Venice's Aquatic Beauty Suffers From Pollution's Dark Cloud

The city of Venice, Italy, is facing a range of environmental issues, including pollution from heavy industries, shipping, and unregulated boat traffic. The city's unique geography and dependence on water transportation have made it vulnerable to the impacts of pollution. In the 1920s, the industrialization of the nearby Marghera area led to the construction of factories, chemical plants, and oil refineries, which released massive quantities of unregulated waste into the Venetian Lagoon, threatening its delicate ecosystem. Today, the city continues to struggle with water pollution and air pollution, as well as the constant threat of flooding due to rising sea levels caused by climate change. With a declining population and an influx of tourists, Venetians are concerned about the future of their city and its cultural heritage.

Water pollution from industrial waste and sewage

Venice, Italy, is a city built on 118 low-lying salt marshes in the Venetian Lagoon. In the 1920s, the nearby city of Marghera became a thriving industrial zone and port, with the rapid construction of factories, including chemical plants and oil refineries. This period of industrialization irreversibly damaged the delicate ecosystem of the Venetian Lagoon, as massive quantities of unregulated waste were released into the water. These pollutants included dioxins and heavy metals, which are toxic to both humans and wildlife.

Although strict environmental action was taken in the 1980s, and now 80% of wastewater is treated in purification plants, the damage caused by industrial waste continues to affect the city. Non-biodegradable pollutants have led to a decline in native plant and animal species, and the long-term effects of these chemicals are still not fully understood.

Adding to the problem of industrial waste, Venice also faces challenges with its sewage system. The city relies on a 16th-century sewage system that releases wastewater directly into its canals. While this system was once considered superior due to the tides that exchanged wastewater with clean water twice a day, it is no longer adequate for the modern city. The ancient system cannot handle the volume of sewage and lacks the capacity to treat chemical contaminants found in personal care products, such as soap, detergent, and shampoo.

Upgrades to the sewage system, including sedimentation and septic tanks, have been implemented in some areas, but these methods are not widespread or comprehensive. The unique historical and geographical characteristics of Venice make it challenging to implement traditional water treatment solutions without causing structural damage, especially in the historic center.

The inadequate sewage system has led to water pollution, with untreated sewage and chemical contaminants ending up in the canals. This poses health and sanitation risks for both residents and tourists. Venice's sewage system, combined with industrial waste, has contributed to the city's struggle with water pollution, threatening the future of the lagoon, the city, and its inhabitants.

Air pollution from diesel-powered boats

Venice, Italy, is a city built on water, with its residents relying on the historic canals in their daily lives. However, the city is facing significant challenges due to pollution from various sources, including diesel-powered boats that contribute to air and water contamination.

Venice's canals are navigated by hundreds of diesel-powered commuter boats, also known as vaporetti or water buses. These boats transport millions of tourists, goods, and services annually, zigzagging through the city's canals and contributing to air pollution. The diesel engines of these boats emit tonnes of carbon and other greenhouse gases, which have a detrimental impact on the environment and human health.

The high levels of air pollution from these boats affect not only the residents' health but also the city's built cultural heritage. The pollution causes corrosion and material loss due to chemical attacks, posing a particular threat to a UNESCO World Heritage Site like Venice.

In response to the air quality concerns, the Venice Municipality took action in spring 2019 by limiting traffic in one of the most congested canals. However, this policy had a minor impact on reducing nitrogen dioxide levels.

To address the issue, some Venetians have proposed an alternative vaporetto powered by hydrogen instead of diesel. Hydrogen is a fuel that emits only water vapour when burnt and produces none of the carbon or greenhouse gases responsible for pollution and climate change. However, Italian law currently prohibits boats powered by alternatives to fossil fuels from sailing, hindering the implementation of this solution.

The debate around hydrogen as a clean energy source is ongoing, with critics pointing out the high cost of production and the fact that most hydrogen is currently derived from fossil fuels, undermining its environmental benefits. Nevertheless, with the growing threat of climate change, some advocates argue for utilising hydrogen created with renewable energy ("green hydrogen"), which has become more affordable.

Other Sources of Pollution:

Venice's pollution challenges extend beyond diesel-powered boats. The city's industrial development in the 1920s, particularly in the nearby Marghera area, irreversibly damaged the lagoon's delicate ecosystem. While strict environmental action began in the 1980s, non-biodegradable pollutants from this era continue to impact the lagoon, contributing to the decline in native plant and animal species.

Additionally, everyday activities also play a role in water pollution. Venice's outdated sewage system, dating back to the 16th century, releases wastewater directly into the canals. Synthetic chemicals from personal care products, such as soaps and detergents, further contaminate the water, as Venice lacks a method to control their release.

Water buses and cruise liners have also been identified as sources of water pollution, with locals expressing anger over the pollution from these large vessels entering the heart of the city.

A Complex Challenge:

Addressing Venice's pollution crisis is a complex task due to the interplay between historical infrastructure, modern demands, and environmental concerns. While there are ongoing discussions and efforts to implement alternative energy sources and improve waste management, finding effective and timely solutions remains a challenge for this unique city.

