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1.
The proposed geothermobarometer is based on an empirical calibration which takes account of two equilibria involving the tremolite, edenite, pargasite and hastingsite components in amphiboles. It has applications to assemblages found in metabasic rocks of widely different chemical compositions (magnesian to Fe-rich metabasalts), and for metamorphism ranging from lower greenschist to highest amphibolite facies. Knowing the Si(T1), Aliv, Alvi, Fe3+, Fe2+, Mg, Ca, NaM4, NaA and A vacancy in an amphibole, and the Al3+ and X Mg in coexisting epidote and chlorite, it is possible to calculate two values of In K d for this assemblage. These equilibria involve edenite-tremolite and (pargasite/hastingsite)-tremolite end-members in amphibole (the calculation program is given). For these equilibria, the isopleths (iso-values of K d) have been calculated for 0.27 < X Mg < 0.75 and 0 < X Fe3+= Fe3+/(Fe3++ Alvi) < 0.8. It is then possible to determine pressure and temperature directly when X Mg, X Fe3+, In K d for tremoliteedenite and In K d for (pargasite/hastingsite)-tremolite are known. Application of this geothermobarometer is limited to Ca-free plagioclase assemblages, and complete P–T paths can be drawn only if all the minerals are considered together. Phase relations at successive stages of crystallization can be constrained by studying the relationships between the coexisting minerals, their zoning and the metamorphic fabrics.  相似文献   

2.
After more than a decade of multidisciplinary studies of the Central American subduction zone mainly in the framework of two large research programmes, the US MARGINS program and the German Collaborative Research Center SFB 574, we here review and interpret the data pertinent to quantify the cycling of mineral-bound volatiles (H2O, CO2, Cl, S) through this subduction system. For input-flux calculations, we divide the Middle America Trench into four segments differing in convergence rate and slab lithological profiles, use the latest evidence for mantle serpentinization of the Cocos slab approaching the trench, and for the first time explicitly include subduction erosion of forearc basement. Resulting input fluxes are 40–62 (53) Tg/Ma/m H2O, 7.8–11.4 (9.3) Tg/Ma/m CO2, 1.3–1.9 (1.6) Tg/Ma/m Cl, and 1.3–2.1 (1.6) Tg/Ma/m S (bracketed are mean values for entire trench length). Output by cold seeps on the forearc amounts to 0.625–1.25 Tg/Ma/m H2O partly derived from the slab sediments as determined by geochemical analyses of fluids and carbonates. The major volatile output occurs at the Central American volcanic arc that is divided into ten arc segments by dextral strike-slip tectonics. Based on volcanic edifice and widespread tephra volumes as well as calculated parental magma masses needed to form observed evolved compositions, we determine long-term (105 years) average magma and K2O fluxes for each of the ten segments as 32–242 (106) Tg/Ma/m magma and 0.28–2.91 (1.38) Tg/Ma/m K2O (bracketed are mean values for entire Central American volcanic arc length). Volatile/K2O concentration ratios derived from melt inclusion analyses and petrologic modelling then allow to calculate volatile fluxes as 1.02–14.3 (6.2) Tg/Ma/m H2O, 0.02–0.45 (0.17) Tg/Ma/m CO2, and 0.07–0.34 (0.22) Tg/Ma/m Cl. The same approach yields long-term sulfur fluxes of 0.12–1.08 (0.54) Tg/Ma/m while present-day open-vent SO2-flux monitoring yields 0.06–2.37 (0.83) Tg/Ma/m S. Input–output comparisons show that the arc water fluxes only account for up to 40 % of the input even if we include an “invisible” plutonic component constrained by crustal growth. With 20–30 % of the H2O input transferred into the deeper mantle as suggested by petrologic modeling, there remains a deficiency of, say, 30–40 % in the water budget. At least some of this water is transferred into two upper-plate regions of low seismic velocity and electrical resistivity whose sizes vary along arc: one region widely envelopes the melt ascent paths from slab top to arc and the other extends obliquely from the slab below the forearc to below the arc. Whether these reservoirs are transient or steady remains unknown.  相似文献   

