Chemical and Isotopic Characters of the Water and Suspended Particulate Materials in the Yellow River and Their Geological and Environmental Implications

The chemical and isotopic characteristics of the water and suspended particulate materials(SPM)in the Yellow River were investigated on the samples collected from 29 hydrological monitoring stations in the mainstem and several major tributaries during 2004 to 2007.TheδD andδ~(18)O values of the Yellow River water vary in large ranges from-32‰to-91‰and from-3.1‰to-12.5‰,respectively.The characters of H and O isotope variations indicate that the major sources of the Yellow River water are meteoric water and snow melting water,and water cycle in the Yellow River basin is affected strongly by evaporation process and human activity.The average SPM content(9.635g/L)of the Yellow River is the highest among the world large rivers.Compared with the Yangtze River,the Yellow River SPM has much lower clay content and significantly higher contents of clastic silicates and carbonates.In comparison to the upper crust rocks,the Yellow River SPM contains less SiO_2,CaO,K_2O and Na_2O,but more TFe_2O_3,Co,Ni,Cu,Zn,Pb and Cd.The abnormal high Cd contents found in some sample may be related to local industrial activity.The REE contents and distribution pattern of the Yellow River SPM are very close to the average value of the global shale.The averageδ~(30)Si_(SPM)in the Yellow River(-0.11‰)is slightly higher than the average value(-0.22‰)of the Yangtze River SPM.The major factors controlling theδ~(30)Si_(SPM)of the Yellow River are the soil supply,the isotopic composition of the soil and the climate conditions.The TDS in the Yellow River are the highest among those of world large rivers.Fair correlations are observed among Cl~-,Na~+,K~+,and Mg~(2+)contents of the Yellow River water,indicating the effect of evaporation.The Ca~(2+)and Sr~(2+)concentrations show good correlation to the SO_4~(2-)concentration rather than HCO_3~-concentration,reflecting its origin from evaporates.The NO_3~-contents are affected by farmland fertilization.The Cu,Zn and Cd contents in dissolved load of the Yellow River water are all higher than those of average world large rivers,reflecting the effect of human activity.The dissolved load in the Yellow River water generally shows a REE distribution pattern parallel to those for the Yangtze River and the Xijiang River.Theδ~(30)Si values of the dissolved silicon vary in a range from 0.4‰to 2.9‰,averaging1.34‰.The major processes controlling the D_(Si)andδ~(30)Si_(Diss)of the Yellow River water are the weathering process of silicate rocks,growth of phytolith in plants,evaporation,dissolution of phytolith in soil,growth of fresh water diatom,adsorption and desorption of aqueous monosilicic acid on iron oxide and human activities.The averageδ~(30)Si_(Diss)value of the Yellow River is significantly lower than that of the Nile River,Yangtze River and Siberia rivers,but higher than those of other rivers,reflecting their differences in chemical weathering and biological activity.Theδ~(34)S_(SO4)values of the Yellow River water range from-3.8‰to 14.1‰,averaging 7.97‰.There is some correlation between SO_4~(2-)content andδ~(34)S_(SO4).The factors controlling theδ~(34)S_(SO4)of the Yellow River water are the SO_4 in the meteoric water,the SO_4 from gypsum or anhydrite in evaporite rocks,oxidation and dissolution of sulfides in the mineral deposits,magmatic rocks and sedimentary rocks,the sulfate reduction and precipitation process and the sulfate from fertilizer.The~(87)Sr/~(86)Sr ratios of all samplesrange from 0.71041 to 0.71237,averaging 0.71128.The variations in the~(87)Sr/~(86)Sr ratio and Sr concentration of river water are primarily caused by mixing of waters of various origins with different~(87)Sr/~(86)Sr ratios and Sr contents resulting from water-rock interaction with different rock types.     

