Benthic macroinvertebrate-based indices are suitable tools for assessment of stream health and human impacts on its biological integrity. Since Ghale Rudkhan River is an attractive tourist destination and its surrounding population is growing, its water quality was examined usning biological indicators. Macroinvertebrate samples were taken monthly by a Surber sampler (mesh = 300 μ,and area = 900 cm2) at five stations from May to December 2017. Samples were preserved in ethanol 96% and transported to laboratory for analysis. Total abundance, EPT index, EPT richness and percentage, EPT/CHIR ratios were determined. In total 5134 macroinvertebrates that belong to 35 genera, 30 families, 10 orders, 4 classes and 3 phyla were identified. The highest EPT richness was observed at the station no. 4 in May (607 ind. m-1) and the lowest was at the station no. 5 in October (7 ind. m-1). The presence of pollution sensitive species such as Epeorus sp. Rithrogena sp., Rhyacophila sp., Isopela sp., Gomphus sp., Cordulegaster sp., Coenagrion sp., Oligoneuriella sp., Heptagenia sp., Philorus sp. in Ghale Rudkhan River indicated the optimal quality of the river water.

Species diversity of macrobenthos in Fusheh River, in Guilan Province, North Iran was studied and biological indices developed based on macroinvertebrates were used to evaluate the health status of the river. Macrobenthos sampling in the river was carried out at 4 stations on a monthly basis beginning from May to December 2016 using a Sorber sampler (mesh size of 300 μm and surface area of 900 cm2) with three repetitions. The sampled macrobenthos were preserved in 96% ethanol and transported to the laboratory for identification. A total of 4928 individuals from two phyla of Arthropoda and Annelida, three classes of insects (Insecta), crustaceans (Crustacea) and Clitellata as well as 8 orders (including Ephemeroptera, Trichoptera, Plecoptera, Diptera, Coleoptera and Haplotaxida) along with 25 families and 31 genera were identified. The most abundant genera were Simulium sp. (35.84-46.65%), Hydropsychae sp. (15.79-33.36%) and Baetis sp. (7.87-17.66%). Parameters of total abundance, EPT richness, EPT percentage and EPT/CHIR ratio were also calculated. The EPT richness showed a significant difference in monthly samplings (p<0.05). The presence of species sensitive to pollution such as Perla sp., Isoperla sp., Chloroperla sp., Oligoneuriella sp., Heptagenia sp., Rithrogena sp., Epeorus sp., Rhyacophila sp. and Philorus sp. belonging to orders Trichoptera, Plecoptera and Ephemeroptera exhibits both the good quality of river water and the desirability of species and genera as natural food for the river fish species.

The invertebrates are one of the most important terrestrial fauna and freshwater taxa. Benthic macroinvertebrates include aquatic insects and spiders, mites, crustaceans, and species of mollusks and worms that are aquatic in their immature stages and terrestrial in their adult stage. Jajrud River originates from the Alborz Mountains and is a source of drinking water for people in eastern part of Tehran and the surrounding villages. For the taxonomic identification of benthic macroinvertebrates, five stations downstream of Jajrud were used. A Surber sampler device was used for sampling with dimensions 30 × 30 cm and mesh size of 250 microns in all four seasons of the year 2013 with three repetitions at each station. In total, five orders (Ephemeroptera, Coleoptera, Diptera, Trichoptera, and Oligochaeta) and 13 families of benthic macroinvertebrates were identified. In all stations, the family Baetidae (Baetis sp. ) belonging to the order Ephemeroptera had the highest abundance, and seasonally the highest abundance was detected in autumn, winter, summer, and spring respectively. After the identification of benthic macroinvertebrates, five biotic indices including EPT, HFBI, SIGNAL, NJIS, and MMIF were calculated for water quality assessment in downstream of the Jajrud River. Regarding the results of the biotic indices, it can be said that the water quality of downstream of Jajrud River is not favorable. Therefore, appropriate management measures should be taken to improve river water quality.

Dear Editor, The nature of the effluents produced in an environment could be understood by sampling and examining materials and particulates in wastewater, and various methods are chosen and implemented for treating and eliminating pollutants (1). The validity of the analyzed data depends greatly on the precision of the sampling procedure (1, 2). Conventional and traditional wastewater sampling is often performed manually using a container attached to a rod or stick (2). . .

The aim of this paper is to learn a Bayesian network structure for discrete variables. For this purpose, we introduce a Gibbs sampler method. Each sample represents a Bayesian network. Thus, in the process of Gibbs sampling, we obtain a set of Bayesian networks. For achieving a single graph that represents the best graph fitted on data, we use the mode of burn-in graphs. This means that the most frequent edges of burn-in graphs are considered to indicate the best single graph. The results on the well-known Bayesian networks show that our method has higher accuracy in the task of learning a Bayesian network structure.

Background: Benzene, toluene, ethylbenzene and xylene (BTEX) compounds are components of motor vehicle fuel. BTEX are released from exhausts of vehicles and also evaporation from the fuel tank, carburetor and crank case of engines. BTEX are dangerous chemicals that participate in photochemical reactions and produce secondary air pollutants such as ozone, peroxyacethyl nitrate, free radicals and nitrogen oxides. BTEX in ambient air of metropolitan areas has been the subject of concern in many studies through elaborate "Environmental Protection Agency" (EPA) method. Level of BTEX in the ambient air of major Iranian cities, has not been measured in concentration range of part per billion (ppbv) due to the inadequate sensitivity of available gas chromatography systems. The aim of this study was to improve the sensitivity of gas chromatography by using a special sampler and thermal desorber (Micro-Packed Injector).Materials and Methods: Our sampler consisted of a 5-centimeter stainless steel tube one millimeter in diameter packed with carbopacked B heat-conditioned samplers utilized for sampling atmospheric BTEX. It was subsequently injected to a custommade thermal desorber (225°C) which was assembled onto the injection port of a gas chromatography device for analysis.Results: BTEX standard atmospheres were analyzed with a gas chromatograph flame ionization detector (GC-FID) with linear range detection of 27.5-275ppb, 23.1-223.6ppb, 20-320-ppb, and 20-320ppb respectively.Conclusion: The Micro-Packed Injector (MPI) installed on ordinary GC-FID improved linear range detection of BTEX from previous ppm detection to ppb range.