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Thứ Tư, ngày 31/05/2023

Environmental effects of some toxic chemical incidents in fertilizer production in the world and lessons learned for Việt Nam



    Toxic chemical incidents are part of environmental incidents arising in the course of human activities due to the leakage, fire, explosion, release and emission of toxic chemicals causing serious effects on the environment, human property and life. In recent years, in some countries, there have been toxic chemical incidents related to fertilizer production activities.

    The article presents the analysis and assessment of the environmental effects of a number of toxic chemical incidents in fertilizer production that have occurred in the world in recent years. Thereby synthesizes some experience for Việt Nam in implementing measures to prevent and limit the environmental effects caused by these chemical incidents.

    ​1.Production of nitrogen fertilizers: causing toxic chemical incidents such as NH3, NH4NO3

  • Production of phosphorus fertilizers (superphosphate) and mixed DAP fertilizers: causing toxic chemical incidents such as yellow phosphorus (P4); NH3 (for DAP fertilizers); GYPs waste.

The origin and cause of these problems may come from:

  • Chemical storage or transport processes.

  • Chemical-related metabolic processes (production, reaction).

  • Physical production processes that use chemicals as agents (deep cooling, heat preservation...).

  • Industrial processes that generate highly toxic (chemicals) or hazardous waste (fire, explosion);

  • Areas where transportation activities are involved (wharves, pumping stations, chemical transfer stations…).

For example, the NH4NO3 chemical explosion incident due to the following reasons: Exposure to strong shocks (from the shock waves of nearby explosions); Exposure to high temperatures in the absence of oxygen (in a closed pipeline); A smaller explosion can trigger an explosion with larger amounts of NH4NO3 stored nearby.

  1. Environmental effects of some toxic chemical incidents in fertilizer production in the world

    In the world, in recent years, there have been a number of chemical incidents from the production of chemical fertilizers that have caused serious damages to the environment, human health and property, for example: Explosion of chemical warehouse containing ammonium nitrate (NH4NO3) at AZF Company, Toulouse (France) in 2001; Ammonia (NH3) explosion at the DAP Fertilizer Plant of Chittagong Urea Co., Ltd., Bangladesh; Phosphogypsum waste (GYPs) spill at ICL's Rotem Fertilizer Plant in the Negev region of Israel in 2017; Leakage of GYPs wastewater at Mosaic Fertilizer Plant, Florida, USA in 2016.

    ​a) NH4NO3 explosion incident at AZF Fertilizer Plant, Toulouse, France

    The AZF Fertilizer Plant is located in an industrial park, South of Toulouse, France, about 3km from the City centre and was established in 1924. The main activity of the Plant is to produce industrial nitrogen and nitrate fertilizers and synthetic compounds containing chlorine.

    At 10:10 am on 21st December 2001, a series of explosions occurred at the Company's warehouse area No. 221, where 300 tons of NH4NO3 were stored. The entire Plant was destroyed, creating a crater about 7m (23ft) deep and 40m (131ft) in diameter.

    The big explosion caused a large impact to an area many kilometres away, with a corresponding magnitude of 3.4 on the Richer scale. The explosion released a large amount of NH3 gas, polluting the air, water and soil environment.

    - For the air environment: Significant dust falls from equipment installation locations and craters observed outside the plant. A large cloud of dust from the explosion and red smoke spread to the Northwest. Atmospheric pollutants released after detonation lead to the formation of nitric acid (HNO3), ammonia (NH3), nitrogen dioxide (NO2) and nitrous oxide (NO2). Atmospheric monitoring results performed by ORAMIP (local air quality measurement laboratory) show that the parameters of HNO3, NH3, NO2, N2O in the vicinity of the AZF Plant all exceed the permitted standards. For the NO2 value, the monitored value is 200µg/m³.

    The emission of NO2, NH3 gases and particles released by the explosion are the cause of temporary eye diseases (such as conjunctivitis, vision defects) and respiratory diseases (such as tracheitis) in the people living around the plant area. These health problems seemed to decrease within 5 weeks of the explosion.

    The explosion at the AZF Plant caused many casualties; 21 people at the AZF Plant area; 1 people at SNPE and 9 people outside the AZF Plant site (including 2 people hospitalized) were killed after the explosion. In addition, about 30 people were seriously injured, of which 21 had to be hospitalized for more than 1 month.

