Major Ions in Atmospheric Deposition in Lake Kivu Basin

This study investigated the major ion composition and sources in wet and dry deposition samples collected over 15 months (December 2017 to February 2019) at four stations representing four different land use/cover types on the western side of Lake Kivu basin in D.R. Congo. The samples were collected every 13 days for dry deposition and two to three times per month for wet deposition. Samples were analyzed for major ionic components (Cl-, NO-3, SO2-4, Na+, K+, NH+4, Ca2+, CO2-3, HCO-3 and Mg2+). Electrical conductivity and pH were analyzed immediately in the field while major ion measurements were in the laboratory. Results showed the pH of both the dry and the wet depositions were higher than what would have been expected based on equilibration with atmospheric CO2 (pH > 5.6) at all four sites, with conductivity less than 50 μS/cm. The neutralization process in dry and wet atmospheric deposition is due to Ca2+, NH+4, HCO-3 and CO2-3. The anion: cation ratio in dry deposition was close to 1 for Iko and Bukavu, and it was greater than 1.0 (1.1 - 1.2) for Lwiro and Goma in wet deposition. The dominant anions in wet deposition were SO2-4 and NO-3, found around the rural area near cement factory and the urban area near active volcanoes, respectively. The most abundant cation was Na+ followed by K+. The enrichment factors and correlation analysis suggest that the main sources of Ca2+, Na+ and Mg2+ were disintegration of soil processes, aeolian suspension of soil and volcanic ash, biomass burning and the cement/lime factory around the Lake Kivu basin.

Differences in major ions as well as hydrogen and oxygen isotopes of sediment pore water and lake water

Isotopic and chemical compositions of pore water(PW) are highly relevant to environmental and forensic study. Five lake water(LW)samples and five sediment samples were collected to investigate the effects of pore sizes of sediments on PW chemistry and stable isotopes and determine mechanisms controlling their variations. Six pore water fractions were extracted from different-sized pores in each sediment sample at six sequential centrifugal speeds for chemical and isotopic analysis. The sediments consisted mainly of quartz, feldspar, and clay minerals. The hydrogen and oxygen isotopic compositions of PW are mainly controlled by the overlying LW, although the lag effect of exchange between overlying LW and PW results in isotopic differences when recharge of LW is quicker than isotopic exchange in PW. Identical isotopic compositions of PW from sediments with different pore sizes indicate that isotopic exchange of water molecules with different pore sizes is a quick process. The ratio of average total dissolved solid(TDS) concentration of PW to TDS concentration of LW shows a strong relationship with adsorption capacity of sediments, demonstrating that remobilization of ions bound to sediments mainly causes a chemical shift from LW to PW.Concentrations of Ca^(2+), Mg^(2+),and Cl^-in PW remain unchanged,while concentrations of Na^+,K^+,and SO_4^(2-) slightly increase with decreasing pore size. Chemical differences of PW from sediments with different pore sizes are governed by ion adsorption properties and surface characteristics of different-si zed particles.

Major Ion Geochemistry of Groundwaters from Southern Nevada and Eastern California, USA

The dissolved ionic constituents of groundwaters are, in part, a record of the minerals and rocks in aquifers through which the water has flowed. The chemical composition and association of these major ions in groundwaters have been used to trace groundwater flow paths and sources. In general, the chemical composition of water in carbonate\|rock aquifers is dominated by calcium, magnesium, and bicarbonate, whereas sodium, chloride, and sulfate can be dominant ions in the water that comes from volcanic aquifers or clay minerals. Since the \{1990’s\}, we have dealt with the geochemistry of groundwaters from more than 100 springs and wells in southern Nevada and eastern California, USA for major solutes and trace elements. This paper compiles the hydrochemical data of major ions of these groundwaters. Based on major ion geochemistry, groundwaters from southern Nevada and eastern California can be classified as carbonate aquifer water, volcanic aquifer water, and mixing water (either mixing of carbonate and volcanic aquifer waters or mixing with local recharges). Piper and Stiff diagrams of major ions have graphically shown the general chemical characteristics, classifications, and mixing relationships of groundwaters from southern Nevada and eastern California.

