental risks either from the generation of dust or migration of filtrates.High alkalinity is the critical factor restricting complete utilization of bauxite residues,whilst the application of alkaline regulation agents is costly and difficult to apply widely.For now,current industrial wastes,such as waste acid,ammonia nitrogen wastewater,waste gypsum and biomass,have become major problems restricting the development of the social economy.Regulation of bauxite residues alkalinity by industrial waste was proposed to achieve‘waste control by waste’with good economic and ecological benefits.This review will focus on the origin and transformation of alkalinity in bauxite residues using typical industrial waste.It will propose key research directions with an emphasis on alkaline regulation by industrial waste,whilst also providing a scientific reference point for their potential use as amendments to enhance soil formation and establish vegetation on bauxite residue disposal areas(BRDAs)following large-scale disposal.

Effects of Soil Salinity and Alkalinity on Grain Quality of Tolerant,Semi-Tolerant and Sensitive Rice Genotypes

Soil salinity and alkalinity adversely affects the productivity and grain quality of rice. The grain quality of 19 rice genotypes characterized as salt tolerant （T）, semi-tolerant （ST） and sensitive （S） was assessed in lysimeters containing saline and highly alkaline soils. Head rice recovery was reduced by salinity stress whereas it was not affected by alkalinity stress. The ratio of length to width （grain dimensions） was significantly reduced in the T genotype even at low electrical conductivity （EC, 4 mS/cm） and alkalinity （pH 9.5）, whereas in the ST genotype, it was significantly reduced at high salinity （EC 8 mS/cm）. There was no significant effect of any levels of salinity or alkalinity on grain dimensions in the S genotype. Amylose content was significantly reduced in T and ST groups even at low EC （4 mS/cm） and alkalinity （pH 9.5） and the effect in the S genotype was only at high salinity. Starch content showed significant reduction at high salinity and alkalinity （EC 8 mS/cm and pH 9.8） in the T and ST genotypes and no significant effect was observed in the S genotype. The effect of both levels of salinity （EC 4 and 8 mS/cm） and high alkalinity （pH 9.8） on gel consistency was observed only in the S genotype. The tolerant genotypes IR36 under high salinity, and CSIR10 and CSR11 under alkali stress showed less reduction in amylose content. The T genotype BR4-10, and ST genotypes CSR30, CSR29 and CSR13 showed better gel consistency under saline and alkali stress. Amylose content was affected even at low salinity stress and thus important to be considered in breeding rice for salt tolerance. Overall, the grain quality of T and ST genotypes was less affected by saline and alkali stress compared to S ones.

Separation of sulfide lead-zinc-silver ore under low alkalinity condition

A complex lead-zinc-silver sulfide ore containing 2.98% Pb, 6.49% Zn and 116.32×10^-4 % Ag （mass fraction） from Yunnan Province, China, was subjected to this work. Research on mineral processing was conducted according to the properties of the lead-zinc-silver ore. Under low alkalinity condition, the lead minerals are successfully separated from the zinc minerals with new reagent YZN as zinc depressant, new reagent BPB as lead collector, CuSO4 as zinc activator and ethyl xanthate as zinc collector. The associated silver is mostly concentrated to the lead concentrate. With the process utilized in this work, a lead concentrate of 51.90% Pb with a recovery of 82.34% and a zinc concentrate of 56.96% Zn with a recovery of 81.98% are produced. The silver recovery in the lead concentrate is 80.61%. Interactions of flotation reagents with minerals were investigated, of which the results indicate that the presence of proper amount of Na2S can precipitate Pb^2＋ and has a sulfidation on oxidized lead minerals. The results also show that NazCO3 and YZN used together as combined depressants for sphalerite can signally improve the depressing effect of new reagent YZN on sphalerite.