Thermal expansion of gehlenite, Ca2Al[AlSiO7], and the related aluminates LnCaAl[Al2O7] with Ln=Tb, Sm

The thermal expansion of gehlenite, Ca₂Al[AlSiO₇], (up to T=830 K), TbCaAl[Al₂O₇] (up to T=1,100 K) and SmCaAl[Al₂O₇] (up to T=1,024 K) has been determined. All compounds are of the melilite structure type with space group Thermal expansion data was obtained from in situ X-ray powder diffraction experiments in-house and at HASYLAB at the Deutsches Elektronen Synchrotron (DESY) in Hamburg (Germany). The thermal expansion coefficients for gehlenite were found to be: α₁=7.2(4)×10⁻⁶ K⁻¹+3.6(7)×10⁻⁹ΔT K⁻² and α₃=15.0(1)×10⁻⁶ K⁻¹. For TbCaAl[Al₂O₇] the respective values are: α₁=7.0(2)×10⁻⁶ K⁻¹+2.0(2)×10⁻⁹ΔT K⁻² and α₃=8.5(2)×10⁻⁶ K⁻¹+2.0(3)×10⁻⁹ΔT K⁻², and the thermal expansion coefficients for SmCaAl[Al₂O₇] are: α₁=6.9(2)× 10⁻⁶ K⁻¹+1.7(2)×10⁻⁹ΔT K⁻² and α₃=9.344(5)×10⁻⁶ K⁻¹. The expansion-mechanisms of the three compounds are explained in terms of structural trends obtained from Rietveld refinements of the crystal structures of the compounds against the powder diffraction patterns. No structural phase transitions have been observed. While gehlenite behaves like a ’proper’ layer structure, the aluminates show increased framework structure behaviour. This is most probably explained by stronger coulombic interactions between the tetrahedral conformation and the layer-bridging cations due to the coupled substitution (Ca²⁺+Si⁴⁺)-(Ln ³⁺+Al³⁺) in the melilite-type structure. Electronic Supplementary Material Supplementary material is available for this article at     

Behavior of epidote at high pressure and high temperature: a powder diffraction study up to 10 GPa and 1,200 K

The thermo-elastic behavior of a natural epidote [Ca_1.925 Fe_0.745Al_2.265Ti_0.004Si_3.037O₁₂(OH)] has been investigated up to 1,200 K (at 0.0001 GPa) and 10 GPa (at 298 K) by means of in situ synchrotron powder diffraction. No phase transition has been observed within the temperature and pressure range investigated. P–V data fitted with a third-order Birch–Murnaghan equation of state (BM-EoS) give V ₀ = 458.8(1)ų, K _T0 = 111(3) GPa, and K′ = 7.6(7). The confidence ellipse from the variance–covariance matrix of K _T0 and K′ from the least-square procedure is strongly elongated with negative slope. The evolution of the “Eulerian finite strain” vs “normalized stress” yields Fe(0) = 114(1) GPa as intercept values, and the slope of the regression line gives K′ = 7.0(4). The evolution of the lattice parameters with pressure is slightly anisotropic. The elastic parameters calculated with a linearized BM-EoS are: a ₀ = 8.8877(7) Å, K _T0(a) = 117(2) GPa, and K′(a) = 3.7(4) for the a-axis; b ₀ = 5.6271(7) Å, K _T0(b) = 126(3) GPa, and K′(b) = 12(1) for the b-axis; and c ₀ = 10.1527(7) Å, K _T0(c) = 90(1) GPa, and K’(c) = 8.1(4) for the c-axis [K _T0(a):K _T0(b):K _T0(c) = 1.30:1.40:1]. The β angle decreases with pressure, β_P(°) = β_P0 −0.0286(9)P +0.00134(9)P ² (P in GPa). The evolution of axial and volume thermal expansion coefficient, α, with T was described by the polynomial function: α(T) = α₀ + α₁ T ^−1/2. The refined parameters for epidote are: α₀ = 5.1(2) × 10⁻⁵ K⁻¹ and α₁ = −5.1(6) × 10⁻⁴ K^1/2 for the unit-cell volume, α₀(a) = 1.21(7) × 10⁻⁵ K⁻¹ and α₁(a) = −1.2(2) × 10⁻⁴ K^1/2 for the a-axis, α₀(b) = 1.88(7) × 10⁻⁵ K⁻¹ and α₁(b) = −1.7(2) × 10⁻⁴ K^1/2 for the b-axis, and α₀(c) = 2.14(9) × 10⁻⁵ K⁻¹ and α₁(c) = −2.0(2) × 10⁻⁴ K^1/2 for the c-axis. The thermo-elastic anisotropy can be described, at a first approximation, by α₀(a): α₀(b): α₀(c) = 1 : 1.55 : 1.77. The β angle increases continuously with T, with β_T(°) = β_T0 + 2.5(1) × 10⁻⁴ T + 1.3(7) × 10⁻⁸ T ². A comparison between the thermo-elastic parameters of epidote and clinozoisite is carried out.     

