北京地区大气中VHCs观测结果的初步分析

采用Tenax TA和碳分子筛吸附富集— 热脱附— 毛细管柱气相色谱法, 测定了北京地区大气中C2～C10可挥发性烃类化合物(简称VHCs)的浓度变化。从2001年9月到2003年8月, 先后采集到有效样品113个。检出55个VHCs组分, 其中烷烃26个, 烯烃19个,芳香烃10个。TVHCs的平均浓度为364.3 ±99.3 μg/ m3;11月份浓度最高, 为546.9 ±353.5 μg/m3, 8月份浓度最低, 为251.8 ±152.4 μg/m3;采暖季比非采暖季高30%, 城区比郊区高10%;有明显的日变化。初步分析发现, 机动车尾气排放和天气气象条件是造成北京地区大气VHCs污染的两个最主要因素。     

Mathematical prediction of lead removal from carbonate-rich illite

The interaction between heavy metal contaminants and surface forces associated with the reactive surfaces of soil particles was studied with the aim of developing an analytical tool that would permit the prediction of heavy metal and soil sorption–desorption phenomena. The predictive model developed in this study considers the energy of the interaction developed between a lead contaminant and illitic soil. Since these energy calculations include both inner and outer sphere complexes, energy balance requirements can be realistically evaluated with respect to environmental mobility. For a comparison between the calculated values obtained from the predictive model and experimentally obtained measurements, laboratory batch equilibrium tests and electro–kinetic tests were used. These were concerned with the sorption–desorption determination of illitic soil samples with the lead contaminant in the form of a lead nitrate solution. The force balance of lead ions indicates that lead ions in the so-called Stern layer, i.e. the first two layers of a water molecule, are non-removable. Good correlations between calculated and measured values were obtained.     

Granitoids and Their Magnetic Susceptibility in South Korea

Abstract: Magnetic susceptibility (MS) measurements were carried out for 1,120 samples in the Middle Proterozoic to Early Tertiary granitoids so far recognized in South Korea, and the lateral and spatial variation of their magnetic susceptibility, i.e., content of magnetite, is studied. The Middle Proterozoic two mica granitoids related to cassiterite (Sn) deposits in northeastern part of the Sobaegsan Massif show very low MS (less than 0.3 A‐ 10^‐3 SI unit), and the Permo‐Triassic tonalitic to granodioritic and monzonitic rocks which are barren in mineralization, distributed in the middle part of South Korea also show low MS (less than 1 A‐ 10^‐3 SI unit). On the contrary the Late Triassic to Jurassic granitoids (= Daebo granitoids) which were evolved from tonalite through granodiorite to granite, and are most widely distributed in South Korea, show a wide variation on MS. Particularly in the Andong, Igsan, Gimcheon and Geochang areas, the granitoids which are barren in mineralization, are characterized by high MS (more than 10 A‐ 10^‐3 SI unit). The Chuncheon, Jecheon, Namyang and Geumsan plutons related to molybdenite (Mo) and/or wolframite or scheelite (W), and fluorite (F) mineralizations show a little high MS (more than 3 A‐ 10^‐3 SI unit). However, more than 60% of the Daebo granitoids show low MS (less than 3 A‐ 10^‐3 SI unit) and the rest show a little high MS (more than 3 A‐ 10^‐3 SI unit). Heterogeneous distribution of magnetite content in the Daebo granitoids is considered to reflect heterogeneity of redox state of the source materials for these granitoids. The Cretaceous to Early Tertiary granitoids (= Bulgugsa granitoids) in the Gyeongsang Basin had been generally evolved in the order of tonalite, diorite, granodiorite, granite and alkali‐feldspar granites, which are closely related to base metal ore deposits, and mostly show higher MS (more than 3 A‐ 10^‐3 SI unit) than other granitoids mentioned above, although some exceptions are recognized in highly evolved alkali‐feldspar granites (SiO₂ > 76%). In contrast, as most of the highly oxidized or evolved Cretaceous granitoids distributed in areas other than the Gyeongsang Basin show lower MS than those of the Gyeongsang Basin, and appear to be magnetite free, ilmenite‐series granites, but they might be hematite bearing magnetite‐series granitoids. Highly oxidized nature of the Bulgugsa granitoids may be due to high Fe₂O₃/FeO ratio of the source materials and also high level intrusion style of the granitic magma activities. Most of the granitic rocks of the Middle Proterozoic, Permo‐Triassic and more than 60% of the Late Triassic to Jurassic (Daebo granitoids) belong to ilmenite–series, however less than 40% of the Daebo granitoids and most Cretaceous ones are magnetite–series. Thus, the granitic magma intruded in Korean Peninsula became oxidized while the intrusive ages become younger.     

