Physicochemical composition and climate response of surface sediments at different altitudes in Motuo on the southern slope of the Himalayas

Background,aim,and scope Certain physicochemical indexes of topsoil are closely related to climatic factors including temperature,and precipitation.Understanding the relationship between modern topsoil properties and climatic factors is essential for quantitative paleoclimate reconstruction.Motuo located in the eastern Himalayas,exhibits a significant elevation gradient of over 7000 m from Nnamjagbarwa Peak(7782 m a.s.l.)to the Baxika(150 m a.s.l.).This region features a complete vertical zonation of vegetation,from alpine meadow to tropical forest,presenting an ideal place to investigate the relationships among vegetation,soil and climate conditions across altitudinal gradients.This study aims to explore the vertical variations in the physicochemical composition of topsoil and its relationship with temperature and precipitation.Materials and methods Twenty-seven topsoil samples were collected at 100 m intervals from 800 m to 3600 m a.s.l.along the southern slope of the Himalayas.Grain size,magnetic susceptibility and geochemical elements were measured to discuss the vertical variation characteristics of topsoil composition and their correlation with climatic factors.Results(1)The grain size of topsoil at different altitudes in Motuo is mainly composed of sand accounting for an averaged 53.2%,followed by silt and clay.(2)In the mixed forest zone,frequency dependent magnetic susceptibility(χfd%)shows a clear relationship with altitude,and clay is positively correlated with both altitude and climatic factors.(3)The oxides of topsoil in this area mainly consist of SiO_(2),Al_(2)O_(3) and Fe_(2)O_(3),followed by MgO,CaO,Na_(2)O and K_(2)O,with slight variations in the primary components at different altitudes.The sensitivity of elements to climate varies across different altitudes and vegetation zone,likely due to the region’s complex topography and vegetation.(4)Physical and biological weathering dominates in the broad-leaved forest zone of Motuo,while chemical weathering is more prominent in the coniferous forest zone,with the mixed forest zone falling in between.Discussion The formation of topsoil across the three vegetation zones is influenced by various factors,including parent material,vegetation,and climate.In the broad-leaved forest zone,physical weathering(precipitation,root wedging etc.)and pedogenesis dominate,resulting in finer grain size.The χ_(fd)% increases with altitude likely due to the high temperature and abundant precipitation in this zone,which facilitate the transformation of strong magnetic miners into weaker ones,particularly when the soil is oversaturated.Zirconium(Zr),primarily found in zircon,is depleted at lower altitudes by strong current erosion.Barium(Ba)is similarly reduced at low altitudes in this zone.In mixed forest zone,clay content is the lowest,indicating weaker physical weathering conditions than broad-leaved forest zone.The coarser grain size may result from the combined effects of topography and vegetation coverage.Magnetic susceptibility and organic matter show a positive correlation with altitude.Zr concentration is higher than that in the broad-leaved forest zone,likely resulting from decreased precipitation.In the coniferous zone,the clay content shows considerable fluctuations,with grain size generally becoming finer as altitude increases.This trend may be explained by intensified soil disintegration from seasonal freeze-thaw cycles.The χ_(fd)% values lack a clear trend or pattern,possibly due to soil erosion causing the migration of magnetic minerals or insufficient iron precipitation,which reduces the concentration of magnetic minerals in the soil.Additionally,a positive correlation is observed between altitude and organic matter content,with higher altitudes associated with greater organic matter accumulation.This may be attributed to lower microbial activity in colder conditions,which slows the decomposition and transformation of organic matter.Conclusions The variations in grain size,magnetic susceptibility,and geochemical elements differ across altitudes and vegetation zones,closely connected to the complex interplay of terrain,vegetation,and climate in Motuo.In the mixed forest,altitude has a significant impact onχfd%,and the clay component is particularly sensitive to changes in altitude,mean annual temperature,and precipitation.Zr shows a strong correlation with altitude and climate factors,making it a valuable indicator for assessing changes in atmospheric precipitation within specific altitude ranges.Recommendations and perspectives This study enhances our understanding of the relationships between the physicochemical properties of topsoil and climate conditions,offering valuable insights for paleoclimate reconstruction in Motuo.

Effects of Different Storage Treatments on Physicochemical Indexes of Green Plums

[Objectives]This study was conducted to discuss the change laws and relationships of the physiological indexes in green plums treated with nisin or 1-MCP in the cold storage process.[Methods]Different storage methods on the physiological and quality indexes of green plums were investigated through two kinds of different treatment methods(treatment 1:1-MCP+cold storage,treatment 2:nisin+cold storage),with rotten fruit rate,weight loss rate,yellow ripeness index,hardness,Vc content,titratable acid,soluble solids and peroxidase(POD)activity as the evaluation indexes.[Results]The storage method of treating green plums with 1-MCP combined with cold storage could delay the quality decline of green plums after harvest,while the effect of nisin treatment was slightly inferior.1-MCP treatment followed by cold storage could more effectively delay the senescence of green plums,delay the decrease of fruit hardness and soluble solid content to the greatest extent,and maintain the titratable acid and Vc contents at relatively good levels.It further reduced weight loss rate and rotten fruit rate,postponed the time of the peak of POD enzyme activity,and reduced the loss of nutrients in the fruit,thereby maintaining good commercial properties of the fruit.[Conclusions]This study plays an important role in the post-harvest storage,preservation and transportation,as well as the development of the green plum industry.

