Investigation of carbon monoxide in heavy traffic intersections of municipal districts

In this research, an investigation of carbon monoxide in heavy traffic intersections of Kerman municipal districts in 2003–2004 has been performed. Kerman City is located at the south-eastern part of Iran. Carbon monoxide in highly toxic for human health and natural ecosystems in metropolition districts especially due to high traffic and industrial activities. For this reason, it was decided to investigate and find out the high concentration of CO pollutants in heavy traffic intersections of Kerman City. In this regards 21 heavy traffic squares and intersections were selected and the concentration of CO were measured. In the middle of each month during the year, sampling and measurement were scheduled three times at daily times according 7–12 a.m.; 12–16 and 16–20 p.m. In each period, 12 samples of 5 minutes were collected and CO concentration for 1-hr was calculated. The results obtained indicate that the hourly mean concentrations were lower than WHO guidelines and also lower than measurements of 1989, which has already done. In spite of more cases and higher populations, natural gas distribution was the cause of decline in CO concentrations.     

A comparison of nearby incremental ground level and in plant concentrations of air pollutants emitted from electronics facilities

Air dispersion modeling by was recently conducted to predict the incremental ground level and inplant concentrations of toxic organic chemicals due to stack and fugitive emissions from Sama Jaya Free Industrial Zone (SJFIZ), Kuching, Sarawak, Malaysia. Simulations of organic air pollutants emitted from industrial facilities in SJFIZ from years 1996 to 2001 were carried out in September 2004 by members of Faculty of Engineering, Universiti Malaysia Sarawak (UNIMAS). The results indicated that there were negligible amount of maximum incremental ground level concentrations of less than 3×10^?2 μg/m³ for 365-day average, and less than 18×10^?2 μg/m³ for 24 h. average. For in-plant maximum incremental concentrations, it is found that the simulated results were much lower than TWA values, except xylene. The predicted in plant concentration of xylene was 119.21 (parts per million) ppm as compared to ACGIH TLV-TWA of 100 ppm approximately 19% higher than ACGIH recommended values. From this study, it was concluded that both nearby population and in plant workers were not potentially at risk to exposing organic chemicals far lower than the threshold limit levels set by ACGIH.     

Modeling of PCB concentrations in water and biota (Mytilus edulis) in New Bedford Harbor, Massachusetts

The water column concentration and bioaccumulation of the polychlorinated biphenyl (PCB) congener CB052 was modeled in New Bedford Harbor, Massachusetts, using site-specific hydrodynamics and loading information. Equilibrium partitioning theory was used to estimate interstitial water CB052 concentrations from sediment concentrations in New Bedford Harbor and Buzzards Bay, Massachusetts. The rate of CB052 vertical flux from the interstitial water to the overlying water column was calculated by multiplying the vertical concentration gradient at the sedimentwater interface by a flux coefficient. The vertical flux coefficient and the flux rate from model-generated water-column concentrations were calculated using an interative procedure. Movement of CB052 within New Bedford Harbor was simulated using calibrated two-dimensional, vertically-integrated, finite element hydrodynamic and transport models. Quasi-steady-state water column concentrations and a field-derived bioconcentration factor were used to predict the expected concentration of CB052 in blue mussels (Mytilus edulis) at two stations in New Bedford Harbor. The model was used to predict the effects of two remedial scenarios (i.e., reducing average sediment total PCB concentrations to 50 ppm or 10 ppm) on concentrations of CB052 in water and blue mussel tissue. Based on the model results, the CB052 concentration in blue mussels would be reduced by 33–53% for the 50 ppm option and by 67–84% for the 10 ppm option.     

Heavy metals in the Ventspils Harbour: normalization based on a multi-parameter dataset

Heavy metals were investigated in the sediments of the Ventspils Harbour located in north-west Latvia (eastern Baltic Sea). Sediment samples were analysed for major and trace metals by ICP-AES, supplemented by inorganic and organic carbon as well as grain-size distributions. Principal component analysis of the data resulted in two main parameter clusters associated with Ca- and Al-rich material and indicated differing behaviour of Pb, Cu, Zn, N and P. Normalization with respect to Ca and Al by least absolute values regression removed the spatial pattern of sediment metal content in the harbour. High residual concentrations at individual sites were associated with local contaminations, whereas the overall concentration pattern was governed by the transport of riverine fine material. Dilution with coarser, quartz-rich marine sediments led to a pronounced heavy metal concentration drop towards the harbour gates. High mixing was an important feature of sediment dynamics in the Ventspils Harbour, hampering contaminant source identification and sediment monitoring.     