    - For the water environment: The explosion destroyed the NH4NO3 solution tanks and caused the leakage of nitric acid (HNO3) into the water environment. On the day of the explosion, the release of HNO3 into the Garonne River was recorded, which severely polluted the river. Out of 120 parameters measured in the Garonne River, only increase in NH4, NO3 and COT parameters was observed. The highest values ​​were observed in the section of Garonne River near the incident site of the AZF Plant. Contamination was determined for NH4, 331mg/l in the river section and 16mg/l in other areas of the Garonne River; for NO3, 1,277mg/l in the river section and 63mg/l in other areas of the Garonne River; for COT, 23mg/l in the river section and 8.7mg/l in other areas of the Garonne River.

    NH3 concentration in the Garonne River has exceeded the permissible value, affecting the water supply for people living around the Garonne River area. An instrument used to monitor ammonia levels from water supplied from the Garonne River showed that the water in the area was significantly contaminated with ammonia.

    - For the soil environment: The explosion made the soil environment in the area contaminated with hydrocarbons, lead, arsenic and mercury. In July 2006, after 2 years of work, more than 750,000m3 of soil has been treated, nearly 90% of contaminated soil has been treated through on-site washing at 805°C. The pollution remediation process was completed in 2008, with an estimated cost of the clean-up at €100 million.

    - For the aquatic ecosystem: NH3 contamination has caused many species of fish in the Garonne River to die. Fish mortality due to the effects of NH3 contamination in water is associated with a high pH (up to 8.6), thus promoting chemical balance towards the non-ionized form of NH3 (free NH3), very toxic to fish. It is estimated that about 9 tons of NH3 seriously contaminate the Garonne River and affect the aquatic ecosystem.

    - Estimated damages: 6 months after the explosion, the direct damages from the explosion estimated include: Nearly 1,300 companies, 20,000 workers were affected. The French Government has spent €10.4 million to help affected companies and proposed €1.7 million to exempt this group of people from tax. According to a statement by insurance companies, the total estimated damages from the explosion were between €1.5 and 2.3 billion.

    The environmental damages caused by this toxic chemical incident have not been specifically and fully estimated. Up to now, the environmental damages have only been estimated for the soil environment through the actual costs paid to restore the soil environment around the incident area and damages to the water environment through methods to restore and clean the water environment.

    b) NH3 explosion at the DAP Plant of Chittagong Urea Fertilizer Limited (CUFL), Bangladesh

    Around 10 pm, on 22nd August 2016, a large amount of toxic ammonia gas was released due to the overpressure explosion of a 500-ton ammonia tank from the Di-ammonium Phosphate (DAP) Plant. The Plant was established in 2006 on the basis of Chittagong Urea Fertilizer Limited (CUFL) located on the South bank of Karnaphuli River, Bangladesh.

    The DAP-1 Plant has a production capacity of 1,600 tons of DAP per day. The Plant has two ammonia tanks (NH3) with a capacity of 500 tons to supply to the fertilizer production through pipelines. At the time of the incident, one of the tanks storing 325 tons of anhydrous NH3 exploded.

    Cause of explosion: There are many causes that can lead to tank explosion, for example faulty tank, internal corrosion, external corrosion, flow interruption, control valve failure, drain valve failure, overheating temperature/overpressure and/or error caused by human. However, an explosion at the CUFL Plant's NH3 tank indicates that the tank was over-pressurized due to an operational error or mechanical failure. In addition, there is no additional layer of protection that can prevent or minimize the release of NH3 and minimize the consequences.

    The NH3 explosion spread a large amount of NH3 gas into the air environment, forming giant clouds that spread, affected the ambient environment.

    For the air environment: Based on published reports, ammonia gas concentrations were recorded as 600 ppm in the vicinity 5 hours after the incident, still well above the tolerable or threshold limit value (TLV). This indicates a fairly high concentration of ammonia at the time of the explosion.

    It is also worth noting that the toxic NH3 gas spread for several kilometres and the wind carried this gas to the other bank of the Karnaphuli River, causing nearly 250 people affected by inhalation of the toxic NH3. Fifty-two of them were plant workers who were required to be hospitalized the same night. Locals in the affected area have severe eye irritation and breathing problems.