3.
Static lattice energy calculations (SLEC), based on empirical interatomic potentials, have been performed for a set of 800 different structures in a 2 × 2 × 4 supercell of C2/c diopside with compositions between diopside and jadeite, and with different states of order of the exchangeable Na/Ca and Mg/Al cations. Excess static energies of these structures have been cluster expanded in a basis set of 37 pair-interaction parameters. These parameters have been used to constrain Monte Carlo simulations of temperature-dependent properties in the range of 273–2,023 K and to calculate a temperature–composition phase diagram. The simulations predict the order–disorder transition in omphacite at 1,150 ± 20°C in good agreement with the experimental data of Carpenter (Mineral Petrol 78:433–440, 1981). The stronger ordering of Mg/Al within the M1 site than of Ca/Na in the M2 site is attributed to the shorter M1–M1 nearest-neighbor distance, and, consequently, the stronger ordering force. The comparison of the simulated relationship between the order parameters corresponding to M1 and M2 sites with the X-ray refinement data on natural omphacites (Boffa Ballaran et al. in Am Mineral 83:419–433, 1998) suggests that the cation ordering becomes kinetically ineffective at about 600°C.  相似文献   

4.
Ice-core samples from Upper Fremont Glacier (UFG), Wyoming, were used as proxy records for the chemical composition of atmospheric deposition. Results of analysis of the ice-core samples for stable isotopes of nitrogen (δ15N, ) and sulfur (δ34S, ), as well as and deposition rates from the late-1940s thru the early-1990s, were used to enhance and extend existing National Atmospheric Deposition Program/National Trends Network (NADP/NTN) data in western Wyoming. The most enriched δ34S value in the UFG ice-core samples coincided with snow deposited during the 1980 eruption of Mt. St. Helens, Washington. The remaining δ34S values were similar to the isotopic composition of coal from southern Wyoming. The δ15N values in ice-core samples representing a similar period of snow deposition were negative, ranging from -5.9 to -3.2 ‰ and all fall within the δ15N values expected from vehicle emissions. Ice-core nitrate and sulfate deposition data reflect the sharply increasing U.S. emissions data from 1950 to the mid-1970s.  相似文献   

5.
We present results of computations on the interaction of solid-phase electrum–argentite–pyrite (weight ratios 210−5/ 210−3/1 and 210−5/410−2/1) association with Cl-containing aqueous moderately acid solutions (0.5m NaCl, pH = 3.08) at 300 °C and 500 bars. These data are a physicochemical basis for predicting the geochemical behavior of Au and Ag during the hydrothermal-metasomatic transformation of Au-Ag-pyrite. We also propose a technique of study of this process based on the phase equilibria of the subsystem Au–Ag–S with the aqueous solution at different liquid/solid (l/s) ratios, with the use of new graphic diagrams. The relationship of the composition of the solid-phase association with l/s ratio in real boundary conditions (Au = 17 ppm, mAu/mAg = 10–3.57–10–2.28) is shown. The maximum l/s values for complete leaching of gold and silver (l/smax = 200–800) are estimated. It has been established that argentite is the first to dissolve when mAu/mAg(s) > mAu/mAg(sol), and electrum, when mAu/mAg(s) < mAu/mAg(sol).

The experimental results showed that at 300 °C, the conversion of electrum (NAu = 300‰) nonequilibrated with pyrite into an Au-richer form (NAu = 730‰) and argentite follows an intricate kinetic scheme. Using the Pilling-Bedwords kinetic equation for processing data yielded the process rate constant K = 2.8(±0.5)10−5 g2cm−4day−1. With this equation, the time of the complete conversion of 200 μm thick flat gold grains is 604 days. These data evidence a significant role of kinetic factors in hydrothermal-metasomatic processes involving native gold, which requires combination of thermodynamic and kinetic approaches on the construction of geologo-genetic models for hydrothermal sulfide formation.  相似文献   


6.
A new petrogenetic grid is presented for the system NCKFMASH (Na2O–CaO–K2O–FeO–MgO–Al2O3–SiO2–H2O), in which Ca is incorporated in garnet, and CaAlNa−1Si−1 solid solution is considered for both the plagioclase and white-mica structures. A compatibility diagram for plagioclase-bearing metapelitic assemblages within the NCKFMASH system also has been derived. A dominant feature of the NCKFMASH grid is the singularities and associated singular reactions which occur along plagioclase+margarite- and plagioclase+paragonite-bearing univariant equilibria. The singularities represent compositional coplanarities which occur in response to the CaAlNa−1Si−1 substitution occurring at different rates in plagioclase and white-mica. This is controlled by a fundamental difference in the mixing within the two mineral structures. The singularities give rise to a number of intriguing phase diagram features, including azeotropes. From the results presented here, it is predicted that the occurrence of margarite and paragonite in pelitic rocks is controlled by equilibria related to the singularities. The presence of these white-micas is strongly dependent upon bulk composition, and plagioclase-bearing, margarite/paragonite-free assemblages, typical of Barrovian-type terranes, are predicted for bulk compositions of Mg/(Mg+Fe)≈0.4 and Ca/(Ca+Na)≈0.4 at for example 5.5  kbar.  相似文献   