Thermal expansion of gehlenite, Ca2Al[AlSiO7], and the related aluminates LnCaAl[Al2O7] with Ln = Tb, Sm

The thermal expansion of gehlenite, Ca₂Al[AlSiO₇], (up to T=830 K), TbCaAl[Al₂O₇] (up to T=1100 K) and SmCaAl[Al₂O₇] (up to T=1024 K) has been determined. All compounds are of the melilite structure type with space group Thermal expansion data were obtained from in situ X-ray powder diffraction experiments in-house and at HASYLAB at the Deutsches Elektronen Synchrotron (DESY) in Hamburg (Germany). The thermal expansion coefficients for gehlenite were found to be: α₁=7.2(4)×10⁻⁶×K⁻¹+3.6(7)×10⁻⁹ΔT×K⁻² and α₃=15.0(1)×10⁻⁶×K⁻¹. For TbCaAl[Al₂O₇] the respective values are: α₁=7.0(2)×10⁻⁶×K⁻¹+2.0(2)×10⁻⁹ΔT×K⁻² and α₃=8.5(2)×10⁻⁶×K⁻¹+2.0(3)×10⁻⁹ΔT×K⁻², and the thermal expansion coefficients for SmCaAl[Al₂O₇] are: α₁=6.9(2)×10⁻⁶×K⁻¹+1.7(2)×10⁻⁹ΔT×K⁻² and α₃=9.344(5)×10⁻⁶×K⁻¹. The expansion mechanisms of the three compounds are explained in terms of structural trends obtained from Rietveld refinements of the crystal structures of the compounds against the powder diffraction patterns. No structural phase transitions have been observed. While gehlenite behaves like a ‘proper’ layer structure, the aluminates show increased framework structure behavior. This is most probably explained by stronger coulombic interactions between the tetrahedral conformation and the layer-bridging cations due to the coupled substitution (Ca²⁺+Si⁴⁺)–(Ln ³⁺+Al³⁺) in the melilite-type structure. This article has been mistakenly published twice. The first and original version of it is available at .     

Potassium leaching in undisturbed soil cores following surface applications of gypsum

Displacement studies on leaching of potassium (K⁺) were conducted under unsaturated steady state flow conditions in nine undisturbed soil columns (15.5 cm in diameter and 25 cm long). Pulses of K⁺ applied to columns of undisturbed soil were leached with distilled water or calcium chloride (CaCl₂) at a rate of 18 mm h⁻¹. The movement of K⁺ in gypsum treated soil leached with distilled water was at a similar rate to that of the untreated soil leached with 15 mM CaCl₂. The Ca²⁺ concentrations in the leachates were about 15 mM, the expected values for the dissolution of the gypsum. When applied K⁺ was displaced with the distilled water, K⁺ was retained in the top 10–12.5 cm depth of soil. In the undisturbed soil cores there is possibility of preferential flow and lack of K⁺ sorption. The application of gypsum and CaCl₂ in the reclamation of sodic soils would be expected to leach K⁺ from soils. It can also be concluded that the use of sources of water for irrigation which have a high Ca²⁺ concentration can also lead to leaching of K⁺ from soil. Average effluent concentration of K⁺ during leaching period was 30.2 and 28.6 mg l⁻¹ for the gypsum and CaCl₂ treated soils, respectively. These concentrations are greater than the recommended guideline of the World Health Organisation (12 mg K⁺ l⁻¹).     

Phase equilibria in the system K2O-FeO-MgO-Al2O3-SiO2-H2O-CO2 and the stability limit of stilpnomelane in metamorphosed Precambrian iron-formations