织金洞洞穴环境变化及成因分析

对比和拟合分析1989年、2011-2013年和2015-2016年织金洞内气候环境因子监测数据以及游客量数据发现:织金洞自开发初期至今,洞内CO2浓度和温度水平增高明显,增加幅度分别可达1 000 ppm和2～3 ℃,而2011-2013年与2015-2016年间CO2差值最大达465 ppm。洞内环境变化的最主要因素是旅游活动和人工光源;游客量从1985年的不足5万人增至2015年的59.457 1万人,洞内CO2浓度总体上呈现出随着时间增加而不断增高的趋势;各年份气温差距不大,但总体上仍展现出逐年降低的趋势,湿度除2011年外,差距并不明显;人工光源产生的温度与环境温度最大温差可达33 ℃,湿度和周边环境的湿度最大差值可达66.7%。      

Spatio-temporal trends of heavy metals and source apportionment in Tolo Harbour,Hong Kong

This study provided a picture of the spatial and temporal distributions of Cr, Co, Ni Cu, Zn, As, Cd and Pb in bottom sediments of Tolo Harbour. The concentrations of the eight heavy metals differed significantly between sites due to the poor tidal flushing in Tolo Harbour. The levels of Cu, Zn, Cd and Pb were generally enriched in sediments from inner Tolo Harbour, while sediments from outer Tolo Harbour (Tolo Channel) had higher levels of Cr, Co and Ni. The redox sensitive element arsenic showed no distinct spatial pattern in Tolo Harbour. The decreasing levels of Cu, Zn, Pb and Cd in sediments with increasing distance from land demonstrated a typical diffusion pattern from land to the direction of sea. Two hot spots of Cu, Zn, Pb and Cd in sediments were located near Tai Po and Sha Tin new town, indicating that Cu, Zn, Pb and Zn were from land-derived sources. The sites with relatively high levels of Cr, Co and Ni in sediments were located in areas close to waste spoil in sea floor. The natural and anthropogenic inputs from Sha Tin and Tai Po to Tolo Harbour were mostly responsible for Cu, Zn, Cd and Pb enrichment in sediments from inner Tolo Harbour. The waste spoil in sea floor was believed to contribute to the Cr, Co and Ni in outer Tolo Harbour. The results of correlation coefficient between the eight heavy metals showed that Cu, Zn, Cd and Pb were strongly positively correlated, and Cr, Co and Ni were also significantly correlated with each other. The best explanation of strong correlation was their similar source. As, however, is not well correlated with the other seven heavy metals. The average concentrations of Cu and Zn displayed general increasing trends from 1978 to 2006 in Tolo Harbour, while the mean levels of Cr and Pb displayed a substantial decrease from 1978 to 1987, then a slight increase after 1987. No distinct temporal trends of the concentrations of Ni and As were observed from 1978 due to the inconsecutive data. On the other hand, the increasing trends of Cr, Cu, Zn, Cd and Pb were observed since 1996.     

Macrobenthic Community in Tolo Harbour,Hong Kong and its Relations with Heavy Metals

The present study investigated the macrobenthic community in Tolo Harbour, Hong Kong, aiming at linking heavy metal concentrations to differences in macrobenthic community. The stations investigated in Tolo Harbour have widely contrasting features, with some areas located in the Plove Cove displaying both high species richness and abundance while other areas displaying quite impoverished or even void of macrobenthos. High diversity and abundance of macrobenthos in areas with low heavy metal concentrations were recorded. Strong negative correlation between macrobenthic diversity and heavy metal concentrations was found, and this implicated the pollution-induced degradation of macrobenthos in some locations in Tolo Harbour. These results support the Pearson–Rosenberg model for succession along a pollution gradient.     