7.
The segregation of ten isovalent impurities (Al3+ Cr3+, Eu3+, Gd3+, Ho3+, La3+, Lu3+, Nd3+, Tb3+, Y3+) to the and the (0001) surfaces of haematite (-Fe2O3) have been studied using atomistic simulation where the forces between the atoms are modelled using the Born model of solids. Segregation is found to be energetically favoured in virtually every case. The results for the surface show that the most favourable impurity surface concentration is 33.33%. The (0001) surface has two possible terminations, one terminated by iron atoms and the other by oxygen. No minimum is calculated for the Fe termination of the (0001) surface at low temperatures, but when the effect of raising the temperature is considered, an energy minimum is found, also at 33.33% impurity coverage. In contrast, the O terminated (0001) surface has a minimum in the segregation energy for between 16.67 and 33.33% depending on the cation being considered.  相似文献   

8.
A recent thermodynamic model for the Na–Ca clinoamphiboles in the system Na2O–CaO–FeO–MgO–Al2O3–SiO2–H2O–O (NCFMASHO), is improved, and extended to include cummingtonite–grunerite and the orthoamphiboles, anthophyllite and gedrite. The clinoamphibole model in NCMASH is adopted, but the extension into the FeO- and Fe2O3-bearing systems is revised to provide thermodynamic consistency and better agreement with natural assemblage data. The new model involves order–disorder of Fe–Mg between the M2, M13 and M4 sites in the amphibole structure, calibrated using the experimental data on site distributions in cummingtonite–grunerite. In the independent set of end-members used to represent the thermodynamics, grunerite (rather than ferroactinolite) is used for FeO, with two ordered Fe–Mg end-members, and magnesioriebeckite (rather than ferritschermakite) is used for Fe2O3. Natural assemblage data for coexisting clinoamphiboles are used to constrain the interaction energies between the various amphibole end-members. For orthamphibole, the assumption is made that the site distributions and the non-ideal formulation is the same as for clinoamphibole. The data set end-members anthophyllite, ferroanthophyllite and gedrite, are used; for the others, they are based on the clinoamphibole end-members, with the necessary adjustments to their enthalpies constrained by natural assemblage data for coexisting clino- and orthoamphiboles. The efficacy of the models is illustrated with P – T grids and various pseudosections, with a particular emphasis on the prediction of mineral assemblages in ferric-bearing systems.  相似文献   

9.
We present here a numerical modelling study of dislocations in perovskite CaTiO3. The dislocation core structures and properties are calculated through the Peierls–Nabarro model using the generalized stacking fault (GSF) results as a starting model. The GSF are determined from first-principles calculations using the VASP code. The dislocation properties such as collinear, planar core spreading and Peierls stresses are determined for the following slip systems: [100](010), [100](001), [010](100), [010](001), [001](100), [001](010), and All dislocations exhibit lattice friction, but glide appears to be easier for [100](010) and [010](100). [001](010) and [001](100) exhibit collinear dissociation. Comparing Peierls stresses among tausonite (SrTiO3), perovskite (CaTiO3) and MgSiO3 perovskite demonstrates the strong influence of orthorhombic distortions on lattice friction. However, and despite some quantitative differences, CaTiO3 appears to be a satisfactory analogue material for MgSiO3 perovskite as far as dislocation glide is concerned.  相似文献   

10.
Jan-Marten Huizenga 《Lithos》2001,55(1-4):101-114
H2O, CO2, CH4, CO, H2 and O2 are the most important species in crustal fluids. The composition of these C–O–H fluids can be calculated if the pressure, temperature, carbon activity, and either the oxygen fugacity or the atomic H/O ratio of the fluid is known. The calculation methods are discussed and calculation results are illustrated with isobaric T–Xi, P–T, and isobaric–isothermal ternary C–O–H diagrams. Fluid inclusion compositions, in particular, the XCO2/(XCO2+XCH4) ratio, can be used for C–O–H model calculations. However, care should be taken about possible post-entrapment changes, which may have modified the chemical composition of the fluid inclusion.  相似文献   

