Chemical properties of suface water-inflows and their effects on soils of Meyghan Lake in Arak

Abstract
Background and Objectives: Infiltered or runoff waters from uplands especially after raining can cause groundwater and water pollution in lowlands which affect soil quality. Monitoring and assesmnet of suface waters in dry lands that alive the wetlands is very important. The objectives of this study were to assess the quality of suface water-inflows to the Meyghan Lake and their consequences on the chemical characteristics of Meyghan wetland soils.
Materials and Methods: Manicipal wastewater of Arak, Shahrab River and wastewater of processing plant of sodium sulfate were sampled in May and November, 2014. Electrical conductivity, differnt solids, major cations and anions, nitrogen, phosphorus and organic carbon were measured and tested in the waters. Two layers (0-30 cm and 30-60 cm) of soils were sampled in the release sites of municipal wastewater, Shahrab River, Farahan River and sodium sulfate plant wastewater in May and November, 2104. Soil chemical properties were measured and statisticaly analized for these 4 sampling sites.
Results: The study showed that manicipal wastewater of Arak has significantly lowere salinity, sodium adsorption ratio, cations and anions concentrations and solids as compared to other sampled waters. But organic carbon, nitrogen and phosphorus concentrations were higher in this water that significantly decreased the salinity and increase organic carbon, phosphorous and nitrogen contents of the soil sampled from this site. The improvement of soil properties can increase aquatic plant growth, which will be the source of water pollution with plant residues and organic materials. In conterast the wastewater of sodium sulfate processing plant has markedly high concentrations of soluble salts, sodium adsorption ratio and particularly suspension solids. It is not suitable for plant growth and can change soil physical properties in this site. Chemical properties of water of Shahrab River were close to the chemical properties of surface and bottom layers of soil in this place. It shows that the the harmony and stability of soil and water environment in this sampling site. But study of surface and bottem layers of wetland soil in the release site of Farah River shows that the surface soil has higher organic carbon, nitrogen and phosphorus contents and lower salinity compared to those measured in the soil sampled from Shahrab River site. It may be related to anthropgenic effect in agriculral uplands, creating a good environment for plants growing in this salty lake, increasing its pollution by plant residues and organic matters.
Conclusion: The high quality of urban wastewater of Arak may improve soil chemical properties for growing of plants. In contrast the low quality of wastewater of sodium sulfate processing plant worsened soil chemical properties. So combining of two waste waters and mixing them before releasinge into the Meighan Lake may be a good suggestion. However this proposal needs a special research.