I don't think there is a blanket answer that selects only one stressor. The one that is most harmful will depend on where you are on the globe (your local/personal perspective). Therefore, I think the more important consideration is not which one is more harmful, but rather when and where do these 4 stressors co-occur and interact and when and where do the environmental and human health impacts of these 4 stressors intersect.

Hi Thomas (USA),

I do agree with your answer that it should depends on country or location. Thanks

The term "pollution" it need to différents of term "stress".

The first dépends of human activity and the second of nature.

Best regards

In general nutrients and metalls are the topic pollutants in Russian waters!!!

All of these pollutants are harmful in some way or another. Here in Washington State, the main focus is persistent organic pollutants also known as POPs, that biomagnify and bioaccumulate in the ecosystem. Only a fraction of these POPs I will name here, but also include heavy metals such as mercury (Hg), cadmium (Cd), lead (Pb), etc. But the POPs that are of interest here in Washington State are Polychlorinated Biphenyls (PCBs) and Polybrominated Diphenyl Ethers (PBDEs).

In the whole country also, each state have its pollution problem, a state which is affected by Carbon pollution may not be having plastic pollution as a serious problem. It is location specific and difficult to point out only one as the primary problem as far as the whole country is concerned.

Dear Marpha (France), Timur (Russia), Nicole (USA) and Asha (India),

Thank you for your inputs. Of course, the pollution impacts could be country specific or location specific, however, in general, all these four pollutions can be considered global pollution affecting many countries in the world. For example,

a) plastic pollution is becoming a threat to all the nations (perhaps now mostly in developing countries due to mismanagement where fast economic growth is occurring but waste management infrastructure is lacking), in addition plastics can adsorbed a number of harmful priority pollutants in micro and nano plastics and can be transferred to humans via food contamination; There are five large patches of marine plastic pollution “hot spots” (North & South Pacific; North & South Atlantic; Indian Ocean). The North Pacific has the highest level of contamination with nearly 1.8 trillion pieces of plastic while the Indian Ocean comes second with 1.3 trillion;

b) heavy metals (HM) pollution could be a threat to many countries, HM can be sourced from 22 sources including agriculture, batteries, cement kiln, coal-fired power plants, electronic- waste, electroplating, fertilisers, tanneries, paper & pulp mills, paints, textiles, shipbreaking yards; oil refineries, mining, paints, pesticides, pipes, sewage treatment plants, urban runoff, smelting, waste incineration, wood preservatives; A Global research Study Found Elevated levels of Mercury in Child–Bearing Women in 25 Countries;

c) hypoxia due to nutrient pollution/eutrophication (use of fertlisers in agriculture) caused more than 550 hypoxic/dead zones in the coastal and marine waters alone in the world, hypoxia is also commonly occurs in freshwater systems in many countries (China), which may cause a significant impact on seafood and ecosystems (in both marine and freshwater), moreover, hypoxia can decrease in species richness and diversity, can cause massive fish kills, and reductions in the biomass and landing of fish and endocrine disruption in aquatic organisms including fish;

d) carbon pollution (though caused by developed countries initially) would impact significantly in poor developing countries in Africa, Asia and Latin America who don’t have the resources and capacity and capabilities to adapt to and mitigate climate change. Climate change would cause significant impacts on biodiversity and ecosystems, water and food security, food safety, public health, and infrastructure across the globe; climate change is projected to cause shifts in distribution of biodiversity towards north and south poles and reduced species diversity in tropical areas/low latitudes.

Thank you for elaborate explanation.

https://www.who.int/gho/phe/outdoor_air_pollution/burden/en/

Here in Washington State the heavy metals and carbon pollution in the more industrialized areas of Washington are of utmost concern. Washington state is extremely careful of its natural resources and environment. Plastic pollution is nearly a non issue here because there are hefty fines for corporations, groups and individual people who dare litter. The litter that occasionally washes onshore from other areas is routinely cleaned up and there are regular patrols of grade school students cleaning the beaches and recycling plastics that are found. Hypoxia is an occasional threat that is strictly monitored by the Washington State Department of Fish and Wildlife and Natural Resources. Since in Washington State shellfish and the fishing industries are large and reliant on clear oxygenated water, any conditions that appear to lead to hypoxia or anoxia are highly and closely monitored. Currently in Washington State there is a task force to figure out how to reduce heavy metals and carbon pollution. This pollution is directly effecting the Resident Killer Whales that live here and their population is in steep decline due to the heavy metals and carbon pollution around the industrialized areas they frequent.

Dear Nicole (USA, Washington)

You have provided a good overview of the pollution situations in the Washington state, USA. It is great to know that plastic pollution is not a threat in the Washing state where there are hefty fines for littering. On the contrary, in developing countries it is an alarming issue, for example, China, Indonesia, Philippines, Vietnam, Sri Lanka are some of the countries polluting the oceans most with plastics. There are some 9 and 34 documented hypoxic areas in Australia and Asia respectively.

Among the four types as you mentioned plastics pollution is the most devastating for our country since the plastic materials are dumping in the environment without any treatment

Dear Shafiqul (Bangladesh)- Plastic pollution

Thanks for your inputs that plastic pollution is one of the major environmental issues for Bangladesh!

Everywhere in Canada we have carbon pollution, locally mercury pollution from flooded forests or pulp mills, nutrient pollution in lakes (some lakes are big but shallow) as well as POP's in northern communities. I expect limited plastic pollution in coastal areas as well as in lakes.

