Distribution and Bioaccumulation of Zinc, Nickel, Lead and Cadmium in Water, Sediment and Some Biota of Al-Gharraf River South of Iraq

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Distribution and Bioaccumulation of Zinc,
Nickel, Lead and Cadmium in Water, Sediment and
Some Biota of Al-Gharraf River South of Iraq

• Introduction
  
• Al- Gharraf is a branch of Tigris River, it is
  considered as the third largest river in Iraq,
  begins near Kut city and runs through Wasit and
  Dhi-Qar provinces, it impacts greatly on the
  socio-economic aspects of that area. It is the
  main water source for agriculture and public
  water supply. The river receives most of the
  wastewater from many cities including industrial,
  agricultural, and domestic wastewater. Associated
  with the development of the area, the increase of
  pollutants into the river has been a recent cause
  for alarm. There is no conducted surveys on heavy
  metals in the river, however little is known
  about metal bioaccumulation in aquatic species
  inhabiting the river.

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Trace elements in biological systems

• Trace elements occur in minute concentrations in
  biological systems, they may exert beneficial or
  harmful effects on plant, animal, and human life
  depending upon their concentrations.
  
• These elements are introduced into aquatic
  systems, rivers, lakes oceans through atmospheric
  fallout, dumping wastes, accidental leaks, runoff
  of terrestrial systems (industrial, agricultural
  and domestic effluents) and geological
  weathering.
• Through the processes of precipitation,
  sedimentation and a variety of factors such as
  chemical reactivity, land use pattern and
  biological productivity, some of the heavy metals
  that are introduced in an aquatic system are
  deposited in the sediment, aquatic plants and
  organisms.
• Although some HMs such as manganese, iron,
  copper, and zinc are essential micronutrients,
  others such as mercury and lead are not required
  even in small amounts by any organism.
  
• Some HMs became a matter of concern because of
  their toxicity and tendency to accumulate in food
  chains. Fish, mollusks or another aquatic life
  located at the end of the aquatic food chain may
  accumulate metals and pass them to human beings
  through food causing chronic or acute diseases.

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The Aim of This Study

• ? To assess the HMs contamination in water,
  sediments and biota, in order to effectively
  monitor and provide possible recommendations to
  improve the water quality in the aquatic
  ecosystem of Al- Gharraf River.
• ? Compare HMs concentration in mixed
  zooplankton, the mosquito fish Gambusia affinis,
  the freshwater shrimp Caridina babaulti basrensis
  and the aquatic plant Ceratophyllum demeresum, to
  compare potential biomonitors of HMs pollution in
  the river.

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Materials and Methods

• The Study Area
• Four sites along the river were selected for
  sampling, these were Kut (upstream site), Hai
  and Qalat Sekar (urban areas) and Bada'a
  (downstream site) with a distance of about 50 km
  between stations. Sampling was conducted from
  October 2009 to September 2010 which included all
  the dry and the wet seasons.

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Sampling Stations on Al-Gharraf River.
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Figure ( 7 ) Bada'a Head Regulator (the forth
station) Summer 2010.
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Field Measurements

• Water temperature, salinity, electrical
  conductivity, dissolved oxygen, total dissolved
  solids, water turbidity and pH were measured in
  each station to know their correlation with the
  concentrations of metals. Four heavy metals were
  investigated monthly in water and seasonally in
  sediment and tissues of three commonly aquatic
  species, namely the mosquito fish Gambusia
  affinis, the freshwater shrimp Caridina babaulti
  basrensis, the submerged aquatic plant
  Ceratophyllum demeresum and mixed zooplankton
  from the river. The metals studied were Zn which
  is known as an essential metal for metabolism in
  organisms, Pb which have no known function in
  biota, Ni and Cd which are micronutrients needed
  in a few organisms.

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Samples Collection and Heavy Metals Analysis

• Water and sediment samples were collected at each
  site and preserved at 4C prior to analysis.
  Enough quantities of the mentioned biota were
  also collected at each site. Water samples were
  filtered with Millipore (0.45 µm) filters and
  treated with HN03 and HCl on a hot plate
  following the method of the (APHA, 2003).
  Sediment was digested using HN03, H202 and HCl
  at 95C according to the method of (USEPA, 1991).
  Aquatic biota samples were prepared and acid
  digested according to (US-EPA, 1991) method. Zn,
  Ni, Pb and Cd in all samples were measured by
  Flame Atomic Absorption Spectrophotometer Phoenix
  986 AAS.

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Heavy Metals Analysis
Figure (13) Atomic Absorption Spectrophotometer
Phoenix 986 AAS.
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Instruments that were used in field and lab works.
Figure (12) a Multi-Parameter (Multi 340i WTW)
b Turbidity meter type WTW (TURB 355 IR/T) c
Global Positioning System (GPS) Geko 201.
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RESULTS AND DISCUSSION

• Results showed that the general annual average of
  Zn, Ni, Pb and Cd in filtered water were 3.36,
  2.14. 10.27 and 0.34 µg/L respectively, in
  sediment were 80.3, 161.1, 16.84, 1.12 µg/g
  respectively. The annual concentrations in the
  mosquito fish were 66.9, 7.17, 1.35 and 0.34 µg/g
  respectively , in the aquatic plant were 13.06,
  7.29, 2.05 and 1.19 µg/g respectively, in the
  freshwater shrimp were 34.82, 2.56, 0.4 and 1.22
  µg/g and in mixed zooplankton were 38.05, 16.35,
  1.01 and 0.58 µg/g respectively.

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Table (18) The general annual concentration
average of the studied metals in Filtered water,
sediment and aquatic biota of Al- Gharraf River
during the study by ppm unit.
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The Bio-Concentration Factor (BCF) and the Bio-
Sedimentation Factor (BSF)

• The Bio-Concentration Factor (BCF) of the studied
  metals in the aquatic biota of Al-Gharraf River
  followed this order
• Ni gt Cd gt Zn gt Pb and the order of
  Bio-sedimentation Factor (BSF) in biota was as
  follow Zn gt Cd gt Pb gt Ni
• The general concentration order of the studied
  metals in the river water was Zn gt Pb gt Nigt Cd,
  in sediment was Ni gt Zn gt Pb gt Cd and in all
  studied biota was Zn gt Ni gt Pb gt Cd
• The ANOVA test showed significant relationship
  among metals in water , sediment and biota,
  therefore it was concluded that the metals came
  from the same source and the selected biota
  samples reflected the metals in the environment.
  The variations of metals in the river and biota
  maybe a result of the change of influencing
  factors in the area and the growth season of
  biota. There were positive correlation among
  metals concentrations in water sediment and biota
  with Temp. , Con. and Sal., but negative with
  pH, DO and Turbidity The results of this study
  clearly demonstrates that the mosquito fish, the
  freshwater shrimp and mixed zooplankton are good
  potential bio-indicators for metals in Al-
  Gharraf River since they reflected concentrations
  of metals in their environment.

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Figure (46) The Bio-Concentration Factor (BCF)
of the studied metals in some aquatic biota of
Al-Gharraf River.
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Figure (47) The Bio- Sedimentation Factor (BSF)
of the studied metals in some aquatic biota of
Al-Gharraf River.
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In the field
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