Environmental Chemistry: Pesticides, Biogeochemical Cycles, and Pollutants

This article discusses various topics in environmental chemistry, including pesticides, biogeochemical cycles, and pollutants. It covers the impact of carbon-based chemicals, organochlorine pesticides, and sulfate pollutants on human health and the environment.

Running head: ENVIRONMENTAL CHEMISTRY
1
Environmental chemistry
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Institution:

ENVIRONMENTAL CHEMISTRY 2
1a, both compounds have hydroxyl group and two dichlorine atoms attached on different
positions on benzene ring. 2, 5-dichlorophenol has chlorine atoms attached on position 2 and 5
while 2, 6-dichlorophenol have chlorine attached on positions 2 and 6 (ortho positions).
b, The possible flaw which exists is that occasionally UV light forms toxic intermediates while
attempting to make octochlorodibenzo-p-dioxin, because it does not fit into the AH receptors.
2, They are insoluble in water but soluble on lipids, poor biodegradable and have strong thermal
stability. PCBs (polychlorinated biphenyls) are chlorinated aromatic compounds with poor
biodegradable, strong physical and chemical stability, low vapor pressure, and high dielectric
constant, chemically inert, non-flammable and inexpensive to produce (Manahan, 2017, pp. 45).
Furan can either be synthetic or naturally moieties such as terpenoids or steroids while dioxin is
produced synthetically.
Other chemicals which are carbon based include; first, pyrethroids which are analogs of
pyrethrum (naturally occurring insect repellent) present in chrysanthemum. Secondly,
thiadendazole and thiaphanate is systematic fungicides which are carbon based and synthetic.
1: example of organic pesticides include; retonone, nicotine, and pyrethrum. Inorganic are
silicates, borated and sulfur (Fest & Schmidt, 2012, pp. 13).
2, Pesticides are grouped according to the type of pest they kill
Insecticides-insects
Herbicides-plants
Bactericides-bacteria

ENVIRONMENTAL CHEMISTRY 3
3, organochlorine pesticides such as HCH and DDT have less biodegradability, stable chemical
properties, persistent organic pollutant, and high risk to the human and environmental health
(Fest & Schmidt, 2012, pp. 14).
4, organochlorine compounds work on insect by opening sodium ion channel in the nerve cells or
neurons of pests, causing them to fire spontaneously. The pest will go into spasms and eventually
die (Reimann & De Caritat, 2012, pp. 80).
5, carbamate acts by binding to and inhibiting the normal action of acetylcholinesterase. Thus,
AChE inhibitors may influence the response to stress and thermoregulation (Manahan, 2017, pp.
48).
Figure 1: structure of carbamate
6, part per billion, part per trillion and parts per million
7, DDT was developed as the key of the contemporary synthetic insecticides in the 1940s. It was
first used with significant effect to fight typhus, malaria and other insect-borne human ailment.
Additionally, it was useful for the insect control in livestock and crop production. The DDT is
currently used to control mosquitos.

ENVIRONMENTAL CHEMISTRY 4
8, BCF is ration of the steady state chemical concentration in water-inhaling body. The water is
examined in a controlled laboratory trial in which test organism are exposed to a chemical in the
water (Reimann & De Caritat, 2012, pp. 83).
BCF=[C organism] at steady state (mgkg-1 wet weight)/[C water] at steady state (mgI-1) =K1/K2
(Manahan, 2017, pp. 51).
QSAR models approaches to estimates BCF is possible and important.
9, Epoxides can be hydrolyzed to generate diols
Carbonates-inorganic
Phosphates-inorganic
Propane-organic
Carbon monoxide-inorganic
Carbon dioxide-inorganic
1, 1-difluoroethane-organic
Dimethyl ether- organic
Water-inorganic
Cyclohexane-organic
1, 4-dichlorobenzene-organic
Chlorine-inorganic

ENVIRONMENTAL CHEMISTRY 5
Weakly assignment
A biogeochemical cycle is repeatable pathway by which molecule or chemical element moves
through abiotic or biotic components of the ecosystems. Some of the critical elements that are in
cyclic pattern are carbon, nitrogen, sulfur, oxygen, phosphorous, hydrogen and water (Manahan,
2017, pp. 46).
Question 1
In the atmosphere, both nitric oxide and sulfur oxide oxidation occur as result of NOx and SO2
which are produced by natural or synthetic process from industry. However, the oxidation of
SO2 causes the formation of sulfates which cools the planets as ozone tend to warm the earth.
Question 2
The two reactions occur in the stratosphere as they are significant concerns about anthropogenic
chemical perturbation to the ozone layer for the past four decades.
Question 3
I disagree as the nitric oxide is naturally and industrially made while sulfur dioxide has natural
and anthropogenic sources (human-made). During the biogeochemical cycles, the chemical
undergoes oxidation to form nitric and sulphuric acid which form nitric acid and acid rain.
Rainwater usually has pH of 5.6 below which is described as acidic (Manahan, 2017, pp. 55).
Question 4
Recent climate change is happening primarily due to rising level of greenhouses gases in the
atmosphere creating greenhouse effect, trapping the sun’s energy causing the ocean to warm

ENVIRONMENTAL CHEMISTRY 6
Question 5
Carbon dioxide, methane, nitrous oxide, sulfur oxide, and chlorofluorocarbons.
Question 6
Like many other precursors, sulfate is pollutants that can detrimentally affect agriculture,
climate, and human health. But, they act differently in the environments, as ozone tends to warm
the planet while sulfate cools it. Oxidation of SO2 produces sulfate by the hydroxyl radicals or
hydrogen peroxide which can be derived from ozone.
Question 7
Benzene is stable: the carbon atoms are bonded to another and their H atom by sigma bonds. It
leaves the single electrons in one of the p-orbitals unused. Each p-orbitals overlaps sideways
with two neighboring orbitals to form a sigma pie bond that extends as a ring of chain above and
below the plane of molecules. Hence, electron in pie bond is free to move through the entire
system are said to be delocalized which gives the benzene its stability (Alpert, Keiser &
Szymanski, 2012, pp. 35).
Question 8
Tetrachloroethylene is used in manufacture of fluorocarbons, textile processing, and dry
cleaning. Tetrachloroethylene is a chlorinated aliphatic hydrocarbon compound having double
bond with chlorine atoms as functional group.

ENVIRONMENTAL CHEMISTRY 7
References
Alpert, N. L., Keiser, W. E., & Szymanski, H. A. (2012). IR: Theory and practice of infrared
spectroscopy. Springer Science & Business Media, pp. 34-39
Fest, C., & Schmidt, K. J. (2012). The chemistry of organophosphorus pesticides. Springer
Science & Business Media, pp. 12-17.
Manahan, S. (2017). Environmental chemistry. CRC press, pp. 44-65.
Reimann, C., & De Caritat, P. (2012). Chemical elements in the environment: factsheets for the
geochemist and environmental scientist. Springer Science & Business Media, pp. 79-89.