Environmental Sciences
Year:2008 | Volume:5 | Issue:3|Papers Count:16

The 'equal compartment-agar method' was used to evaluate the allelopathic potential of wheat (Triticum aestivum) cultivars on the seedling growth of field bindweed (Convolvulus arvensis) and rye (Secale cereale). The experiment was carried out during 2005 at the Weed Research Department of the Iranian Crop Protection Research Institute, in a factorial form on a completely randomized design with three replications. Wheat cultivars in four levels (Shiraz and Niknejad, as more competitive cultivars; Tabasi and Roshan, as less competitive cultivars) and the density of wheat seedlings on four levels – 0 (control), 8, 16 and 24 − were considered as factors. Mean comparison showed that higher seedling density (at 24) had the greatest effect on decreasing rye growth (seedling, radicle, and hypocotyl) and all of the wheat cultivars showed a decrease in seedling, radicle and hypocotyl length in comparison with the control. All the wheat cultivars, especially at the highest density, decreased seedling and radicle length, but increased the hypocotyl length of field bindweed.

Rural Guide Projects, Are the main comprehensive plans for development of country areas in Iran. Since 1987, more than 16440 projects have been provided and about 7670 projects have been implemented. In Spite of great interaction between natural environment of country areas and development plans, there is no evaluation about the impact of this plans on the natural environment of rural areas. This research, on the basis of some essential criterions, has explored some implemented projects. The main achievements are: 1. Lack of environmental studies in project designs and preparations.2. Having no ideas about the impact of projects on natural environment of rural areas in two phases: project design and project implementation. Finally, some guidelines are suggested as feedbacks of projects to correct their strategies and tactics about intervention in natural environment of rural areas. Main guidelines are:1. Correction of project checklists. 2. Giving priority to environmental studies.3. Localization in preparation and implementation of projects.

Organochlorine pesticides including lindane, heptachlor, aldrin, dieldrin and DDT were analized in muscle tissue of two commercial fish species, (Cyprinus carpio and Rutilus frisii) from five stations in the southwest Caspian Sea (Astara-Hashtpar-Anzali-Kiashahr and Ramsar). There was no pesticide contamination in fish samples of Astara. Heptachlor in muscle tissue of Cyprinus carpio from Anzali had the highest concentration (11.964 mg/kg - lipid weight basis) among all fish samples. Mean level of each pesticide was calculated in all fish samples. The results showed that among other pesticides, heptachlor is the main contaminant in southwest of Caspian Sea (2.6479 mg/kg - lipid weight basis). Generally, in comparison with Acceptable Daily Intake (ADI) established by FAO/WHO, the levels of heptachlor in muscle tissue of Cyprinus carpio from Anzali and Ramsar, Rutilus frisii from Hashtpar and level of dieldrin in muscle tissue of Rutilus frisii from Kiashahr can have health risk to consumers. The concentration of above mentioned pesticides in the same fish samples are higher than Maximum Residue Limit (MRL). In addition, level of DDT in muscle tissue of Rutilus frisii from Ramsar exceeds the MRL values.

This research has been conducted in order to study the effect of lead at different concentrations [0, 100, 200, 400, 600, 800, 1000 mM Pb(NO3)2 ] on germination and different concentrations of lead [0, 100, 200, 400 mM Pb(NO3)2 ] on the protein and proline contents and Pb2+accumulation in root, shoot and index of tolerance (TI) of two varieties of oilseed rape (PF 7045.91 and Hyola 401) in hydroponic culture. Samples were digested (wet digestion) using a mixture of nitric and perchloric acid which was used for the concentration of lead. The protein and proline contents were determined using a spectrophotometer (UV) model Hitachy U–2000. Statistical methods as a completely randomized block design have been used for analysis of data through a one-way analysis of variance procedure. Lead decreased seed germination in both varieties, though the reduction in Hyola 401 was greater than in PF 7045.91. Root length in both varieties decreased as the concentration of lead increased. The index of tolerance of Hyola401 was greater than that of PF 7045.91. Pb increased root protein in both varieties. The shoot protein of PF 7045.91 increased with increasing Pb while it decreased in Hyola 401. The percentage of increase for root protein in PF 7045.91 was greater than in Hyola 401. Pb increased root and shoot proline in both varieties. The percentage of increase for root and shoot proline in Hyola 401 was greater than in PF 7045.91. By increasing the lead concentration of the nutrient solution, Pb2+accumulation in root and shoot of both varieties was increased in comparison with control. Pb+2 accumulation in roots and shoots of Hyola 401 was greater than for PF 7045.91. As a result, it has been concluded that oilseed rape particularly Hyola cultivar could possibly be used for the phytoremidation of lead in polluted soils.

