Preface Climate change refers to any change in climate over time, whether due to natural variability or as a result of human activity. The United Nations Framework Convention on Climate Change (UNFCCC) defines ‘climate change’ as ‘Change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods’.  Our climate is changing. These changes are due to two main reasons. The first and foremost is due to emissions of green house gases (GHGs) to atmosphere. The principal GHGs are carbon dioxide, methane and nitrous oxide. Human activities such as burning of fossil fuels, and agricultural activities (growing rice, application of nitrogen fertilisers, livestock rearing) have increased the amount of GHGs in the atmosphere in recent times. The enhanced greenhouse effect (an increase in the concentrations of GHGs) has resulted in a change in weather and climate of our planet. Some of these effects are rising of surface and ocean temperatures, rising of sea levels, widespread melting of glaciers and snows, rising of atmospheric CO2 concentrations and extreme weather events (intense drought, intense precipitation, heat waves). The likely negative impacts of climate change or GHG effects are acidification of oceans, changes in river hydrology, changes in abundance and distribution of biodiversity, coral bleaching, increased incidence of pests and diseases (malaria, dengue),  harmful algal blooms and increase in the toxicity of common harmful pollutants and more heat waves, etc. Despite several negative impacts, there are a few beneficial aspects of  enhanced GHGs effects, for example, higher atmospheric concentrations of CO2  (or Carbon dioxide fertilisation) may enhance the productivity of seagrasses, mangroves and crop production including rice, wheat, soybeans (so called C3 crops). Higher temperatures may accelerate the growth of temperate fish. Part 1 of the book (chapter 1-5) provides an introduction to GHGs and its relationships with climate change and likely impacts of climate change on freshwater resources, agriculture and livestock, fisheries and aquatic ecosystems and human health.

Key Facts      •    The United Nations Framework Convention on Climate Change (UNFCCC) defines ‘climate change’ as a ‘Change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods’.      •    The main green house gases (GHG) that have caused the global climate change or global warming are carbon dioxide (CO2), methane (CH4) and nitrous oxide (NO2).      •    CO2 is the principal anthropogenic greenhouse gas that affects the Earths radiative balance. It is the reference gas against which other GHGs are measured and therefore has a Global Warming Potential (GWP) of 1. CH4 and N2O have a GWP of 21 and 310 respectively.      •    CO2 is responsible for most of the enhanced green house effect of more than 50%, CH4 about 10 to 15% and NO2 about 4%.      •    The global atmospheric concentrations of carbon-dioxide, methane and nitrous oxide have increased since 1750, CO2 increased from a pre-industrial value of 280 ppm to 379 ppm in 2005, CH4 increased from 715 ppb to 1774 ppb and NO2 increased from 270 ppb to 319 ppb in 2005.

Key facts      •    Though water is the most widely occurring substance on earth, freshwater accounts for only 2.5% whereas the rest of water is saltwater. The agriculture sector uses more than 75% of freshwater available.       •    The current observed climate change impacts on water resources include increased precipitation at high latitudes and temperate areas, decreasing precipitation at low latitudes; decreasing snow covers, and glaciers in most regions; decreasing flows in some river basins; floods and droughts in some countries and significant decreases in lake and river size in Africa.      •    A number of climate models projected that a doubling of atmospheric concentrations of CO2 would increase global precipitation by at least 5%.  The precipitation is expected to increase in some areas, such as, at high latitudes and in the tropics (south east monsoon regions and over the tropical Pacific), whereas the precipitation is likely to decrease in the sub-tropics (e.g. much of North Africa and northern Sahara).

Key facts      •    Agriculture is the major land use across the globe. Agriculture production (plant growth) is highly dependent on climate since crop growth is influenced by solar radiation, temperature and precipitation. Agriculture is also sensitive to climate variability and weather extremes (droughts, floods, severe storms).      •    The yields of C3 crops (rice, wheat, and soybean) is expected to increase (10-20%) with predicted doubling of CO2 concentrations compared to C4 crops (maize, sorghum, millet, sugarcane) since C3 plants respond readily/positively to increased CO2 levels. Therefore, CO2 enrichment may benefit temperate and humid tropical agriculture compared to semi-arid tropics.      •    The predicted rise of temperature could impact crop and horticulture yield if it exceeds optimal temperature range. For example, low latitudes crops are being grown near the limits of temperature tolerance and global warming may put them to higher stress.      •    On a world wide basis, global warming would benefit the mid to high latitude zones for agriculture (for a small change of temperature of 1-3ºC), whereas low latitudes, semi-arid and tropical areas will have much reduced crop and livestock yields. However, adaptation measures may reduce such impacts.

Key facts      •    Fish is an important source of animal protein for billions of people (estimate 2.6 billion people). About 200 million people and their dependants worldwide, mostly in developing countries, live by fishing and aquaculture.       •    Fish living in temperate and Polar Regions could be benefited from climate changes since an increase in water temperature would extend the fish growing season. Moreover, rising temperature could reduce over-wintering stress normally experienced by temperate fishes.      •    Rise of temperature may cause a decrease in dissolved oxygen (DO) or hypoxic conditions (as temperature and DO are inversely related) and can impair fish reproduction and may cause endocrine disruption in fish (increase incidence of malformations and may alter sex differentiation and sex determination in fish).      •    Bioavailability and toxicity of common pollutants such as pesticides and heavy metals may be enhanced with increasing temperatures. Therefore, exposure of toxicants at elevated temperatures may cause a decline in recreational and commercial fisheries.

