Environmental Education Water Pollution

Content Types of Water Pollution Dissolved Oxygen and Oxygen Depletion Petroleum Pollution Indicators of Water Pollution Water Pollution in Hong Kong Water Quality Control in Hong Kong Provision of Infrastructure

Types of Water Pollution [1] Oxygen-demanding wastes Diseases-causing agents Thermal pollution Sediments Plant nutrients Petroleum hydrocarbons Inorganic chemicals and minerals Synthetic organic compounds

Types of Water Pollution [2] Oxygen-demanding wastes All organic materials and wastes Sources Sewage from domestic and animals sources Industrial wastes from food processing, papermills, tanning operations, meatpacking plants, etc Decay of dead plant and animals Broken down or decomposed by bacterial and other biological activity (biodegradation) It consumes oxygen (oxygen demanding) It causes oxygen depletion in water

Types of Water Pollution [3] Importance of oxygen Basic requirement of almost all plant and animal life-forms in water body Insufficient amount of oxygen to support life and damage the ecosystem

Types of Water Pollution [4] Disease-causing agents Pathogenic microorganisms Sources: Wastes from human and other animals (hosts) Spreading diseases through drinking water consumption or through other water contact activities Indicators Fecal Coliform Count e.g. E. coli

Types of Water Pollution [5] Thermal Pollution Discharge of cooling water Sources: Industrial and commercial operations Power Plants Heating up the aquatic environment Aquatic organisms may become physiologically stressed or even be killed Interference of the natural life processes, e.g. reproduction, growth rates, distribution of species Decreasing dissolved oxygen (DO) in water

Types of Water Pollution [6] Sediments Release of weathered sediments through runoff to water bodies Sources: Clearing and developments adjacent to water bodies Natural weathering of soils Sewage discharge Littering in water bodies Directly smother and kill aquatic life Directly destroy habitats and spawning areas Reduce the sunlight penetrating into water

Types of Water Pollution [7] Plant nutrients Phosphates, nitrates, potassium, etc. Sources: Fertilizers application in farming Sewage treatment plant effluents Leading to eutrophication and algal blooming

Types of Water Pollution [8] Petroleum hydrocarbons Crude oil, petroleum, gasoline, etc. Sources: Wastewater discharges, leaching, Recreational boating, Underground tank leakage Underground water supplies, direct smothering, toxic effects, loss of habitat

Types of Water Pollution [9] Inorganic chemicals and minerals Heavy metal (cadmium, lead, mercury, copper, etc.), Cyanide, ammonia, hydrogen sulfide, etc. Sources: Industrial discharges, like eletroplating, bleaching and dyeing, gold milling Marine sediments Toxic (direct or long term) Odour Disease and Death Carcinogenic

Types of Water Pollution [10] Synthetic organic compounds Pesticides, plastics, solvents, detergents, PCBs, paints, pharmaceuticals, etc. Sources: discharges of these compounds from domestic, agricultural, industrial and commercial operations, etc. Resistant to biological breakdown and persist and accumulate in the environment Directly toxic to aquatic life Causing odours

Dissolved Oxygen and Oxygen Depletion [1] Processes Affecting Dissolved Oxygen in Water Photosynthesis light 6 CO2 + 6 H2O  C6H12O6 + 6 O2 Respiration C6H12O6 + 6 O2  6 CO2 + 6 H2O + Energy Re-aeration Decomposition

Dissolved Oxygen and Oxygen Depletion [2] Factors Affecting Dissolved Oxygen in Water Temperature Light Turbidity Color Salinity Turbulence Aquatic organisms

Dissolved Oxygen and Oxygen Depletion [3] Oxygen Sag Curve

Dissolved Oxygen and Oxygen Depletion [4] Natural Purification Process

Petroleum Pollution Municipal and industrial wastewater discharges (31.1%) Tanker operations (22%) Other marine transportation (12.5%) Tanker accidents (12.5%) Atmospheric fallout (9.4%) Natural seepage and erosion (7.8%) Refinery wastewater discharges (3.1%) Offshore oil production (1.6%)

Indicators of Water Pollution Biochemical Oxygen Demand (BOD) Indicators Amount of oxygen needed by aerobic decomposers to break down the organic materials in a given volume of water at a certain temperature over a specified time period. Chemical Oxygen Demand (COD) Amount of oxygen needed in the oxidation of chemicals in a given volume of water at a certain temperature over a specified time period. Fecal Coliform Count (FCC) Dissolved Oxygen (DO) Total Inorganic Nitrogen (TIN) Living organisms in the water

Water Pollution in Hong Kong [1] Beach Water Quality Beach Grading System Situation in Hong Kong Southern District Sai Kung District Islands District Tuen Mun District Tsuen Wan District

Water Pollution in Hong Kong [2] River Water Quality Improved steadily since the late 1980s Significant increase in dissolved oxygen and decreases in suspended solids, aggregate organics, nutrients and metals The number of E. coli bacteria in many of the rivers remains fairly high (Source: EPD website, 16/4/2001)

Water Pollution in Hong Kong [3] Causes Multiplicity of Sources Anthropogenic (household, industrial, commercial, farming, construction, etc.) Natural Lack of Infrastructure Treatment facilities Sewerage provision Insufficient Control Illegal connection of wastewater pipes

Water Pollution in Hong Kong [4] Consequences Economic Loss Industries (tourism, mariculture), recreational facilities Ecosystem Disruption Ocean, rivers, streams Coral, offshore habitats Health Impacts Food Poisoning

Water Quality Control in Hong Kong [1] Legislation Waste Pollution Control Ordinance (WPCO) Water Control Zones (WCZs) Water Quality Objectives (WQOs) Technical Memorandum (TM)

Water Quality Control in Hong Kong [2] Source: EPD website, 2001

Water Quality Control in Hong Kong [3] Water Quality Objectives Define the maximum levels of pollutants which are acceptable the minimum levels of essential constituents which are required if designated resources and uses are to be maintained in rivers and marine waters The values of the WQOs vary among WCZs and depend upon the resource the use to be protected

Provision of Infrastructure [1] Sewerage Master Plans (SMPs) Source: EPD website, 2001

Treatment and Disposal Source: EPD website, 2001

Provision of Infrastructure [3] Strategic Sewage Disposal Strategy (SSDS) Source: EPD website, 2001

Provision of Infrastructure [4] Strategic Sewage Disposal Strategy (SSDS) Source: EPD website, 2001

Discussion What are the main types of water pollution in Hong Kong and what are the causes? What is/are your opinion(s) about the pollution control carried out in Hong Kong? With reference to the locations of beaches/streams, can you explain their differences of water quality? Can you suggest other methods to improve the water pollution problem in Hong Kong? According to the data from the EPD, the water quality in Hong Kong is improving, do you agree? Why?

Relevant Websites Environmental Protection Department (EPD) Webpage (http://www.info.gov.hk/epd) Water Supplies Department (WSD) Webpage (http://www.info.gov.hk/wsd/)

References Schmitz, R.J., 1995, Introduction to Water Pollution Biology, Gulf Publishing Company, Houston, Texas, USA. ISBN 0-88415-927-2 EPD, 2001 online, EPD Homepage – Water, EPD, http://www.info.gov.hk/epd/water