Hydrogeochemistry of the sawa lake, Southern Iraq

Other Title(s)

هيدروجيوكيماء بحيرة ساوه جنوب العراق

Dissertant

al-Qurayshi, Rua Isa Muslim

Thesis advisor

Awad, Salih Muhammad

Comitee Members

Ali, Sawsan Majid
al-Khafaji, Abd al-Sattar J.
Jasim, Rafi Zair

University

University of Baghdad

Faculty

College of Science

Department

Geology Department

University Country

Iraq

Degree

Master

Degree Date

2013

English Abstract

Hydrochemistry of the Sawa Lake water and geochemistry of its sediments are studied.

Twenty three water samples were collected from the lake during both dry (7/10/2011) and wet periods (22/3/2012), as well as three groundwater samples that are collected from wells adjacent to the lake in the wet period.

Nineteen samples are collected from the lake sediments during the dry period of the year 2011. Water samples are analyzed for physico-chemical parameters which included turbidity, color, taste, odor, total suspended solid (TSS), hydrogen number (pH), total dissolved solid (TDS), electrical conductivity (EC), and temperature (T), major cations (K+, Na+, Mg2+, Ca2+), major anions (Cl-, SO4 =, HCO3 -, CO3 =), minor anions (PO4 3- and NO3 -), trace elements (Pb, Cd, Ni, Fe, Mn, Co, As, Cu, B and Sr), radiation measurements (226Ra, 137Cs, 40K, 228Ac, 232Th, 238U, and 214Bi).

Biological analyses such as dissolved oxygen (DO), biological oxygen demand (BOD), chemical oxygen demand (COD), and some bacterial tests also are achieved.

The results of the Physico-chemical parameters analysis are compared with international standards and classifications to assess the water quality for different purposes. Hydrochemically, Sawa Lake water is classified as brackish to saline of alkaline water, while ground water taken from wells was slightly-brackish water.

The chemistry of Sawa Lake differs from the groundwater of wells is characterized as Mg-chloride whilst, wells water are Mg-sulfate.

Genetically, the source of the lake water is deep ground water of marine origin ascending upwards through cracks and joints to be mixed with shallower water of aquifers underneath the Lake, especially the Euphrates, Dammam and Umm Er Radhuma aquifers.

It reaches the surface filling the depression with water forming the lake body.

Trace elements concentration in the lake water (Zn, Pb, Cu, Cd, Ni, Co, As, Mn, Fe, Sr and B) is higher than their concentration in sea water, where B and Sr are characterized by very high concentrations. The radiation level in the sediment and water are within the acceptable limit.

But in sediment, radiation seems to be higher than its level in water. Two radioactive decay series are detected; these are 232Th decay series and 238U decay series as well as 40K, while the 235U decay series and 137Cs were not detected.

The radioactive isotope concentrations were recorded in higher level in sediments rather than that in the water Assessment of lake water for drinking (human and animal), irrigation, industrial and building purposes showed that the water quality is unacceptable for these purposes.

Sawa Lake is classified as bad water quality according to Water Quality Index (WQI).

Sawa Lake is characterized by limit of mechanical sediments, while, chemical precipitation is active. Generally, mechanical sediment is characterized by being fine particles settled from the atmosphere. Nineteen sediment samples were collected and studied in term of mineralogy and geochemistry.

Sawa Lake sediment is mainly composed of gypsum (87%) as dominant mineral, clay minerals (5.5%), quartz (4.5%) and halite (3%).

The lake is surrounded by a gypseous wall.

Gypsum plays major role in the process of building this wall by the equilibrium between evaporation and precipitation.

The length of gypsum barrier surrounding the lake is 12.5 km with 3-6 m high.

The Dissolution processes of the gypsum wall form caves, and collapses of part of this wall contributing to increase the surface area.

Many patterns of gypsum are identified.

The dominant oxides in the lake sediments are CaO (31%), SO3 (34%) and LOI (18%) which reflect the abundance of gypsum.

Other oxides, SiO2 (8.0%), Al2O3 (1.5%), MgO (3.0%) and Fe2O3 (0.6%), Na2O (1.5%) and Cl (2.0%) reflect quartz, clay minerals and halite.

Heavy metals (23 ppm Pb), (41ppm Ni), (19 ppm Co) in the Sawa Lake sediments are concentrated within the salts sediments with tendency to be more than the concentration of average of global soil, except Fe recorded a decrease in concentration.

Main Subjects

Earth Sciences, Water and Environment

Topics

• Iraq
• Sawa lake

No. of Pages

146

Table of Contents

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-609720