Accumulation of Heavy Metals in Epiphytic Lichens Near a Municipal Solid Waste Incinerator (Central Italy)

The epiphytic lichen Parmelia caperata was usedas biomonitor in the area of a municipal solid wasteincinerator (Poggibonsi, central Italy) to investigatethe levels and the spatial distribution of the heavymetals Al, Cd, Cr, Cu, Fe, Hg, Pb and Zn. Levels ofAl, Cu and Hg were similar to those in unpollutedareas, whereas high values were found for Cr, Zn andespecially Cd. The distribution pattern of the lastthree metals and the exponential relationship of theirconcentrations with distance from the incinerator,showed that the disposal plant is a local source ofatmospheric pollution due to Cd, Cr and Zn. For thesemetals, long-term hazard should be seriously taken into account.     

Land-cover changes in an urban lake watershed in a mega-city, Central China

Urbanization can exert a profound influence on land covers and landscape characteristics. In this study, we characterize the impact of urbanization on land cover and lacustrine landscape and their consequences in a large urban lake watershed, Donghu Lake watershed (the largest urban lake in China), Central China, by using Landsat TM satellite images of three periods of 1987, 1993 and 1999 and ground-based information. We grouped the land covers into six categories: water body, vegetable land, forested land, shrub-grass land, open area and urban land, and calculated patch-related landscape indices to analyze the effects of urbanization on landscape features. We overlaid the land cover maps of the three periods to track the land cover change processes. The results indicated that urban land continuously expanded from 9.1% of the total watershed area in 1987, to 19.4% in 1993, and to 29.6% in 1999. The vegetable land increased from 7.0% in 1987, 11.9% in 1993, to 13.9% in 1999 to sustain the demands of vegetable for increased urban population. Concurrently, continuous reduction of other land cover types occurred between 1987 and 1999: water body decreased from 30.4% to 23.8%, and forested land from 33.6% to 24.3%. We found that the expansion of urban land has at least in part caused a decrease in relatively wild habitats, such as urban forest and lake water area. These alterations had resulted in significant negative environmental consequences, including decline of lakes, deterioration of water and air quality, and loss of biodiversity.     

Landscape as a predictor of wetland condition: an evaluation of the Landscape Development Index (LDI) with a large reference wetland dataset from Ohio

RecentAbstract. Recent approaches to wetland assessment have advocated a multilevel approach which incorporates assessments based on landscape (remote sensing) data, on-site but “rapid” methods, and intensive methods where quantitative data is collected. Brown and Vivas (2004) recently pro- posed an assessment method that uses remote sensing information (Landscape Development Index or LDI) and propose that it may also be usable as a quantified human disturbance gradient. The LDI was evaluated using a large reference wetland data set from Ohio using land use percentages within a 1 km radius circle of the wetlands. The LDI had interpretable and significant relationships with another human disturbance gradient (the Ohio Rapid Assessment Method for Wetlands or ORAM) and with most metrics and scores from the Vegetation Index of Biotic Integrity (VIBI) developed for use in the State of Ohio. Metrics from emergent wetlands had the most significant correlations with the LDI (10 of 10 metrics), followed by forested wetlands (8 of 10 metrics) and shrub wetlands (4 of 10). Poor correlation for VIBI scores and metrics of shrub wetlands was due to differences in attainable LDI scores based on ecoregion and natural buffers shielding the wetland from otherwise intensive land uses. The ORAM and VIBI were developed for use in wetlands in Ohio completely independent of the LDI. It is an important test of the LDI concept that so many interpretable and significant relationships occurred between the VIBI scores, VIBI metric values, and the ORAM scores. For the purposes of VIBI development, the LDI is an independent, quantified disturbance gradient that has provided an additional test of the VIBI. Given its theoretical underpinnings and the fact that it uses quantified land use percentages, the LDI has many advantages over more qualita- tive human disturbance gradients. Using land use percentages from increasingly smaller distances from the wetland edge (100-200 m) may improve the resolution of the LDI to detect on-site dis-turbances to a wetland which degrade its ecological condition. The LDI should be evaluated with other large reference data sets in other regions to evaluate its validity and usefulness as an assessment tool.     

