Environmental Pollution Overview

Introduction

Pollution is the most prominent and impactful problem facing the environment.
Environmental pollution increases with technological advancements due to the release of harmful substances into water, soil, and air.
Pollution disrupts the balance of the ecosystem, negatively impacts living organisms, and harms the environment.
It is the quantitative change in components of living and non-living environments exceeded by the capacity of ecosystems to absorb these changes.
Ecosystem's efficiency significantly declines during disruption of harmonious movement between different components.

Degrees of Environmental Pollution

Acceptable pollution: The initial stage where the ecosystem's balance is not affected and does not pose major environmental threats.
Dangerous pollution: An advanced stage where the amount and type of pollutants surpass the critical environmental limit resulting in negative impacts on the natural and human environmental elements.
Destroying pollution: The stage where the ecosystem collapses and becomes unable to sustain life due to a significant imbalance.

Water Pollution

Water is the most abundant substance in protoplasm and is essential for life.
Human and other living organisms depend on water for survival.
Water pollution occurs continuously from various sources, decreasing its suitability for human use and negatively impacting aquatic organisms.
Water has a self-purification capability, where it can purify itself with the help of other environmental factors if the pollutants are within the water source's tolerance.
Water pollution occurs when undesirable changes happen in water's physical, chemical, or biological properties.

Types of Water Pollutants

Oxygen Demanding Wastes: Substances requiring oxygen for decomposition. This includes organic materials that are converted into stable compounds by aerobic bacteria.
- These substances use dissolved oxygen in water, leading to oxygen depletion, affecting aquatic life, and causing bacterial decomposition and water decay.
- Sources include domestic and industrial sewage.
Pathogens: Contaminated water is responsible for spreading disease epidemics.
- These contaminants contain waste from humans and animals, food leftovers, and debris, harboring millions of harmful and non-harmful microorganisms.
- These pathogens can be classified into:
  - Waterborne disease: Diseases caused by the presence of pathogens in the water. Sources include human and animal waste. Examples include cholera, typhoid, fever, and bacterial dysentery.
  - Water-washed disease: Diseases caused by lack of proper water use for hygiene and sanitation. Examples include skin and eye infections.
  - Water-based disease: A part of the life cycle of a microbe or disease vector that lives in the water. Examples include tapeworms and Schistosomiasis.
  - Water-related disease: Diseases spread through animals, insects, or other disease vectors that live in or near water. Examples include malaria spread by mosquitos and sleeping sickness spread by the tsetse fly.
Chemical water pollution: Contamination of water bodies by chemicals from industrial and agricultural activities.
- These chemicals, including xenobiotics, oil spills, phenols, detergents, and heavy metals like mercury, cadmium, and lead, pose a significant risk to the environment and human health.
Nutrient pollution: Occurs from wastewater and agricultural fertilizers containing phosphorus, nitrogen, sulfur, carbon, calcium, and iron. These nutrients, found in excessive concentrations, lead to the excessive growth of aquatic plants, especially algae, which can release toxins into the water.
- This excess growth can also clog water filters and cause Eutrophication, a phenomenon where algal blooms deplete oxygen in the water, harming aquatic life.
Pesticides: Chemicals used to kill pests that damage crops.
- These pesticides fall into three categories:
  - Organochlorine Compounds: Known for their persistence in the environment.
  - Organophosphate Compounds: Known for their ability to quickly spread and move.
  - Carbamate Compounds: Known for their relative novelty, with limited information available on their movement and research.
Thermal pollution: Occurs from releasing hot water from power plants and other industries.
- This excess heat can lead to various environmental impacts, including reduced density of aquatic life, increased evaporation rates, and altered chemical reactions.
Nuclear wastes: Generated from nuclear reactors and industrial, medical, and scientific processes that use radioactive materials.
- These wastes can end up in surface and groundwater, harming organisms within the aquatic environment.

Sampling Collection & Storage

Sampling and analysis are crucial to understand different environmental ecosystems, monitor changes, and find solutions.
Samples must represent a larger population and provide sufficient information about that population.
The choice of sampling method, size, equipment, location, timing, storage, and analysis time are critical factors.
Water samples are susceptible to changes, particularly in their physical, chemical, and biological properties, due to various reactions within the sample container between collection and analysis.
These changes can occur due to:
- Consumption of materials by bacteria, algae, and other organisms in the sample.
- Oxidation of compounds and materials by dissolved oxygen in the sample.
- Absorption and addition of materials into the sample (such as carbon dioxide from the air).
- Loss of materials from the sample due to evaporation, volatilization, or changes in physical state.
- Precipitation reactions of some materials (calcium carbonate, aluminum hydroxide).
- Polymerization reactions of polymeric materials.
These changes occur due to factors like temperature variations, exposure to light, the material of the sample container, and time elapsed between sampling and analysis.

Necessary Precautions During Sampling

The sample must meet the requirements of the sampling program and must not be contaminated before reaching the laboratory.
When collecting water samples, the container should be rinsed with the same water before filling it, unless it contains preservatives or disinfectants.
For samples examining organic matter, the container should be filled completely with no air space. If the sample contains volatile organic matter, it should be stored in glass containers with silicone lids that have a Teflon liner.

Sample Collection and Preservation

Microbiological content samples should be collected in pre-sterilized containers with air space to allow for aquatic life's activity.
Trace elements are collected in High-Density Polyethylene (HDPE) bottles, except for mercury, which is collected in glass bottles.
Sample records: Document the sample name, location, time, temperature, water depth, and any other relevant climatic information.

Types of Samples

Grab or catch samples are taken directly from the source and represent a specific time and place. They are suitable for water quality monitoring and provide a general overview of water conditions.
Average samples are collected manually over a specific period to obtain an average representation of the water quality.
Composite samples are a combination of grab samples from a single location at different times. They can be continuous or non-continuous.
- Continuous samples: A consistent amount of sample is taken at regular intervals.
- Non-continuous samples: The volume of the sample varies depending on the flow rate, but the time interval remains constant.
- Volume-based samples: The sample is collected at regular intervals (e.g., every 10 meters), with a constant quantity.

Sample Preservation

Maintain sample integrity by minimizing changes in the sample's properties.
Common preservation method: Refrigeration at 4°C.
Avoid freezing samples: It can cause changes in the sample's composition.
Additional preservation techniques: adding chemicals to adjust pH levels or remove interference from organic materials.
Storage: Use borosilcate glass containers with tight lids or clean HDPE bottles, avoiding plastic or metal containers which can interact with the sample.

Sample Size

**Physical and chemical analysis: **Typically requires one liter (1000 ml) of sample.
Microbiological analysis: Requires specific procedures depending on water type or waste type being analyzed.
- Taste: Analyzed only for drinking water.
- Color and Turbidity: Analyzed for drinking and surface water.
- pH: Analyzed for all water types.
- COD, BOD: Analyzed for wastewater and surface water, not drinking water.
- TDS (Total Dissolved Solids): Analyzed for drinking and irrigation water.