Investigation Anthropogenic Impacts and Climate Factors on Drying up of Urmia Lake using Water Budget and Drought Analysis

The water level of Urmia Lake, the largest inland lake in Iran with maximum water surface area of about 6000 km², has been shrinking for the last two decades. Although a number of study have been performed to determine drought condition and coastline changes of Urmia Lake, there has not been a detailed study to distinguish anthropogenic effects from climate impacts on the drying of Urmia Lake. In this study, water budget of Urmia Lake and the intensity of drought in the basin were analyzed in the period from 1985 to 2010 and a new hypothesis is proposed to quantify anthropogenic and climate impacts in reducing the volume of Urmia Lake. The results of this study indicate that human impacts on the Lake and its basin are more important than climate factors. Though previous studies assumed that ground water output from Urmia Lake is negligible, the results of this study show the presence of significant groundwater seepage from Urmia Lake. Major changes in the variables that reduced the water level of Urmia Lake were observed since 1998. Anthropogenic impacts and climate factors have roughly 80% and 20% effects on the drying up of Urmia Lake, respectively. Hence, the first step to recover Urmia Lake could be the revision of management surface water, operation of dams and groundwater resources. The second step could be the review and classification of agricultural products grown in the region in terms of water consumption and teach local people the best practice methods for irrigation.     

Comparison of the dielectric and viscoelastic properties of two poly (propylene glycol) liquids

The complex relative permittivities of two poly(propylene glycol) liquids, of molecular weights 380 and 3030, have been determined. Measurements were made in the frequency range 60 Hz to 200 MHz and at temperatures from ?64° to +25°C. The lower molecular weight liquid showed only one relaxation region, which could be described by the Williams-Watts function with $\text{}\text{?}\text{gb = 0.51}$. The higher molecular weight liquid exhibited a similar main relaxation region and a secondary relaxation, of smaller amplitude, at lower frequencies. The relaxation times and their temperature dependencies are compared with previously determined viscoelastic relaxation and retardation times for the same liquids, and with the results from earlier dielectric studies by Baur and Stockmayer, and by Williams. The differences between the dielectric and mechanical times are discussed.     

Silica‐Supported Dendrimer‐Palladium Complex‐Catalyzed Selective Hydrogenation of Dienes to Monoolefins

The selective hydrogenation of cyclic and acyclic dienes to monoolefins occurs under very mild conditions, in the presence of silica‐supported PAMAM‐Pd complexes. The activity and selectivity of this reaction is sensitive to the dendrimer structure. These dendritic complexes display excellent recycle properties, retaining activity for up to eight recycles.