A contemporary contamination record of stormdrain and harbour sediments, Wellington, New Zealand

 Sediments from stormdrain catchments and outlets in Wellington city and sediment traps from Wellington Harbour were sampled for trace metal content. Samples were analysed for total metal content using XRF and ICP-MS. High values of Pb and Zn were found in stormdrain catchments and outlets, decreasing to elevated background rock levels in the harbour. Maximum values were recorded in an inner city stormdrain catchment, with levels of Pb (4605 ppm), Cu (2981 ppm) and Zn (3572 ppm) all higher than the biological probable effects levels (PEL). Concentrations of As, Cr, Cu, Pb, Ni and Zn concentrations in all harbour sediment trap samples were below the PEL. The mean values for each harbour sediment trap sample can be used as an accurate historical baseline in future studies. Stormdrain samples with high trace metal levels were close to industrial and construction sites. The proximity of these outlets to recreational areas should be of concern to local authorities. Received: 28 August 1997 · Accepted: 15 December 1997     

Gold and other metals in big sagebrush (Artemisia tridentata Nutt.) as an exploration tool, Gold Run District, Humboldt County, Nevada

Big sagebrush — a cold-desert species that dominates the terrain over large parts of western United States — was sampled along several traverses that crossed thermally metamorphosed limestone, phyllitic shale, and schist of the Middle and Upper Cambrian Preble Formation that host skarn-, disseminated gold and silver-, and hot springs gold-type mineral occurrences. Patterns of detectable levels of gold (8 to 28 ppb or ng g⁻¹) in ash of new growth were consistent with areas affected by known or suspected gold mineralization. Soils collected along one of the traverses where a selenium-indicator plant was common contained no gold above background levels of 2ppb, but were consistently high in As, Sb, and Zn, and several samples were unusually high in Se (maximum 11 ppm or μg g⁻¹). Sagebrush along this traverse contained Li at levels above norms for this species. We also found a puzzling geochemical anomaly at a site basinward from active hot springs along a range-front fault scarp. Sagebrush at this site contained a trace of gold and an unusually high concentration of Cd (13 ppm) and the soil had anomalous concentrations of Cd and Bi (3.2 and 6 ppm, respectively). The source of this anomaly could be either metal-rich waters from an irrigation ditch or leakage along a buried fault. Despite the limited nature of the study, we conclude that gold in sagebrush could be a cost-effective guide to drilling locations in areas where the geology seems favorable for disseminated and vein precious metals.     

Gaseous air pollution background estimation in urban,suburban, and rural environments

There is a great demand for estimating the ambient air pollutant background concentrations in order to assess the effectiveness of different emission control strategies. In this paper, the background concentrations of four pollutants, namely sulfur dioxide (SO₂), nitrogen oxides (NOx), carbon monoxide (CO), and ozone (O₃) pollutants in urban, suburban, and rural environments were investigated using Kolmogorov–Zurbenko (KZ) filter technique. Air quality data from monitoring stations over a period of 4 years (2007–2010) was analyzed for three locations in Kuwait, namely urban, suburban, and rural. The spatial and temporal (daily, weekly, and monthly) variations of the four pollutants were analyzed. The results show that the levels of ambient air pollutant background concentrations were high in the urban site compared to suburban and rural area. The diurnal variation of SO₂ concentration showed an early morning peak, while the diurnal variation of NOx concentration constituted has two peaks, one was in the early morning hours (5 to 8 a.m.) and the second was in nighttime hours (8 to 11 p.m.). These two peaks were observed at all three locations. The monthly background NOx concentration reached a maximum in winter and minimum in summer. Diurnal variation of CO concentration showed a similar trend to SO₂ concentrations in all three locations. Because of the photochemical reactions that occur in the atmosphere, the background concentration of O₃ showed an inverse relation with respect to background concentration of NOx.     

The development and application of a mass balance model for mercury (total,elemental and methyl) using data from a remote lake (Big Dam West,Nova Scotia,Canada) and the multi-species multiplier method

Big Dam West, located in Kejimkujik Park, Nova Scotia, Canada, is a remote lake with elevated Hg concentrations in fish due in part to low pH and high dissolved organic carbon (DOC) concentrations. These features reflect the poor buffering capacity of peat lands in the flat drainage basin. To address the multiple species of Hg, a model was developed by coupling the “multiplier method” for multi-species chemicals with average concentration ratios to the Quantitative Water Air Sediment Interaction (QWASI) model. Elemental Hg was the “key species” modeled. Total Hg fluxes and concentrations were computed using concentration ratios. Many of the concentrations and Hg flux processes within the Big Dam West catchment had been previously measured with concentration ratios that were either computed or taken from the literature when measured data were not available. Measured values for total Hg concentration in each compartment (air, water, sediment) and Hg fluxes (e.g., precipitation, sediment deposition) enable verification of model concentration and flux estimates for total Hg in each environmental compartment. The model was also run with and without the inclusion of upward Hg fluxes from the underlying sediment to determine the significance of this controversial flux. The Hg QWASI model presented in this paper could be a valuable screening tool, especially for remote lakes, due to its ability to provide reasonable Hg estimates with a limited amount of data (water inflow rate, suspended particulate matter, sediment deposition velocity, and concentration of Hg in atmosphere and inflow water).     