Soil nematodes and bacteria play an important role in soil function. In order to evaluate the effects of agricultural practices on these organisms, a study was conducted in winter wheat fields of Shirvan, Mashhad and Gonabad, three regions of Khorasan Province. In each region, high and low input fields of winter wheat were selected, along with a natural system for comparison. Use of agricultural inputs was the criterion for the selection of low and high input fields in each region. Soil sampling was undertaken on fields and natural systems. Organic matter and the number of nematodes and culturable bacteria in soil samples were measured. The percentage of soil organic matter in all systems was low but, in agro-ecosystems, it was greater than in natural systems. Results showed that organic matter, soil moisture and mean annual temperature has an affect on soil nematodes. The number of nematodes in agro-ecosystems was reater than in natural systems in all three regions. The mean number of soil nematodes in 100g dry weight of soil in the natural systems of Shirvan, Mashhad and Gonabad was 166, 184 and 132, respectively; in the low input systems of Shirvan, Mashhad and Gonabad it was 550, 459 and 1067, respectively and in the high input systems of Shirvan, Mashhad and Gonabad it was 348, 1084 and 485, respectively. Agricultural practices had no negative effects on soil bacterial numbers and the number of soil bacteria increased in some agro-ecosystems. Results showed that agroecosystems improved the conditions for nematodes and bacteria and increased the number of these organisms in soil.

Organochlorine pesticides are very important, due to their carcinogenic and delayed toxic function and their effect on nervous system of fish and human. In this study concentration of organochlorine pesticides including Lindane, Heptachlor, Dieldrin, Aldrin and DDT was measured in muscle tissues of stellate sturgeon of southern coasts of the Caspian Sea from Astara, Hashtpar, Bandare Anzali, Kiashahr, Ramsar, Chalous, Noor, Feraidoun Kenar, Khazarabade Sari and Bandare Turkman stations. In sampled stellate sturgeon, Heptachlor with an average concentration of 3.933 mg/kg on lipid weigth basis and Aldrin with an average concentration of <0.288 mg/kg on lipid weigth basis had the highest and lowest concentrations, respectively. The order of these pesticides according to average of concentration are as follow: Heptachlor > DDT > Lindane > Dilderin > Aldrin. Comparison of measured concentrations with Maximum Residue Limit (MRL) established by FAO/WHO showed that the average concentration of Heptachlor in all sampling stations exceeded the MRL value, also concentration of DDT in samples from Chalous and Bandare Turkman exceeded the MRL value.

A study was conducted to determine probable impacts of construction of Alamut Dam on the status of the fish community of the Alamut and Taleghan Streams in autumn 2000. The fish species found were: Alburnoides bipunctatus, Barbus capito, B.lacerta, B.mursa, Capoeta capoeta, Leuciscus cephalus, Salmo trutta, Onchorhynchus mykiss, Nemachilus bergianus. B.capito and B.mursa are both highly prized taxa in terms of their population status and for sport fishing; the latter needs full habitat protection to survive. Salmo trutta will face little impact from the Alamut Dam construction since its habitat is mainly confined to a stretch of river well upstream of the construction site. It should be kept in mind, however, that the Manjil (Sefid Rud) Dam has some affect on the operation of the Alamut Dam, both being constructed on the same water body. Therefore, any interpretation of the possible impact of the Alamut Dam on hydrobiology of the area must be focused on the entire water basin ecology.