Dear Michael (Canada)- Carbon, Metals, Nutrients Pollution

Thanks for sharing information that in Canada you have problems with carbon, metals (Hg) and nutrients pollution but less with plastic pollution!

Hola en Colombia tenemos problemas con flujos de nutrientes y residuos industriales a los sistemas acuáticos como el Río Bogotá, el más grave con mercurio en cuenca del río Magdalena y río Cauca, contaminación difusa por plaguicidas en zonas agropecuarias ( asociado con cultivos semiindustrializados como de caña de azúcar, cafe, palma y otros como cebolla en Lago de Tota) y descargas de glifosato en zonas de cultivos ilicitos, compuestos orgánicos usados para extracción de narcóticos. Lo de contaminantes emergentes apenas lo estamos registrando en ríos como el río Bogotá y Río Medellin, de resto poco sabemos de las presiones por polutantes en agua, entonces un panorama muy preocupante y con bajo seguimiento,... lo de microplásticos no creo que tengamos aún ningún trabajo, estamos en contaacto

Dear Adriana (Colombia)- Heavy metals, Pesticide Pollution

Glad to receive your reply from Colombia that nutrients, industrial waste (River Bogota), heavy metals (Hg) (River Magdalena & Cauca River) and pesticides (glyphosate use in sugarcane, coffee, palm and onion) caused water pollution problems but there are no statistics about plastic pollution

translation from Spanish

Hello in Colombia, we have problems with nutrient flows and industrial waste to aquatic systems such as the Bogotá River, the most serious one with mercury in the Magdalena river basin and the Cauca river, diffuse contamination by pesticides in agricultural areas (associated with semi-industrialized crops such as sugarcane of sugar, coffee, palm and others like onion in Lago de Tota) and glyphosate discharges in areas of

Illicit crops, organic compounds used for the extraction of narcotics. As for emerging pollutants, we are only registering it in rivers such as the Bogotá River and the Medellin River, for the rest we know little about pressures from waterborne pollutants, so a very worrisome and low-tracking scenario ... what about microplastics I do not think we have still no work, we are in contaacto

Here at the cost of Kudat, Northern tip of Sabah, Malaysia (South East Asia) plastic pollution is a major problem as there are some stilt villages (that are basically tiny houses built on wooden stilts above coastal waters) whereby these villagers have a history of just dumping all of their waster and even sewage directly into the seawater below them. You can imagine the extent of damage as you can just view household plastic pieces almost everywhere especially during low tides . It's extremely hard to educate and spread awareness as some of them do not below to any state and live below the poverty line. However, efforts are being carried out by various governmental and non-governmental organizations. Hopefully things will change for the better soon, for the sake of our marine life and hence ourselves too.

Dear Paramjeet (Malaysia)-Plastic Pollution

You have brought an important issue related to plastic pollution in Malaysia, in particular in the coast of Kudat, Northern tip of Sabah where villagers just dump plastic and other waste straight to the environment where they live. Thanks for this important highlight. Would it be possible to attach 1-2 images of those stilt villages with plastics pollution so that others in this thread can benefit from this?

Hi All

I have provided a link of a publication on plastic pollution below (a presentation). It covers the following aspects i) global consumption of plastic; ii) classification of plastics; iii) global plastic pollution; iv) plastic pollution sources; v) impacts of plastic pollution on global biodiversity, vi) effects of plastic additives; vii) global marine plastic pollution “hot spots” and viii) adsorption of organic and inorganic chemicals by different types of plastic; viii) factors related to adsorption of contaminants by plastics ix) innovative solutions to mitigate the plastic pollution across the globe

Presentation Presentation: Plastic Pollution- Sources, Global Production,...

Dear Kibria,

Thank you for sharing the informative presentation on plastic pollution.

Kindly share your other PDF too indicating the level of plastic pollution in the sea.

Regards

Dear Asha (India)

I am happy to see that you found my presentation PPP on Plastic pollution attached above is informative. Please see PPP pages 15,16,20,21, 28 and 29 for some information relating to the level of plastic pollution in the sea

Dear Md Abdul Wahab (Bangladesh) - Heavy metals pollution

Many thanks for indicating and identifying that heavy metals and plastics are the major sources of pollution affecting the water-based ecosystems and their biodiversity. Indeed you are right, in the case of heavy metals, since our marathon research study found seven heavy metals pollution ‘Hot spots” across Bangladesh (see the weblink)

https://www.researchgate.net/publication/311216906_Monitoring_of_metal_pollution_in_waterways_across_Bangladesh

Dear Md Abdul Wahab (Bangladesh) - Heavy metals pollution

It is threatening to see elevated levels of Cr and Mn in waterways in Bangladesh in particular, in the lower Meghan river (nursing and breeding place of the most prized fish Hilsa Tenualosa ilisha).

It is more alarming in the sense since heavy metals are highly bio-accumulative, and it is possible both Cr and Mn would bioaccumulate in Hilsa and can be transferred to humans via the food chain, i.e. from consumption of the fish (Hilsa) harvested from the Cr, Mn contaminated rivers/waterways in Bangladesh, for example. Both ATSDR (Agency for Toxic Substances & Disease Registry, USA) and IARC (International Agency for Research on Cancer) classified Cr as one of the most harmful heavy metals to the environment and public health. IARC classified Cr as a Class I carcinogen. Cr can be sourced from effluents discharged from textiles; tanneries, cement factories and fertilizers industries.