美国犹他州中部Green River流域农业区硒的淋出速度和形态

尽管硒(Se)是一种重要的生命元素,但是即使浓度很低,也有可能会造成危害。在美国西部,包括犹他州中部GreenRiver流域斯图尔特湖水鸟管理区,大面积的农业排水区中都存在硒。为了对该场地进行地球化学研究和进行修复,取未受扰动的岩芯分析了硒的形态、浓度和迁移。用酸消解进行前处理对土壤和曼柯斯页岩风化壳进行了分析,结果表明,硒的最高浓度为3ppm,采用连续萃取法的分析结果表明,有19%~79%的硒是以有机物形式存在的,有17%~67%的硒是以元素形式存在的。柱实验研究结果表明,硒可以从深部土壤迅速淋出,可溶性硒的质量分数很高,达到了292×10-9。表层土壤中硒的淋出速度最初很慢,但是非常稳定,最终淋出速度会超过深部土壤。当对岩心通过放射灭菌后,表层土壤和深部土壤的淋出速度都会加快。计算结果表明,在修复富含硒的土壤时,所需的水量很大,每kg土壤需要约500L的水量。     

Heavy metals in bottom sediments of great slave lake (Canada): A reconnaissance

Near the shores of Great Slave Lake, natural sources of heavy metals include gold and base metal deposits, mineralized greenstone belts and sedimentary bedrock, and uraniferous granites. Potential anthropogenic sources of heavy metals (As, Zn, Pb) include large gold and base metal extraction -processing facilities on the shores of the lake. Six sediment cores were collected on a traverse of the lake. Heavy metal concentrations and distributions are related to the regional bedrock geochemistry in the drainage basin. Higher uranium concentrations in the northernmost core are attributed to extensive uraniferous areas north of the lake. More subtle variations of concentration are related to sedimentologic characteristics and processes in the lake. The west basin is a natural sink for most of the heavy metals determined. Two centrally located west basin cores had mean zinc concentrations of 145 ppm, whereas cores closer to the north and south shores had mean concentrations of 80–110 ppm. Mn, Ni, and Pb were enriched in some of the cores from the area of shallower water near the MacKenzie River outlet, rather than in the central west basin. The enrichment is related to Mn-, Ni-, and Pb-rich amorphous coatings on quartz grains. Elevated zinc or lead levels from anthropogenic activities were not detected but elevated levels are suspected for arsenic. In the two cores from the center of the west basin, surface sediment contains up to 12 ppm arsenic, not high in comparison with noncontaminated freshwater lakes elsewhere in Canada but considerably elevated relative to concentrations of 1 ppm found deeper in the same cores. Contribution from the National Water Research Institute, Western and Northern Region. Presented at the 10th International Sedimentological Congress, Jerusalem, Israel, 1978.     

A test of the Tate equation to predict bubble size at an orifice in the presence of frother

Air bubbles of uniform size (ca. 1 mm diameter) were generated at a submerged orifice (glass capillary) under controlled frequency (down to ca. 0.06 s^− 1) in aqueous solutions of frother (Dowfroth 250). The bubbles were sized with an imaging technique. One objective was to establish whether the Tate equation (static balance between buoyancy and capillary forces) could be used as a standard sizing calibration method. Another aim was to verify whether with decreasing surface tension (due to increasing frother concentration) the anticipated decrease in bubble size agreed with the equation prediction. An effect of frother was detected compatible with the role of surface tension but divided into two concentration regions, seemingly the result of a gradual change in bubble shape and wetting: > 6 ppm the bubble holds a spherical shape and the capillary appeared to be completely wetted while at ≤ 6 ppm a degree of non-wetting and bubble distortion (neck formation just prior to detachment) were apparent, supported by qualitative observations. In addition, at > 6 ppm the Tate value was only approached by decreasing the bubble frequency but not attained. Plausible causes for the failure to reach the predicted size are discussed.     