SPECTRUM CHARACTERISTICS OF MAJOR IONCONCENTRATIONS AT WUHAN SECTOIN OF THECHANGJIANG RIVER

ABSTRACT: Spectrum analyses of water quality time series have been carried out for five hydrometric stations including Wuhan hydrometric station of the Changjiang( Yangtze) River, etc. The fluctuations of Ca2 +, Mg2+ and HCO3-concentrations in river water under different physical geography conditions have about two-year cycle which is corresponding to hydrometeorological quasi-biannual-oscillation(QBO). Na + Cl- SO2-4 have about two-year cycle in the area lightly affected by human activities while two-year cycle doesn’t exist in the area heavily affected by human activities. All the fluctuations of major ions have about three-month cycle. The river discharge fluctuation accounts for 43. 9% , 45.1%, 54.3%, 33.9%, 30.3% and 42. 7% of the variance of Ca2 +, Mg2+ HC03-, Na+ Cl-, SO2-4, respectively, at Wuhan from 1962 to 1985. According to the spectrum characteristic of major ions, the duration of the time series has to be at least 13 years for trend analysis of monthly water quality data.

蔚蓝之境——服装表演专业毕业创作教学与实践

毕业设计是检验学生综合能力的重要课程,从最初的设计构思和概念确立,到设计草图、确定款式,之后进行配饰选择、妆面设计和时装展示,要求学生能够综合运用本科四年所学的专业知识完成指定选题下的设计创作。与服装设计专业相比,服装表演专业的学生因其专业背景和培养模式的不同,在毕业创作和实践的过程中有一定的特殊性;指导教师应根据服装表演专业学生的特点做到有的放矢、因材施教。本文以北京服装学院2021届服装表演专业本科毕业创作为例,分析了在蓝色主题背景之下,服装表演专业毕业生的设计实践过程,详细阐述了毕业创作教学的工作方法,旨在为相关院校服装表演专业教学与实践活动提供建议和参考。

Groundwater Geochemistry and Saltwater Intrusion in the Dakar Coastal Area, Senegal

Groundwater levels and water samples were collected from 20 drinking water pumping and piezometer wells in the urban area of Dakar coastal region in the year 2019. The pH-value, electrical conductivity, as well as calcium, magnesium, sodium, potassium, chloride, sulfate, bicarbonate, and nitrate concentrations were measured to assess the hydrochemical quality of the infrabasaltic aquifer in the area. The present work carried out a hydrochemical analysis to interpret the groundwater chemistry of the aquifer. The results of this chemical analysis indicate that Na+ > Mg2+ > Ca2+ > K+ was the most dominant cation sequence in the groundwater, while Cl- > HCO3- > SO42- > NO3- was the most dominant one for anions. The chemical analysis of our samples showed, that the Cl-Ca-Mg facies was dominant in the aquifer, while Cl-Na-K and HCO3-Na-K facies represent 20% and 10% of the groundwater sampled, respectively. A comparison of the measured groundwater quality in relation to WHO drinking water quality standards revealed that 80% of the water samples are suitable for drinking purposes. Ca enrichment, Simpson ratio, ratio of sodium chloride, and calculating Base Exchange (BEX) indices for the samples revealed that the groundwater is mainly affected by three factors: seawater intrusion due to aquifer overexploitation on one hand, and freshening processes and nitrate pollution, on the other, mainly caused by the groundwater flow from the unconfined aquifer.