    For the water environment: Firefighters are trying to prevent emissions by spraying water on the fire to dissolve NH3 into the water. Diffusion of ammonia into water bodies will increase the pH and have a negative impact on the overall aquatic ecosystem. The environment and biodiversity in the area surrounding the incident were seriously affected. The fishermen found a lot of dead fish in the nearby polluted ponds.

Fishermen collect dead fish from the river, about 50 meters from the Plant, died because of NH3

explosion at DAP Plant, Chittagong on 22nd August 2016

    ​c) Phosphorus spill at ICL's Rotem phosphate Fertilizer Plant in the Negev region of Israel

    ICL (Israel Chemicals Ltd.) is a global company in fertilizers and chemicals. ICL products and solutions are used in key agricultural and industrial markets such as phosphorus, potassium and special fertilizers that ICL produces and sells, very important for farmers around the world, improving crop yield and quality.

    On 30th June 2017, a serious environmental incident occurred at ICL Rotem, a subsidiary of ICL located in the Negev region of Israel. According to ICL's report, an embankment has partially collapsed at the plant's lake No. 3. This reservoir is used to store GYPs wastewater, a by-product of phosphate fertilizer production. Immediately after the incident, the company was ordered to halt operations of the relevant reservoir and stop the flow of wastewater. However, it is estimated that around 100,000 cubic meters of GYPs (equivalent to 35,000 tons) have been released into the surrounding environment. GYPs waste contains many impurities (residual acids, fluorine compounds, trace elements such as mercury, lead and radioactive components). These impurities and significant amounts of phosphates can be released into the environment (soil, groundwater and surface water).

    - For the water environment: The incident caused wastewater containing toxic substances to flow into the Ashalim Stream bed. The results showed that the acid concentration was high in the Ashalim Stream bed after the incident. The highly acidic toxic water flows through the desert, picking up anything in its path, before flowing into a reservoir a few dozen kilometres from the Dead Sea.

    Local authorities estimated more than 200 million NIS to rehabilitate the river and its ambient environment. Toxic, highly acidic liquid from the ICL Rotem Plant seeps into groundwater systems, or aquifers. Groundwater contamination can appear many years after the initial contamination event occurs.

    - For the soil environment: After the incident, the ground is still dyed a dark brown colour and emits an unpleasant sour smell, more intense than a chlorinated swimming pool.

    - For the ecosystem: Toxic wastewater destroyed everything in its path as it crossed the desert, poisoning one-third of the local ibexes as well as other animals and plants.

    The ecosystem surrounding Bokek Nature Reserve was also severely affected. Bokek Nature Reserve's freshwater habitat once allowed rare flora and fauna communities to thrive in a dry and salty environment. But salt level rose from about 500 - 600mg/l in the 1990s - at that time, the highest permissible level for drinking - to 4,550mg/l recorded in the aquifer at the end of 2017. According to the court's ruling, the ICL must pay an amount of $400 million to compensate for damages caused by water pollution in the Bokek conservation area.

An animal carcass was found near Ashalim Stream after the ICL incident on 30th June 2017

    d) GYPs wastewater leakage incident at Mosaic Fertilizer Plant, Florida, USA (2016)

    Mosaic Fertilizer Company, Florida is based in Tampa, Florida. Mosaic is currently the largest producer and distributor of phosphorus and potassium fertilizers in the United States and around the world.

    According to a report by Mosaic, on 27th August 2016, their workers discovered a pit in the GYPs waste storage area at the New Wales Facility, Mulberry Town, Florida. The sinkhole is as deep as Florida's groundwater, which is the source of drinking water for millions of people in this state. The hole allowed wastewater containing GYPs to leak into the drainage system and gradually seep into the state's aquifer. An estimated 980 million litres of radioactive water passed through the sinkhole, leaking into the main groundwater source, one of Florida's main aquifers.

    GYPs waste leakage has a huge impact on the surrounding environment, ecosystems, specifically wetlands, water quality and quantity as well as wildlife habitat.

    - For the water environment: The incident causes pollution to the surface water environment of the Alafia River: With pH of two, the wastewater of the discharge process significantly changes the pH throughout the length of the Alafia River. The incident seriously affected surface water quality within a radius of about 7 miles. An excess of phosphorus in the aquatic environment caused algal blooms and increased chlorophyll concentrations in both rivers and bays until May of the following year.