11.
This study assesses the ability of two low-cost adsorbents made from waste of Rapanea ferruginea treated with ethanol (WRf) and its H2SO4-treated analog (WRf/H2SO4) for the removal of two cationic dyes methylene blue (MB) and crystal violet (CV) from aqueous solutions. The adsorbent was characterized by scanning electron microscopy, Fourier transform infrared spectrometry, thermogravimetric analysis, point of zero charge (pHpzc), specific surface, and functional groups. The adsorption of dye onto the adsorbents was studied as a function of pH solution (2–12), contact time (up to 120 min) and initial concentration (20–120 mg/L), and temperature (25, 35, and 55 °C). The influence of these parameters on adsorption capacity was studied using the batch process. The response surface methodology (RSM) was used in the experimental design, modeling of the process, and optimizing of the variables and was optimized by the response involving Box–Behnken factorial design (15 runs). The results show that the data correlated well with the Sips isotherm. The maximum adsorption capacities of MB and CV onto WRf were found to be 69 and 106 mg/g, and onto WRf/H2SO4, the adsorption capacities were 33 and 125 mg/g, respectively. The kinetic data revealed that adsorption of cationic dyes onto the adsorbents closely follows the pseudo-second-order kinetic model. Regression analysis showed good fit of the experimental data to the second-order polynomial model, with coefficient of determination (R2) values for MB (R2?=?0.9685) and MB (R2?=?0.9832) for WRf and CV (R2?=?0.9685) and CV (R2?=?0.9832) for WRf/H2SO4 indicated that regression analysis is able to give a good prediction of response for the adsorption process in the range studied. The results revealed that waste from R. ferruginea is potentially an efficient and low-cost adsorbent for adsorption of MB and CV.  相似文献   

12.
Noblesse multi-collector noble gas mass spectrometer is specially designed for multi-collection of Ar isotopes with different beam sizes, especially for small ion beams, precisely, and hence is perfectly suitable for 40Ar/39Ar geochronology. We have analyzed widely used sanidine, muscovite, and biotite standards with recommended ages of ~ 1.2–133 Ma, with the aim to assess the reliability of Noblesse for 40Ar/39Ar dating. An ESI MIR10 30W CO2 laser was used for total fusion or incremental heating samples. Extracted gases were routinely purified by four SAES NP10 getters (one at ~ 400 °C and others at room temperature). A GP50 getter and a metal cold finger cooled by liquid N (? 196 °C) were also attached for additional purification if necessary. The Ar isotopes were then measured by Noblesse using Faraday or multiplier according to the signal intensities. Over a period of 1.5 months 337 air calibrations produced a weighted mean 40Ar/36Ar of 296.50 ± 0.08 (2σ, MSWD = 4.77). Fish Canyon sanidine is used to calculate J-values, which show good linear relationship with position in irradiation. The age of four mineral standards (Alder Creek sanidine, Brione muscovite, Yabachi sanidine, and Fangshan biotite) are within error of the accepted ages. Five Alder Creek sanidine aliquots yielded an age range of 1.174–1.181 ± 0.013 Ma (2σ) which broadly overlaps the established age of the standard and the uncertainty approaches those of the foremost Ar/Ar laboratories in the world. The weighted mean ages of four Brione muscovite aliquots (18.75 ± 0.16 Ma, 2σ), five Yabachi sanidine aliquots (29.50 ± 0.19 Ma, 2σ), and three Fangshan biotite aliquots (133.0 ± 0.76 Ma, 2σ) are consistent with the recommended values of these standards, and the uncertainties are typical of modern Ar/Ar laboratories world-wide.  相似文献   