Classification and mapping forest sites using geographic information system (GIS): a case study in Artvin Province

The productivity of forest sites has been indirectly determined with solo wood production objective in forest management. Forest site productivity should, however, be determined directly in order to implement ecosystem based multipurpose forest management philosophy. This article tackles the problem in distinguishing and mapping forest sites using both direct method and indirect method in Genya Mountain located in central of Artvin State Forest Enterprise. About 112 sample plots were designed and distributed over the area. In each sample plot, soil samples were collected and the classical timber inventory measurements were taken. According to direct method, Soil Moisture Regime (SMR) method is preferred due to a water deficiency in the study area. Water holding capacity was used as an essential criterion for the classification of the forest site. Forest site classifications were assigned regarding the physiographic factors such as landform, aspect, and slope. Five different forest sites classes; dry, moderate fresh, fresh, humid and hygric were determined. According to direct method, the guiding curve was used to generate anamorphic site index (SI) equations and three site index classes; good (SI=I–II), medium (SI=III) and low (SI=IV–V) were determined. Some important differences between the methods were realized. The forest sites determined with site index estimation method indicate that site index I and II is 505.99 ha, III 1095.79 ha and IV and V 992.95 ha, whereas forest sites determined with direct method related to dry site of 937.58 ha, moderate fresh site of 931.90 ha, fresh site of 1,797.71 ha, humid site of 80.48 ha and hygric site of 356.55 ha. The forest site maps of both methods were created using GIS functions. The forest sites of open and degraded areas should be determined according to direct method.     

Environmental Monitoring of Land-Use and Land-Cover Changes in a Mediterranean Region of Turkey

Unprecedented rates of human-induced changes in land use and land cover (LULC) at local and regional scales lead to alterations of global biogeochemical cycles. Driving forces behind LULC changes mainly include rapid growth rates of population and consumption, lack of valuation of ecological services, poverty, ignorance of biophysical limitations, and use of ecologically incompatible technologies. One of the major ecological tragedies of the commons in a Mediterranean region of Turkey is the loss of Lake Amik at the expense of increasing the area of croplands, which used to provide vital ecosystem goods and services for the region. In this study, we aimed at quantifying the effects of past land-use transitions on soil organic carbon (SOC) pools (0–20 cm) in a Mediterranean region of 3930 km², between 1972 and 2000. LULC changes were quantified from a time series of satellite images of Landsat-MSS in 1972, Landsat-5 TM in 1987, and Landsat-7 ETM+ in 2000 using geographic information systems. The study showed that the increase in croplands between 1972 and 1987 took place at the expense of the irreversible losses of Lake Amik and its related wetlands of over 53 km². In the period of 1972 to 2000, croplands, settlements, and evergreen forests increased by 174%, 106%, and 14%, respectively. The increase in settlements occurred mostly to the detriment of croplands. Given the average rates of all the land-use transitions, and associated changes in SOC density for the study region of 3930 km², total SOC pool was estimated to decrease by 14.1% from 130.1 Mt in 1972 to 111.7 Mt in 2000.     

Inorganic constituents of urban air pollution in the Lazio region (Central Italy)

A field study was carried out at six locations in the Lazio region (Central Italy) aimed at characterising atmospheric particulate matter (PM₁₀ and PM_2.5) from the point of view of the chemical composition and grain size distribution of the particles, the mixing properties of the atmosphere, the frequency and relevance of natural events. The combination of four different analytical techniques (ion chromatography, X-ray fluorescence and ICP for inorganic components, thermo-optical analysis for carbon compounds) yielded sound results in terms of characterisation of the air masses. During the first three months of the study (October-December 2004), many pollution events of natural (sea-salt or desert dust episodes) or anthropogenic nature were identified and characterised. More than 90% of the collected mass was identified by chemical analysis. The central role played by the mixing properties of the lower atmosphere when pollution events occurred was highlighted. The results show a major impact of primary anthropogenic pollutants on traffic stations and a homogeneous distribution of secondary pollutants over the regional area. An evaluation of the sources of PM and an identification of possible reliable tracers were obtained using a chemical fractionation procedure.     