Alkalinity stabilization behavior of bauxite residue:Ca-driving regulation characteristics of gypsum

Alkaline anions,include CO3^2–,HCO3^–,Al(OH)4^–,OH^–,continuously released from bauxite residue(BR),will cause a potential disastrous impact on surrounding environment.The composition variation of alkaline anions,alkaline phase transformation pathway,and micro-morphological transition characteristics during the gypsum addition were investigated in an attempt to understand alkalinity stabilization behavior.Results demonstrated that alkaline anions stabilization degree in leachates can reach approximately 96.29%,whilst pH and alkalinity were reduced from 10.47 to 8.15,47.39 mmol/L to 2 mmol/L,respectively.During the alkalinity stabilization,chemical regulation behavior plays significant role in driving the co-precipitation reaction among the critical alkaline anions(CO3^2–,HCO3^–,Al(OH)4^–,OH^–),with calcium carbonate(CaCO3))being the most prevalent among the transformed alkaline phases.In addition,XRD and SEM-EDX analyses of the solid phase revealed that physical immobilization behavior would also influence the stability of soluble alkali and chemical bonded alkali due to released Ca^2+from gypsum which aggregated the clay particles and stabilized them into coarse particles with a blocky structure.These findings will be beneficial for effectively regulating strong alkalinity of BR.

Spatial and temporal variations in pH and total alkalinity at the beginning of the rainy season in the Changjiang Estuary, China

The results of field observation carried out in May 2003 were used to examine pH and total alkalinity behaviors in the Changjiang Estuary. It was showed that pH and total alkalinity took on clear spatial variations in values with the minima in the low salinity region. Like salinity, transect distributions of pH and total alkalinity （TA） in a downriver direction had a sharp gradient each. These gradients appeared in such a sequence that the TA gradient was earlier than salinity and pH gradients, and the salinity gradient was earlier than the pH gradient. These distribution characteristics seemed to be strongly influenced by the mixing process of freshwater and seawater, for both pH and total alkalinity had significant linear relationships with salinity and temperature. For pH, phytoplankton activities also had a significant impact upon its spatial distribution. During a period of 48 h, pH and total alkalinity changed within wide ranges for every layer of the two anchor stations, namely, Stas 13 and 20, which were located at the mixed water mass and seawater mass, respectively. For both Stas 13 and 20, pH and TA fluctuation of every layer could be very wide during a 4 h period. As a whole, the data of the two anchor stations showed that neither variations in salinity and temperature nor phytoplankton activities were the main factors strongly influencing the total alkalinity temporal variability on a small time scale. The data of Sta. 20 implied that both salinity variation and phytoplankton activities had a significant influence on pH temporal variability, but the same conclusion could not be drawn from the data of Sta. 13.

Activity origin and alkalinity effect of electrocatalytic biomass oxidation on nickel nitride

Electro-oxidation of 5-hydroxymethylfurfural(HMFOR)is a promising green approach to realize the conversion of biomass into value-added chemicals.However,considering the complexity of the molecular structure of HMF,an in-depth understanding of the electrocatalytic behavior of HMFOR has rarely been investigated.Herein,the electrocatalytic mechanism of HMFOR on nickel nitride(Ni3 N)is elucidated by operando X-ray absorption spectroscopy(XAS),in situ Raman,quasi in situ X-ray photoelectron spectroscopy(XPS),and operando electrochemical impedance spectroscopy(EIS),respectively.The activity origin is proved to be Ni^(2+δ)N(OH)ads generated by the adsorbed hydroxyl group.Moreover,HMFOR on Ni3 N relates to a two-step reaction:Initially,the applied potential drives Ni atoms to lose electrons and adsorb OH-after 1.35 VRHE,giving rise to Ni^(2+δ)N(OH)ads with the electrophilic oxygen;then Ni^(2+δ)N(OH)ads seizes protons and electrons from HMF and leaves as H_(2) O spontaneously.Furthermore,the high electrolyte alkalinity favors the HMFOR process due to the increased active species(Ni^(2+δ)N(OH)ads)and the enhanced adsorption of HMF on the Ni3 N surface.This work could provide an in-depth understanding of the electrocatalytic mechanism of HMFOR on Ni3 N and demonstrate the alkalinity effect of the electrolyte on the electrocatalytic performance of HMFOR.

