Thesis Abstract

The effect of xylene on the biochemical
and physicochemical properties and algal dynamics in culture were investigated
ex-situ between May, 26th and July 9th, 2017. The
biochemical and physicochemical parameters Viz Temperature, Dissolved oxygen,
Biochemical oxygen demand, and volume were analyzed. Air temperature ranged
between 25 – 310C, Water temperature ranged between 28 – 340C,
Dissolved oxygen ranged between 42 – 90mg/l, Biochemical oxygen ranged between
9 – 72 and Volume ranged between 1000 – 4000 ml. There was no significant
difference on all the parameters analyzed. The algal species present include Chlorella vulgaris, Scenedesmus acuminatus,
Cladphora spp, Oedogunium grande, Sururella spp and their pattern of
colonization is of the order Chlorella
vulgaris whichwas the pioneer species, followed by Scenedesmus acuminatus followed by Oedogonium grande followed by Sururella
spp followed by Cladphora spp. The
division Chlorophyta represented by Chlorella
vulgaris, Scenedesmus acuminatus, Cladphora spp, Oedogunium grande and Sururella spp were the dominant group.
The result obtained in this study could be a useful tool in understanding the
bioremediation potential of various algal species.

Thesis Overview

1.0                                                   INTRODUCTION

Algae
are autotrophs in many aquatic ecosystems and are well represented in fresh
waters. Many factors contribute to algal diversity and reproduction, including
variation in nutrient supply and temperature (Turpin and Harrison, 1979). It is
known that microalgae respond with physiological alterations to the
environmental conditions where they grow (Scragg et. al., 2002, Valenzuela-Espinoza et. al., 2002). This behaviour can be viewed as biotechnological
attribute that can be manipulated in order to control the algae biochemical
composition and growth.

The
influence of physical and chemical environment on a water body together with
the rate of growth of individual species play important roles in algae
diversity. Among the physical factors, light and temperature are the major ones
that control the algal dynamics (Emeka et.
al., 2011). Physicochemical parameters are the major factors which controls
the dynamics and structure of the phytoplankton of aquatic ecosystems (Huyal
and Kaliwa, 2009). Changes in the physicochemical parameters may positively or
negatively affect the biota of water body in a number of ways which increases
the survival and growth rate and these may eventually result in the
disappearance of some species of organisms or its reproduction (Edward and
Ugwumba, 2010).

Temperature
has major structuring effects at all levels of biological organization. The
rate at which biochemical reactions occur is temperature dependent (Brown et. al., 2005). Temperature is important
because the rate of chemical reactions increases at high temperature which in
turn affects biological activities and growth of aquatic organism (Waziri et. al., 2012). The increase in water
temperature is an important factor when toxic substances are present in the
water. Most of the substances (cyanides, Xylene) exhibit increased toxicity at
elevated temperature. These toxicities and other physiological interactions are
also influenced by increased temperature and history of the species In an algal
culture, the optimal temperature for algal survival is generally between 200C
and 240C, although may vary with the composition of the culture
medium and the strain culture.

Most
phytoplankton isolates originating from alkaline lakes reach their optimum
growth rate and photosynthetic capacity at a neutral and alkaline pH and are
unable to survive in acidic conditions. Whether a species can grow at neutral
pH or not defines it as acid-tolerant or acidophilic specie (Gross, 2000).
Maintaining an alkaline, cystolic pH is one of the major problems these
organisms are faced with as many enzymes are highly pH dependent and become
inactive at acidic pH values (Gimmer, 2004). The pH in water governs biological
processes while temperature in water governs the availability of oxygen
(Kowalkowski et. al., 2006).

Both
aquatic plant and animals depend on dissolved oxygen (DO) for survival. DO is
important in aquatic ecosystem because it determines the types and abundance of
species that can survive and flourish there (Huyal and Kalliwa, 2009). The
maximum concentration of oxygen that can be dissolved in water is a function of
temperature and therefore, dissolved oxygen of water may vary from place to
place and from time to time (Prasad and Patil, 2008). Fluctuations in dissolved
oxygen are due to fluctuations in water temperature and addition of sewage
waste demanding oxygen (Koshy and Nayar, 2000). The dissolved oxygen of water
is greatly affected by the content of Biochemical oxygen demand (BOD). BOD
determination is used to measure the amount of organic material of an aquatic
system, which supports the growth of organisms (Keramat, 2008).

The
persistence of organic pollutants introduced into the environment through
industrial discharges, or improper waste disposal practices poses a chronic
threat to the health of human and wildlife (Pavlostathis et. al., 2001). Depending on biogeochemical processes, many organic
pollutants like hydrocarbon are involved in adsorption, desorption and
transformation processes and can be made available to benthic organisms as well
as organisms in the water column through the sediment-water interface (Perele,
2010). Investigations on organic xenobiotics bioaccumulation/ biodegradation in
green algae are of great importance from environmental point of view because
widespread distribution of these compounds in agricultural areas has become one
of the major problems in aquatic ecosystems (Jin et. al., 2012). The algae proved to be effective in hyper
accumulation of heavy metals as well as degradation in xenobiotics (Suresh and
Ravishankar, 2004).

The
impact of xylene on the biochemical and physicochemical properties and algal
dynamics are presently unknown as there is no documented information. Thus,
this study was structured with the following aims:

1.                
To determine the effect of xylene on
physicochemical properties of water.

2.                
To determine the effects of xylene on
biochemical properties of water.

3.                
To determine the effect of xylene on
algal dynamics.