Key facts      •    The climate change is likely to affect millions of people both directly (via increased deaths, disease and injury from heatwaves, floods, storms, fires and droughts) and indirectly (through changes in the water, air, food quality and quantity and ranges of vectors, such as mosquitoes, water-borne pathogens).      •    Recent observed climate change related effects include: (a) an increase in heat related deaths across the globe (Australia, Canada, France, Germany, the Netherlands, Portugal, Switzerland, UK and USA; (b) spread of vector- and rodent-borne diseases such as malaria (Africa, India) and dengue and (c) increase in food poisoning (New Zealand).      •    Heatwaves can cause adverse health effects such as heat cramps, fainting, heat exhaustion and heat stroke. Human deaths due to heatwaves are associated with cardiovascular and respiratory diseases and in 2003 in Europe 70,000 deaths were recorded from heatwaves alone.      •    Projections : (a) cold temperature is expected to become less frequent, while heat waves will become more frequent; (b) increases in heat related deaths and illness across the globe including Australia, Germany, Portugal, UK, and USA;  (c) malaria zone may expand in Australia, Africa (highlands), India and  260-320 million more people will be affected by malaria by 2080;  (d) dengue area is likely to increase as climate would be more suitable and by 2085, about 6 billion people will be at risk of contracting dengue fever including Australia and New Zealand; (e) diarrhoeal disease may increase with temperature increase; and (f) cholera outbreaks may rise as a result of more plankton blooms providing nutrients for Vibrio cholerae.

Key facts      •    The use of chemicals has many benefits, however, there are potential risks that some of these chemicals may cause harm to organisms and human health if they enter into the environment.      •    Harmful chemicals are those chemicals which are persistent, bio-accumulative, as well as toxic (PBT).       •    Environmental or ecological risk assessment (ERA) consists of hazard identification, effect assessment, exposure assessment, risk characterization, risk classification, risk-benefit analysis, risk reduction and monitoring.      •    The five types of environmental monitoring are: chemical monitoring, bio-accumulation monitoring, biological effect monitoring, health monitoring and ecosystem monitoring.       •    An integrated monitoring program is a coordinated monitoring activity comprising of both chemical and biological measurements in a variety of environmental compartments. There are four different monitoring levels in an integrated ERA, these are: suborganismals (biomarkers), organisms (bioassays), populations (bio-indicators) and ecosystems (ecological indicators).

Key facts      •    Arsenic (As) is a metalloid, with properties intermediate between those of a metal and a non-metal. Arsenic can exit in the environment and biological systems in various inorganic and organic forms (species). These are arsenite - AsIII, arsenate - AsV, monomethyl arsonic acid (MMAA), dimethyl arsinic acid (DMAA), arsenocholine, arsenobetaine and arsenosugars.       •    Arsenicals have a wide range of toxicity. In general, inorganic arsenicals are more toxic than oragnoarsenicals to biota and trivalent arsenic (arsenite) is more acutely toxic than pentavalent (arsenate) form in the following orders:          Arsenous acid (AsIII) ®  arsenic acid (AsV) ® MMAA ®DMAA ® arsenocholine ® arsenobetaine.      •    Under oxidizing and aerobic conditions, the predominant form of arsenic (As) in soil and water is arsenate (AsV), whereas under anaerobic and reducing/or waterlogged conditions, arsenite (AsIII) predominates.      •    Inorganic AsIII and AsV are the major As species in groundwater, soils, terrestrial plants, whereas the main species found in marine animals is Arsenobetaine (AsB), which is considered to be non-toxic.      •    The LD50 values of different arsenicals show that arsenite (AsIII) is most toxic (LD50 range 15-42 mg/kg) and arsenobetaine is least toxic (LD50 > 10,000 mg/kg).

Key Facts     •    The heavy metals (HM) or trace metals in an aquatic environment can come from natural (e.g. geological minerals, wind blown silicate dust, volcanic emissions, sea spray and combustion) and anthropogenic sources (e.g. mining, industry and sewage treatment discharges as well as electronic waste and agriculture fertilisers). In aquatic systems, the heavy metals of greatest concerns are cadmium, copper, lead, mercury and zinc.     •    Metals may exist in a number of physico-chemical states in aqueous systems such as particulate matter and dissolved forms. Metal speciation in freshwater is strongly influenced by hardness, alkalinity, pH, natural dissolved organic matter (DOM) and redox potential.      •    Water hardness is quantitatively related to metal toxicity in freshwater (i.e. toxicity of heavy metals decrease with increasing hardness and alkalinity; on the other hand, toxicity increases with decreasing salinity, dissolved organic matter and chelators). The uptake and toxicity of heavy metals of most metals in marine waters is low as compared to freshwater because metals are easily complexed with chloride ions.     •    The toxicity of HMs is related to the dissolved ionic form of the metal rather than total concentration of the metal. Each different physico-chemical forms of an element has a different toxicity, for example, if the element (e.g. Cu) is absorbed on a colloidal particles it is expected to be of little or no effect on aquatic organisms, however,  if the copper is available as free Cu (II) ion, few aquatic organisms may survive.

