MINISTRY OF EDUCATION
AND TRAINING
VIETNAM ACADEMY
OF SCIENCE AND TECHNOLOGY
GRADUATE UNIVERSITY SCIENCE AND TECHNOLOGY
----------------------------
NGUYEN QUOC THANG
THE ACCUMULATION, ELIMINATION AND
EFFECT OF HEAVY METALS (As, Cd, Pb)
ON CORTISOL LEVELS IN OREOCHROMIS SP.
Major: Inorganic Chemistry
Code: 9.44.01.13
SUMMARY OF CHEMISTRY DOCTORAL THESIS
Ho Chi Minh City - 2018
The dissertation was completed at: Graduate University of Sciences
and Technology, Vietnam Academy of Science and Technology;
Institute of Applied Materials Science; Industrial University of Ho Chi
Minh City, Korea Instite of Toxicology – Gajeong-ro, Yuseong-gu,
Daejeon; The Department of Biology and Chemistry - Changwon
National University; HoChiMinh City Institute of Resources
Geography.
Scientific Supervisors:
1. Assoc. Prof. Dr. Le Van Tan
2. Assoc. Prof. Dr. Nguyen Thi Kim Phuong
1 st Reviewer: ...........................................................................
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2 nd Reviewer: ..........................................................................
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3 rd Reviewer:...........................................................................
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The dissertation will be defended at Institute of Applied Materials
Science, Graduate University of Science And Technology, Vietnam
Academy of Science and Technology, 01A, Thanh Loc 29, Thanh Loc
ward, 12 District, Ho Chi Minh City.
At ….. hour….. date….. month …..2018.
The dissertation can be found in National Library of Vietnam and the
library of Graduate University of Science And Technology, Vietnam
Academy of Science and Technology.
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INTRODUCTION
1. The necessity of the thesis
Heavy metals are particularly significant in ecotoxicology because
of their toxicity, persistence, and bioaccumulation in the food chain.
Among aquatic organisms, fish are particularly sensitive to many
toxicants and are valuable bioindicators for an estimation of the metal
pollution level. Fish typically occupy higher positions in the aquatic
food chain and may accumulate metals and pass them to human beings
through food, which can cause chronic or acute diseases. It is well
known that heavy metals easily accumulate in bones, gills, kidneys,
and the liver of fish and can cause various detrimental effects. Heavy
metals can induce histological changes and can cause changes in
enzymatic activity, carbohydrate metabolism and electrolyte levels;
they can also introduce metallothionein and reduce glycogen content,
leading to disturbances in neuromuscular transmission and
contraction, and can alter metabolic functions and impair
detoxification mechanisms. The routes of metal uptake in fish are
through the gills, the digestive system and the skin. Therefore, the
importance of studies of heavy metal bioaccumulation in fish, which
represent a valuable source of food for humans, in the context of
environmental pollution, seems unquestionable.
2. Objectives
Study on the accumulation, elimination of heavy metals (As, Cd,
Pb) and its effects on plasma cortisol levels in Oreochromis. sp in
waterborne.
3. Research scope and content
- Study on Lethal Concentration 50 (LC50 - 96 hours) of As and
Cd and Pb in Oreochromis sp.
-The accumulation, elimination of heavy metals (As, Cd, Pb) in
Oreochromis sp. in exposure phase and elimination phase.
- The effects of heavy metals (As, Cd, Pb) on plasma cortisol
levels in Oreochromis sp.
4. Structure of the thesis
The dissertation has 112 pages, including the Preface, Chapter 1:
Overview, Chapter 2: Experiment, Chapter 3: Results and discussions,
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Conclusions, Publications, with 43 images, 17 tables and 194
references.
Chapter 1. OVERVIEW
Cadmium belongs to a group of toxic metals which have no
function in the physiological processes of human, thus its
bioaccumulation in different organs and tissues of living organisms
exposed to Cd is a common occurrence.
