Lead concentration in Teheran's atmosphere

Aerosol Pb pollution in Teheran was repeatedly measured at nine crossroads in the city from April to November 1976. The mean value of atmospheric Pb in the city was 3.6 μg m^?3. The average values obtained for the Pb in the air of the crossroads were close to each other except in the southern parts of the city where it was higher. Stagnation of motor vehicles and higher dustfall may have a role in this increase. Since industrial Pb pollution is not significant in Teheran, it was concluded that the contamination by Pb in the city is mainly from gasoline consumption.     

A Comparison of Spectrophotometric and Gas Chromatographic Measurements of Heavy Petroleum Products in Soil Samples

Laboratory studies were conducted to compare the infrared spectrophotometry (TPH-IR) and gas chromatography (TPH-GC) measurements of total petroleum hydrocarbon in soil samples.Real world soil samples containing #2 to #6 fuel oils, mechanical lubricating oil, diesel fuel, kerosene, jet fuel andweathered gasoline were extracted with trichlorotrifluoroethane(Freon-113) and methylene chloride. The extractants were analyzed using gas chromatography with flame ionization detection (GC-FID) and infrared spectroscopy (TPH-IR) methods.A paired statistical t-test was applied to compare the average of paired differences in the analytical results. Statistical tests were evaluated with graphical presentation of the results. In general, a trend was observed in the measured concentrations.Total petroleum hydrocarbon (TPH) concentrations measured withTPH-IR had the highest readings. The same samples extracted withmethylene chloride and analyzed with GC-FID showed lower concentrations than the TPH-IR method while the GC-FID analysisof the same samples extracted with Freon-113 produced the lowestconcentrations. Laboratory experiments indicated that TPH concentrations measured with the TPH-IR method were higher thanthe actual quantities of petroleum hydrocarbon in the soil samples.     

Oxidation and Removal of 1,2,4-Trichlorobenzene using Sodium Persulfate in a Sorption-Desorption Experiment

Peat soils with a gradient of naturally high Cd and Zn (up to 190 and 70,000,mg/kg, respectively) were sampled at several depths from a wetland overlying Zn-rich dolomitic bedrock. Total concentrations of Zn, Cd and S were generally much higher in the seasonally water-saturated subsoils than at the surface. Leaching studies with intact soil columns showed the subsoils generally have a greater tendency to release Zn, Cd and S than the topsoils. Zn and Cd leaching were correlated to sulfate dissolution, with 6 successive leaching events removing up to 4% and 13% of the total Zn and S, respectively, from the most metal-rich subsoils. Relative leaching losses were less from the surface soils, not exceeding 1% and 3% of total Zn and S. Because Zn was relatively more soluble and extractable by 0.01,M CaCl₂ than Cd, Zn/Cd ratios in column leachates and field-sampled groundwater were higher than the soil Zn/Cd ratios. Consequently, the potential for loss of Zn from the soil by leaching was higher than that of Cd, particularly from the subsoil. Nevertheless, some soil layers of the profile were enriched in total Zn relative to Cd, indicated by Zn/Cd ratios well above that of the Cd-rich sphalerite in the parent dolomitic rock. This enrichment may be explained by historical migration and re-immobilization of Zn as sulfides. The low solubility of Cd in the peats despite high total Cd suggests preferential immobilization of this metal by organic sulfur or sulfide.     

Improving Water Use Efficiency in Semi-Arid Regions through Integrated Aquaculture/Agriculture

Two experiments were performed in the Bekaa plain in Lebanon to evaluate the feasibility of integrating aquaculture with established agriculture production in order to increase water productivity. Both experiments consisted of four plant management treatments: 1) Aquaculture effluent irrigation and no fertilizer; 2) aquaculture effluent irrigation and inorganic fertilizer; 3) well water irrigation and no fertilization; and 4) well water irrigation with inorganic fertilizer. In the first experiment, tilapia growth and radish production using aquaculture effluent were evaluated. All fish survived and grew, and radish production was improved by irrigating with aquaculture effluent. In the second experiment, maize (Zea mays) in large plots was irrigated with aquaculture effluent. Irrigation with effluent water improved maize production and improved soil nitrogen availability. In both experiments, fish production improved water value index and water use efficiency. Results suggest that aquaculture effluent can supplant inorganic fertilizers and could actually yield better crop production.     

Seroprevalence of, and risk factors for, peste des petits ruminants in sheep and goats in Northern Jordan

Peste des petits ruminants (PPR) is an economically important disease that affect sheep and goat industry in Asia and Africa. In this study, we investigated the seroprevalence, and risk factors, of PPR in sheep and goat flocks from five different governorates (Irbid, Jarash, Ajloun, Mafraq and Zarka) located in Northern Jordan. Serum samples from 929 and 400 sheep and goats, respectively, corresponding to 122 sheep flock and 60 goats flock were collected. Seroprevalence was determined using PPR competitive ELISA. Health status and management information were collected using a semi-structured pre-tested questionnaire. The individual true prevalence of PPR in sheep and goats was 29 and 49%, respectively. The flock level true prevalence of PPR was 60 and 74% in sheep and goats, respectively. In both sheep and goat flocks, large flock size, visiting live animals market and inadequate veterinary services were identified as risk factors for PPR seropositivity. Mixed (sheep and goats) raising was identified as a risk factor for PPR seropositivity in sheep flocks only.     

The Effect of Precipitation Amount and Atmospheric Concentrations on Wet Deposition Fluxes of Oxidized and Reduced Nitrogen Species in Connecticut

The effects of precipitation amount and atmospheric concentrations of inorganic nitrogen species on precipitationconcentrations and wet fluxes of oxidized and reduced nitrogen inConnecticut were studied for a period of 152 weeks (7 February,1997 through 31 December, 1999). The annual volume weighted mean(VWM) concentration in precipitation of oxidized and reducednitrogen varied with precipitation amount between sites andyears. To investigate the effect of varying precipitation amountand mean monthly temperatures on concentrations of inorganicnitrogen species in precipitation, the precipitation events wereclassified into seven groups and each year was divided into twowarm and cold sampling periods. Increasing precipitation amounthad a substantial decreasing effect on the VWM concentration ofnitrate and ammonium ions in precipitation. The highest VWMconcentrations of oxidized and reduced nitrogen in precipitationwere found in the lower weekly precipitation range of 0 to 0.5 cm. The results of this study indicated that precipitationamount was one of the main factors affecting volume weighted meanconcentrations and fluxes of oxidized and reduced nitrogen. Chemical composition of inorganic nitrogen species in theatmosphere showed that during warm and cold sampling periodsreduced nitrogen was the predominant atmospheric specie, andoxidized nitrogen was the predominant wet specie in precipitationat all sampling sites.