Page 29 - AJWEP-22-6

Hydrocarbons in seawater

archaea metabolize hydrocarbons, breaking them into Given the great relevance of hydrocarbon mixtures
less harmful byproducts, and eventually carbon dioxide in the oceans, the present review aims to consolidate
and water. 22,25,41 Other processes include sedimentation current scientific knowledge about the origin and fate
of dense oil components and the formation of aerosols of these compounds in seawater, exploring the complex
that can transport hydrocarbons over long distances. interplay of processes governing their distribution and
42
Understanding these intricate processes is fundamental transformation, the impact on marine biota and human
to predicting the relevance and impact of hydrocarbon health, and the evolving strategies employed for their
spills and developing effective response strategies. containment, monitoring, and remediation. Although
The environmental and human health impacts in-depth knowledge of each specific topic discussed
of hydrocarbons in seawater are profound and here is available, scientific literature does not always
multifaceted. For example, seabirds are particularly provide a comprehensive and coherent synthesis of
vulnerable to dense oil pollution, which affects their various issues concerning hydrocarbons in the sea,
feather insulation, leading to hypothermia, mobility which is the primary focus of the present systematic
issues, and buoyancy issues. At the same time, marine review. By integrating geochemistry, oceanography,
mammals can suffer from ingestion, aspiration, and marine biology, and environmental sciences insights,
organ damage. 11,43 Chronic, sublethal effects are equally this review provides a holistic overview of the critical
concerning, including impaired growth, reproduction, environmental issue associated with hydrocarbon
immune suppression, developmental abnormalities, and mixtures and highlights areas for future research
behavioral changes in fish and invertebrates. 1,44 Besides perspectives.
direct toxicological effects, hydrocarbon mixtures
can also degrade critical habitats, such as coral reefs, 2. Natural origins of hydrocarbons in seawater
seagrass beds, and mangrove forests, leading to long-
term ecosystem damage and loss of biodiversity and Hydrocarbon mixtures are intrinsically linked to the
ecosystem services. 45,46 Earth’s geological and biological cycles; their presence
Considering the relevant threats posed by in the marine environment is a fundamental and ancient
hydrocarbon pollution, various containment measures, phenomenon, pre-dating human civilization by millions
monitoring programs, and remediation strategies of years. Natural processes contribute to introducing
have been developed and continuously refined. various hydrocarbons into the oceans, influencing
Generally, initial responses to accidental spill events background levels, shaping unique chemosynthetic
focus on containment using booms and mechanical ecosystems, and playing a role in the global carbon
recovery through skimmers to physically remove oil cycle. 52-54 Understanding these natural origins is crucial
from the water surface. Chemical dispersants are for distinguishing between background levels and
47
sometimes used to break down oil slicks into smaller pollution events and appreciating the inherent capacity
droplets, enhancing natural dispersion and microbial of marine systems to process these compounds. 1,2,50
degradation. However, their use remains controversial Among the primary natural pathways of hydrocarbon
due to potential toxicity to marine life. Monitoring the input into seawater, geological seepage represents one of
48
contamination caused by aliphatic hydrocarbon mixtures the primary continuous sources of emissions, being the
may involve various techniques, from remote sensing most significant and well-studied natural hydrocarbon
for large-scale tracking to chemical analyses of water, emission processes. 5,12,17,34,50 These occur when deeply
sediment, and biota samples, alongside biomonitoring buried petroleum and natural gas, formed from the
programs. 49,50 Remediation strategies aim to restore thermogenic alteration of organic matter in sedimentary
affected environments, with bioremediation a prominent basins, migrate upward through faults, fractures, and
approach. This involves enhancing the activity of porous rock formations in the seafloor to reach the
native oil-degrading microorganisms through nutrient water column and eventually the surface. 5,12,17 Seeps are
addition (biostimulation) or introducing specialized commonly found globally along continental margins,
microbial strains (bioaugmentation). Other methods in active tectonic regions, and within sedimentary
51
include in situ burning, shoreline cleaning, and natural basins. 12,17
attenuation, where the environment can recover over The Gulf of Mexico, which hosts one of the world’s
time. The selection of the most appropriate strategy most extensive and active deep-sea seep areas, is
depends on factors, such as oil type, environmental characterized by thousands of individual seeps releasing
conditions, and the sensitivity of the affected ecosystem. variable quantities of oil and gas, from small, chronic

Volume 22 Issue 6 (2025) 23 doi: 10.36922/AJWEP025290224