نشریه علوم محیطی
سال نهم شماره 2 (پیاپی 34، زمستان 1390)

Recycling is a promising approach for rescue of the earth from recoverable solid waste. Among different wastes, paper has a lot of importance. The effects of wastepaper recycling times on properties of their recycled paper have always been considered but less attention has been paid to semi-chemical papers. In this study, the effect of recycling times of NSSC wastepaper on WRV (Water Retention Value), Hornification of fibers, tensile strength index, burst strength index and tear strength index was investigated. Results indicated that successive recycling of NSSC wastepaper presents an identical behavior to successive recycling of chemical wastepapers. WRV, tensile strength index, burst strength index and tear strength index decreased and Hornification of fibers increased.

In the past half century, sustainable development and its policy implications have attracted a number of researchers in recent decades. In this literature, two rival theories are recognizable which are called weak and strong sustainability. These two theories are based on different assumptions, have different policy implications and expectedly lead to different results. Weak sustainability assumes that all different kinds of capital – especially physical and natural capitals – are complete substitutions while according to strong form of sustainability, none of other forms of capital – including physical, human and social- are substitutes for natural capital. This paper, using the most recent natural capital data provided by UN, compares these theories empirically. Using alternative variables for sustainability as dependant variable, we have compared the explanatory significance of different types of capitals in several regression equations. The results show that natural capital significantly explains sustainable development indices. Even, when other forms of capital are included in the regression equation, the positive relation between natural capital and sustainability indices remains statistically significant. So, we can conclude that empirically speaking, as stated in strong sustainability theory, other forms of capital are not substitutes for the natural capital.

In order to study the quantitative and qualitative characteristics of sunflower (Alestar hybrid) under the effects of bio fertilizer and winter wheat as a green manure in combination with the integrated nitrogen sources (chemical-farmyard manure, FYM), an experiment was carried out on experimental farm at faculty of agriculture, Tarbiat Modares University, Tehran, Iran in 2008. The experimental design was a split plot in a randomized complete blocks with three replications, in which seven fertilizer treatments including F1 (100% FYM), F2 (75% FYM + 25% chemical), F3 (50% FYM + 50% chemical), F4 (25% FYM + 75% chemical), F5 (100% chemical), F6 (50% FYM + 50% chemical + green manure), F7 (75% FYM + 25% chemical + green manure) were randomized to the main plot units and two levels of bio fertilizer I1 (inoculation) and I0 (control) to the sub plot units. The results revealed that grain and biological yield, yield components in integrated systems was significantly more than organic and chemical systems. The highest grain yield (3034.5 kg/ha), head weight (90.06 g), head diameter (19.40 cm). 1000 seed weight (67.99 g) and seed number in head (925.5) were obtained in F6 treatment (F6>F3>F4>F7>F2>F5>F1). Inoculation of bio fertilizer improved the grain yield and yield components, oil and protein content and the oil quality of sunflower compared with untreated plants. Saturated fatty acids decreased significantly, while unsaturated fatty acids (linoleic acid and oleic acid) increased in response to raising the organic manure and using bio fertilizer.

Land consolidation programs in Iran rice fields following numerous targets that the most important of them is the decrease of consumption of chemical inpouts: chemical fertliezer and chemival toxity in paddy field. The goal of this research is the comparison of inputs consumption sustainability in traditional and developed paddy fields in Iran (case study of Gilan province). The research was conducted in the form of survey study. Necessary data for this research collected squarely by 188 farmers of land consolidation programs in Gilan province were sampled by using stratified random sampling procedure. Data was collected through a questionnaire. The reliability of questionnaire was obtained by calculating the cronbach alpha coefficient (0.65) after conducting a pilot study. The results showed that the rate of paddy fields with chemical fertilizer equipment and renovation of land by the average consumption of 363 kg of fertilizers per hectare to 55 ha, on average, more fertilizer than traditional paddy paddy land and equipped (with use 5. 7 kg / ha), compared to paddy land traditional (with use 7. 1 kg / ha) toxin less refer. The test results t-test showed the two groups paddy land and traditional paddy land equipped and renewal rate of use of bee Trykvgrama (biological struggle) but almost equal in terms of consumption of animal manure, rotten paddy land and renovation to equip higher than traditional land paddy fields. Also in terms of consumption of fertilizers are significant differences in the two communities and the rate of urea fertilizer in paddy fields, but rice farmers in equipped paddy feilds in terms of chemival toxity consumption especially chemical chemical insecticides, use altogether more than equioped paddy fields farmers.