Inorganic constituents of urban air pollution in the Lazio region (Central Italy)

A field study was carried out at six locations in the Lazio region (Central Italy) aimed at characterising atmospheric particulate matter (PM₁₀ and PM_2.5) from the point of view of the chemical composition and grain size distribution of the particles, the mixing properties of the atmosphere, the frequency and relevance of natural events. The combination of four different analytical techniques (ion chromatography, X-ray fluorescence and ICP for inorganic components, thermo-optical analysis for carbon compounds) yielded sound results in terms of characterisation of the air masses. During the first three months of the study (October–December 2004), many pollution events of natural (sea-salt or desert dust episodes) or anthropogenic nature were identified and characterised. More than 90% of the collected mass was identified by chemical analysis. The central role played by the mixing properties of the lower atmosphere when pollution events occurred was highlighted. The results show a major impact of primary anthropogenic pollutants on traffic stations and a homogeneous distribution of secondary pollutants over the regional area. An evaluation of the sources of PM and an identification of possible reliable tracers were obtained using a chemical fractionation procedure.     

Landscape ecological planning through a multi-scale characterization of pattern: studies in the Western Ghats,South India

This article analyzes landscape pattern in the WesternGhats mountain ranges in south-western India at two scales,comparing small-scale, detailed studies of landscapepattern, with broader, regional-scale assessments of theWestern Ghats. Due in large part to their inaccessibility,relatively little is known about the landscapes of thisbiodiverse region, which also supports some of the highestpopulation densities in the world. A broad-scale NDVI-basedIRS 1B satellite image classification is used to analyzenorth-south and east-west trends across the entire WesternGhats and western coast of India, an area over 170 000 km². Northern and eastern landscapes are morefragmented compared to the southern and western slopes.Western slopes also have greater landscape diversity withland cover types more interspersed compared to the easternslopes. These differences can be related to north-south andeast-west variations in rainfall and plant distribution. Data from thirteen landscapes 10–50 km² in area, arefurther utilized to analyze trends in landscape pattern, anddescribe the geographical distribution of major natural andmanaged ecotope types. At this scale, very high levels ofintra-ecotope type variability in landscape pattern areencountered for all land cover types. Results at these twoscales are integrated to suggest a hierarchical stratifiedapproach for monitoring land cover and biodiversity in the region.     

Land-Cover Changes and Its Impacts on Ecological Variables in the Headwaters Area of the Yangtze River, China

Land cover changes affect ecological landscape spatial pattern, and evolving landscape patterns inevitably cause an evolution in ecosystem functionality. Various ecological landscape variables, such as biological productivity (plant biomass and stock capacity), soil nutrients (organic matter and N content) and water source conservation capacity are identified as landscape function characteristics. A quantitative method and digital model for analyzing evolving landscape functionality in the headwaters areas of the Yangtze River, China were devised. In the period 1986–2000, patch transitions of the region's evolving landscapes have been predominantly characterized by alpine cold swamp meadow, with the highest coverage tending to be steppified meadow or steppe, and desertification landscape such as sand and bare rock land expansion. As the result of such changes, alpine swamp areas decreased by 3.08 × 10³ km² and the alpine cold sparse steppe and bare rock and soil land increased by 6.48 × 10³ km² and 5.82 × 10³ km², respectively. Consequently, the grass biomass production decreased by 2627.15 Gg, of which alpine cold swamp meadows accounted for 55.9% of this loss. The overall stock capacity of the headwaters area of the Yangtze River decreased by 920.64 thousand sheep units, of which 502.02 thousand sheep units decreased in ACS (Alpine cold swamp) meadow transition. Soil organic matter and N contents decreased significantly in most alpine cold meadow and swamp meadow landscape patches. From 1986 to 2000 the total losses of soil organic matter and total N in the entire headwaters region amounted to 150.2 Gkg and 7.67 Gkg. Meanwhile, the landscape soil water capacity declined by 935.9 Mm³, of which 83.9% occurred in the ACS meadow transition. In the headwater area of the Yangtze River, the complex transition of landscape resulted in sharp eco-environmental deterioration. The main indication for these changes involved the intensity of the climate in this region is becoming drier and warmer, resulting in a gradual degradation of the permafrost.     

