Environmental Challenges in Southern Brazil: Impacts of Pollution and Extreme Weather Events on Biodiversity and Human Health

Abstract

The Amazon rainforest plays a fundamental role in regulating the global climate and therefore receives special attention when Brazilian environmental issues gain prominence on the global stage. However, other Brazilian biomes, such as the Pampa and the Atlantic Forest in southern Brazil, have been facing significant environmental challenges, either independently or under the influence of ecological changes observed in the Amazon region. The state of Rio Grande do Sul is located in the extreme south of Brazil and in 2024 was hit by major rainfalls that caused devastating floods. The Pampa is a non-forest biome found in Brazil only in Rio Grande do Sul. This biome is seriously threatened by loss of vegetation cover and many classes of pollutants, including pesticides and plastics. Mining ventures are also important sources of soil, water and air pollution by potentially toxic elements in Rio Grande do Sul, threatening both the Pampa and the Atlantic Forest. Furthermore, southern Brazil is often affected by pollution caused by smoke coming from fires observed in distant biomes such as the Pantanal and the Amazon. Considering the significant environmental challenges observed in southern Brazil, this article revisits the historical participation of Rio Grande do Sul in Brazilian environmentalism and highlights the main environmental challenges currently observed in the state, followed by an in-depth analysis of the effects of pollution and extreme weather events on biodiversity and human health in the region. This review encompassed specifically the following categories of pollutants: potentially toxic elements (e.g., arsenic, cadmium, chromium, cobalt, copper, lead, mercury, titanium), air pollutants, plastics, and pesticides. Pathogen-related pollution in the context of extreme weather events is also addressed. This article emphasizes the critical importance of often-overlooked biomes in Brazilian conservation efforts, such as the Pampa biome, while also underscoring the interconnectedness of climate change, pollution, their shared influence on human well-being and ecological balance, using Rio Grande do Sul as a case study.

Keywords: Brazil; Rio Grande do Sul; biodiversity; climate change; extreme weather events; particulate matter; pesticide; plastics; pollution; potentially toxic elements.

Figure 1

Brazil’s map showing the distribution of the terrestrial Brazilian biomes. Rio Grande do Sul state is highlighted on the edge in bold. In orange: coverage of the Pampa biome. In light green: coverage of the Atlantic Forest biome. In yellow: coverage of the Cerrado biome. In red: coverage of the Pantanal biome. In pink: coverage of the Caatinga biome. In dark green: coverage of the Amazon biome. Brazil is located in Latin America and shares borders with the following countries: French Guiana (GUF), Suriname (SUR), Guyana (GUY), Venezuela (VEN), Colombia (COL), Peru (PER), Bolivia (BOL), Paraguay (PAR), Argentina (ARG), and Uruguay (URU), as shown on the map. Chile (CHL) is also visible. Coordinates obtained using SIRGAS2000.

Figure 2

Representative images of Rio Grande do Sul landscapes. (A) Pampa biome in São Gabriel City, showing predominant grassy vegetation in the foreground and forestry activity in the background, one of the biggest current threats to the Pampa (photo credit: Alexandre Copês). (B) Ecotone zone near Porto Alegre City, showing the transition between the Pampa and Atlantic Forest biomes (photo credit: Joel H. Ellwanger). (C,D) Mountainous region of Rio Grande do Sul, Canela City, showing mixed ombrophilous forest belonging to the Atlantic Forest biome (photo credits: Joel H. Ellwanger).

Figure 3

Map of Rio Grande do Sul. The state border is highlighted on the edge in bold. In green: distribution of forests. In yellow: distribution of grasslands. In pink: distribution of agriculture. In red: distribution of areas without vegetation (composed of urban areas, mining, beaches, dunes, sand spots, and other regions without vegetation). In blue: water bodies. Images from Google Satellite and data from MapBiomas.

Figure 4

Main anthropogenic activities and pollution classes observed in Rio Grande do Sul. Atmospheric pollution fuels climate change, which exacerbates the impacts of other pollution classes. PTEs—potentially toxic elements. CO₂—carbon dioxide.

Figure 5

Rio Grande do Sul 2024 flood. (A) Central region of Porto Alegre City. (B,C) The Guaíba Lake shore. (D) Vegetation on the Marinha Park shore (Porto Alegre) severely impacted after being submerged for several days. (Photo credits: Alexandre Copês).

Figure 6

Sanitation-related problems observed in Porto Alegre City. A and C: Ipanema Beach (freshwater beach) in Porto Alegre showing a sign indicating that the water is unfit for swimming during the 2023 summer season (A) and the release of domestic sewage into the water at the beach (B). (C) Presence of domestic sewage in a stream located in a public park in Porto Alegre. (D) Presence of accumulated garbage in a bridge repair structure located in Dilúvio Stream, which flows into the Guaíba Lake. The Dilúvio Stream is a habitat for varied fauna, but it presents several classes of pollutants, including toxic metals and biological contamination, thus fueling pathogen pollution and other health issues that affect humans and animals (photo credits: Joel H. Ellwanger).

Figure 7

Combined consequences of pollution and climate change.

Figure 8

Health problems observed in the human population of Rio Grande do Sul, which may be exacerbated by climate change. PTEs—potentially toxic elements.