As the population of the world increases, the demand for food, food security and hence maximizing the yield is becoming a challenging subject in modern agriculture. In the last decades, applying chemicals like fertilizers, pesticides and herbicides has increased dramatically. Although improving in plant breeding programs reduces the demand for chemicals, but herbicide use is still increasing worldwide. According to the reports, continuous use of heavy doses of chemicals is encouraging resistance development in different weed spices and endangering the ecosystem and consequently, the resistance development among weeds to herbicides is of great concern. Now some research efforts concentrated on finding some natural extracts to control this threat, thereby reducing the use of herbicides in future. In general, the term allelopathy is the chemical interaction between plants in which one plant may be affected by another plant’s chemical extracts. An experiment was designed and conducted to examine the effects of some extracts obtained from 3 plants (wheat, barley and rapeseed) on number and speed of germinated seeds as well as early growth of 3 weed species (barnyard grass, lambs quarters and redroot amaranth) and one goal crop (tomato). Also distilled water was used as a control treatment. The experiment was done in two conditions: laboratory and glasshouse based on randomized complete block design. Collected data were exposed to advanced statistical analysis including ANOVA and multivariate analysis (PCA). The results indicated that some extracts can reduce the germination and early growth of some weeds and crop, for example weed extract on barnyard grass, rapeseed extract on tomato and redroot amaranth. Thereby the application of these extracts may effectively control some weeds like barnyard grass and redroot amaranth. However some extracts affected positively the rate and speed of germination of some plants. Froe example rapeseed extracts increased barnyard grass germination and early growth. This result indicated the caution of using of specific extracts on plants.

Waterbirds are exposed to many contaminants. Heavy metals like lead and cadmium are known as most important toxic pollutants in aqutic ecosystem. Elements poisoning had never been reported in Larus birds (Larus heuglini) in Iranian Mangrove Biosphere. The aim of this investigation was the measurment of metal concentration on Liver, Kidney and muscle tissues of larus in Mangrove Biosphere. Fifteen birds were collected on November 2010. The result indicated that the average lead, cadmium and zinc level were highest in kidney and lowest in muscle. For male and female, there was no significant difference in tissues concentrations for Cd and Pb. In the present study, levels of Cd and Pb in tissues no change with age. However, the concentrations of trace elements in Larus heuglini were generally comparable to values reported in other studies. The results of the investigation do not show an excessive exposure to cadmium, whereas some interesting data have emerged in the case of lead. The concentration of the latter in the liver and the kidney of larus seem to suggest the possibility of recent exposure.

The probability of Barnyardgrass resistance to some common rice herbicides used in Gilan, Mazandaran and Fars rice fields was investigated by conducting a series of greenhouse and Petri dish bioassay tests on 37 biotypes collected in 2005-2006. Greenhouse experiments implied screening tests with Petri dish tests implementing dose response assays to determine doses of herbicides inhibiting root and stem length growth by 50% (ID50) as well to determine the sensitivity of biotype to herbicides. Screening tests were carried out for each province separately for a given herbicide using a randomized complete blocks design with four replications. Minimum recommended doses of Butachlor, Molinate, and Thiobencarb added to pots of 8cm water height before 2-leaf growth stage of Barnyard grass. Propanil were sprayed at 3-4 leaf stage. Measurement of dry weight, number of surviving plants and visual rating (based on EWRC rating scale) were made 4 weeks after treatments. A completely randomized design with four replications also used in Petri dish tests. Sensitive biotype was subjected to a range of herbicides doses resulting in 50% inhibition of root and stem growth and the response of biotypes to the ID50 of sensitive biotype was further studied. Root (for Propanil) and stem length (for Butachlor, Molinate, and Thiobencarb) was measured 7 days after treatments. According to results obtained from greenhouse and Petri dish assays, it was revealed that Barnyardgrass biotypes collected from Gilan, Mazandaran and Fars were not resistance to testes herbicides (Propanil, Butachlor, Molinate, and Thiobencarb). The results from Petri dish tests were correlated to those of greenhouse experiments.

In the third millennium, Tourism undoubtedly has been upgraded to one of the thriving bases of the global economy and on the base of findings, it has turned into the main economic source for many countries. Tourism, along with the many benefits, has many negative effects as well; coping with those, needs relying on a suitable approach and proactive measures by planners and mangers especially in the public sector. In this article we have attempted to study tourism development approaches, selecting the most suitable approach in relation to local community development. The spectrum of approaches includes: Boosterism, Economic (Industry-oriented), Spatial-Geographical, Community-oriented, and Sustainable Development which have been described and compared, using SWOT analysis and finally, the most appropriate approach in terms of the development of community-centered tourism have been elaborated.

Regarding careless consumption of fossil fuels in Iran and the resulting greenhouse gases emissions and related risks to the environment and human health, many attempts are undertaking to control the consumption. Agricultural sector is not exceptional from this vital and important issue. The objectives of this research were: (1) to determine amount of fuel consumption and related energy use in wheat fields in Gorgan, (2) to estimate environmental impact of consumed fuel using global warming potential (GWP), and (3) to explore options to optimize fue l consumption. Data were gathered from 6 representative fields by monitoring production practices and inputs used. Data were analyzed with regard to fuel consumption, energy inputs related to consumed fuel and greenhouse gases emission from the consumed fossil fuels. Fuel ranged between 53 to 123 L ha-1 and the energy of the consumed fuel varied between 2026 to 4664 MJ ha-1. Results indicated that seedbed preparation had the highest rate of fuel consumption (59.5 % of total) that followed by harvesting, irrigation and sowing operation, 10.5, 9.4 and 8.1 %, respectively. Average of greenhouse gases emission (CO2, CH4 and N2O) from the consumed fossil fuels was estimated as 244 kg equivalent CO2 ha-1. It concluded that through better farm management and more research it is possible to reduce fuel consumption and greenhouse gases emission.