Levels of airborne man-made mineral fibres in U.K. dwellings. I—Fibre levels during and after installation of insulation

This paper gives the details of airborne levels of man-made mineral fibres (MMMF) found during installation of loft insulation in 12 dwellings. About 250 samples of air were collected and analyzed by transmission electron microscopy (TEM).Respirable fibre levels measured in static samples collected in the lofts during installation generally were < 0.1 f ml⁻¹. In living spaces respirable fibre levels were< 0.006 f ml⁻¹. Personal samples on the installers gave < 1 f ml⁻¹, with the exception of a fine glass fibre blanket. A few selected samples were also analyzed by phase contrast optical microscopy (PCOM) which showed lower values than those recorded by TEM. Static gravimetric concentrations in the lofts were in the 0.3–6.5 mg m⁻³ range, and in the living spaces 0.11–0.44 mg m⁻³, but in both environments most of this dust was not MMMF.     

Levels of airborne man-made mineral fibres in U.K. dwellings. II—Fibre levels during and after some disturbance of loft insulation

In this study airborne levels of MMMF were determined in 11 dwellings during and after disturbance of loft insulation. The disturbance was in two stages.

• 1.(a) Minor disturbance. Household items (such as suitcases) stored in the lofts were moved around for about 10 min. The disturbance to the insulation material was kept to a minimum.
• 2.(b) Major disturbance. Insulation wools were physically handled for about 30 min, simulating the disturbance associated with activities such as rewiring or plumbing.

About 250 samples of air were collected on membrane filters and analyzed by transmission electron microscopy (TEM) in conjunction with energy dispersive X-ray analysis. A few selected samples were analyzed by phase contrast optical microscopy (PCOM). During physical disturbance of the insulation, fibre levels in lofts measured over a 4-h period were up to 0.03 f ml⁻¹. Personal exposure during the disturbance activity was up to 0.2 f ml⁻¹. Contamination of the living space was not detected even though the access door to the loft remained open throughout the disturbance and sampling period.     

Journal of Environmental Sciences Index （ No. 1 - No. 6）

OrganiccarbonstockintopsoilofJiangsuProvince,China,andtherecenttrendofcarbonsequestrationPANGen xing,LILian qing,ZHANGQi,WANGXu kui,SUNXing bin,XUXiao boandJIANGDing an(1)………………………………………………InvestigationofnaturalVOCemittedfromtropicalvegetationsinChinaWANGZhi hui,BAIYu hua,LIUZhao rong,WANGXue song,LIQing junandL.F.Klinger(8)……………………………………………………………PhytoremediationforphenanthreneandpyrenecontaminatedsoilsGAOYan zhengandZHULi zh…     

Journal of Environmental Sciences Index （No. 1- No. 12）

Review Development of analytical methods for Polyeyclie aromatic hydrocarbons(PAHs)in air伙〕rne Particulates:A review LIULi一hin，LIUY自11，LIN Jin一而ng，TANG Ning，HAYAKAW人Kazulchi and MAEDA Tsuneaki··························     

Journal of Environmental Sciences 2004 Index (No.1-No.6)

No.1PredicationofFhhhpotentialinPTAwastewatertreatment　CHENGShu pei,SHILei,ZHANGXu xiang ,YANJun ,DINGZhong haiandHAOChun bo ( 1 )………………………………………………………………Phosphorusreleasefromphosphaterockandironphosphatebylow molecular weightorga     

Comparison of physiological responses to oxidative and .heavymetal stress in seedlings of rice paddy, Oryza sativa L.

ＩｎｔｒｏｄｕｃｔｉｏｎＯｒｇａｎｉｓｍｓｌｉｖｉｎｇｕｎｄｅｒｐｏｌｌｕｔｉｏｎｓｔｒｅｓｓｖａｒｉｅｄｒｅｓｐｏｎｓｅｓ,ｆｒｏｍｃｈａｎｇｅｓｉｎｇｒｏｓｓｍｏｒｐｈｏｌｏｇｙｔｏｃｈａｎｇｅｓｉｎｂｉｏｃｈｅｍｉｓｔｒｙ .Ｐｌａｎｔｓｉｎｐａｒｔｉｃｕｌａｒｈａｖｅｅｖｏｌｖｅｄｄｉｖｅｒｓｅｗａｙｓｏｆｒｅｓｐｏｎｄｉｎｇｔｏａｄｖｅｒｓｅｃｈａｎｇｅｓｉｎｔｈｅｉｒｅｎｖｉｒｏｎｍｅｎｔ.Ｐｌａｎｔｓｏｖｅｒｃｏｍｅｓｅｖｅｒｅｅｎｖｉｒｏｎｍｅｎｔａｌｓｔｒｅｓｓｂｙｄｅｖｅｌｏｐｉ…     

