it is necessary to care the quantity and quality of the water resources especially in arid and semi-arid regions. shahrekord plain where it has a 551 km2 total area, groundwater is discharging almost 255 mcm annually and uses for drinking and agriculture. the main objective of this study was classification of groundwater quality and comparison with the drinking water standard limits in shahreko...

Bahía Concepción (Gulf of California) was studied to describe some extremely low dissolved-oxygen values at the bottom of the bay. Surveys included measurements of vertical distribution of temperature, dissolved oxygen, nitrate, nitrite, phosphates and hydrogen sulfide. Thermal stratification from early spring to autumn and a well-mixed water column during the winter were present. Dissolved-oxy...

A strategy for sequential hydrocarbon bioremediation is proposed. The initial O(2)-requiring transformation is effected by aerobic resting cells, thus avoiding a high oxygen demand. The oxygenated metabolites can then be degraded even under anaerobic conditions when supplemented with a highly water-soluble alternative electron acceptor, such as nitrate. To develop the new strategy, some phenome...

dissolved organic nitrogen (don) is an important constituent of dissolved organic matter (dom). it has a considerable effect on total dissolved soil nitrogen and it is very important as a nitrogen source of many aquatic and terrestrial ecosystems. dissolved inorganic nitrogen, which is another form of total soil dissolved nitrogen, includes no3, no2 and nh4, which is very important for plant nu...

Denitrification is a microaerophilic, microbially-mediated process, by which nitrate is reduced to biologically-unavailable N2 gas; the reaction is generally coupled to the oxidation of organic carbon. We hypothesized that denitrification rates in groundwater in the Waquoit Bay watershed on Cape Cod, USA, were controlled by both nitrate and dissolved organic carbon (DOC) concentrations, and tha...

The occurrence of the iron-reducing phenomenon among some common fungi was studied. Results indicated that (i) the reduction of ferric iron to the ferrous state by fungi seems to be restricted to nitrate reductase-inducible strains such as Actinomucor repens, Alternaria tenuis, Fusarium oxysporum, and F. solani and (ii) the amount of dissolved ferrous iron may be reduced progressively by increa...

Several recent studies have shown that phytoplankton growth rate and production at 0”, 14O”W is physiologically limited by iron. Therefore, changes in iron supply to the euphotic zone will result in variations in phytoplankton growth. We show that the flux of iron to this region is dominated by upwelling of the iron-rich Equatorial Undercurrent waters. Variations in the depth and strength of up...

Background: This research aims to measure and study spatial changes, and the reason behind the increasing nitrate content in water wells in the Central District of Khodabandeh County in the Zanjan Province. Methods: The nitrate and nitrite content, electrical conductivity, dissolved oxygen, temperature, total hardness and pH were measured at 40 sampling stations in the study area. The obtained...

Limitations in nutrients and physicochemical parameters play a key role in aquatic ecosystems. The present study aimed to determine the influential physicochemical factors in the chlorophyll-a content for wetland management by identifying the restricting factors in primary production. Sampling was conducted during March 2017-February 2018. Factors such as water salinity, temperature, pH, nitrat...