Environmental Engineering Reference
In-Depth Information
organs that contain fats, like kidneys and liver, where they changed into different
substances that may even be more harmful than the original PAHs
[13]
.
Due to the toxicity of PAHs, particularly their carcinogenic and mutagenic char-
acter, they are listed by Environmental Protection Agency (EPA) as priority pollut-
ants because they have negative impact and also affect quality of life negatively
[14]
. Due to their environmental importance, PAHs have been studied extensively
in mussels, surface runoff, sediment and soil
[10, 15-17]
. The increasing presence
of these compounds necessitates their regular monitoring in the environment.
In South Africa however, particularly in the study area, the status of PAHs is not
clearly known because of paucity of data (these compounds are rarely studied)
which might be due to analytical problem of recovery from complex matrices. Due
to the complexity of the matrix and the very low concentrations they are found to
be present in aqueous media, PAH determination in environmental samples is often
a difficult task even after fractionation of sample extracts, therefore good chromato-
graphic selectivity both in separation and detection are required during environ-
mental analysis
[2, 18]
This study investigates the levels of PAHs (pyrene, azulene, anthracene, diben-
zothiophene and fluoranthene) in some rivers and surface runoffs in Venda,
Limpopo Province of South Africa. This relatively poor region of South Africa is
subjected periodically to environmental degradation because of poor water sully
and infrastructure. Many people in this region are still using water directly from
streams and rivers in the area for household purposes.
Materials and Method
The study area in this work was the Vhembe district in the Limpopo Province of
South Africa (Fig.
1
). Thohoyandou is the major town in the area and it is the capital
city of the former Venda homeland.
Quality Assurance Studies
Validation of liquid-Liquid extraction procedure for analysis of PAHs in water
samples was done by extracting spiked doubly distilled water with dichlo-
romethane. As indicated in the tables below, 1 mL of 1,000 mg/L standard mixture,
consisting of the six PAHs mixtures, were added to 500 mL of doubly distilled
water. This was first pre-extracted thrice with 30 mL dichloromethane to serve as
blank sample. Spiking of sediment samples was done by adding 1 mL of 1,000
mg/L PAH standard mixtures to 10 g of dried sediment (also pre-extracted
with 30 mL of dichloromethane). The spiked water and sediment samples were
then extracted and analyzed using the methods described below for water and
sediment samples.