Mn is less harmful compared to Cr but still can cause rare neurological disorder associated with excessive manganese ingestion. Mn can be sourced from coal and cement, tanneries and pesticides!

Images of the plastic pollution problem off the coast of Kudat, Northern tip of Sabah where villagers just dump plastic and other waste straight to the environment where they live as requested...

Dear Paramjeet (Malaysia) - Plastic & Sewage pollution

Thank you so much for the inclusion of images on plastic pollution off the coast of Kudat, Northern tip of Sabah, Malaysia (where villagers just dump them). It is a showcase demonstrating how devastating the problems could be with plastic.

Other problems could be with sewage pollution in the area, which can cause a chain of problems like spreading of diseases (cholera, diarrhoea), eutrophication, and increase in Biological Oxygen Demand (BOD) and contamination of fish with toxins!

Awareness, education and behavior change program would be vital

Dear Doctor, In my country, France, many regions are polluted either with pesticides, secondly with sewage, and thirdly with concrete replacing very large surfaces of natural vegetation and cultivated fields in France. Sincerely yours, André Panis, Associated Scientist at French National Research Institute for Agriculture en Ph Doctor of the University of Rangueil-Toulouse

Dear Dr Andre Panis (France)- Pesticide pollution

It is really surprising to know a pristine, beautiful country like France does have pollution with pesticides, sewage problems!

Anyway recently I came to know that almost half of the European soils (11 Countries) (including UK, Denmark, Portugal, Italy, Greece, Spain, Hungary, Poland, Netherlands, France and Germany) are contaminated with glyphosate (Silva et al. 2018). Glyphosate is known to be global herbicides but WHO/IARC reclassified glyphosate as probably carcinogenic.

A comprehensive meta-analysis of 838 peer-reviewed studies (in 73 countries including France) found that the world surface waters is threatened by 28 toxic insecticides (comprising organochlorine, organophosphate, carbamate, pyrethroid & neonicotinoid) (Stehle and Schulz, 2015, a figure from Stehle and Schulz, 2015, is attached for the benefits of researchers/scientists following this thread ) ( the figure is showing the global crop area and the distribution of regulatory threshold level (RTL) exceedance rates for reported measured insecticide concentrations )

Dear Doctor Kibria, I don't know in what country you live.

But I have cited first: pesticide, second: sewage, third: concrete.

Yes France lives for un important economic part from tourism (you write: a so pristine and beautiful country).

But in at least 4 big towns of my country are quarters of very old houses.Polluted water is conducted into river water, after unsufficient filtration. Examples:

Many old quarters of Paris where unsufficiently filtered water runs into ducts. A lot of these ducts reach the Seine river.

Lyon (departement of Rhône) with the old houses of Fourvière hill, samething in Rhône river.

Bordeaux in Gironde (the estuary of Garonne river) with unsufficiently filtered water from old quarter around the cathedral.

Rennes with many old houses in center of the town, in the Vilaine river.

The town of Toulouse has a bit better situation with urban used water. Sincerely yours. André Panis

Dear Doctor Andre (France)

Thank you for your inputs; I live in Australia by the way! From outside we always feel that France is a pristine and beautiful country since a lot people goes there to visit

I have had no knowledge before those old quarters of old houses becomes a source of pollution. Thanks for that

Kind regards Golam

CARBON

Dear Aung Ze Ya (Myanmar) - Carbon pollution

Yes, Myanmar is threatened by climate change (third in the world ranks for most vulnerable to climate change) caused by carbon pollution (CO2, CH4, N2O), though Myanmar caused little GHG emissions. Cyclone Nargis (2008) is an example of how severe the climate change impacts could be on Myanmar. The main CC impacts in Myanmar would be due to the fact the rural people (60-70% of the country’s population) mostly depend on climate-sensitive agriculture and ecosystems for their livelihoods, which are also threatened by climate change. for example, the rising sea level will impact rice production and contamination of freshwater with salt

In my country (Niger), plastics pollution is the more harmful.

Dear Assane (Niger)- Plastic Pollution

Yes, you are correct, up to 95 per cent of plastic polluting the world's oceans comes from just ten rivers, one of which is in Niger. I have attached a map showing the 10 most plastic polluting Rivers in the world.

https://www.dailymail.co.uk/sciencetech/article-4970214/95-plastic-oceans-comes-just-TEN-rivers.html

Thank you Dear Golam, my country is Niger, not Nigeria.

Sorry Dear Assane for the typo mistake, corrected it now to Niger!

In Mosul city (north of Iraq) ISIS troops have burned 12 oil wells which continue to spew out foul toxic fumes and emit immense amounts of pollutants into the atmosphere. As a result, Mosul and its surrounding environs are currently the most contaminated places on Earth. Also collapced building after the war.

Dear Rana (Iraq) - Oil pollution

The oil spill is an environmental disaster. Crude oils are mixtures of hydrocarbon compounds including BTEX, and PAH, some of which are toxic and exposure of which may cause cancer and other health effects (such as benzene and some PAHs).

Mr. Golam

I agree with you.