Spatial and Temporal Performance of the MiniFACE (Free Air CO2 Enrichment) System on Bog Ecosystems in Northern and Central Europe

The Bog Ecosystem Research Initiative (BERI) projectwas initiated to investigate, at five climaticallydifferent sites across Europe, the effects of elevatedCO₂ and N deposition on the net exchange ofCO₂ and CH₄ between bogs and the atmosphere,and to study the effects of elevated CO₂ and Ndeposition on the plant biodiversity of bogcommunities. A major challenge to investigate theeffects of elevated CO₂ on vegetation andecosystems is to apply elevated CO₂concentrations to growing vegetation without changingthe physical conditions like climate and radiation.Most available CO₂ enrichment methods disturb thenatural conditions to some degree, for instance closedchambers or open top chambers. Free Air CO₂Enrichment (FACE) systems have proven to be suitableto expose plants to elevated CO₂ concentrationswith minimal disturbance of their natural environment.The size and spatial scale of the vegetation studiedwithin the BERI project allowed the use of a modifiedversion of a small FACE system called MiniFACE. Thispaper describes the BERI MiniFACE design as well asits temporal and spatial performance at the five BERIfield locations. The temporal performance of theMiniFACE system largely met the quality criteriadefined by the FACE Protocol. One minute averageCO₂ concentrations measured at the centre of thering stayed within 20% of the pre-set target for morethan 95% of the time. Increased wind speeds werefound to improve the MiniFACE system's temporalperformance. Spatial analyses showed no apparentCO₂ gradients across a ring during a 4 day periodand the mean differences between each sampling pointand the centre of the ring did not exceed 10%.Observations made during a windy day, causing aCO₂ concentration gradient, and observations madeduring a calm day indicated that short term gradientstend to average out over longer periods of time. On aday with unidirectional strong winds, CO₂concentrations at the upwind side of the ring centrewere higher than those made at the centre and at thedownwind side of the ring centre, but the bell-shapeddistribution was found basically the same for thecentre and the four surrounding measurement points,implying that the short term (1 sec) variability ofCO₂ concentrations across the MiniFACE ring isalmost the same at any point in the ring. Based on gasdispersion simulations and measured CO₂concentration profiles, the possible interferencebetween CO₂-enriched and control rings was foundto be negligible beyond a centre-to-centre ringdistance of 6 m.     

Spatial Variability of Soil Organic Carbon in Relation to Environmental Factors of a Typical Small Watershed in the Black Soil Region, Northeast China

A total of 292 soil samples were taken from surface soil (0–20 cm) of a typical small watershed–Tongshuang in the black soil region of Heilongjiang province, northeast China in June 2005 for examining the concentration of soil organic carbon (SOC). Spatial variability of SOC in relation to topography and land use was evaluated using classical statistics, geostatistics and geographic information system (GIS) analyses. The objective of this study was to provide a scientific basis for land management targeting at improving soil quality in this region. Classical statistical analysis results indicated that the variability of SOC was moderate (C _V = 0.30). Slope position and land use types were discriminating factors for its spatial variability. Geostatistics analyses showed that SOC had a strong spatial autocorrelation, which was mainly induced by structural factors. Mean concentration of SOC in surface soil was 2.27% in this watershed, which was a very low level in the northern black soil region of northeast China. In this small watershed, present soil and water conservation measures played an important role in controlling soil loss. But SOC's restoration was unsatisfactory. Nearly three-quarters of the area had worrisome productivity. How to improve SOC concentration targeting at soil fertility is a pressing need in the future.     