Simulation of the energy budget of an urban canyon—II. Comparison of model results with measurements

A simple numerical model that attempts to simulate the energy budget of an urban canyon is assessed by comparing its predictions against measurements made at an urban field site. A street is chosen that satisfieds many of the model's requirements and a measurement scheme is devised to measure variables which are also simulated. The model is run using input information collected from the field and the data produced are compared with the measured data. The results indicate that the model is capable of simulating many of the climate attributes (such as surface temperatures and net radiation at the canyon top) accurately, but does not simulate the dominant mechanism of sensible heat exchange between the canyon and its environment. Nevertheless, the model predicts a small and largely invariant exchange, similar to that measured. The results of the field study, when compared with other published work, indicates that as street canyons become narrower they become increasingly isolated in terms of heat exchange from the overlying atmosphere. The results of the computer runs appear to follow this pattern.     

Numerical simulation of wet scavenging of air pollutants—II. Modeling of rain composition at the ground

The modeling of rain composition for a convective shower (Tucson, AZ, 10 September 1977) and a frontal precipitation event (Den Helder, Holland, 12 December 1978) is performed in this paper by including the pollutant species and wet scavenging mechanisms into the mass transport equation of the sequential sampling model described in Part I of this series. The results indicate that: (1) the major scavenging mechanisms of most pollutants in convective showers appear to be similar to those in frontal precipitations; (2) the major scavenging mechanisms of NH₄ and NO₃ are gas absorption, whereas the absorption of SO₂ by aqueous drops and oxidation of S(IV) by H₂O₂ and O₃ in the aqueous phase are the major formation and scavenging mechanisms for SO₄; (3) the scavenging by raindrops in the below-cloud region is the dominant removal mechanism for coarse particles, whereas nucleation is the major scavenging mechanism for submicrometer particles; (4) H₂O₂ is the most important oxidant responsible for the oxidation of S(IV) and the formation of sulfate in precipitation; (5) the contributions of both (SO₂ + H₂O₂) and (SO₂ + O₃) reactions to sulfate concentration in precipitation are larger for convective precipitation than for frontal precipitation.     

Competition of the acitive roots of Cassia siamea Lam. and Zea mays L. (cv. Katumani Composite B) in an alley cropping trial in semi-arid Kenya

A study on root competition in alley cropping was carried out in an agroforestry system, involving Cassia siamea Lam. and maize (Zea mays L. cv. Katumani composite B). The existence and intensity of root competition in the top soil as manifested by the distribution of the active roots of cassia and maize, in space and time, was assessed. The root length density of maize was far greater than that of cassia in the upper 10 cm, implying that cassia was not competing with maize for water and/or nutrients at that depth. However, at maize crop tasselling and grain filling stages there was a marked overlap of roots of the two plants at lower depths (20-50 cm). This varied with distance from the cassia hedge in a way that there was a tendency for highest overlap near middle maize rows. This partly explained observed yield differences. Therefore cassia may not be a suitable choice for alley cropping with maize under semi-arid conditions on non-sloping land, unless most of its active roots can be properly managed to absorb resources below the feeding rhizosphere of the active maize roots.     

A study of the aerosol of Santiago de Chile—I. Light extinction coefficients

The atmosphere of Santiago de Chile has been investigated by telephotometry in several parts of the city. Spectral extinction coefficients were measured during the time period between September 1988 and January 1989 (mid-spring to mid-summer) and again between February 1990 and June 1990 (autumn to mid-winter). The values measured show a distinct daily pattern with high values in the morning and a steady decrease in the afternoon. This pattern is attributed to a steady increase in the height of the mixing layer during daytime which allows an increasing dilution of the aerosol; unfortunately systematic measurements of vertical temperature profiles are not available for Santiago. In contrast to the urban area, measurements at an elevated site in the Andes Mountains showed a constant increase in light extinction during daytime. In the morning the extinction coefficients were similar to the background values off the coast on the Pacific. In the afternoon after expansion of the mixing layer extinction coefficients in the mountains were comparable to those in the urban area. Some sight paths were reached at later hours by the mixing layer and had a maximum of light extinction coefficient later in the morning hours. The transport of aerosols can cause dramatic changes in extinction coefficients within a short time; changes of up to a factor of five have been observed within an hour. In such cases the wavelength dependence of the aerosol underwent changes with the advection or production of a different aerosol. A comparison with the pollution of other large cities shows that the daily pattern of variation of the extinction coefficient in Santiago is different; the values of the extinction coefficients observed in Santiago de Chile are compared to those in European and Asian cities. With this study part of the complex behaviour of the Santiago atmosphere has been understood but much further work is needed. The optical technique used here has proven useful in investigating the atmosphere in real time with adequate time resolution and the possibility to make space-resolved measurements also.     