A linear regression model (LRM) for groundwater chemistry in and around the Vaniyambadi industrial area, Tamil Nadu, India

A linear regression model in conjunction with cluster analysis was applied to the groundwater quality parameters for the Vaniyambadi industrial area, Tamil Nadu, India. These physico-chemical parameters were collected from 25 wells by intensive groundwater sampling conducted during January 2010. All the major ions, pH and electrical conductivity were analyzed. The abundances of cations were in the order of Na <Ca <Mg <K and those of anions were in the order of Cl <HCO3 <SO4 <CO3, respectively. This was in agreement with the water types, Na-Cl and Na-Ca-HCO3, determined by the Piper plot. High concentrations of the ions Na, Cl and SO4 were recorded near the tanneries that operate within the study area. While the elevated concentrations of HCO3 and F were observed away from the tanneries. This peculiar hydrochemical behaviour suggests that the chemistry of water is predominantly influenced by tannery effluents and weathering of silicate minerals. Results of the linear regression model yielded 11 regression equations for the 5 most correlated parameters. A dendrogram from the cluster analysis showed 2 major clusters representing the influence of tanneries and geological formations in the study area, which confirmed the results of major ion chemistry.

FRESH SNOW CHEMISTRY FROM HIGH MOUNTAIN REGIONS IN CENTRAL HIMALAYAS

During 1997 summer, fresh snow samples were collected from the high elevation region (5400－ 7000 m) of Dasuopu Galcier on the northern slope of Mt. Xixabangma (28° 33’N, 85° 44’E). Compared with other remote regions in the world, major ion concentrations in fresh snow are very low during summer in Mt. Xixabangma, suggesting that the atmosphere is very clean and may represent background value for the middle/upper troposphere in the middle/low latitude area. During summer at Mt. Xixabangma the fresh snow chemistry is minimally influenced by anthropogenic pollutants as revealed by the snow pH (mean value of 6.0). Conductivity of fresh snow are low and constant. A multi regression curve of pH vs conductivity shows a strong correlation; snow pH is negatively correlated with conductivity when pH < 6.0, and positively correlated when pH > 6.0. This suggests that the dominant chemical species of snow are interchanging between acid anions (e.g.) and crustal cations.

Mesopotamian Marshlands: Salinization Problem

Salinization becomes a very serious problem affecting the restoration assessment of the newly re-flooded marshes of the Mesopotamian southern Iraq. From mid-1970 to early-1990, the whole marsh area was influenced by water shortage and desiccation processes. Increasing the average salinity level in the re-flooded marshes is acting versus their recovery progress and significantly affecting their aquatic biota. This study will examine the contributions of dams’ construction and desiccation on increasing the salinity level with in the Mesopotamian marshlands overtime. Water discharge and salinity concentration were monitored in the direct water inputs and outlets of the three marshlands from May 2006 to February 2007 on a monthly basis, while salinity and major ions concentrations including “Ca1+, Mg2+, Cl1-, and SO42-” were monitored in 28 re-flooded marshes from March 2005 to August 2008 on a seasonal basis. The study indicate that increasing the salinity level in the Mesopotamian marshlands is due to three reasons: 1) The overtime increasing in the salinity level of their direct water inputs, due to dams’ constructions;2) the increase of the Arab Gulf tide via Shatt Al-Arab river due to the reduction of the water level in the outlets of the Central and Al-Hammar marshlands;and 3) the huge accumulation of salts due to desiccation.

某海水功能饮品中常量离子对脂肪酶的影响

为揭示某海水功能饮品的作用机理并强化其功能,通过检测加入某海水功能饮品及其所含5种常量离子(Mg^(2+)、Ca^(2+)、Na^(+)、K^(+)和B^(3+))后脂肪酶的活力、Zeta电位、紫外和荧光光谱的变化,初步揭示了该饮品及其所含5种离子对脂肪酶的影响和作用机理。结果表明:该饮品及其所含5种离子对脂肪酶的活力和稳定性均有促进作用,且随着离子浓度的升高作用增强;海水功能饮品可使脂肪酶的Zeta电位绝对值增加,紫外吸收和荧光强度增强,最大吸收峰位红移3 nm,由此说明海水功能饮品中的5种离子可能通过改变蛋白质分子的微环境极性,改变氨基酸残基的带电性等特性,影响酶分子构象,从而改善酶活力及功能。