Community Based Interventions as a Strategy to Combat Desertification in the Arid and Semi-Arid Rangelands of Kajiado District, Kenya

Vegetation degradation, especially the disappearance of woody vegetation and a diminished grass cover, has aroused the concern of the Maasai community (semi-nomadic pastoralists) of Kajiado District, Kenya. The district is one of Kenya’s arid and semi-arid districts. Over recent years, they have observed their land resources deteriorate due to the desertification process caused by the land use practices of man. They have identified indicators of desertification such as increase of bare lands, which have been invaded by previously unknown grasses and weeds that are of no economic value, and also the disappearance of some useful plant species. It is due to the above concerns that a group of 30 farmers have been very keen to participate in on-farm research to strategize on ways to halt and even reverse the desertification process. The participatory research has identified useful trees that the farmers have been planting around homesteads, as woodlots on their farms to provide woodfuel, shade, and to act as windbreaks. They have also identified species for planting as live fences instead of using thorny tree branches as fencing material, which contributes further to the desertification process. Due to the termite menace on young tree seedlings, the farmers use indigenous knowledge to prepare concoctions using locally available materials, which they apply to planting holes and on seedlings. During awareness campaigns, the farmer research group highlights the need to conserve vegetation resources and also expounds on the concept of planting two trees after one is felled.     

Heavy Metals in Liver and Muscle of Bluefin Tuna (Thunnus thynnus) Caught in the Straits of Messina (Sicily, Italy)

The present investigation was carried out on the bluefin tuna (Thunnus thynnus) collected during the month of April 2003 from the Straits of Messina. The aim of this study is to determine heavy metal levels (Cd, Cu, Hg, Mn, Pb and Zn) in liver and muscle tissues of 14 Thunnus thynnus of different age and sex and to investigate the relationships between fish sex and size (length and weight and metal concentrations in the tissues. The concentrations of the various metals were determined by a Varian atomic absorption spectroscopy instrument. The results showsignificant variations (p < 0.01) for Hg and Zn concentrations in muscle than in liver samples. Concentrations of Cd and Pb are below the instrumental detection limits in almost all muscle samples. Levels of Hg (3.03 + 0.55 μg/g) are above the MRLs only in muscle (1μg/g) establishing toxicological risks for the consumer. Regression analysis shows a negative correlation between mercury level and weight and length in samples from both female and male. No significant difference between mean heavy metals concentrations and male or female tuna is seen. For greater food safety, it would be advisable to reduce the mercury intake by selecting safer fish, species and size and by the avoidance of tuna fish consumption by pregnant women, young children and old people, who are more sensitive to mercury exposure.     

Temporal and spatial changes in primary biomass as a diagnosis and prognosis in environmental impact (Rapel Reservoir,Central Chile)

Extensive mortality of silversides (Atherinidae), Odontesthes bonariensis, was recorded during July 1989 in the Rapel Reservoir. Temporal and spatial changes observed in biomass concentration (chlorophyll-a) through both ground and remote sensing samples (LANDSAT), allowed us to establish a potential environmental impact. Ground measurements established an input of sulfate (SO₄) in a eutrophic area. The mean concentration of biomass tended to decrease in this area in comparison with other mesotrophic areas. The local disfunction associated with the observed biomass changes has been used to develop a prediction in species composition and in biomass concentration.

---

Resumen Durante la primera semana de Julio de 1989, se registró una muerte masiva de pejerreyes, Odontesthes bonariensis en el Embalse Rapel. En los procesos de monitoreo de la calidad de agua en el Embalse Rapel, se utilizó una representacion espacial primaria de las variables de estado elegidas. Las tendencias témporo-espaciales observadas en la concentración de biomasa fitoplanctónica (clorofila-a) permitieron establecer un impacto ambiental potencial por un agente exógeno al sistema. A partir de mediciones de terreno se estableció la presencia de sulfato (SO₄) en una zona de características eutróficas. Los efectos observados en esta zona, en comparación al resto del embalse, fueron una disminución en la concentración media de la biomasa. La disfunción local observada, permitió sustentar una prognosis asociada a la composición de especies fitoplanctónicas y la concentración de biomasa local.