The phase relations of Al- and Fe-bearing silicates in the system K₂O-FeO-MgO-Al₂O₃-SiO₂-H₂O-CO₂, in the presence of quartz and magnetite, are discussed on the basis of mineralogic and petrologic data from Precambrian iron-formations and blueschist facies meta-ironstone from the Franciscan Formation, California. These relations allow an estimation of the physiochemical conditions during low-grade metamorphism of iron-formations. Petrologic data together with available experimental and predicted thermodynamic data on the associated minerals place the upper stability limit of stilpnomelane in iron-formations at about 430–470° C and 5–6 kilobars. Fe-end member stilpnomelane can persist to a maximum temperature of 500° C and pressures up to 6–7 kilobars, although it is unlikely to occur in metamorphosed iron-formations. In iron-formation occurrences the stilpnomelane stability field is bordered by four equilibrium reactions with the assemblages stilpnomelane-zussmanite-chlorite-minnesotaite, stilpnomelane-zussmanite-chlorite-grunerite, stilpnomelane-biotite-chlorite-grunerite, and stilpnomelane-biotite-almandine-grunerite. The stability field is reduced by increasing X(CO₂) and X _Mg ^Stil , and is also a function of a(K ⁺)/ a(H ⁺) in the metamorphic fluid. If the value of a(K ⁺)/ a(H ⁺) is smaller than that defined by the above assemblages, stilpnomelane decomposes to chlorite, but if larger, it is replaced by biotite. At pressures less than 4 kilobars, the zussmanite field is restricted to a very high value of a(K ⁺)/a(H ⁺) (> 5.0 in log units at 1.0 kilobar) where iron-formation assemblages are not stable.     

Anthropogenic gadolinium as a micropollutant in river waters in Pennsylvania and in Lake Erie, northeastern United States

“Anthropogenic” gadolinium, Gd, used in contrast agents in magnetic resonance imaging, is a micropollutant that enters river and lake waters with the discharge from wastewater treatment plants, WWTPs. Such discharge is also the source of other micropollutants, for example pharmaceuticals, such as steroids, antihistamins, and antibiotics. Together with the “natural” Gd, the anthropogenic Gd produces positive Gd anomalies in rare-earth element distribution patterns and is, therefore, easily detectable. This pilot study reports on the occurrence of anthropogenic Gd in rivers in Pennsylvania (Ohio, Beaver, Allegheny, Monongahela, Juniata, and Susquehanna) and in near-shore surface water from Lake Erie close to the city of Buffalo. Additional data are reported for the Delaware River and the headwaters of Spring Creek in Central Pennsylvania, and for Lake Ontario and Niagara River, all of which do not show significant anthropogenic Gd. Most pronounced impact of anthropogenic Gd discharged from WWTPs is observed in the Pittsburgh Metropolitan area. Such contamination is similar to that observed in densely populated areas with highly developed medical and healthcare systems in Europe and Japan. Its worldwide applicability adds to the promising potential of anthropogenic Gd as a cost-effective tracer for the presence of WWTP effluent in river, lake, ground, and drinking waters.     

Geomorphic,hydroclimatic and hydrothermal controls on the formation of lithium brine deposits in the Qaidam Basin,northern Tibetan Plateau,China

Qaidam Basin is a hyperarid inland basin with an area of 121 × 10³ km² located on the northern Tibetan Plateau. Today, one fourth of the basin is covered by playas and hypersaline lakes. Nearly 80% of brine lithium found in China is contained in four salt lakes: Bieletan (BLT), DongTaijinaier (DT), XiTaijinaier (XT) and Yiliping (YLP). In the past decade, great attention was paid to improving the technology for the extraction of lithium from the brine deposits, but studies on origin and mode of formation of the brine deposits remained limited. Our recent investigations found that: (1) ~ 748.8 t of lithium was transported annually into the lower catchment of the four salt lakes via the Hongshui–Nalinggele River (H–N River), the largest river draining into the Qaidam Basin, (2) Li⁺-rich brines are formed only in salt lakes associated with inflowing rivers with Li⁺ concentrations greater than 0.4 mg/L, and (3) the water Li⁺ concentration is positively correlated with both the inflowing river and the associated subsurface brine, including saline lakes with low lithium concentrations. These findings clearly indicate that long-term input of Li⁺ from the H–N River controls the formation of lithium brine deposits. Here we determine that the source of the lithium is from hydrothermal fields where two active faults converge in the upper reach of the Hongshui River. The hydrothermal fields are associated with a magmatic heat source, as suggested by the high Li⁺ and As^3 + content water from geysers. Based on the assumption of a constant rate of lithium influx, we estimate that the total reserves of lithium were likely formed since the postglacial period. Our data indicate that lithium reserves in each of the four salt lakes depend on the influx of Li⁺-bearing water from the H–N River. The data also suggest that during the progradation of the alluvial Fan I, the H–N River drained mostly into the BLT salt lake until the Taijinaier River shifted watercourse to the north and began to feed the salt lakes of the DT, XT and YLP, alongside with the Fan II progradation. The inference is consistent with stratigraphic evidence from the sediment cores of the four salt lakes. One of the major findings of our work is the importance of the contrasting hydroclimatic conditions between the high mountains containing ice caps and the terminal salt lakes. The greater than 4000 m of relief in the watershed enables a massive amount of ions, such as K⁺, to be weathered and transported together with detrital material from the huge, relatively wet alpine regions to the hyperarid terminal basins, where intense evaporation rapidly enriches the lake water, resulting in evaporite deposition and associated K⁺- and Li⁺-rich brine deposits.     