Impacts of Alkalinity Drops on Shifting of Functional Sulfate-Reducers in a Sulfate-Reducing Bioreactor Characterized by FISH

Alkalinity is one of the most important parameters that influence microbial metabolism and activity during sulfate-laden wastewater biological treatment. To comprehensively understand the structure and dynamics of functional microbial community under alkalinity changes in sulfate-reducing continuous stirred tank reactor （CSTR）, fluorescent in situ hybridization （FISH） technique was selected for qualitative and semi-quantitative analysis of functional microbial compositions in activated sludge. During 93d of bioreactor operation, the influent alkalinity was adjusted by adding sodium bicarbonate from 4000mg·L^-1 down to 3000mg·L^-1, then to 1500mg·L^-1, whereas other parameters, such as the loading rates of chenucal oxygen demand （COD） and sulfate （SO4^2-）, hydraulic retention time （HRT）, and pH value, were continuously maintained at 24g·L^-1·d^-1 and 4.8g·L^-1·d^-1, 10h,and about 6.7, respectively. Sludge samples were collected during diflerent alkalinity levels, and total Bacteria, tlae sulfate-reducing bacteria （SRB）, and four SRB genera were demonstrated with 16S ribosomal .RNA-targeted oligonucleotide probes. The results indicated that bioreactor started-up successfully in 30d. The two instances ot drop in alkalinity resulted in the fluctuation of sulfate removal rate. The diversity of SRB community showed significant shift, and the alteration of microbial community directly resulted in the corresponding statuses of bioreactor. The dominant genera during the bioreactor start-up and alkalinity drops were Desulfovibrio, Desulfobacter, Desulfovibrio, Desulfobacter, and Desulfovibrio, respectively. In addition, the acetotrophic SRB sutterecl more trom me reduction of alkalinity than the non-acetotrophic SRB. This strategy can present the functional microbial community structure during start-up and alkalinity drop stages, and provides a powerful theoretical guideline for optimization and adjustment of bioreactor, as well.

Sulfate-Exchange Alkalinity of Ferralsol Colloid

The amount of OH- replaced by sulfate, i.e., sulfate-exchange alkalinity, from the electric double layer of ferralsol colloid was measured quantitatively in different conditions with an automatic titration equipment.The amount of OH- release increased with the amount of Na2SO4 added and decreased with raising pH in the suspension of ferralsol colloid. The exchange acidity was displayed as PH was higher than 5.6. If the negative effect of sodium ions was offset, the amount of OH- replaced by sulfate was larger than the original amount of OH- released in the PH range of lower than 5.8. The amount of OH- released decreased rapidly as PH was higher than 6.0 and dropped to zero when PH reached 6.5. In the solution of 2.0 mol L-1 NaClO4, the amount of OH- replaced by sulfate from the surface of ferralsol colloid could be considered as the amount of OH- adsorbed by ligand exchange reaction. The amount of OH- released in the solution of NaClO4 concentration below 2.0 mol L-1 from which the amount o f OH- adsorbed by ligand exchange reaction was subtracted could be considered as the OH- adsorbed by electrostatic force. The OH- adsorbed by electrostatic force decreased with increases in the concentration of NaClO4 and PH and increased almost linearly with the increasing amount of Na2SO4 added. The percentages of OH- adsorbed by electrostatic force in water and in the electrolyte solutions of 0.05 and 0.5 mol L-1NaClO4 in the total OH- released were calculated, respectively.