Lead can enter the human and cause several unwanted effects,
such as: Disruption the biosynthesis of haemoglobin and anaemia, a
rise in blood pressure, kidney damage and subtle abortions, disruption
of nervous systems, brain damage. The LC50 values of Pb was vary
from species to species and organism age.
Main effect of As were coagulation of protein, reaction coenzym
to complex, destroys the phosphate. Arsenic combinate with
sulfhydryl groups of mitochondrial enzymes and prevents cellular
respiration. Inorganic As (III) was the most toxicity.
The major routes of toxic chemistry uptake in organism are
through the respiratory system, the digestive system and the skin.
Metals enter to the cell via membrane protein transporters and passive
diffusion through the cell membrane. The accumulation of heavy
metals in fish tissue is dependent on numerous of factors including
water concentrations of metals, exposure period, water temperature,
oxygen concentration, pH, hardness, salinity, alkalinity and dissolved
organic carbon, …The elimination of metals from the tissues depends
on time, age, metabolic activity, interacting agents, the biological half-
life of the metals and aquatic species. Toxic chemistry got into the
other organs from the blood, in here, it was bio-transformed,
eliminated or accumulated. The rate of elimination depend on toxic
chemistry concentration, metabolic activities in fish and depended on
metal species.
Cortisol is the most potent and abundant glucocorticoid secreted
by the outer cortex of the adrenal gland. Cortisol plays an important
role in mobilizing fuels such as glucose, lipids, and fatty acids, for the
maintenance of homeostasis. Additionally, it exerts direct and
indirect effects on an organism’s intermediary metabolism,
particularly in response to stress. In some cases, stress can lead to
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disease and/or death. Factors such as water pollution, grading,
handling, transportation, and vaccination cause stress for fish. Cortisol
is one of the most common stress indicators in fish.
In recent years, accumulation of heavy metals in aquatic organism
have attracted the intention of many research groups. Mohammed
Aldoghachi Jasim Aldoghachi (2016), Kah Hin Low (2011), Abdulali
Taweel (2011) Mohammed Aldoghachi Jasim Aldoghachi et al.
(2016) reported on heavy metal accumulation in fish living in the
natural environment. Several previous studies documented that metal
accumulation in the liver tissue was higher than in muscle (Elzbieta
Kondera, 2014, El-Moselhy KM, 2014, Canli M, 2003). Many authors have
reported that gill have a high tendency to accumulate heavy metals
(Wong et al. 2001, Altındağ and Yiğit, 2005, Karadede-Akin and
Ünlü, 2007). In Vietnam, several studies have been conducted on the
accumulation of heavy metals in plants and bivalve mollusk. No
research has been done to study heavy metals accumulation and
biochemical changes in fish.
In general, until now, no work has been done to study on the
accumulation, elimination and effects of heavy metals (As, Cd, Pb) on
the biochemical composition of Oreochromis sp.
Chapter 2. EXPERIMENT
2.1. LC50 test
Oreochromis sp. were exposed to waterborne arsenic or cadmium
or lead at each concentration for 96 h. Thirty fish were randomly
assigned to each treatment, and each treatment consisted of three tanks
with ten fish per tank. Fish mortality was recorded after 0, 24, 48, 72,
and 96 h of exposure to heavy metal solution. LC50 value was
calculated by simple graphic method.
2.2. Sub-chronic exposure
Oreochromis sp. were divided into seven treatments, which were
exposed to control water (control treatment) and water contaminated
with different concentrations of arsenic or cadmium or lead (3.5%, 5%,
and 10% of 96 h LC50):
- As concentrations: 1.00 mg/L; 1.50 mg/L and 3.00 mg/L.
- Cd concentrations: 0.66 mg/L; 1.00 mg/L and 2.00 mg/L.
- Pb concentrations: 0.12 mg/L; 0.18 mg/L and 0.33 mg/L.