QSPR Analysis of the Physicochemical Properties for Phthalic Acid Esters

Based on quantitative structure-property relationship （QSPR） of organic compounds, the molecular connectivity indices of 21 phthalic acid ester compounds were extracted. Relationship between the physicochemical properties （n-octanol/air partition coefficient, vapor pressure, water solubility） and the molecular connectivity indices of phthalic acid ester compounds have been established by multiple linear regression （MLR） method. The results showed that the zero-order valence connectivity index （0Xu） is the topology parameter which affects octanol/water partition coefficient and water solubility, and the topology parameter which affects vapor pressure is the first-order connectivity index （1X）. This indicated to a certain extent_that the molecular connectivity indices can be well used to express the quantitative relationship between the physicochemical properties and structure descriptions of phthalic acid ester compounds. The models constructed have good robustness and highly predictive capability.

Physicochemical properties of aqueous solutions of sodium glycinate in the non-precipitation regime from 298.15 to 343.15 K

The physicochemical properties,including the density,viscosity,and refractive index of aqueous solutions of sodium glycinate as a solvent for CO_2 absorption in the non-precipitation regime were measured under the wide temperature range of 298.15 to 343.15 K.The concentration of the sodium glycinate in an aqueous form in the non-precipitation regime was identified up to 2.0 mol ? L^(-1).The coefficients of thermal expansion values were estimated from measured density data.It was found that,the densities,viscosities and refractive indices of the aqueous sodium glycinate decrease with an increase in temperature,whereas with increasing sodium glycinate concentration in the solution,all three properties increase.Thermal expansion coefficients slightly increase with rising temperature and concentration.The measured values of density,viscosity and refractive index were correlated as a function of temperature by using the least squares method.The predicted data obtained from correlation equations for all measured properties were in fairly good agreement with the experimental data.

Characteristics of Phytoplankton and Its Correlation with Water Environment in SFTWs

[Objective] The aim was to carry out study on characteristics of phytoplankton and its correlation with water environment in SFTWs. [Method] Based on the pilot-scale SFTWs in Hongqiao transportation hub of Shanghai,phytoplankton＇s community structure,diversity index and their correlation with water purification performance were investigated. [Result] 57 species of seven phylum of phytoplankton were detected in this tested river,including 12 species of Cyanophyta,2 of Cryptophyta,10 of Bacillariophyta,1 of Xanthophyta,7 of Euglenophyta,1 of Pyrrophyta and 24 of Chlorophyta,respectively. Additionally,it was found that Cyanophyta was the dominant phytoplankton,followed by Bacillariophyta and Cyanophyta. Biological density was far more than 10×105 ind./L,thus it could be considered that the river was eutrophic. The range of Shannon-Wiener index was 0.6-2.2,Pielou index was 0.5-2.5 and Margalef index＇s range was 0.35-0.85,which could further prove that the water was eutrophic. The biological density and species were significantly positively correlated with temperature and N content,indicating that the absorption of N by phytoplankton was the main N-removal pathway in SFTWs. [Conclusion] This study had provided basis for the river regulation and ecological restoration.

Effects of Different Microbes on Fermenting Feed for Sea Cucumber(Apostichopus japonicus)

The effects of different microbes on fermenting feed for sea cucumber （Apostichopus japonicus） were compared to select the optimal fermentation strain in this study. Saccharomgces cerevisae, Candida utilis, Bacillus subtilis and Geotrichum candidum were independently added into the experimental compound feed, while only saline was mixed with the control feed. The fermentation treatments were inoculated with 10% seed solution under the condition of 25 ~C and 70% water content, which lasted for 5 days to elucidate the optimal microbe strain for fermenting effect. Physicochemical indexes and sensorial characteristics were measured per day during the fermentation. The indexes included dry matter recovery （DMR）, crude protein （CP）, the percentage of amino acid nitrogen to total nitrogen （AA-N/tN）, the percentage of ammonia nitrogen to total nitrogen （NH3-N/tN）, and the ratio of fermentation strains and vibrios to the total microbes, color, smell and viscosity. The results showed that DMR, CP and AA-N/tN of the S. cerevisae group reached the highest level on day 3, but the ratio of fermentation strain was second to C. utilis group. In addition, its NH3-N/tN and the ratio of vibrios were maintained at low levels, and the sensory evaluation score including smell, color and viscosity was the highest in S. cerevisae group on day 3. Therefore, S. cerevisae could be the optimal strain for the feed fermentation for sea cucumber. This research developed a new production method of fermentation feed for sea cucumber.