     

Baseline Concentrations of Trace Elements in Surface Soils of the Torrelles and Sant Climent Municipal Districts (Catalonia,Spain)

An investigation was conducted to study the baseline levels of Ba, Cd, Cu, Cr, Ni, Pb, Sr, V and Zn (aqua regia-extractable) based on 51 representative soils of the Torrelles and Sant Climent Municipal Districts (Catalonia, Spain). The baseline concentrations of those elements were (mg kg⁻¹): Ba 73.9–617.9, Cr 9.2–120.2, Cu 4.0–111.6, Ni 6.1–118.6, Pb 5.6–217.5, Sr 19.6–128.8, V 12.1–101.2, and Zn 16.8–326.8, respectively.Forty-nine samples were reported as having less than the 0.67 mg kg⁻¹ detection limit for cadmiun and were therefore not useful for baseline determination; however, these results suggest that the baseline average is probably below 0.67 mg kg⁻¹.Upper baseline values for most of the elements corresponded with those reported in the literature, except for Pb and Zn, which were two to four times greater.Soil properties, including clay fraction, OC, CEC and pH_w were related to metal concentration using correlation and factorial analysis. R-mode factor analysis separates the soil analysis data into three factors. These factors explain 67.3% of the total variance, suggesting that metal concentration was controlled by soil composition.     

Floristics, performance and prognosis of historical trees in the urban forest of Guangzhou City (China)

Outstanding historical trees embedded in cities constitute pertinent environmental assets, yet they are widely threatened in third-world cities. Inadequate understanding of this valuable natural-cum-cultural heritage hinders proper conservation. A case study of Guangzhou in south China evaluated floristic composition, age profile and biomass structure of historical trees, assessed their performance in major habitats (institutional, park and roadside), and established a prognosis for future growth and management. The 348 historical trees examined belonged to only 25 species, vis-à -vis 254 trees in the entire urban forest, dominated by five species and native members. Roadside had more trees, followed by institutional and park, with merely the most common four species shared by all habitats. The limited commonality reflected tree-performance differentiation by habitats exerting selection pressure on species. The institutional growth-regime was more conducive to nurturing high-caliber specimens, whereas park is less capable. Individual species achievement by habitats, derived from tree-count ranking and relative-abundance indices, could inform species choice and tree conservation. Few trees exceeded 300 years of age in the millennium-old city, echoing a history of intense tree—city conflicts. Potential life-span, trunk and crown diameters indicated ample opportunities for further expansion of biomass and landscape impacts, which would be straitjacketed by the tightening urban fabric.     

Seasonal and Interannual Variations in the Frequency and Severity of Deformities in Larvae of Chironomus riparius (Meigen, 1804) and Prodiamesa olivacea (Meigen, 1818) (Diptera, Chironomidae) collected in a polluted site

Larvae of Chironomus riparius and Prodiamesa olivacea were sampled at intervals overthe period November 1993 and October 1995 from theriver Sar in Galicia (N.W. Spain), with the aim ofinvestigating possible temporal variations in thefrequency of deformed individuals and in `Toxic Score'values (Lenat, 1993), a score for severity of theabnormalities calculated for each species. The resultsobtained indicate that, in both species, deformitiesare more frequent during the colder period of theyear. Similarly, Toxic Score values are higher duringthis period. These finding suggest that studies usingchironomid larvae as indicators of contaminationsshould involve sampling over an extended period, tominimize the influence of temporal variation.     