    - For the ecosystem: The incident resulted in large numbers of fish deaths along the length of the river from Mulberry to Hillsborough Bay including approximately 1.3 billion small fish (fish as bait, food for other animals) and shellfish (shrimp, crab) and 72,900 fish caught. With habitat loss and mass mortality of small fishes that are food for various species, the spills can also cause fish-eating birds in the Alafia River and surrounding wetlands to indirectly affect, including reproductive activity.

    In addition, the open waters of Hillsborough Bay that provide important habitat for seabirds, marine fish and mammals have also reported negative impacts.

  1. Some experience for Việt Nam

    It is obvious that the above incidents have leaked and released a large amount of toxic chemicals (such as NH3; NH4NO3; GYPs waste...) into the environment. The leaked chemicals will then be released into the atmosphere or seep into the soil or groundwater, river water causing serious damages. In addition to direct damages to the natural environment, the above incidents also cause damages to human property and health due to pollution and degradation of the natural environment.

    In Việt Nam, in recent years, there have been a number of toxic chemical incidents in fertilizer production (mainly in the production of nitrogen, phosphorus and NPK fertilizers). These toxic chemical incidents mainly arise from production materials (NH3); yellow phosphorus (P4); and GYPs waste. Some typical incidents are: Spill, leak of GYPs waste at Lâm Thao Superphosphate and Chemical Company (2009); NH3 leak incident at DAP Joint Stock Company of Đình Vũ Industrial Park, Hải An District, Hải Phòng City (2011); The incident of spilling GYPs waste dam causing a big fire at Lào Cai Yellow Phosphorus Joint Stock Company in February 2012; Breaking incident of GYPs dam at DAP Fertilizer Company, Đình Vũ, Hải Phòng (2013); NH3 leak incident at DAP Joint Stock Company No. 2, Tằng Loỏng Industrial Park, Bảo Thắng District, Lào Cai (2015)...

    In the coming time, in order to limit the environmental effects caused by toxic chemical incidents in fertilizer production, enterprises in this sector need to:

    First, need to develop a plan to prevent and respond to chemical incidents suitable to the type and scale of production and business activities of the enterprise.

    Second, strictly comply with legal regulations and guidance of competent agencies on the implementation of safety measures in the management and use of chemicals, especially toxic chemicals. Because when a chemical incident occurs in fertilizer production, the level of damages to the water, soil, air environment, ecosystem and other indirect damages such as human health, life or infrastructure is great.

    Third, in case of incidents, it is necessary to do early zoning of the effects, especially for plants located in sensitive locations such as: near water sources (rivers, streams, ponds, lakes) or placed in the windward position... The implementation of zoning will soon prevent and limit the spread of chemicals in the environment, significantly reducing the effects on the environment, people and the ecosystem.

MSc. Trần Bích Hồng

Trần Thị Giang

Environmental Science Institute

(Source: Vietnam Environment Administration Magazine, English Edition III - 2021)


    1.Craig Pittman, 2016, Florida sinkhole at Mosaic fertilizer site leaks radioactive water.

    2. Dechy N., Gaston D., Salvi O., 2004, “First lessons of the Toulouse ammonium nitrate disaster, 21st September 2001, AZF plant, France”, Journal of Hazardous Materials, Volume 111, Issues 1 - 3, 26th July 2004, Pages 131-138.

    3.Easir Khan A, 2016, “Dap-1 Ammonia Tank Explosion: Safety and Security Concerns in Chemical Process Plant in Bangladesh”, Int J Petrochem Sci Eng. 2016;1(1):10 - 11.

    4. French Ministry of Sustainable Development, 2001, Explosion in the AZF fertilizer plant September 21st, 2001, Toulouse (France), File last updated: July 2013.

    5. Nicolas Dechy, 2004, Damages of the Toulouse disaster, 21st September 2001

    6.Sue Surkes, 2019, Negev phosphate plant over pollution.

    7.Sue Surkes, 2020, Popular stream in south to reopen 3 years after deadly chemical spill.

    8. Thierry LangValérie SchwoebelEloi DièneEric BauvinEric GarrigueKarine Lapierre‐DuvalAnne Guinard and Sylvie Cassadou, 2007, “assessing post‐disaster consequences for health at the population level: experience from the AZF Factory explosion in Toulouse”, J Epidemiol Community Health. 2007 Feb; 61(2): 103 - 107.



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