"Basic data concerning the sources of coastal marine pollution of both urban and industrial origin in Tunisia are presented (see attached document) as well as basic information regarding the relationship between marine pollution and oceanography, topography and hydrology and human activity." (Andren, L. E. & Hadj Ali Salem, M.).

Dear Oum Kalthoum Ben Hassine (Tunisia)- Marine pollution

Thank you for your contribution and the attachment. As the document is not in English, would it be possible to write down a few sentences about the type(s) of marine pollution in Tunisia for the benefits of researchers following this thread?

Pesticides and heavy metals pollution in Australia

We have carried out significant research in Australia related to pesticides pollution and heavy metals pollution in waterways (using innovative passive sampling technology) (all conducted continuously for the two consecutive years plus one year for the testing/trial of the technology).

We found endosulfan (an organochlorine insecticide), atrazine (a herbicide) on a regular basis in our targeted waterways covering 68.,000 square kilometers

We found elevated levels of copper (Cu) during the dry year, while elevated levels of Zn during the wet year in our targeted waterways covering 68.,000 square kilometers

References

Rose, G. and Kibria, G. 2007. Pesticide and heavy metal residues in Goulburn Murray irrigation water, Australia 2004-2006. Australasian J of Ecotoxicology. 13: 65-79.https://search.informit.com.au/documentSummary;dn=376927357196148;res=IELHEA;type=pdf

Kibria, G, Lau, T.C and Wu, R. 2012. Innovative 'Artificial Mussels' Technology for Assessing Spatial and Temporal Distribution of Metals in Goulburn-Murray Catchments Waterways, Victoria, Australia: Effects of Climate Variability (dry vs. wet years). Environment international 50C:38-46 · October 2012 DOI: 10.1016/j.envint.2012.09.006

https://www.ncbi.nlm.nih.gov/pubmed/23070068

Useful details

Dear Noori Abdul-nabi Nasir (Iraq)

Many thanks for your comments of “useful details” of this thread “ on the seven types of pollution!

The oil spill is an environmental disaster. Crude oils are mixtures of hydrocarbon compounds including BTEX, and PAH, some of which are toxic and exposure of which may cause cancer and other health effects (such as benzene and some PAHs).

Dear Usman Atique (Pakistan)- Heavy metals, pesticides & sewage pollution

Thanks for informing that heavy metals, pesticides and sewage are major pollution problems in Pakistan.

Nutrients

Dear Michel Dedual (New Zealand) – Nutrients pollution

Thank you for informing that nutrients pollution is a problem for New Zealand. I do know you have significant agriculture farming, in particular, dairy farming effluents are polluting New Zealand’s waterways causing toxic algal blooms and depletion of dissolved oxygen in waterways

In Brazil, we have expressive agrotoxic pollution in central-west region of country, and in the Amazon it is possible to highlight the emission of carbon derived from deforestation and fires.

Dear José Sabino (Brazil) - Pesticide Pollution and Carbon Pollution

Thank you for your inputs; yes I came to know that Brazil is one of the world’s biggest food producers and biggest consumers of pesticides. I understand Brazil is still using highly toxic herbicide paraquat which can cause kidney, heart and liver failure. It is reported more human intoxication by pesticide in Brazil (pesticides residues in food). I do also come to know that the frequency of forest fires has increased in Brazil in recent time. In fact, the carbon originally held in forests is released to the atmosphere, when the trees are burned

For Tunisia :

- Pollution of urban origin: sewage, solid waste particularly plastics,

- Industrial pollution: phosphogypsum, metals

- Pollution of agricultural origin: fertilizers (nutrients), pesticides

Dear Oum Kalthoum Ben (Tunisia)- Sewage, pesticide, Metals, Nutrients (phosphate gypsum) pollution

Thank you for your new information that Tunisia is faced with a number of pollution. It is alarming to know that your phosphate gypsum mining is causing many problems as air and water pollution. The phosphogypsum waste from the wet-acid refining process is reported to be with radioactive substances including uranium and radium. Though phosphate mining is boosting the national economy, it comes at the expense of your environment!

Carbon & Pollution

Due to the series of wars that erupted in Iraq, a lot of pollution causes are found in our country. One of the most dangerous pollutants is depleted uranium that was used comprehensively by the Anericans to destroy the Iraqi tanks. Its impact will last for thousands of years as it was mentioned by independent international reports. Today the level of pollution is very high especially the river water where thousands of poisonous cases among citizens of Basrah, in the southern part of Iraq, have been reported and taken to hospitals.

Dear Lotfi Aleya (France)- Car and Industrial pollution

Many thanks for your inputs, yes air pollution due to car and industries are a problem in France. It is reported that overall, air quality in France’s towns and cities is improving or fallen

Dear Hazim Al Dilaimy (Iraq)- Depleted Uranium

Thank you for bringing in a new environmental topic, a localized problem with depleted uranium.

Dear Aung Ze Ya (Myanmar)- Carbon and Pollution

Many thanks for your inputs, Yes, Myanmar may already experiencing both air and water pollution problems (in addition to threats posed by climate change). For example, both rural and urban people still depend on wood, crop waste, charcoal, coal and dung for cooking, lighting and heating causing indoor pollution (particulate matter pollution) and exposing people/families to hazards of smoke and fumes

It is reported that the gold mining industry in Myanmar is dumping an estimated 16.3 kilograms (36 pounds) of mercury into Myanmar’s waterways per day. If it is correct, it is highly likely that Hg (which is toxic and very highly bioaccumulative) can reach to humans via the water and food contamination (e.g. if crops or vegetables are irrigated with elevated levels of Hg-contaminated water).