The impacts of common ions on the adsorption of heavy metal

Researches on the impact of common ions onto sediments are of great importance for the study of the heavy metal adsorption mechanisms. Considering the surface sediments from the relatively clean reach in the Baotou section of the Yellow River as the adsorbent, this work presents the impacts of common ions (Na⁺, Mg²⁺, K⁺, Ca²⁺, Cl⁻, SO₄ ²⁻, and NH₄ ⁺) on heavy metals (Cu²⁺, Zn²⁺, Cd²⁺, and Pb²⁺) adsorption. The experimental results reveal that the adsorptive capacities of the heavy metals are controlled by different adsorption mechanisms in different ion concentration ranges. With the increase of the ionic strength, the adsorption of the heavy metals increases for the compression of the electric double layer, whereas decreases for the decreasing of the ionic activities of the heavy metals. The competitive adsorption and complexations between the heavy metals and common ions are also important factors controlling the heavy metal adsorption. According to the experimental results and the real concentration of common ions in the Baotou section of the Yellow River, the increase of the concentrations of Na⁺, Mg²⁺, K⁺, and Ca²⁺ would cause the increase of Zn²⁺ adsorption and reduce the Zn pollution. The NH₄ ⁺ from the industrial discharge of the tributaries has a strong impact on the heavy metal adsorption.     

Land application: Its effectiveness in purification of urban and industrial wastewaters in La Mancha,Spain

The area studied is located in the basin of the River Guadiana. This work establishes the effectiveness of the treatment of wastewater by land application and compares the results of discharging urban and industrial effluents. We found that all the contaminants analyzed in the discharged wastewater in both land applications undergo considerable reduction as they pass through the soil, which acts as a filter, eliminating organic compounds, nutrients, and microorganisms. As regards the sodium and potassium cations, the soil acts in a different way than might be expected (fixing of K⁺ and washing of Na⁺), by releasing potassium and fixing sodium in the first few centimeters of soil. This occurs, apparently, because irrigation with wastewater modifies the chemical conditions.     

Channel constituents in synthetic beryl: ammonium

 The infrared spectra and electron paramagnetic resonance (EPR) of channel constituents in beryls synthesized hydrothermally in the presence of NH₄Cl were investigated. Two forms of ammonium ion were observed to be incorporated into the c -channel. IR-spectra show the double band at 3295 and 3232 cm⁻¹ and two broad bands between 2600 and 3000 cm⁻¹ which were assigned to the NH₃ molecule and NH₄ ⁺ ion, respectively. Similar N–H stretching vibrations are also observed in Regency hydrothermal synthetic beryls and can be used to separate these synthetic beryls from their natural counterparts. After γ-irradiation of hydrothermally grown samples at 77 K, the EPR of the NH₃ ⁺(I) radical was observed. The NH₃ ⁺(II) radical replaces the NH₃ ⁺(I) radical when the sample is heated to room temperature. Both the NH₃ molecule and the NH₃ ⁺ radical have their C₃ symmetry axes perpendicular to the crystal c-axis. The spin Hamiltonian parameters of the NH₃ ⁺(I) are axial-symmetric due to the rapid rotation of the radical about the c-axis. The NH₃ ⁺(II) radical has a low symmetry and shows a hindered rotation because of its shift from the c-axis position and an interaction with the proton in the near neighbourhood. Possible models for the paramagnetic centres are discussed. Received: 16 May 2000 / Accepted: 5 July 2001     