Germination and Photosynthetic Responses to Salinity and Alkalinity in Avicenna marina Propagules

Avicenna marina(Forssk.)Vierh is a halophytic mangrove.The reproductive unit is green and has photosynthetic propagules.Mangroves are naturally exposed to fluctuations in some abiotic factors at the soil surface,including salinity and alkalinity.The objective of this study was to determine the effects of two salts including NaCl and NaHCO_(3)on germination processes and discuss the relationships between cotyledon photosynthesis and embryo axis growth in A.marina propagules.These propagules came from Al Birk,located on the shoreline of the Saudi Red Sea.The results showed that the studied salts did not affect neither the final germination percentage nor the embryo axis growth.However,rooting and root growth were delayed by both salts at 300 mM and were strongly inhibited by 600 mM NaHCO_(3).Both NaCl and NaHCO_(3)reduced the photosynthetic activity.These two salts did not affect the other photosynthetic parameters,including stomatal conductance,net transpiration,and intercellular CO_(2).Thereafter,the reduction in net photosynthesis was not related to any limitation of stomatal conductance.The early germination phase was independent of cotyledon photosynthesis,whereas rooting and root growth may be limited by reduced photosynthesis under NaCl and NaHCO_(3).

Summertime freshwater fractions in the surface water of the western Arctic Ocean evaluated from total alkalinity

As a quasi-conservative tracer, measures of total alkalinity （TA） can be utilized to trace the relative fractions of freshwater and seawater. In this study, based on the TA and related data collected during the third Chinese National Arctic Research Expedition （JulySeptember 2008, 3rd CHINARE-Arctic） and the fourth Chinese National Arctic Research Expedition （JulySeptember 2010, 4th CH1NARE-Arctic）, fractions of sea-ice meltwater, river runoff, and seawater within the surface water of the western Arctic Ocean were determined using salinil~~ and TA relationships. The largest fraction of seeL-ice meltwater was found around 75~N within the Canada Basin during both surveys, which is located at the ice edge. Generally, it was found that the frac- tion of river runoff was less than that of sea-ice meltwater. The river runoff, composed mainly of contributions from the Yukon River carried by Bering inflow water and the Mackenzie River, was influenced by the currents, leading to two peak areas of its fraction. Our results show that the dilution effect of freshwater carried by Bering inflow water during the 3rd CH1NARE-Arctic in 2008 expedition period may be stronger than that during the 4th CH1NARE-Arctic in 2010 expedition period. The peak area of sea-ice meltwater fraction during the 4th CH1NARE-Arctic was different from that of the 3rd CHINAR-E-Arctic, corresponding to their sea-ice condition.

Distributions of dissolved inorganic carbon and total alkalinity in the Western Arctic Ocean

The third Chinese National Arctic Research Expedition （3rd CHINARE-Arctic in 2008） was carried out from July to September 2008. During the survey, numerous sea water samples were taken for CO2 parameter measurement （including total alkalinity TA and total dissolved inorganic carbon DIC）.The distribution of COs parameters in the Western Arctic Ocean was determined, and the controlling factors are addressed. The ranges of summertime TA, normalized TA （nTA）, DIC and normalized DIC （nDIC） in the surface seawater were 1 757 2 229 umol.kg 1 2 383-2 722 umol.kg-1, 1 681 2 034 pmol.kg 1, 2 119--2 600 umol.kg-1, respectively. Because of dilution from ice meltwater, the surface TA and DIC concentrations were relatively low. TA in the upper 100 m to the south of 78°N had good correlation with salinity, showing a conservative behavior. The distribution followed the seawater-river mixing line at salinity 〉30, then followed the seawater mixing line （diluted by river water to salinity = 30） with the ice meltwater. The DIC distribution in the Chukchi Sea was dominated by biological production or respiration of organic matter, whereas conservative mixing dominated the mixed layer TA distribution in the ice-free Canada Basin.