Since Myanmar is an agriculture-dependent country, therefore, pesticides and nutrients pollution could be other problems. Additional problems could be mismanaged plastics and discharges of effluents from industries such as textiles (containing dyes and heavy metals) and deforestation (current deforestation is 0.3% per year in Myanmar).

It is important and essential that residue levels of hazardous pollutants (heavy metals, pesticides) in water and food are monitored routinely to safeguards both ecological and public health.

In Macedonia we are facing with air pollution that is associated with particles with sizes smaller than 10 micrometers (PM10) as one category and smaller than 2.5 micrometers (PM2.5) as another, and even more dangerous category. These particles can penetrate into the lungs and cause a lot of health issues. They could have variety of chemical compositions, including substances that are proven to be carcinogenic. Another pollutant, which is mostly present in the cities is the noise cause by many sources like: traffic, loud music, industry and etc..

Well among the the seven types of pollution (carbon, metals, nutrients, oil, pesticides, plastics, sewage), in my country the most serious one is air pollution caused by Carbon and low quality Oil.

Dear Sasho Stojkovikj (Macedonia)- Particulate pollution & Noise pollution

Thanks for informing that Macedonia is facing significant pollution with PM. It appears that you are still using fuelwood (as the primary source of energy in the households), old and poorly maintained vehicle fleet and burn agricultural biomass/residues.

Yes, unfortunately that is how it is nowadays, and of course you can also find a lot of research considering pollution with heavy metals, pesticides (especially lindane) and etc. The expert in this area is Prof. Trajce Stafilov (https://scholar.google.com/citations?user=vwH_jr0AAAAJ&hl=en)

Best regards,

Sasho

It will be carbon

Dear Abdullah Noori (Afghanistan) (PM Air Pollution)

Many thanks to letting us know the air pollution is a major problem in Afghanistan. Yes, I came to know that Pollution is killing more people in Afghanistan than armed violence!

The use of old vehicles, and poor quality of fuel, and burning of forest wood, animal dung, and charcoal for fires as well waste burning (plastics, old car tires) and burning of coal ash in brick kilns, bakeries, bathhouses appears to be causing much air pollution in Afghanistan.

According to WHO estimates, deaths due to environmental risks constitute 26% of all deaths in Afghanistan. In Afghanistan, it is estimated that Household Air Pollution (HAP) causes over 27 000 deaths per year, whereas Ambient Air Pollution (outdoor) causes over 11 000 deaths annually, which is very alarming

Dear Justin R Nayagam (India)- Carbon pollution

I feel that climate change will cause a significant impact on water resources in India (due to droughts, floods, cyclones, sea-level rise) in India. Most of the rivers in India are already contaminated with domestic, industry and sewage pollution. In particular, the melting of the Himalayas would be a significant threat on water resources. For example, Rivers depending on the Himalayan glaciers such as the Indus, Ganges, Brahmaputra, Syr Darya and Amu Darya could face water shortages or reduce river run-off due to retreat of glaciers, and this would cause a dramatic impact on drinking water supplies, biodiversity, hydropower, industry, agriculture and ecosystems on which about 2.4 billion people in Asia depend

sewage is most hahaful as it affect water quality and thereby enters into food chain. Many dreadfull diseases affected all livingbeings.

Dear Manohara Tn (India)- Sewage pollution

Yes, you are right; it is known that most of sewage generated in India remains untreated. Several chemicals and microbes can be found in sewage water including, microbial pathogens (total coliform, Escherichia coli) and chemicals (heavy metals, nutrients like nitrate). It is reported that Rivers like Yamuna, Ganga, Gomti, Ghaghara River, Chambal, Mahi, Vardha are amongst the most coliform polluted water bodies in India. Wastewater/sewage water, if used without treatment and above the recommended guideline threshold values for beneficial wastewater uses (irrigation/ growing crops/vegetables/fish), can cause harmful pollutants (chemicals and pathogens) be accumulated in edible biota (plants and animals parts/organs) and be transferred to humans via the food chain (from consumption of contaminated agri-produces)

Oil Spill & Oil Pollution (global)- Impact

Oil exposure to fish can cause edema (fluid accumulation), cardiac toxicity, tissue death, and abnormal development; Phytoplankton and zooplankton can accumulate oils rapidly via diffusion; oil can be accumulated in the food chain (algae-zooplankton-invertebrates-fish-birds) and can be transferred to humans via the food chain. Corals exposed to oil caused mortality, decreased growth rates, survival of larvae & gonadal development and increased bleaching. Oil exposure to seagrasses can lead to decreased growth rates, smothering (suffocating) of leaves, changes in the chlorophyll content of leaves and reduced photosynthetic ability. Mangrove plants may die from suffocation (reduced O2 flow), starvation, yellowing (chlorosis), increases rates of defoliation, reduced pneumatophores, reduced photosynthetic efficiency and other physiological/toxicological impact

https://www.researchgate.net/publication/329074954_Presentation_Oil_Spill_Oil_Pollution-_Chemistry_Ecotoxicology_Impact_On_Biodiversity_Ecosystems_Management

The front figure related to oil spills from tankers 1970-2016 sourced from https://ourworldindata.org/oil-spills

Oil pollution

Dear Noori Abdul-nabi Nasir (Iraq)- Oil Pollution

Thank you

Lighter oils are highly acute toxic to animals and plants and heavier oil can cause long-term effects on biota and ecosystems via smothering or coating (birds) or remains as residues on or in sediments.