The aim of this study was to assess the relationship between biodiversity and the richness of woody and ground vegetation species, soil physicochemical and physiographic characteristics of the Zagros forests. This study was conducted at Arghavan reservoir in the North of Ilam Province in Iran. For this study, plots with a systematic distribution across the northern (n=24), southern (n=20) and western (n=13) aspects were selected and vegetation, soil and physiographic data were measured. Results showed that, in the southern aspect, ground vegetation diversity had a negative relationship with clay and sand while it had positive correlation with silt. In the northern aspect, ground vegetation diversity had a negative correlation with elevation above sea level. In the western aspect, ground vegetation diversity had a positive correlation with CaCo3 while it had negative correlation with salinity and elevation above sea level. Results also showed that, in all the aspects, woody species only had a relationship with physical factors. These results suggest that in ecological studies for assessing the relationship between vegetation and environment, soil factors should be measured for the assessment of ground vegetation and, for woody species, physical and physiographic factors.

Municipal solid waste (MSW) leachate contains micro elements that can be used by plant. They are essential for plant growth cycle at sufficient level and impose a vital role in increasing yields of most agricultural crops. Greenhouse experiment was carried out with four treatments (control, 20%, 40%, 60% leachate to water (V/V) ratios) with three replications by using a completely randomized design to study the effect of (MSW) leachate on growth and concentration of Fe, Cu, Zn and Mn in green chilli plant .Plant fresh biomass and plant height were highest in 40%(MSW) leachate, with an increase of 68% and 107% respectively compared to control. Number of branches in 40%(MSW) leachate showed an increase of 80% compared to control indicating a positive impact of (MSW) leachate application of up to 40% on these parameters. Fe, Cu, Mn concentrations in plant showed an increasing trend with increasing the percentage of (MSW) leachate to water. As 60% (MSW) leachate increased Fe, Cu, Mn concentrations by 6%,31%,6% respectively when compared to control, but no significant changes were observed between the treatments. Highest Fe, Cu, Mn contents in soil after plant harvest were observed in (MSW) leachate of 60% indicating, their highest uptake and concentrations in plant for this treatment, probably due to limited plant growth. Highest Zn were observed in plant and soil of 60% (MSW) leachate treatment, as Zn concentration in plant showed 46% increase compared to control, probably, due to its highest soil content for this treatment. In general, application of (MSW) leachate up to 40%(V/V) leachate to water ratio for green chilli had a positive impact on plant growth parameters and concentrations of Fe, Cu, Zn, Mn in plant and soil (except Fe).However, their concentrations were much less than their standard critical values and therefore leachate applications in calcareous soils is recommended while considering soil EC and plant tolerance.

Screening experiments were carried out to isolate bacterial strains capable of solubilizing coal tailings for use in biofuel production from these byproduct wastes. Using enrichment in medium containing coal as sole carbon source, seven bacterial strains able to grow on coal hydrocarbons were isolated. The bacterial consortium was then cultured in mineral salt liquid media containing 1% (w/v) hard coal or coal tailings and incubated for 15 days at 25 degree centigrade on an orbital shaker (150 rpm). Spectrophotometric analysis of supernatants resulted from centrifugation of cultures showed 1.475 increases in absorbance at 450 nm for coal tailing and 0.832 for hard coal, compared to blank lacking bacteria. Gravimetric measurements also performed wich confirmed the solubilization of coal by bacteria.

Tiab and Kolahy estuaries are regarded as part of the Ramsar sites, that are located in the delta of Rud Shirin, Rud Shour and Minab River 37o 05' N 56o 50' E. The total area of the region is about 20000 ha. In this study, 96 species from 27 families of the birds of Iran were recognized at these wetlands.Fifty seven species were waterbirds. Species of White and Dalmation Pelicans,Great Cormorant, Greazer Flamingo and some Gulls and Terns were counted monthly in this survey. All species were migrant birds. Density of birds population in Kolahy was 2/99 and in Tiab 3,00 per hectare. There was no significant statistical difference between populations and species diversity of any known species in both estuaries. The bird's population in both wetlands were maximum in winter and minimum in summer, from which 60% were Fish-eating, 35% omnivores and the remaining were Planktoneater. Dalmation Pelican Pelecanus crispus, one of the threatened species observed in winter in both estuaries. Diversity of Sternidae with 9 species was more than the other bird family and Phoenicopterus ruber and Phalacrocorax carbo with one species werethe families with lowest bird species number.