Impact of stormwater infiltration basins on groundwater quality, Perth metropolitan region, Western Australia

Twelve bores were sunk adjacent to three stormwater infiltration basins in the Perth metropolitan area to examine the impact of runoff from a light industrial area, a medium-density residential area, and a major arterial road on groundwater quality, and to examine the hydrological response of the aquifer to runoff recharge. Automatic and manual water level monitoring between April and November 1990 indicated that groundwater levels responded within minutes to recharge from the infiltration basins. Peak water levels of up to 2.5 m above rest levels occurred 6–24 h after the commencement of ponding in the infiltration basins. There was a marked reduction in salinity and increase in dissolved oxygen concentrations in the upper part of the aquifer downgradient of the infiltration basins. Concentrations of toxic metals, nutrients, pesticides, and phenolic compounds in groundwater near the infiltration basins were low and generally well within Australian drinking water guidelines. However, sediment in the base of an infiltration basin draining a major road contained in excess of 3500 ppm of lead. Phthalates, which are US EPA priority pollutants, were detected in all but one bore near the infiltration basins. Their detection may be a sampling artifact, but they may also be derived from the plastic litter that accumulates in the infiltration basins. The concentration of iron in groundwater near the infiltration basins appears to be controlled by dissolved oxygen concentrations, with high iron concentrations occurring where dissolved oxygen concentrations are low. Pumping bores located near infiltration basins may suffer from iron encrustation problems caused by the mixing of shallow, oxygenated groundwater with water containing higher concentrations of iron from deeper in the aquifer.     

贵州织金洞洞穴CO2的来源及其空间分布特征

为探索喀斯特高原峡谷地区高位旱洞内CO2来源及其空间分布特征,于2015年1月至2015年7月按月实施定位监测,对贵州织金洞洞穴CO2浓度和洞穴水、土壤CO2浓度和土壤水以及大气降水、山顶泉水进行监测。结果表明:（1）织金洞上覆土壤CO2浓度是大气CO2浓度的11~17倍,是洞穴CO2的4~7倍。织金洞洞内CO2的来源,横向上主要来自于气流的交换、游客的呼吸作用;垂直方向上主要来自于洞穴上方延伸入基岩中植物根系的呼吸作用,洞穴上覆基岩溶隙、溶管中进入洞穴内的大气CO2,地下河水脱气以及洞穴滴水碳酸钙的沉积释放的CO2。（2）织金洞为多进口洞,CO2浓度插值空间分布呈现两端低中间高的空间分布特征,同时在1 200×10-6~1 400×10-6高值区范围内出现800×10-6~1 000×10-6低值区特征。整体上,洞穴CO2随着进、出洞口两端海拔向洞内升高而呈上升趋势,在洞穴中部灵霄殿达到最大值。（3）洞内水和洞外土壤水均为HCO3--Ca2+型水,大气降水、山顶泉水为SO42--Ca2+型水。在垂直迁移过程中,大气降水-山顶泉水-土壤水-洞穴水不同部位水中各化学成分（硬度、Ca2+/Mg2+、HCO3-/SO42-、PCO2、SIc）各不相同。      

湿润亚热带典型白云岩区不同土地利用的土壤CO2浓度特征及其影响因素

以中国南方岩溶施秉世界自然遗产地杉木河流域的子流域——黄洲河岩溶小流域为研究区,对3种不同利用方式土地（林地、旱地、水田）中的土壤CO2浓度进行为期一年的观测,并采集土壤样品,分析其理化性质。结果显示:（1）不同土地利用方式下土壤CO2的年平均浓度为:水田（21 008×10-6）>林地（9 038×10-6）>旱地（5 660×10-6）;（2）一年中林地与旱地的土壤CO2月浓度曲线与月均气温曲线的变化形态具有相似性,年变化规律总体上表现一致:1-7月土壤CO2浓度逐渐升高,8月浓度达到峰值,分别为16 157×10-6和13 458×10-6;（3）水田土壤CO2浓度在1-3月逐渐下降,3月出现最低值11 727×10-6,3-12月逐渐升高,8月开始波动升高,在10月达到峰值（29 993×10-6）;（4）白云岩区土壤CO2浓度有显著的季节变化规律（夏秋高、冬春低）;（5）气温、降雨对林地和旱地土壤CO2浓度有显著影响,而对水田土壤CO2浓度影响不显著;（6）土壤有机碳含量的差异对土壤CO2浓度有一定影响,且土壤pH增高,其土壤CO2浓度也随之增大。      