灌溉方式对石嘴山地区土壤盐渍化程度的影响

在宁夏石嘴山地区漫灌、喷灌、滴灌农田分别采集0~20、21~40、41~60、61~80、81~100 cm土层土壤样品,分析3种灌溉方式对土壤盐渍化程度的影响。结果表明:(1)漫灌和喷灌下不同土层盐分质量比均值的变化趋势基本一致,喷灌下表层土壤脱盐和下层土壤积盐现象明显,滴灌下土壤盐分表聚现象明显。(2)石嘴山地区(除平罗县外)现有耕地发生不同程度盐渍化的面积为542.47 km~2,占耕地总面积的52.33%,根据土壤盐渍化分级标准,漫灌下土壤无盐渍化,喷灌、滴灌下土壤均为轻度盐渍化。(3)喷灌和滴灌对土壤中阴、阳离子质量比的影响明显,漫灌基本无影响,其中SO_(4)^(2-)、Na^(+)质量比受灌溉方式的影响显著。

长江水系河水主要离子化学特征

2007年夏季采集了长江从上游沱沱河至入海口的干流原水样品36个,长江各主要支流水样品40个,分析了江水Ca2+、Mg2+、Na+、K+、HCO3-、SO42-、Cl-离子含量及溶解性SiO2等溶质成分。结果显示,长江流域水系离子化学组成主要受碳酸盐和蒸发岩风化控制,长江上游水离子化学呈现阳离子以K+和Na+为主,阴离子以Cl-和SO42-为主的蒸发岩类风化控制特征,但随着采样点位下移,离子含量逐渐呈现阳离子以Ca2+为主,阴离子以HCO3-为主的逐渐向碳酸盐风化过渡的特征;从时间变化上看,与20世纪50年代至1990年长江水离子化学数据相比,以Na+、K+、SO42-和Cl-为代表的所有阴阳离子均有明显增加;从通量上看,洞庭湖和鄱阳湖是长江离子两个最大的输入源,除洞庭湖和鄱阳湖外的其他长江各大支流中,岷江是长江Na+、K+、Ca2+、Mg2+、F-和HCO3-的最大输入源,嘉陵江是SO24-和溶解性SiO2的最大输入源;在几大世界河流中,长江是对海洋Mg2+、SO24-和Cl-的输入通量最大的河流,Ca2+和HCO3-通量仅次于亚马逊河。

藏南普莫雍错流域水体离子组成与空间分布及其环境意义

对藏南普莫雍错湖水及其周围入湖河流水体进行了离子化学成分分析,对部分湖泊和河流水样作氧同位素分析.结果显示,不同入湖河流离子组成与湖水本身离子组成有较大差异.湖水的主要离子组合是Mg2+-Ca2+-HCO3--SO42-,而主要补给河流加曲为Ca2+-Mg2+-HCO3-.加曲入湖河口2m水深以内水化学性质差异大,湖泊其他地区差异小.加曲对河口三角洲之上湖水影响显著.其他河流对河口处湖水影响较小.Gibbs图显示湖水离子的组成主要与流域内的岩石风化有关.离子比例和三角图分析说明控制入湖河水离子主要过程是碳酸盐、黄铁矿和硅酸盐风化.湖泊与河流水体离子的组成差异较大,原因可能是蒸发浓缩导致的CaCO3的沉淀.其结果有助于正确理解湖泊沉积碳酸盐的环境指示意义.

