Nearly half a century after poorly regulated oil producers began dumping billions of litres of wastewater and other toxic substances into the rivers and tropical forests of northern Peru, the government is taking its first steps towards cleaning up the damage in the country’s oldest and largest Amazonian oil field.
Government contractors are drawing up plans for the remediation of 32 polluted sites — out of up to 2,000 identified so far — in an oil-producing area known as Block 192. The sites have been listed as priorities by both environmental authorities and local indigenous organizations. Meanwhile, a government-funded study conducted by the United Nations Development Programme (UNDP), and released publicly in August, recommends a more comprehensive remediation strategy based on health risks, along with changes to environmental regulations.
Block 192 covers about 4,970 square kilometres overlapping the Pastaza, Corrientes and Tigre rivers, which flow into the Marañón, one of the main tributaries of the Amazon. It is located in a remote region near Peru’s northern border with Ecuador that is inhabited mainly by Quechua, Achuar and Kichwa people. The US-based company Occidental Petroleum began operating there in the mid-1970s, two decades before Peru passed environmental regulations for the oil and gas industry. Oil production in Block 192 peaked in 1982, at 120,000 barrels a day.
For four decades, the environmental effects of this activity were largely uncontrolled and unremediated. The hot, salty, metals-laden water pumped out of wells with oil was dumped into streams and rivers until 2009, nine years after Occidental transferred its lease to the Argentinian firm Pluspetrol. In 2015, Occidental announced that it had settled — for an undisclosed sum — with five Achuar communities who sued in a US court over pollution in the Corrientes River. The company denies that its operations contaminated Block 192.
That discharge of polluted water, combined with ongoing spills from the pipelines criss-crossing the block, has resulted in chronic exposure of fish, frogs and other aquatic life to salts, heavy metals and hydrocarbons, according to the UNDP-sponsored study, which included on-site inspection of 72 areas along the main rivers and their tributaries.
Residents of villages in Block 192 have also been exposed to these pollutants. Until 2015, when the government began installing temporary water-treatment plants, rivers and streams were virtually the only source of water for drinking, cooking and washing. Villagers recall bathing in salty water and pushing oily scum aside to draw water for drinking or cooking. Many continue to question whether fish are safe to eat. Near the Kichwa community of Doce de Octubre on the Tigre River, for instance, oil seeps to the surface of a former lake in the midday heat and a small stream of salty water trickles past a set of decades-old pipes, says Segundo Cariajano Hualinga, the community's president.
Indigenous federations have fought for more than a decade to get Peru’s government to commit to remediating sites polluted with oil, and to agree to the UNDP study. Remediation plans are under way for the 32 priority sites, but a US$15-million contingency fund is nearly exhausted. The UNDP study estimated that the clean-up work on 92 sites could cost $300 million. Although full funding is not yet assured, Peru's minister of energy and mines, Francisco Ismodes, told reporters on 6 September that his ministry would request an additional $51.5 million in budget funds in 2019 to clean up Block 192.
But the Amazon itself presents major challenges to any clean-up effort. Environmental remediation is daunting in rainforest ecosystems, with their seasonal flooding, varying water chemistry and poorly understood groundwater flows, says Margarita Núñez, a biologist and consultant in Costa Rica who headed the UNDP study team.
The saturated, nutrient-poor clay soil in Block 192 contains little oxygen. She says that this makes it difficult to use one of the cheapest and least invasive methods of cleaning up oil and gas pollution — introducing microorganisms that can break down hydrocarbons.
Because of those conditions, along with the accumulation of metals from decades of polluted water discharge, the UNDP study recommends a combination of measures. These include bioremediation with plants and microbes, removal and incineration of contaminants, stabilization or solidification of polluted areas, and thermal desorption, in which heat is used to separate individual contaminants from a mixture.
Many clean-up options put forth by the study would be difficult to use in Block 192, says Raúl Yusta García, a chemical engineer at the Monterrey Institute of Technology in Mexico. His ongoing research suggests that pollution levels in water discharged from oil operations have been underestimated, in part because monitoring sites often were located farther from discharge sites than required by law.
Defining the goal
Because Peruvian law lacks a clear definition of environmental remediation, government officials, company executives and local communities have different expectations about what a clean-up effort should entail. Although the “occidental, technified world” sees the goal of remediation as reducing health risks, indigenous people think of it “more as restoration”, returning a site to its former state, says Fernando Morales, an environmental chemist at Simón Bolívar University in Caracas, Venezuela, who worked on the UNDP study.
Peru’s environmental-quality standards are inadequate for gauging risks to human health and the environment, especially the aquatic ecosystems on which people depend for food, said Diana Papoulias, an aquatic toxicologist retired from the US Geological Survey, who was also part of the UNDP team.
Peru has quality standards for water and soil, but not for sediments — where hydrocarbon residue and metals have probably settled, and which might be redistributed throughout the forest by floodwaters during the annual rainy season, she said. The standards that do exist were taken from countries such as the United States, Canada and the Netherlands, whose largely temperate ecosystems are very different from the Peruvian Amazon, with its low-pH rivers and nutrient-poor soils.
That very ecosystem might put local residents at further risk from pollution. Health exams have found cadmium and lead in indigenous villagers’ blood and urine. Núñez and her colleagues suspect that people might be more likely to absorb those elements in nutrient-poor environments lacking sufficient calcium and magnesium.
The UNDP team has recommended further study of contaminants in the ecosystem, but that should not delay the clean-up, Núñez says. “Of course you’d do a better job of remediation if you had more knowledge, but I believe the remediation, as such, has to begin now.”
Nature 562, 18-19 (2018)