a b s t r a c tBenthic macroinvertebrate communities from the middle of Zayandeh Rud River were analyzed monthly during 1 year at 8 stations, in order to assess changes in their diversity and richness in relation to water quality. Two major groups of sites based on similarity between macroinvertebrate communities were identified by cluster analysis. The performances of the original and revised BMWP score systems were assessed by comparing the community structure indices of benthic macroinvertebrates along with physico-chemical parameters of the water. The biotic indices (BMWP, ASPT, revised BMWP and ASPT) showed better correlation with water quality parameters than that of the richness and diversity indices. The revised ASPT had the highest correlation with water quality parameters. It seems that the application of the revised BMWP score system could be useful for assessment of the water quality in Zayandeh Rud River.
Water quality of the Zayandehrud River, located in an arid region of central part of Iran, was assessed using National Sanitation Foundation Water Quality Index (NSF WQI) calculated by four aggregation methods. Water samples were collected monthly (July 2006 to June 2007) from eight stations in the middle of the river. The parameters required for the NSF WQI calculations including saturation percent of dissolved oxygen, biochemical oxygen demand, fecal coliforms, pH, nitrate, total phosphate, temperature deviation, total dissolved solids and turbidity were measured. According to WQI(m) which appeared to be more adapted to environmental conditions of the Zayandehrud River, the studied section of the river was considered as "reasonable" to "polluted" water quality. All of the calculated water quality indices showed the lowest values in August. In addition to BOD(5) and fecal coliform amounts which were generally high, nitrate and total phosphate concentrations were also considerably increased due to agriculture practices in August. Generally, BOD(5) and fecal coliforms are the main water quality subindices that reflect the effect of anthropogenic activities on the water quality of this river.
Contamination by polycyclic aromatic hydrocarbons (PAHs) in the southwest Caspian Sea was assessed by examination of 45 sediment samples, collected from the coasts of the Guilan Province in 2012 and analyzed for 29 PAHs. The concentrations of PAHs were in the range of 232.1-1,014 ng g(-1) dry weight (mean 520±246.4 ng g(-1)). The predominance of alkyl-substituted naphthalenes and phenanthrenes and the higher contributions of petrogenic compounds (NPD=35.4-74.4%) compared to pyrogenic PAH compounds (COM=18.1-47.4%) reveal a petrogenic source for PAHs with ubiquitous distribution in the study area. Offshore increase of total PAH concentrations was found to be correlated with increase of organic matter content of sediments, but no correlations with particle size fractions were found. The evaluation of ecotoxicological risk by sediment quality guidelines indicated that total PAH concentrations at all sites were below the effects range-low (ERL), but some individual petrogenic PAHs at some stations were significantly above their ERL and likely to adversely affect benthic biota. According to the diagnostic ratios used, most stations revealed the major source of the PAHs to be petrogenic, but some stations suggested a mixed petrogenic-pyrogenic source.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.