Influential factors on the levels of cation exchange capacity in sediment at Langat river

An exploratory study was carried out at 22 sampling stations along the Langat River, Selangor in order to investigate on the vitality of cation exchange capacity (CEC) in sediment (0–5 cm). Parameters such as pH, Eh, salinity, and electrical conductivity (EC) were determined. The CEC in sediment has been calculated by the determination of Ca²⁺, Na⁺, Mg²⁺, and K⁺ using the flame atomic absorption spectrophotometer, while the organic matter content in sediment was ascertained using the loss on ignition method. The characteristic of the sediment shows that pH (3.09–7.46), salinity (0.02–10.71 ppt), EC (3.39–517 μS/cm) and Eh (?16.20–253.10 mV) were substantially high in variation. This study also revealed that exchangeable Ca²⁺ and Mg²⁺ were controlled by organic matter contents, while exchangeable Na⁺ and K⁺ were influenced by salinity. Salinity was observed to play a major part in controlling all the exchangeable cations, as it gives strong significant correlations with Na⁺, K⁺, Mg²⁺, CEC, and organic matter at p?<?0.01. The presence of seawater, clay mineralogy, and organic matter proves that it does play an important role in determining the CEC and soon relates to the pollution magnitude in the sediment.     

Characteristics of winter mass balance of Glacier No.1 at the headwaters of the Urumqi River,Tianshan Mountains

This study analyzes the response of glacier to climate change during the past 49 years in Urumqi River source region, the Tianshan Mountains of China. The temporal and spatial variations of winter mass balance (bn-w) at different time scales were analyzed to identify their response to climate change during 1988–2006 (The observation of winter mass balance observation began in 1988) on the Glacier No.1 at the headwaters of the Urumqi River, Tianshan Mountains, China. The winter accumulation shows a significantly decreasing trend. The results show that the cumulative values on Glacier No.1 is 2,202 mm water equivalent during 1988–2006 and the mean values is 116 mm a⁻¹. Furthermore, the trend analysis of the winter mass balance indicates a rapid decrease since 1990, and the mean mass balance is only 79 mm a⁻¹ during 1997–2006. Winter mass balance correlates well negatively with the total evaporation from September to April (r = −0.68, α = 0.01), and positively with the total precipitation from September to April (r = 0.74, α = 0.01). However, winter mass balance shows a weak correlation with mean minimum air temperature during September to April (r = −0.35), and runoff on September (r = −0.13).     

A theoretical study of the absorption spectra of Pb+ and Pb3+ in site K+ of microcline: application to the color of amazonite

The blue-green color of amazonite has been assigned by various authors to ions Pb⁺ (6 s)² (6 p) and/or Pb³⁺ (6 s) in site of K⁺ of microcline. Owing to the complex which forms between the ion Pb³⁺ and the lone pairs of the oxygen atoms surrounding it, the peripheral electron of Pb³⁺ passes on the levels (6 p) of the latter, which results in a great similarity of the spectra of Pb⁺ and Pb³⁺ in amazonite (the transition energies are multiplied by a factor greater than 1), whereas, in the isolated state, these spectra are completely different from one another. An analytical development of the crystal field around a site K⁺ is established. Under the effect of the crystal field, the transition ² P _1/2→² P _3/2 (6 p) is split into two double transitions. The lower transition only falls in the visible domain (1.6–1.8 eV for Pb⁺), the second in U−V. The green color would arise from the ion Pb⁺, whereas the blue one would be attributed to the ion Pb³⁺. Received: 23 January 1997 / Revised, accepted: 10 September 1997     

Statistical and geostatistical features of streambed hydraulic conductivities in the Platte River, Nebraska

This paper presents streambed hydraulic conductivities of the Platte River from south-central to eastern Nebraska. The hydraulic conductivities were determined from river channels using permeameter tests. The vertical hydraulic conductivities (K _v ) from seven test sites along this river in south-central Nebraska belong to one statistical population. Its mean value is 40.2 m/d. However, the vertical hydraulic conductivities along four transects of the Ashland test site in eastern Nebraska have lower mean values, are statistically different from the K _v values in south-central Nebraska, and belong to two different populations with mean values of 20.7 and 9.1 m/d, respectively. Finer sediments carried from the Loup River and Elkhorn River watersheds to the eastern reach of the Platte River lowers the vertical hydraulic conductivity of the streambed. Correlation coefficients between water depth and K _v values along a test transect indicates a positive correlation – a larger K _v usually occurs in the part of channel with deeper water. Experimental variograms derived from the vertical hydraulic conductivities for several transects across the channels of the Platte River show periodicity of spatial correlation, which likely result from periodic variation of water depth across the channels. The sandy to gravelly streambed contains very local silt and clay layers; spatially continuous low-permeability streambed was not observed in the river channels. The horizontal hydraulic conductivities were larger than the vertical hydraulic conductivities for the same test locations.     