Titratable Acidity and Alkalinity of Red Soil Surfaces

The surfaces of red soils have an apparent amphotenc character, carrying titratable acidity and titratable alkalinity simultaneously. The titratable acidity arises from deprotonation of hydroxyl groups of hydrous oxide-type surfaces and dissociation of weak-acid functional groups of soil organic matter, while the titratable alkalinity is derived from release of hydroxyl groups of hydrous oxide-type surfaces. The titratable acidity and titratable alkalinity mainly depended on the composition and content of iron and aluminum oxides in the soils. The results showed that the titratable acidity and titratable alkalinity were in significantly positive correlation not only with the content of amorphous aluminum oxide(Alo) and iron oxide(Feo) extracted with acid ammonium oxalate solution, free iron ox-ide(Fed) extracted with sodium dithionite-citrate-bicarbonate (DCB) and clays, but also with the zero point of charge (ZPC) of the samples. Organic matter made an important contribution to the titratable acidity. The titratable alkalinity was closely correlated with the amount of fluoride ions adsorbed. The titratable acidity and titratable alkalinity of red soils were influenced by parent materials, being in the order of red soil derived from basalt > that from tuff > that from granite. The titratable acidity and titratable alkalinity were closely related with origination of the variable charges of red soils, and to a certain extent were responsible for variable negative and positive charges of the soils.

Surface distribution of alkalinity and specific alkalinity and their application to water mass tracing in Kuroshio area of the East China Sea

Surface distribution and seasonal variation of alkalinity and specific alkalinity in Kuroshio area of the East ChinaSea and their application to the water mass tracing are discussed in this paper. Results show a distinct seasonal variation of the alkalinity, which is concerned with the process of vertical mixing. Different specific alkalinity in various water masses has been found. On the basis of the difference of the specific alkalinity and the distribution of alkalinity, two water fronts in summer season, located at 27°-30°N and 124°-1 27°E, (Ⅰ), and at the northern waters about one latitude from the Taiwan Island, (Ⅱ); one in winter season at about one longitude from coast of mainland of China and 26°-30°N were found. In summer season, about 1-2 longitudes eastward shift of front (Ⅰ) is found by comparison of data in May and August. And the high alkalinity of the northern East China Sea in summer season may be caused by the Huanghe River runoff flowing southward along with the Huanghai Sea Coastal Current.

Floral Species as Environmental Quality Indicators in Jordan: High Salinity and Alkalinity Environments

In this study the occurrence and ecology of plant assemblages are investigated, mainly for use as indicator plants of saline grounds in several locations in Jordan. High alkalinity and H2S-rich water tolerant species of plants are also discussed. Plants growing on salty grounds have distinct composition regarding their place in the taxonomic system. Plant assemblages and their degree of tolerance to salinity as in Karama area in the Jordan Valley are found to be distinct from that of Azraq Sabkha (Cental Jordan) with salt-tolerant flora. Karama area provides the living space for Mesembryanthemum on the saltiest ground, Suaeda further up on wetter surrounding and Salicornia succeeding on moist and less salty grounds. Drier places with rather salty grounds have bushes of Arthrocnemum, while slightly less salty places are preferred by Tamarix tetragyna. When Prosopis bushes appear, salt is only present periodically in the ground, as is also the case with Atriplex halimus and Capparis. In Azraq the former beach of a temporal lake is characterized by two species of Spergularia in its saltier parts and by Tamarix passerinoides. It was recognized that Tamarix, Phragmites, Chenopodium, and Inula represented alkaline water tolerant plants. The study concludes that the salt concentration in the ground is reflected in the composition of the flora growing on it. On the other hand, plants are also found vulnerable to fluctuation in the salt concentration of their environments with different resistance degrees. This makes them excellent bioindicators of salty environments.

Soil Salinity and Alkalinity Map Preparation Based on Spatial Analysis of GIS (Case Study: Tabriz Plain)