13.
The paragenetic relationships between sillimanite, andalusite, kyanite, chlorite, cordierite, biotite, garnet and staurolite in the Early Proterozoic Puolankajärvi Formation (PjF), together with mineral compositions, are used to construct a partial petrogenetic grid for metapelites with significant Mn content (MnO = 0.1–0.5%) by adding a six-phase invariant point over the garnet-absent invariant point for Mn-free AMF-phases.
The grid and textural relations of the PjF are used to construct part of the P–T –deformation path for the PjF. Relatively short deformation pulses and associated flow of oxidizing fluid along shear zones were responsible for the paragenetic and compositional changes during cooling and decompression at 600–500°C and 6.0–2.5 kbar. Oxidation led to decreased Fe2+ and further stressed the importance of Mn (increased Mn/divalent cations).
A tectonothermal evolution of the Kainuu Schist Belt is presented which includes crustal thinning and steepening of a previously established thermal gradient. This was followed by thrusting and folding of the isotherms into a thermal antiform on the western side of the belt.  相似文献   

14.
Atomistic model was proposed to describe the thermodynamics of mixing in the diopside-K-jadeite solid solution (CaMgSi2O6-KAlSi2O6). The simulations were based on minimization of the lattice energies of 800 structures within a 2 × 2 × 4 supercell of C2/c diopside with the compositions between CaMgSi2O6 and KAlSi2O6 and with variable degrees of order/disorder in the arrangement of Ca/K cations in M2 site and Mg/Al in Ml site. The energy minimization was performed with the help of a force-field model. The results of the calculations were used to define a generalized Ising model, which included 37 pair interaction parameters. Isotherms of the enthalpy of mixing within the range of 273–2023 K were calculated with a Monte Carlo algorithm, while the Gibbs free energies of mixing were obtained by thermodynamic integration of the enthalpies of mixing. The calculated T-X diagram for the system CaMgSi2O6-KAlSi2O6 at temperatures below 1000 K shows several miscibility gaps, which are separated by intervals of stability of intermediate ordered compounds. At temperatures above 1000 K a homogeneous solid solution is formed. The standard thermodynamic properties of K-jadeite (KAlSi2O6) evaluated from quantum mechanical calculations were used to determine location of several mineral reactions with the participation of the diopside-K-jadeite solid solution. The results of the simulations suggest that the low content of KalSi2O6 in natural clinopyroxenes is not related to crystal chemical factors preventing isomorphism, but is determined by relatively high standard enthalpy of this end member.  相似文献   

15.
Crystals of hydronium jarosite were synthesized by hydrothermal treatment of Fe(III)–SO4 solutions. Single-crystal XRD refinement with R1=0.0232 for the unique observed reflections (|Fo| > 4F) and wR2=0.0451 for all data gave a=7.3559(8) Å, c=17.019(3) Å, Vo=160.11(4) cm3, and fractional positions for all atoms except the H in the H3O groups. The chemical composition of this sample is described by the formula (H3O)0.91Fe2.91(SO4)2[(OH)5.64(H2O)0.18]. The enthalpy of formation (Hof) is –3694.5 ± 4.6 kJ mol–1, calculated from acid (5.0 N HCl) solution calorimetry data for hydronium jarosite, -FeOOH, MgO, H2O, and -MgSO4. The entropy at standard temperature and pressure (So) is 438.9±0.7 J mol–1 K–1, calculated from adiabatic and semi-adiabatic calorimetry data. The heat capacity (Cp) data between 273 and 400 K were fitted to a Maier-Kelley polynomial Cp(T in K)=280.6 + 0.6149T–3199700T–2. The Gibbs free energy of formation is –3162.2 ± 4.6 kJ mol–1. Speciation and activity calculations for Fe(III)–SO4 solutions show that these new thermodynamic data reproduce the results of solubility experiments with hydronium jarosite. A spin-glass freezing transition was manifested as a broad anomaly in the Cp data, and as a broad maximum in the zero-field-cooled magnetic susceptibility data at 16.5 K. Another anomaly in Cp, below 0.7 K, has been tentatively attributed to spin cluster tunneling. A set of thermodynamic values for an ideal composition end member (H3O)Fe3(SO4)2(OH)6 was estimated: Gof= –3226.4 ± 4.6 kJ mol–1, Hof=–3770.2 ± 4.6 kJ mol–1, So=448.2 ± 0.7 J mol–1 K–1, Cp (T in K)=287.2 + 0.6281T–3286000T–2 (between 273 and 400 K).  相似文献   