Plutonium and radiocesium in the water column of the Hudson River estuary

Isotopes of plutonium (Pu), cesium (Cs), and cobalt (Co) introduced into the Hudson River Estuary from fallout deposition, the erosion of fallout-contaminated surface soils, and nuclear reactor effluent (isotopes of Cs and Co only) have been measured in water column samples collected from 1975 to 1980 Isotopic measurements conducted independently by two research groups utilizing different sampling and analytical techniques have been summarized. The major conclusions drawn from the work are that for water samples collected by the two laboratories over similar time periods, the mean concentrations of nonfilterable^239,240Pu (<0.45 μm) were identical at 0.13 fCi/l, mean concentrations of both¹³⁷Cs and^239,240Pu in suspended particulates were more divergent at 2,270±920 pCi/kg (±1 SD) and 1,430±430 pCi/kg for¹³⁷Cs, and 19±8 pCi/kg and 12±4 pCi/kg for^239,240Pu The behavior of^239,240Pu and¹³⁷Cs within the water column is shown to diverge within brackish waters Specifically, the magnitude of the¹³⁷Cs distribution coefficient (K _d ) can be expressed as an inverse power function of the chloride ion concentrations for chlorinities between 0.1 and 4 g Cl⁻/l No difference in the^239,240PuK _d has been observed between fresh and brackish waters Based on the expected inventories of^239,240Pu and¹³⁷Cs within watershed soils, the current downstream transport of these radionuclides represents fractional mobilization rates on the order of 1–4 (×10⁻⁴) per year     

Damming effects on dissolved inorganic carbon in different kinds of reservoirs in Jialing River,Southwest China

To assess the effects of river damming on dissolved inorganic carbon in the Jialing River, a total of 40 water samples, including inflow, outflow, and stratified water in four cascade reservoirs (Tingzikou, Xinzheng, Dongxiguan, Caojie) were collected in January and July, 2016. The major cations, anions, and δ¹³C_DIC values were analyzed. It was found that the dissolved compositions are dominated by carbonate weathering, while sulfuric acids may play a relatively important role during carbonate weathering and increasing DIC concentration. Different reservoirs had variable characteristics of water physiochemical stratification. The DIC concentrations of reservoir water were lower in summer than those in winter due to the dilute effects and intensive aquatic photosynthesis, as well as imported tributaries. The δ¹³C_DIC values in Tingzikou Reservoir were higher during summer than those in winter, which indicated that intensive photosynthesis increased the δ¹³C_DIC values in residual water, but a similar trend was not obvious in other reservoirs. Except for in Xinzheng Reservoir, the δ¹³C_DIC values in inflow and outflow reservoir water were lower than those in the surface water of stratified sampling in summer. For stratified sampling, it could be found that, in summer, the Tingzikou Reservoir δ¹³C_DIC values significantly decreased with water depth due to the anaerobic breakdown of organic matter. The significant correlation (p < 0.01 or 0.05) between the DIC concentrations, the δ¹³C_DIC values and anthropogenic species (Na⁺+K⁺, Cl^–, \({\text{SO}}_{4}^{2 - }\)and \({\text{NO}}_{3}^{ - }\)) showed that the isotope composition of DIC can be a useful tracer of contaminants. In total, Tingzikou Reservoir showed lacustrine features, Xinzheng Reservoir and Dongxiguan Reservoir had “transitional” features, and Caojie Reservoir had a total of “fluvial” features. Generally, cascade reservoirs in the Jialing River exhibited natural river features rather than typical lake features due to characteristics of reservoir water in physiochemical stratification, spatiotemporal variations of DIC concentrations and isotopic compositions. It is evident that the dissolved inorganic carbon dynamics of natural rivers had been partly remolded by dam building.     