An experimental study of algal uptake of U,Ba, V,Co and Ni from dilute solutions

Experiments in which two species of freshwater green algae, Ankistrodesmus sp. and Selenastrum, were cultured in dilute solutions of metals chelated with EDTA reveal massive uptake of U and Ba, but relatively minor uptake of Ni, Co and V. For 2-ppm metal-spiked TBIM culture media at pH 8.1–8.2 and growth durations of 3–21 days at 13–16°C, both species accumulate U and Ba at levels of 1000 to 10,000 ppm by dry weight, representing a concentration factor of up to 5000 times the aqueous metal solute concentration. Uptake was comparable for passage of 100-ml spiked culture media through algal mats over 100 min. For aqueous solute concentrations of 20 ppb Ba, Co, Ni and U the algae adsorbed 3000–4000 ppm U and Ba giving concentration factors up to 200,000. With 40 ppb U, the algae adsorbed 6000 ppm, representing a concentration factor of 150,000. Co and Ni in the algae were present at levels below analytical sensitivity. The Ba aqueous concentration was about equivalent to, and the U concentration 100 times natural marine water abundances. For 2-ppm Co-, Ni- and V-spiked culture media, algal uptake was 40–600 ppm Ni, 17 ppm Co and 12 ppm V, respectively.Given the abundance of algae in both fresh and marine waters, coupled with the known association of plankton with U-rich Black Sea muds, the experimental results may indicate that algae also play a significant role in mediating U and Ba uptake from the hydrosphere. The recorded levels of algal uptake for metals are ～1000 × (U), ～100 × (Ba), ～100 × (Ni), ～20 × (Co), and ～6 × (V), previously reported abundances for “typical” marine plants.     

Solvent extraction followed by ultraviolet detection for investigation of tetramethylthiuram disulfide at soil-water interface

Tetramethylthiuram disulfide is a widely used pesticide and a soil treatment agent in the agricultural sector. Consequently, its detection in the environment and investigation of the distribution between the aqueous and soil phases would be of highly importance. In this study, the detection of tetramethylthiuram disulfide in CHCl₃ was successfully achieved through absorbance measurements at 280 nm, which resulted in linear calibration curves. This detection method was extended for the determination of the partition coefficient (K_D) of tetramethylthiuram disulfide between CHCl₃ and H₂O phases at ambient temperature. The partition coefficient was subsequently used to determine the apparent partition coefficient (K_D) of tetramethylthiuram disulfide between sieved soil of diamater < 2.0 mm used for agricultural practices and water where by the quantification of tetramethylthiuram disulfide in water after adsorption equilibrium with soil was achieved through a solvent extraction step of tetramethylthiuram disulfide-contaminated water into CHCl₃. The K_D determined for an initial tetramethylthiuram disulfide concentration ranging from 3.00 ppm to 10.00 ppm showed a decreasing trend, which leveled off at high concentrations, indicating the strong irreversible adsorption behavior of tetramethylthiuram disulfide on soil at low concentrations. The proposed detection method would have the potential to determine the extent of adsorption of tetramethylthiuram disulfide in soil or its levels in water when tetramethylthiuram disulfide is introduced to soil systems for agricultural practices.     

Radioactivity dosage evaluation of Brazilian ornamental granitic rocks based on chemical data, with mineralogical and lithological characterization

One hundred samples of granitic rock were collected from granite traders in Belo Horizonte. Autoradiography, optical microscopy, diffractometry, and chemical analysis (X-ray spectrometry, X-ray fluorescence, neutron activation, gravimetry, and electron probe microanalysis) were used to determine the mineral assemblages and lithotypes. Autoradiographic results for several samples showed the presence of monazite, allanite, and zircon. Chemical analysis revealed uranium concentrations ≤30 ppm and thorium ≤130 ppm. Higher concentrations generally correlated with high concentrations of light rare earths in silica-rich rocks of granitic composition. Calculations were made of radioactive doses for samples, of floor tiles in a standard room, with total concentration of uranium and thorium greater than 60 ppm. On the basis of calculations of ²³² Th, ⁴⁰ K, and ²²⁶ Ra from analysis of Th, K, and U, the doses calculated were between 0.11 and 0.34 mSv/year, which are much lower than the acceptable international exposure standard of 1.0 mSv/year.