The mentioned all pollution are harmful. But CO2 is most harmful.

Dear Alex Rodrigues Nogueira (Brazil) – Air & water pollution, deforestation, pesticides, and mining

Yes, Brazil is facing several environmental problems from air & water pollution, deforestation, agricultural pesticides to oil spills. According to a report air pollution is causing about 49,000 deaths in Brazil every year, caused by both outdoor (vehicles & industrial emissions) and indoor pollution (cooking with wood and other solid fuels). Overall, about 40% of the Brazilian population is estimated to breathe air which is more polluted than the WHO guidelines. I understand you are still using some harmful pesticide like Paraquat & mining could be other environmental problem!

Dear Suparna Roy (India)- CO2 Pollution (Ocean acidification) (Global)

Yes, CO2 could be harmful to your marine sector. Ocean acidification (OA) (absorption of CO2 by the ocean and consequent reduction of pH of the ocean) might impact India’s marine fisheries and seafood security. A lot of people may depend on marine seafood sector for both income and protein supply.

It is known that calcifying organisms with CaCO3 shells/skeleton such as krills, pteropods (food of marine organisms) and oysters, mussels, abalone, sea urchins, sea cucumbers (commercial fisheries), and corals (habitat of marine species and tourist attraction) would be impacted due to the decrease in ocean pH. Fish could be impacted due to loss of habitat (such as coral reefs).

However, OA may enhance productivity of non-calcifying seagrasses and seaweeds.

Oil spills can make fatal for plant, animal and human life. The substance is so toxic that it can cause massive loss of species that live in the sea. Oil spill penetrates into the plumage and fur of birds, breaks down the insulating capabilities of feather which makes them heavier, disallow them to fly and kill them via poisoning or hypothermia.

CO2 Pollution/climate change and Women (Global)

Women in the least developed countries (LDCs) and developing countries in Africa and Asia are responsible for food production (agriculture, livestock, fisheries, and aquaculture), the collection of water, and biofuel (wood, non-timber forest products) from forests, cooking, the management of natural resources (forestry & fisheries) and taking care of children and the elderly. Climate change is projected to cause a severe impact on rural women via crop failure, food and water contamination, shortages of biofuel and clean water, diseases and natural disasters etc. The environmental degradation due to climate change will force women to move further to obtain natural resources such as clean water and fuel-wood and increase the likelihood of exposure to harmful chemicals and biological toxins and diseases

https://www.researchgate.net/publication/327655468_Presentation_Climate_Change_Impacts_on_Women_in_the_LDC_Developing_Countries

sewage pollution had serious affect on the rivers and other freshwater sources

Dear Noori Abdul-Nabi Nasir (Iraq)- Sewage pollution and Climate change

Yes, sewage pollution is a serious water quality problem in waterways in both developing and developed countries, in particular, many rivers in developing countries are contaminated with sewage. Sewage pollution can cause deoxygenation and turbidity; resulting in suffocation, disease and death of fish and other marine organisms.

Sewage wastes are contaminated with pollutants like inorganic and organic chemicals (heavy metals, detergents, and pesticides), biological pollutants (bacteria, viruses, fungi, parasites).

Sewage pollution is one of the main causes of nutrient pollution/eutrophication that results in hypoxia (dead zones) in water bodies worldwide. A recent research (Mekonnen Hoekstra 2018) reveals that domestic sewage contributes 54% of phosphorus load to freshwater

Furthermore, climate change-related flooding and excessive rainfall (where it will occur) would facilitate/enhance entry of human and animal wastes and pathogens into waterways and drinking water supplies, which are potential for waterborne diseases such as diarrhoea and cholera (Kibria et al. 2017)

Mekonnen, M. M. & Hoekstra, A. Y. (2018). Water Resources Research, 54, 345–358.

Kibria et al. (2017). Water security and Climate change https://www.researchgate.net/publication/303218799_Climate_Change_Water_Security

Grasshopper Effect: Transport of Pollutants from Warmer to Colder region (Global)

The Grasshopper/global distillation effect occur when persistent organic pollutants (POPs) (e.g. DDT, Dioxins, PBDE (Brominated Flame Retardants), PFCs (Perfluorinated chemicals) are transported from one region (warmer) to another region (colder-polar regions) through wind cycles and heat differences. These POPs evaporate with warm air and return to earth with rain and snow in the colder areas of the globe. In fact, POPs released in one part of the world can, through a repeated (and often seasonal) process of evaporation and deposit, be transported through the atmosphere to regions far away from the original source. As a consequence, a region which is generally considered as a pristine wilderness (arctic) can become polluted with POPs.

Climate change effects: climate change and global warming would facilitate increase volatilization of chemicals such as POPs, therefore, would increase their presence in the air and other matrices in the future

https://www.unenvironment.org/news-and-stories/story/grasshopper-effect-serves-pollutants-plates-arctic-peoples

cathyramos.com/images/GrasshopperPPT.pdf

http://archive.li/qQEbK

In France, we have a lot of nutrient pollution, especially in terms of N in our rivers an lakes. Atrazine, a derivative of glyphosate is also found in almost every soil. In French Guiana, the extensive gold exploitation enriches the region in heavy metals, particularly Hg.