Key facts      •    Pesticides are chemicals that are broadly used to protect crops, livestock and other animals and plants from pests and diseases. They are classified according to the type of pest to be controlled (algicides, herbicides, fungicides and insecticides).      •    Commercial production of DDT began in 1943. At that time, DDT was considered to be a wonderful invention. It was cheap to produce, very toxic to insects and much less toxic to mammals and its usage resulted in a sharp decline of mosquito borne diseases. In 1962, it was discovered that DDT was causing egg-shell thinning in bird eggs and thus was leading to the near extinction of bird species such as peregrine falcons and bald eagles.      •    Pesticides use has greatly helped to increase and improve the world food production. Use of pesticides also increases farmer’s profits by preventing crop losses due to pest attacks and weed infestation.

Key facts      •    Dioxins are the most dangerous and ‘super toxic’ chemicals so far known on the earth and three closely related families are collectively known as dioxins. These are Polychlorinated dibenzo-p-dioxin or dioxins (PCDDs), Polychlorinated dibenzofurans or furans (PCDFs) and polychlorinated biphenyls (PCBs).      •    2, 3, 7, 8-TCDD (or called TCDD) is the most potent of all the congeners. The toxicity equivalency factor or TEF of TCDD has been assigned as 1, while all other congeners assigned in order of toxicity ranking magnitude relative to TCDD.      •    There are 75 compounds/congeners in the dioxin family (PCDD), 135 compounds in the furan family (PCDF) and 209 possible compounds in the PCBs based on the possible number of chlorine atoms.      •    The toxicity of dioxins and dioxin-like compounds vary substantially among the different PCDDs, PCDFs and PCBs. It is generally accepted that only 29 out of the 419 congeners of dibenzo-p-dioxins, dibenzofurans and polychlorinated biphenyls are toxic to humans and other organisms. The TCDD is most toxic and registered by the WHO as carcinogenic for humans.

Key facts      •    Endocrine disrupting chemicals (EDCs) are micropollutants with estrogenic or androgenic activities at very low concentrations and are emerging as a major concern for water quality.      •    EDCs include natural and synthetic hormones (Estrone or E1, 17b-estradiol or E2, Estriol or E3, 17a-ethynylestradiol or EE2); alkylphenols (nonylphenol or NP; octyphenol or OP), phenols (bisphenol-A or BPA), phthalates (Di-n-butyl phthalate or DBP, Di-2-(ethylhexyl)-phthalate or DEHP); organotins (tributyltin or TBT); and phytoestrogens (b-sitosterol, coumestrols, genistein).       •    Wastewater treatment plants, intensive livestock effluents, industrial wastewaters, landfill, paper and pulp mill effluents and antifouling paints are important sources of EDCs in the environment.

Key facts      •    Biotoxins are naturally occurring toxic compounds produced by some freshwater cyanobacteria (blue-green algae) and marine algal species (dinoflagellates, diatoms).      •    Tonnes of pharmacologically active substances are used annually in human and veterinary medicines, some of these substances are excreted (human and animal) non-metabolised or an active metabolites and enter into the environment since waste water treatment plant (WWTP) cannot degrade them.      •    In Europe, around 4,000 different pharmaceutically active compounds are used as human and veterinary drugs and the annual consumption is about several hundred tonnes.      •    European Union and the United States laws require an assessment of potential risks to the environment as part of license application processes for new medicinal products. •    Pharmaceutical products are generally polar, water soluble and low volatile molecules, it means that they have high mobility in the environment.

Key facts Freshwater biotoxins      •    Biotoxins are naturally occurring toxic compounds produced by some freshwater cyanobacteria (blue-green algae) and marine algal species (dinoflagellates, diatoms).      •    Cyanobacteria are now recognised as a serious water quality problem with regard to drinking water supply and recreational use.      •    Environmental conditions that can promote cyanobacterial/blue-green algal blooms are: excessive nutrients (phosphorus and nitrogen); warm water temperatures (15-30OC); sunlight for photosynthesis; and quiescent or stagnant water.      •    Outbreak of human poisoning attributed to cyanobacteria are neurotoxins (e.g. anatoxin-a, anatoxin-a(s), saxitoxins) and hepatotoxins (e.g. microcystins, nodularin) produced by some strains of the cyanobacteria including Microcystis, Anabaena, Aphanizomenon spp.

A Acaricide 191, 194, 204, 207, 211, 215  Accumulation of toxins 371, 390  Acetaminophen (paracetamol) 331  Aeetylcholinesterase 187, 188, 211, 405 Acidic 16, 29, 59, 61, 68, 107, 135, 164, 291, 341, 368, 379, 389, 428, 432  Acidification 61, 67, 68, 77  Action potential 374, 376