Damage to buildings from boat wakes

Venice, built on a muddy lagoon, is slowly sinking into the sea. The city's unique geography and dependence on water transportation have made it vulnerable to the impacts of pollution and climate change. One significant issue is the damage caused by boat wakes to the buildings in the historic city centre.

Boat wakes refer to the waves created by motorboats as they move through the water. In Venice, this issue is known as "moto ondoso". The wakes generated by boats can have a significant impact on the surrounding environment, particularly in shallow coastal areas and narrow waterways like those found in Venice. The transit of large vessels through the Venetian canals has been shown to have serious impacts on the adjacent shallow water areas.

The waves created by boat wakes can cause erosion and damage to the city's buildings and infrastructure. In Venice, it is estimated that wave-related water damage has affected 60% of the buildings along the Grand Canal, one of the city's most iconic waterways. The waves generated by boat traffic can weaken the stone foundations of the buildings and increase the need for maintenance and repairs.

The issue of boat wakes in Venice has been exacerbated by the large number of boats that operate within the city's canals, including diesel-powered commuter boats, water buses, and cruise ships. These boats transport millions of tourists who visit Venice each year, as well as goods and services. The frequent boat traffic and large vessel sizes contribute to the magnitude of the wakes and the extent of their impact on the city's infrastructure.

To address the problem of boat wakes and their impact on Venice's buildings, several measures have been proposed and implemented:

• Banning cruise ships from entering the historic city centre: In 2021, cruise ships were banned from the centre of Venice, and they now must dock at the industrial port instead. This measure helps reduce the size of the waves generated within the confined space of the canals.
• Reducing boat speeds: Venice has implemented a speed limit of 11 km/hr (7 mph) for boats within the canals to prevent wake damage. However, this limit is often flouted, and some argue for even lower speed limits to minimise the impact on the city's buildings.
• Alternative boat technologies: There have been efforts to introduce more sustainable boat technologies in Venice, such as electric hydrofoil boats that produce smaller wakes and reduce energy consumption. While these boats have been tested, their widespread implementation may be challenging due to speed requirements and other factors.

Threat of flooding due to rising sea levels

Venice has always been at risk of flooding, but the threat of rising sea levels due to climate change has increased this risk. In November 2019, the city experienced its second-worst flood ever recorded, with more than 80% of the city underwater. This was caused by a combination of high tides and storm surges, which have become more frequent and severe due to rising sea levels. Venice's ground level is sinking, which further increases the city's vulnerability to flooding.

The city's location in a shallow coastal lagoon makes it particularly susceptible to flooding. The Venetian lagoon has an average depth of just one metre, and the lowest part of St. Mark's Square is only 55cm above the current average sea level. As a result, even small increases in sea level can have a significant impact, and the frequency and severity of floods have increased.

According to official records, there have been 324 very intense high-water events since 1872, with more than half occurring in the past 30 years. The average sea level in Venice is now 32cm higher than it was when records began in 1872, and climate experts predict that it will continue to rise.

The combination of rising sea levels and Venice's sinking ground level has made the city increasingly vulnerable to flooding. The city's ground level is sinking by around 1mm per year due to natural processes, and human activities such as groundwater pumping in the 20th century have worsened the problem. As Venice sinks, it becomes more exposed to tides and storms from the Adriatic Sea.

The increasing frequency and severity of floods have had significant impacts on Venice's buildings and infrastructure. High waters have caused damage to historic buildings, monuments, and businesses, and the city's unique architecture is being damaged by the constant cycle of flooding and drying.

To protect against flooding, Venice has been working on the MOSE Project, which involves constructing underwater gates at the entrances to the Venetian lagoon. When seawater levels rise, these gates will rise and shut out the Adriatic Sea. However, the project has been plagued by delays, corruption scandals, and technical challenges, and it remains uncertain if it will be effective in protecting the city from rising sea levels.

The threat of flooding due to rising sea levels poses a significant risk to the future of Venice. With climate change accelerating sea-level rise, there are concerns that Venice could become a "new Atlantis," succumbing to the rising waters. The city is at the forefront of the battle against climate change and is seeking solutions to protect its unique heritage and residents from the increasing flood risk.

Noise and light pollution

In addition to road noise, underwater noise pollution in Venice is also a growing concern. The fragile environment of the Venice lagoon is particularly susceptible to the impact of motorboat traffic, which has been shown to affect the behaviour of fish and other marine life. The noise generated by motorboats falls within a frequency range that is known to bother several coastal fish species, and it has been found to affect the reproductive behaviour of the Sciaena umbra, a common species in the Venice lagoon.

The increase in tourism has also led to more light pollution in the city. More lights in buildings and on the streets, as well as bright LED signs, can create an adverse environment for animals, pushing them away from their natural habitats.

To address these issues, some residents have called for the implementation of sound walls or the replanting of vegetation to act as a buffer against noise. Others have suggested that regulations should be put in place to reduce disruption to animal life, with a reasonable impact on human activities.

Overall, noise and light pollution are significant issues in Venice, affecting both the human and animal residents of the city. The increase in tourism has been a major contributor to these issues, and finding a balance between accommodating tourists and protecting the environment and well-being of residents is crucial.

Frequently asked questions