Redox equilibria and the structural role of iron in alumino-silicate melts

The relationship between the redox ratio Fe⁺²/(Fe⁺²+Fe⁺³) and the K₂O/(K₂O + Al₂O₃) ratio (K₂O^*) were experimentally investigated in silicate melts with 78 mol% SiO₂ in the system SiO₂-Al₂O₃-K₂O-FeO-Fe₂O₃, in air at 1,400° C. Quenched glass compositions were analyzed by electron microprobe and wet chemical microtitration techniques. Minimum values of the redox ratio were obtained at K₂O^*0.5. The redox ratio in peralkaline melts (K₂O^*>0.5) increases slightly with K₂O^* whereas this ratio increases dramatically in peraluminous melts (K₂O^*<0.5) as K₂O is replaced by Al₂O₃. These data indicate that all Fe⁺³ (and Al⁺³) occur as tetrahedral species charge balanced with K⁺ in peralkaline melts. In peraluminous melts, Fe⁺³ (and Al⁺³) probably occur as both tetrahedral species using Fe⁺² as a charge-balancing cation and as network-modifying cations associated with non-bridging oxygen.     

Cation-exchange characteristics of Amazon River suspended sediment and its reaction with seawater

The cation-exchange characteristics of Amazon River suspended sediment have been studied in order to determine the contribution of exchangeable cations to the geochemical fluxes from the river. Sediment samples were obtained throughout most of the Amazon Basin. The range of exchangeable cation compositions is very narrow in the river and in seawater as well. In river water, the exchangeable cation complement (equivalent basis, exclusive of H⁺) is 80% Ca²⁺, 17% Mg²⁺, 3% Na⁺ plus K⁺. In seawater Na⁺ and Mg²⁺ are about equal (38%) while Ca²⁺ ~ 15% and K⁺ ~ 9%.On reaction with seawater, river suspended sediment took up an amount of Na⁺ equal to nearly one-third of the dissolved river load, as well as amounts corresponding to 15–20% of the dissolved fluvial K⁺ and Mg²⁺. These estimates reflect an unusually high suspended-sediment:dissolved-solids ratio of 6.4 at the time of sampling. At a more representative world average ratio of four, the uptake of Na⁺ would be 20% of the dissolved fluvial load, and that for K⁺ and Mg²⁺ about 10%. Over the annual cycle of the Amazon, it is estimated that ion exchange has a still smaller effect, as a consequence of the low average suspended-solids:dissolved-solids ratio of 1.7.Variations in the ratio $\text{X}{}_{\mathrm{Ca}}\text{X}{}_{\mathrm{Mg}}$, the equivalent fraction of exchangeable Ca²⁺ and Mg²⁺, throughout the river, can be described by a single isotherm. This same isotherm accurately describes the distribution of exchangeable Ca²⁺ and Mg²⁺ on sediment equilibrated with seawater, despite that a high proportion of exchange sites is occupied by Na⁺ and K⁺.     

Statistical analysis of groundwater chemistry of the Tarim River lower reaches,Northwest China

This study applied a comprehensive quantitative approach including statistical, principal component and gray relation analyses to assess the groundwater chemistry based on monitored data from 840 samples collected from the lower reaches of Tarim River from 2000 to 2009. The main findings were: (1) there were six types of groundwater chemistry in the lower reaches of Tarim River where Cl·SO₄–Na·Mg was the dominant type accounting for 73.57% in all samples. There were linear relationships among chemical parameters, where TDS had significant multiple correlations with Na⁺, K⁺, Mg²⁺, Ca²⁺ and Cl⁻, respectively. (2) Three principal components (PC1, PC2 and PC3) were extracted. They included comprehensive measurements for salinization, alkalinity and pH, respectively. Most parameters showed decreasing trends during the period of 2000–2009, as well as the scores on PC1, because the concentrations of various chemical substances were diluted due to the uplift of the groundwater table in the lower reaches and the implementation of the ecological water delivery project in 2000. (3) HCO₃ ⁻ was the most sensitive chemical parameter affected by the groundwater table followed by TA, Mg²⁺, TH, SO₄²⁻, K⁺, TDS and TS. PC2 was the most sensitive principal component to the change of the groundwater table followed by PC1 and PC3.