Transport and deposition of indoor radon decay products—II. Influence of environmental conditions

The effects of indoor radon decay product behavior on overall concentrations have generally been characterized using uniformly-mixed models, mathematical formulations based on steady-state macroscopic mass-balances, assuming uniform concentrations within the enclosure. The uniformly-mixed model parameterizes the deposition process as a constant volumetric removal rate, given different values for the free and attached progeny. The model requires prior knowledge of the deposition rates, and assumes them to be constant, independent of environmental conditions, and identical for all decay products. There has generally been little agreement regarding the actual values of the deposition rates, and the uncertainty in these required values presents an important limitation.In response to the limitations of existing mass-balance models, an indoor radon mass-transport model, RADTRAN, was developed using a microscopic mass-balance. Deposition by molecular diffusion is accounted for through boundary conditions, and deposition velocity is calculated based on the concentration distribution near the wall. Parametric sensitivity studies using RADTRAN examined the sensitivity of the deposition of radon decay products to several factors: the size of the free progeny (measured by its diffusivity, D^f), particle concentration (using the attachment rate, X), and air motion. Deposition is described in terms of the deposition velocities of the free and attached progeny, u^f and u^a. The development of RADTRAN is described in a companion paper. This paper presents the results of the parametric sensitivity studies examining the influence of environmental conditions on radon progeny deposition. Results primarily focus on the influence on the free mode of the first radon decay product, ²¹⁸Po. RADTRAN is also used to examine the variations of deposition velocity between the decay products.     

Numerical simulation of wet scavenging of air pollutants—I. Modeling of sequential precipitation rates at the ground

A one-dimensional Eulerian transport/transformation/removal model is developed to explain and predict existing field data and chemical compositions of precipitation. The PLUVIUS model is used as the framework for the proposed model with significant modifications. In Part I, cloud dynamics and microphysics, and water phases have been considered in the model. The equation of motion is solved to generate a vertical wind velocity profile for convective precipitation. The upwind scheme is used to handle the convective, non-linear transport problem.The modeling results of ground precipitation rates for a summer convective shower indicate that the precipitation rate is sensitive to the following precipitation parameters: autoconversion rate, cloud water concentration, relative humidity, entrainment rate, and the heights of cloud base and cloud top. The modeling results for pollutant rain concentrations will be presented in Part II of this series.     

The effect of freezing on the composition of supercooled droplets—II. Retention of S(IV)

S(IV) dissolved in droplets is partially evolved as SO₂ during freezing. A spray of droplets with average diameter 39μm, produced by an ultrasonic transducer, was let to fall through a controlled atmosphere with known SO₂ concentration, at varying temperatures between −8 and −23°C, attaining thermal and chemical equilibrium. In a first arrangement, the droplets fell by gravitation on an ice surface. Two other arrangements simulated the riming ventilation conditions: in one series of experiments, the droplets were projected by a gas jet at several m s⁻¹ against a target; in another, the droplets were caught by rotating rods. The fraction of S(IV) retained in the ice Γ was determined by analysis of the samples and comparison with the equilibrium concentration in the liquid droplets. Samples collected by gravitation showed a retention coefficient Γ = 0.25 + 0.012 T_s (T_s = supercooling); rime samples showed large dispersion in the results, the retention coefficient being best represented by an average value Γ = 0.62, independent of temperature.     

A synopsis of the book Striking a balance: improvingstewardship of marine areas(by the U. S. National Research Council the operating arm of the U. S National Academiesof Science and Engineering)

Sustainable use of the planet will require a more robust regulatory and management framework for marine areas as advances in offshore technology and changes in market conditions lead to an increase in coastal populations and marine recreation and tourism. Although each area of the world presents unique problems, many principles of stewardship, which can appropriately modified, will serve well anywhere on the planet. The purpose of this brief synopsis is to share these principles ot stewardship with colleagues in China. This volume (Striking a balance: improving stewardship of marine areas) notes:" In addition to the governance problems created by multiple nonmarket uses of marine resources and maintaining access to them, existing systems have two fundamental problems first, fragmentation among federal and local agencies and second, not enough participation and coordination of interests at the local level"( p. 4 ). Although this book focuses on marine ecosystems associated with the United States coastline( such as the Gulf of maine/Massachusetts Bay, the Florida Keys National Marine Sanctuary/Florida Bay ecosystem, and the Southern California coast), the issues, the problems, and strategies should be, with minor adjustments, fully applicable anywhere in the world. The following general elements of the framework for improved governance and management of marine areas are given as recommendations(p. 5)[Comments given in brackets are those of the author].