Better management of agricultural fields is related to valuable information which can derived from soil salinity and alkalinity maps. These maps are considered as one of the most important factors which restrict plant growth as well as decline crops yield. The objective of this research was preparing of soil salinity and alkalinity maps in Tabriz plain over 50,000 hectares based on different techniques of spatial analysis in GIS software. For this mean, study area was divided in 1500 × 1500 m2 grid cells. Then, geographical coordinate of each grid recorded in UTM system. So, they were transferred into GPS for navigating to the exact excavation location. After soil sampling and transferring to the lab, their EC and PH were measured in saturation extract of soil samples. So, spatial distribution of soil sampling points was prepared in form of point map by GIS software. Generalization of point information to surface was performed using different interpolation algorithms and based on standards of Soil and Water Research Institute. Accuracy of interpolated maps was evaluated due to the MAE and MBE values. The results showed that the lowest observed error is related to the Spline method and therefore, this method was used for spatial modeling of salinity and alkalinity maps in the intended area. The research findings demonstrated that from total of 50,000 hectares, only 3066 hectares were without salinity and alkalinity limitation (6.1%), 9066 hectares had low salinity and alkalinity (18.1%);17,772 hectares had average limitation for salinity and alkalinity (35.6%) and the remaining 20,096 hectares had high and very high limitation for salinity and alkalinity.

Use of conductivity method for online measurement of alkalinity of caustic washing liquid

In this paper,the online measurement of the alkalinity of caustic washing liquid by the conductivity method was discussed,and a working curve of the conductivity vs.alkalinity was established,for which the correlation coefficient is 0.9979(n=7).The influence of the temperature of the caustic washing liquid and the presence of coexisting ions,such as iron and oil,on the accuracy of the conductivity method was discussed.The temperature is compensated for by establishing the correlation between conductivity and temperature.When the iron concentration is≤1000 mg/L,and the oil concentration is≤1000 mg/L,the deviation in the results obtained using the conductivity and titration methods is≤2.5 g/L.The t-test results show that there is no systematic devia-tion between the conductivity and titration methods.The conductivity method has the advantages of a fast response and good real-time performance,which meet the requirements for the online determination of the alkalinity of caustic washing liquid.

A New Approach to Carbonate Alkalinity

The article provides experimental data applied to the determination of carbonate alkalinity (CAM) according to modified Gran II functions. CAM is related to the mixtures NaHCO3 + Na2CO3 and Na2CO3 + NaOH. In addition to the determination of equivalence volumes, one of the main novelties of the proposed method is the possibility of determining the activity coefficient of hydrogen ions (γ). Moreover, CAM can be used to calculate the dissociation constants (K1, K2) for carbonic acid and the ionic product of water (KW) from a single pH titration curve. The parameters of the related functions are calculated according to the least squares method.

Effects of salinity, carbonate alkalinity, and pH on physiological indicators of nutrition transporter for potential habitat restoration of amphipod Eogammarus possjeticus

The effects of three environmental factors,salinity,carbonate alkalinity,and pH,on the survival,feeding,and respiratory metabolism of Eogammarus possjeticus(Amphipoda:Gammaridae)were investigated experimentally.The results show that E.possjeticus could tolerate a broad salinity range.The 24-h lowest median lethal salinity was 2.70,and the highest was 47.33.The 24-h median lethal alkalinity and pH were 23.05 mmol/L and 9.91,respectively;both values decreased gradually with time.Different values of salinity,carbonate alkalinity,and pH resulted in significant differences in the cumulative mortality(P<0.05).The ingestion rate and feed absorption efficiency were significantly affected by the coupling of the three environmental factors(P<0.05).With increases in carbonate alkalinity,salinity,and pH,both ingestion rate and feed absorption efficiency exhibited a downward trend,indicating a decline in feeding ability under high salinity and more alkaline water conditions.The coupling of salinity,carbonate alkalinity,and pH also had a significant effect on respiration and excretion(P<0.05).The oxygen consumption rate increased first and then decreased with increasing carbonate alkalinity.Under the same carbonate alkalinity values,the oxygen consumption rate increased with increasing salinity.Under the same carbonate alkalinity and salinity,the oxygen consumption rate initially increased and then decreased with increasing pH.The O:N ratio first increased and then decreased with increasing carbonate alkalinity.When carbonate alkalinity was less than 6 mmol/L,the O:N ratio increased with increasing salinity and decreased with increasing pH.The results demonstrate that changes in salinity,carbonate alkalinity,and pH had a measurable impact on the osmotic pressure equilibrium in E.possjeticus and affected the energy supply mode(i.e.ratio of metabolic substrate).