Dear Alex (France) Mercury (Hg) pollution in France Guiana

Yes, the run-off from gold mining activities is known to contribute to Hg pollution in France Guiana.

It is reported that in 1997, France's National Public Health Network studied four Wayana Amerindian villages along the Maroni River in French Guiana and found that 57 percent of the population had Hg levels above the WHO safety limit. The mercury exposure of the Wayana population was related to diet (fish) which were highly contaminated for certain species (up to 1.62 mg/kg fresh weight or 8.1 mg/kg dry weight in skeletal muscle). Overall, 14.5% of the fish collected exceeded the 0.5 mg/kg (fresh weight) safety limit.

French Guiana is located in northern South America and borders the North Atlantic Ocean between Suriname and Brazil. The country covers an area of about 83,534 km2 and its total population is 237,200 as per 2011 reports. The country’s principal mineral commodities are gold, sand, cement, clays, niobium, crushed stone, tantalum and petroleum. Gold is widely mined in the country and is the country’s major export commodity.

Fréry, N. et al. 2001. Gold-mining activities and mercury contamination of native amerindian communities in French Guiana: key role of fish in dietary uptake. Environ Health Perspect. 2001 May; 109(5): 449–456. doi: [10.1289/ehp.109-1240303]

https://pulitzercenter.org/reporting/french-guiana-mercury-global-threat

Oil pollution has important role

Dear Noori Abdul-nabi Nasir (Iraq)- Oil Pollution

Yes, a number PAH compounds found in crude and refined oils are of high risk to the environment having have high log kow values (high bioconcentration and bioaccumulation potential-log kow ranged (3.37-7.44) as well high acute toxicity (median lethal concentration or LC50 0.06-4870 µg/L). For example, Indeno[1,2,3cd]pyrene has log kow 7.0 and LC50 0.6 µg/L; C4 chrysenes has low kow 8.0 and LC 0.06 µg/L; bezo[a)pyrene has low kow 6.04 and LC50 7.6 µg/L as well as some PAHs are carcinogenic (naphthalene, bezo[a)pyrene, Indeno[1,2,3cd]pyrene)

References

Neff, J.M. Scott A. Stout, and Donald G. Gunster. 2005. Ecological Risk Assessment of Polycyclic Aromatic Hydrocarbons in Sediments: Identifying Sources and Ecological Hazard. Integrated Environmental Assessment and Management. 1 (2): 22–33.

Kibria , G. 2018. Presentation: Oil Spill & Oil Pollution- Chemistry, Ecotoxicology, Impact On Biodiversity & Ecosystems & Management

https://www.researchgate.net/publication/329074954_Presentation_Oil_Spill_Oil_Pollution-_Chemistry_Ecotoxicology_Impact_On_Biodiversity_Ecosystems_Management

Sewage is one of the must important sources of pollution in my county (Sanct i Spiritus, Cuba) as well as pesticides just because agriculture is the principal economic activity of the region

Dear Leonardo Hurtadoluna (Cuba) Sewage and pesticides pollution

yes, sewage pollution could be a serious problem for Cuba as large number of industries dumps their sewage straight into the water, such as the Bay of Havana. It is also known that part of the sewage from the urban area ends up in the sea and is mixed with the water where people swim. Pesticides pollution such as DDTs uses decreased from 1980 on wards as the use of these pesticides discouraged according to some reports. However, there are reports of heavy metals pollution problems in Cuba , such as Arsenic and lead

References

https://www.iaea.org/sites/default/files/publications/magazines/bulletin/bull53-1/53105913237.pdf

https://thecaribbeancurrent.com/cuba-has-11000-sources-of-pollution-that-affect-water/

I think the heat from heat sources should be added as pollutants. The heat supplied to both water and air causes an increase in temperature. This increase disrupts the natural environment. So it pollutes the natural environment. These include nuclear power plants, thermal energy power plants. In particular, the delivery of the cooling water of nuclear power plants to the seas causes pollution of the seas.

https://inis.iaea.org/collection/NCLCollectionStore/_Public/05/133/5133629.pdf

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/291077/scho0610bsot-e-e.pdf

https://www.qualenergia.it/wp-content/uploads/2018/07/nucleare-acqua_0.jpg

I think heavy metals and plastics are affecting the biodiversity of Bangladesh more than any other contaminants.

Dear Soner Çetinkaya (Turkey)- Power Plant Cooling Water Pollution

Many thanks for bringing in an important pollution topic related to power plant cooling water impacts on biodiversity and aquatic ecosystems.

Power plants cause negative impacts on biodiversity and the aquatic environment by killing billions of fish, other aquatic life, early life stages of fish (eggs, larvae) (trapping against screens of the intake) and degrading aquatic ecosystems (from discharge of warmer water) by increasing the temperature of rivers, lakes, and ocean waters and lowering dissolved oxygen levels (oxygen solubility in water is inversely related to temperatures). Discharge of warmer water to a river or lake can stress and kill fish and other wildlife (if it exceeds the species tolerance limits)

It should also be noted that power plants are the biggest user of water compared to other beneficial users, for example, in the USA power plant accounts for 49% of water uses, compared to irrigation 31%, public supply 11%, aquaculture 2%, mining 1%, livestock

Dear Subrata Kumar Ghosh (Bangladesh)- Heavy Metals Pollution

Yes, you are right!. Heavy metals pollution could threaten water quality and biodiversity in Bangladesh and could bring in major environmental disaster for Bangladesh. An international research carried out recently using innovative artificial mussels technology found eight heavy metals (Cd, Cu, Fe, Mn, Ni, Pb, U, Zn) on a regular basis in waterways (rivers, estuaries and coastal areas) across Bangladesh (Chittagong, Dhaka and Khulna).