岩性和气候条件对长江水系河水主要离子化学的影响

在分析长江流域１２０ 余水文站点近３０ 年水质监测数据的基础上，运用主成分分析、相关分析等数理统计方法研究岩性和气候条件（ 降水量） 对长江水系河水主要离子化学的影响。

鄱阳湖流域水化学主离子特征及其来源分析

系统采集了鄱阳湖流域湖水、河水,分析测定各单元水体主离子组成.结果表明,鄱阳湖流域枯水期主离子浓度大于丰水期主离子浓度,TDS集中在60—100 mg.L-1,属于弱矿化度水;总硬度浓度40—60 m.gL-1,属于软水;其中Ca2+和SO24-是占绝对优势的离子,分别占阳离子和阴离子总量的45.0%和47.5%.湖区阴阳离子主要以SO24-和Ca2+为主,湖区的水化学类型为HCO3--Ca2+和SO24--Ca2+;河流的阴阳离子以SO24-、HCO3-和Ca2+为主,其水化学类型为受碳酸盐岩和蒸发岩溶解作用的影响较大的HCO3--SO24--Ca2+.鄱阳湖流域丰水期受大气降水和岩石风化影响显著,枯水期由于降雨量大大减少,鄱阳湖流域水化学成分此时主要受岩石风化和蒸发沉淀作用的影响,此时组分点分布在G ibbs图的中部偏向蒸发-沉积区域.通过SPSS软件做离子的相关性分析,各离子之间的相关系数都呈正相关,说明它们之间有共同的来源;各个离子与各产业之间的相关性均为负,除SO24-与第一产业和第二产业的相关性达到|r|>0.3,人类活动对水化学类型影响很小.

长江水质地球化学

文章在对1958-1990年期间长江水系191个站点水质监测资料进行统计分析的基础上，研究了长江主要离子的地球化学。结果表明，长江水系各地河水总溶解性固体（TDS）含量的差别达一个数量级（49．7～518．1mg／L），TDS的平均值为205．9mg／L，是全球河流均值的3倍。相比之下，河水TDS含量的季节性变化并不大，尽管河水流量的季节变化很大。长江的主要离子化学主要受岩石风化作用，尤其是碳酸盐矿物的溶解作用所控制。长江中上游的川贵地区酸雨严重。酸雨作用于当地广泛分布的石灰岩和富含碳酸盐的三叠纪砂页岩，导致近半个世纪来长江水质的酸化趋势，使大部分河段SO4^2-和Ca^2＋含量增高，总硬度与总碱度的比值增高。

黄河水质地球化学

在对1958--2000年期间黄河水系100个站点水质监测资料进行统计分析的基础上，研究了黄河主要离子的地球化学。结果表明，黄河流域各区河水总溶解性固体（TDS）含量的差异达2～3个数量级，TDS的总平均值为452mg／L，是全球河流均值的4倍。Na^＋、K^＋、SO4^2-和Cl^-的含量是世界河流均值的10-20倍。相比之下，河水TDS含量的季节差异却不大，远不及与此呈反比关系的流量的季节差异。黄河洪水期的水量通常是枯水期的4～5倍，但枯水期河水的TDS通常只是洪水期的2倍，完全不同于世界其他大河。黄河的离子化学主要受沉积岩（尤其是富含碳酸盐矿物的黄土）化学风化作用和在干旱气候影响下水中溶解盐的蒸发浓缩和结晶作用的控制。近半个世纪来黄河河道径流量有显著减少的趋势，这与新修建的众多水库的蓄水有关，与此相适应，近半个世纪来黄河水质表现出明显的盐渍化过程，这一过程主要由含盐量高的农田灌溉回水所引起。

赤水河中下游冬季河水化学空间分布特征分析

通过在枯水期对赤水河中下游干流及其支流共25个河水样品进行水化学采样,水化学分析结果表明：在阴阳离子组成中,Ca^2＋为主要阳离子,占总阳离子的64%以上;阴离子以HCO3^-和SO4^2-为主,占总阴离子75%-91%,其中HCO3^-占51%以上。Gibbs图研究区河水化学组成受岩石风化作用控制,阴阳离子三角图、水化学比值分析表明研究区河水化学组成主要受碳酸盐岩风化作用影响,在下游部分支流存在一定硅酸盐岩风化作用。水化学时空分布的对比分析表明,人为活动的对赤水河流域岩石风化速率和水化学组成产生了一定的影响。