Air pollution impact assessment on agroecosystem and human health characterisation in the area surrounding the industrial settlement of Milazzo (Italy): a multidisciplinary approach

In order to evaluate the impact of atmospheric pollutants emitted by the industrial settlement of Milazzo (Italy) on agriculture, sulphur dioxide and ozone levels in air were monitored and the data were used to estimate yield losses of the most widespread cultures. Trace element concentrations in crops and soils were also detected and metabolic profiles of soil microbial communities were considered. Vibrio fischeri test was used to appraise airborne pollutant ecotoxicity and epidemiological studies on causes of death distribution were carried out to characterize health state of people living in the area. All the sampling points were selected in farms on the basis of a theoretical meteo-diffusive model of industrial air pollutants. Experimental SO₂ and O₃ values mainly exceeded the threshold established by Italian and EU regulations to protect vegetation and they correspond to estimated significant crop losses. Conversely toxic element residues in soils and in agroalimentary products were generally lower than the fixed values. SO₂ and O₃ concentrations, toxic element contents and ecotoxicity levels of airborne pollutants were not related only to industrial site emissions, while the fluctuations on metabolic profiles of soil microbial communities seem to agree with the predicted deposition of xenobiotic compounds from the industrial plants. The epidemiological study evidenced a better health state of populations living in the investigated area than in the Messina province and the Sicily region but, inside the area, males living in the municipalities closest to the industrial settlement exhibited a worst health state than those in the very far ones.     

Organic Liquids Storage Tanks Volatile Organic Compounds (VOCS) Emissions Dispersion and Risk Assessment in Developing Countries: The Case of Dar-Es-Salaam City, Tanzania

The emission estimation of nine volatile organic compounds (VOCs) from eight organic liquids storage tanks companies in Dar-es-Salaam City Tanzania has been done by using US EPA standard regulatory storage tanks emission model (TANKS 4.9b). Total VOCs atmospheric emission has been established to be 853.20 metric tones/yr. It has been established further that petrol storage tanks contribute about 87% of total VOCs emitted, while tanks for other refined products and crude oil were emitting 10% and 3% of VOCs respectively. Of the eight sources (companies), the highest emission value from a single source was 233,222.94 kg/yr and the lowest single source emission value was 6881.87 kg/yr. The total VOCs emissions estimated for each of the eight sources were found to be higher than the standard level of 40,000 kg/yr per source for minor source according to US EPA except for two sources, which were emitting VOCs below the standard level. The annual emissions per single source for each of the VOCs were found to be below the US EPA emissions standard which is 2,000~kg/yr in all companies except the emission of hexane from company F1 which was slightly higher than the standard. The type of tanks used seems to significantly influence the emission rate. Vertical fixed roof tanks (VFRT) emit a lot more than externally floating roof tanks (EFRT) and internally floating roof tanks (IFRT). The use of IFRT and EFRT should be encouraged especially for storage of petrol which had highest atmospheric emission contribution. Model predicted atmospheric emissions are less than annual losses measured by companies in all the eight sources. It is possible that there are other routes for losses beside atmospheric emissions. It is therefore important that waste reduction efforts in these companies are directed not only to reducing atmospheric emissions, but also prevention of the spillage and leakage of stored liquid and curbing of the frequently reported illegal siphoning of stored products. Emission rates for benzene, toluene, and xylene were used as input to CALPUFF air dispersion model for the calculation of spatial downwind concentrations from area sources. By using global positioning system (GPS) and geographical information system (GIS) the spatial benzene concentration contributed by organic liquid storage tanks has been mapped for Dar-es-Salaam City. Highest concentrations for all the three toxic pollutants were observed at Kigamboni area, possibly because the area is located at the wind prevailing direction from the locations of the storage tanks. The model predicted concentrations downwind from the sources were below tolerable concentrations by WHO and US-OSHA. The highest 24 hrs averaging time benzene concentration was used for risk assessment in order to determine maximum carcinogenic risk amongst the population exposed at downwind. Established risk for adult and children at 2.9×10^-3 and 1.9×10^-3 respectively, are higher than the acceptable US-EPA risk of 1×10^-6. It is very likely that the actual VOCs concentrations in some urban areas in Tanzania including Dar-es-Salaam City are much higher than the levels reported in this study when other sources such as petrol stations and motor vehicles on the roads are considered. Tanzania Government therefore need to put in place: an air quality policy and legislation, establish air quality guidelines and acquire facilities which will enable the implementation of air quality monitoring and management programmes.