16.
In this work, permeation of mixed gases H2S/CH4 through commercial polyphenylene oxide (PPO) hollow fiber and poly (ester urethane) urea (PEUU) flat membranes was studied at pressures of 345–689 kPa, at ambient temperature and at 313.15 K. Various H2S concentrations of about 100–5000 ppm in CH4 binary synthetic gas mixtures as well as a real natural gas sample obtained from a gas refinery containing 0.3360 mol.% H2S (equivalent to 3360 ppm) were tested. It was observed that the permeance of components was affected by the balance between competitive sorption and plasticization effects. Separation factors of H2S/CH4 were in the range of 1.3–2.9, 1.8–3.1 and 2.2–4.3 at pressures of 345, 517 and 689 kPa, respectively. In the range of 101–5008 ppm of H2S in CH4, the effect of temperature on the separation factor was nearly negligible; however, permeances of both components of the mixtures increased with temperature. Additionally, the results obtained by PEUU membrane indicated that it was a better choice for hydrogen sulfide separation from H2S/CH4 mixtures than PPO. For PPO membrane, removal of hydrogen sulfide from high-concentration (up to 5008 ppm) binary mixtures of H2S/CH4 was compared with that of low concentration (as low as 101 ppm) through PPO. At concentrations of 101–968 ppm, plasticization was dominant compared with the competitive sorption, while for the H2S feed concentrations of 3048 ppm, the competitive sorption effect was dominant. For H2S concentration of 5008 ppm, the balance between these two effects played an important role for explanation of its trend.  相似文献   

17.
 Raman spectra of a single-crystal fragment of hydrous γ-Mg2SiO4, synthesized in a multianvil press, have been measured in a diamond-anvil cell with helium as pressure-transmitting medium to 56.5 GPa at room temperature. All five characteristic spinel Raman modes shift continuously up to the highest pressure, showing no evidence for a major change in the crystal structure despite compression well beyond the stability field of ringwoodite in terms of pressure. At pressures above ∼30 GPa a new mode on the low-frequency site of the two silicate-stretching modes is clearly identifiable, indicating a modification in the spinel structure which is reversible on pressure release. The frequency of the new mode (802 cm−1 extrapolated to 1 bar) suggests the presence of Si–O–Si linkages and/or a partial increase in the coordination of Si. Direct determination of the subtle structural change causing the new Raman mode would require high-pressure, single-crystal synchrotron X-ray diffraction experiments. The Raman modes of hydrous and anhydrous Mg-end-member ringwoodite are nearly identical up to 20 GPa, suggesting that protonation has only minor effect on the lattice dynamics over the entire pressure stability range for ringwoodite in the mantle. Received: 7 December 2001 / Accepted: 16 April 2002  相似文献   

18.
This study reports on trace metal uptake by the grass species Melinis repens, growing in roadside soils and sediments in tropical northeastern Australia. Median total Cu, Pb, Ni and Zn concentrations were significantly (P < 0.05) higher in road edge soils (Cu = 61.1 mg/kg, Pb = 97.3 mg/kg, Ni = 28.6 mg/kg, Zn = 729 mg/kg) than in background soils collected away from roads (Cu = 5.8 mg/kg, Pb = 11.2 mg/kg, Ni = 3.7 mg/kg, Zn = 21 mg/kg). Significantly (P < 0.05) elevated Zn values were recorded in the stems of the M. repens specimens growing on roadside soils (231.6 mg/kg dry weight of tissue) compared with those of grasses growing on background soils (40.8 mg/kg dry weight of tissue). Moreover, median Cu, Ni and Zn values in the roots of roadside grasses (Cu = 29.1 mg/kg, Ni = 2.73 mg/kg, Zn = 169 mg/kg) were significantly (P < 0.05) higher than their respective levels in the roots of background M. repens samples (Cu = 5.98 mg/kg, Ni = 0.70 mg/kg, Zn = 22 mg/kg). A greenhouse experiment showed that Cu and Zn in road sediments are labile and are available for uptake by M. repens. The studied roadside soils and sediments were leached with a diethylenetriaminepentaacetic acid–CaCl2–triethanolamine–HCl extraction solution, which proved to be a rudimentary indicator of Zn availability and uptake to the root tissue of M. repens. The results demonstrate that trace metals in roadside grasses have the potential to be directed up the food-chain as grasses are consumed by herbivores. In addition, bioavailable metal contaminants hosted by road sediments have the capacity to impact on ecosystems downstream of roads because these sediments are mobilised by road runoff waters from road surfaces into adjoining catchments.  相似文献   

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