The study identified seven metal pollution “hot spots” of which, five “hot spots” (Cu, Fe, Mn, Ni, Pb) were located in the Buriganga River, close to the capital Dhaka. Direct effluents discharged from tanneries, textiles are, most likely, reasons for elevated concentrations of heavy metals in the Buriganga River. The study concluded that metal pollution may cause significant impacts on water quality (irrigation, drinking), aquatic biodiversity (lethal and sub-lethal effects), food contamination/food security (bioaccumulation of metals in crops and seafood), human health (diseases) and livelihoods of people associated with wetlands in Bangladesh.

References

Kibria et al. 2016 a. Trace/heavy metal pollution monitoring in estuary and coastal area of Bay of Bengal, Bangladesh and implicated impacts. Marine Pollution Bulletin 105 (2016) 393–402. doi: 10.1016/j.marpolbul.2016.02.021. Epub 2016 Feb 23.

Kibria et al. 2016b. Monitoring of metal pollution in waterways across Bangladesh and ecological and public health implications of pollution. Chemosphere 165 (2016). 1-9. https://doi.org/10.1016j.chemosphere.2016.08.121

there are many factors determined which one is the most effected by interaction between these factors and environmental cases

Environmental factors has significant affect on fish population

Dear Noori Abdul-nabi Nasir (Iraq)- Fish- Pollution-Climate Change

Yes, pollution in waterways due to pesticides, herbicides, heavy metals, acid drainage (acid mine drainage), nutrients (N,P), and algal blooms, oil spill and the release of cooling water from electric/nuclear power generations are existing environmental problems that are causing a significant impact on the natural fish population.

In addition, there is a significant and alarming threat posed by climate change and global warming on the fish population. For example, the rise in ocean temperatures due to global warming causing wild fish to move north and south poles from tropical and sub-tropical areas (to escape the heat/warming of ocean water). Coral reef bleaching (due to increase in temperatures) would be other threat to fish population since one-third of world fish uses coral as a habitat. Changes in climate (rise in temperature) may enhance proliferation of harmful algal blooms (HAB) in marine environments such as diatoms, dinoflagellates which causes Diarrhoeic shell-fish poisoning (DSP), paralytic shellfish poisoning (PSP) and ciguatera fish poisoning (CFP) and may cause fish kills. The rise in temperatures would cause a decrease in oxygen supply (since oxygen solubility in water is inversely related with temperature) and may cause more fish kills in the wild due to hypoxic or anoxic conditions to be created (Kibria et al. 2016).

Hypoxia (dissolved oxygen

Golam Kibria

Good details. thanks

Regards

Well,

the most important sources of surface water bodies pollution in Iraq are sewage and salinity.

Sincerely

Dear Bayan Hussien (Iraq): Salinity, Sea-level Rise/climate change and Iraq

Yes, Iraq already facing with serious salinity problems. It is known that agriculture is the second largest economic sector in Iraq after oil, however, drought, low water flows, water shortages, and most importantly the increase in soil salinity is preventing to cultivate vital crops like rice and wheat. Salinity is also reported to have killed fish and livestock in Iraq and, even in some areas tap water is too salty to be used.

In the future, the sea-level rise (SLR) due to climate change may increase the threat to southern part of the Tigris- Euphrates delta, low elevated Basrah city (inundation of the Tigris and Euphrates delta, saltwater intrusion and increase in soil salinity, impacts on infrastructures-ports, people’s displacement). The SLR and increasing in salinity can impact the Hammar Marsh (UNESCO world heritage site) which is globally significant wetlands with high biodiversity and traditional cultures. In fact, rising sea level is a major threat to coastal habitats and coastal communities worldwide

References

Adamo, N, , Nadhir Al-Ansari, Varoujan K. Sissakian, Sven Knutsson and Jan Laue. 2018. Climate Change: Consequences on Iraq’s Environment. Journal of Earth Sciences and Geotechnical Engineering, 8 (3), 2018, 43-58

Kibria, G. 2014. Sea-level rise and its impact on wetlands, water, agriculture, fisheries, aquaculture, public health, displacement, infrastructure and adaptation.https://www.researchgate.net/publication/266794121_Sea-level_rise_and_its_impact_on_wetlands_water_agriculture_fisheries_aquaculture_public_health_displacement_infrastructure_and_adaptation

https://www.bloomberg.com/news/articles/2018-08-02/water-crisis-salts-the-earth-in-iraq-s-long-neglected-south

https://reliefweb.int/sites/reliefweb.int/files/resources/Climate%20change%20In%20Iraq%20Fact%20sheet%20-%20English.pdf

I think that plastics are the main problem of the global pollution, especially of water bodies, from ponds to oceans.

Plastics and other visible pollutants are easy to locate and is to implement management measures. What about invisible chemical pollutants especially from industries?