Modelling metolachlor exports in subsurface drainage water from two structured soils under maize (eastern France)

The study investigated the processes involved in metolachlor transport in two artificially drained, structured soils in eastern France. Measured losses of bromide and metolachlor in drainage water were compared with results simulated by the mechanistic, stochastic AgriFlux model. Simulated drainage water volumes were generally similar to the measured volumes when the spatial variability of the soil water properties was taken into account. When such variability was disregarded, cumulative water volumes of the clay soil were over- or underestimated by more than 20%. Two types of adsorption were tested. For instantaneous, reversible adsorption, using the partition coefficient Koc, metolachlor losses were underestimated in the first drainage water volumes and overestimated for the total study period. The use of slow adsorption and desorption kinetics (ADK) produced an export pattern similar to the observed one. A sensitivity analysis indicated that the simulated results are very sensitive to the values of the ADK rates, especially for the silty loam soil. The effect of ADK on the attenuation of metolachlor exports was more significant than the effect of degradation (2.3 and 6.7 times higher for the clay and silty loam soils, respectively). For the same four-month period, the bromide and metolachlor losses (using ADK) in the clay soil were 2.1 and 1.3 times greater, respectively, if the macroporosity was set at 10% than if it was not simulated. Conversely, macroporosity did not significantly affect these losses in the silty loam. The main factors involved in the metolachlor transport in the studied soils were: (i) the macroporosity, especially in the clay soil because of the low hydraulic conductivity of the matrix and (ii) the sorption kinetics rates which varied according to the soil physico-chemical characteristics.     

Pb (II) Sorption with Calcite: A Radiotracer Study

A ²¹⁰Pb radiotracer was used to monitor Pb solid-aqueousphase partitioning in sorption experiments at ambient temperature, pH = 8.2, and atmospheric PCO₂ in 0.15 M NaNO₃ solutions. A 24 h isotherm is linear up to Pb concentrations of 4 × 10^-6 M, above which an increase in slope suggests precipitation. The effect of Pb concentration, calcite loading, and ionic strength on Pb sorption with time was monitored. Sorption kinetics are rapid, followed by a slower sorption step.At a constant calcite loading500 mg L^-1,fractional sorptiondecreases with increasing initialPb concentration. The reverse isobserved for surface coverage, with0.6, 5.6 and 40.2% of availableCa²⁺sites occupied at10^-8,10^-7 and10^-6 MPb after 96 h. At a constant Pb concentration of10^-6 M,fractional sorption increases with increasing particleloading, however surface coverage decrease with72.5 and 22.1%Ca²⁺sites occupied at 100 and200 mg L^-1calcite after 96 h.The adsorption coefficient (K_d) is approximately 10³,increases with initial Pb concentration, but remains unaffected by variable calcite loading. Absence of an ionic strength effect on Pb sorption is interpreted as the dominance of inner-sphere complexation. For desorption experiments conducted over a range of initial sorption times, an average desorption index > 0.8 but < 1 indicates that sorption is largely reversible, but is accompanied by slight incorporation. Solid-solution formation increases with time, as observed by slower initial desorption rates for samples with longer sorption times. These findings indicate that Pb may be effectively sequestered by calcite; however re-release via desorption is likely as Pb does not become significantly incorporated into the mineral structure.     

Dynamics of Ore-Forming Processesof the Stratabound Skarn Copper Depositsof Tongling, Anhui Province

The skarn and ore bodies of the stratabound skarn copper deposits of Tongling, Anhui Province, are both controlled by definite stratigraphic horizons, and they are concordant with the strata. They occur as layers and layer-like bodies in permeable carbonate rocks of the Middle-Upper Carboniferous Huanglong and Chuanshan Formations which are underlain by impermeable shale or siliceous rocks of the Upper Devonian Wutong Formation. The authors study the dynamics of ore-forming processes of the ore deposits with the dynamic model of coupled transport and reaction, and the following results are obtained: The salinity gradient and flow rate of the ore-forming fluids can both promote the mixing and reaction of juvenile water and formation water, and the permeable strata are favourable sites for the intense transport-reaction of mixing and the formation of deposits. (2) As isothermal transport-reaction took place along the bedding of strata, the moving transport-reaction front formed at the contact between the     

提高解吸速度是煤层气藏工业化生产的关键

煤层气开采机理是排水—降压解吸—扩散—渗流—生产。提高解吸速度是煤层气藏工业化生产的关键。解吸速度可分为单位体积解吸速度和体积解吸速度。通过井网选择,增大解吸体积、提高解吸体积是实现煤层气工业化生产的有效途径,特别是割理不发育、含气量不太高、致密低渗透煤层气藏工业化生产的可靠措施。方形井网的解吸体积、解吸速度比直线井网大。     

固定化海藻对金属离子解吸的实验研究

本文研究了固定化海带吸附含铜、镉溶液的解吸过程，结果表明：在所选的HCl、HNO3、Na2CO3、NaHCO3 4种解吸剂中，HCl、HNO3均有一定的解吸效果，但HCl比HNO3更适合做解吸剂．当解吸剂盐酸的浓度为0．1mol／dm^3时，解吸率最大，     

氯化钙－氨吸附／脱附过程传热特性研究

报导采用管式结构的氯化钙－氨吸附／脱附过程传热特性试验台．试验结果表明ＣａＣｌ２对ＮＨ３的吸附／脱附化学反应对ＣａＣｌ２－ＮＨ３介质的传热机理有较大影响．通过建立相应物理模型对ＣａＣｌ２吸附／脱附过程进行了数值分析