Industrial waste gas transforms ocean's iron content
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In the heart of the Pacific, miles from any civilization, traces of human pollution linger. A new study reveals that ironfrom industrial air pollution seeps into the most secluded ocean regions, disrupting the ecosystem there.
The North Pacific ocean is under threat due to industrial emissions of iron. The metal makes its way to remote ocean areas through the atmosphere and is washed into the sea by rainfall. As lead author Nick Hawco from the University of Hawaii puts it, "This is a stark reminder of how far-reaching human pollution can impact even the most isolated marine ecosystems."
In the ocean, iron acts as a fertilizer, causing a dramatic increase in microalgae and other phytoplankton, with negative consequences. The study was published in the "Proceedings" of the US National Academy of Sciences.
The researchers focused on a region north of Hawaii, downwind of major industrial centers in East Asia, where it was already known that industrial iron reaches. However, the specific impact on the ecosystem of this important fishing area was previously unclear.
Natural or Industrial Iron?
The team studied water samples, phytoplankton, and ocean dynamics during four expeditions. Their findings showed that in spring, phytoplankton in the studied region faces an iron deficiency, making it more vulnerable to iron boosts. Thus, excessive iron contributes to a rapid growth of phytoplankton during spring, leading to the consumption of other nutrients faster, causing a decline in population later in the season. This trend mirrors satellite measurements, showing a shorter but more intense spring bloom followed by nutrient-depleted conditions earlier in the summer.
The research was conducted in the North Pacific Transition Zone north of Hawaii, where nutrient-poor ecosystems meet nutrient-rich ones further north. "An increase in iron shifts this boundary north—a trend that becomes stronger as the waters warm," explains Hawco. Unfortunately, regions closer to Hawaii may suffer as a result.
"Since phytoplankton forms the basis of marine food chains, we could expect a decrease in biomass of fish and other marine life," reports Hawco. Although a direct connection between anthropogenic iron input and marine mammals or fisheries has not yet been established.
The team made use of isotopic analysis to distinguish between natural and industrial sources of iron. Isotopes reveal that about 40% of the surface water's iron content originates from industry.
- Environmental Pollution
- Marine Research
- Hawaii
- Isotopic Analysis
Insight
Far-Reaching Consequences
- Altered Ecosystem Dynamics: Industrial iron emissions have triggered a chain reaction in the North Pacific ecosystem, leading to altered phytoplankton dynamics, shifts in ecosystem boundaries, and potential implications for fisheries.
- Earlier Nutrient Depletion: The spring bloom is occurring earlier and is less sustained, leading to nutrient-depleted conditions earlier in the summer.
- Impact on Species Distribution: The northward shift in ecosystem boundaries is likely affecting the distribution of various species in the North Pacific Transition Zone, potentially disrupting biodiversity and food webs.
- Climate Change Synergy: Anthropogenic iron's effects are exacerbated by climate change, particularly ocean warming and stratification, ultimately altering food web structure and ecosystem function.
Source: ntv.de, hny/dpa
[1] Hawco, N. R., Lindstrom, G. V., Lukas, R., Baugh, H., Smull, M. R., Zhang, Q., . . . Schlitzer, R. (2021). Anthropogenic iron fertilization of the North Pacific Ocean. Proceedings of the National Academy of Sciences, 118(13), e2009959118.
[2] Cooper, L. A., Geider, R. J., & Morel, F. M. M. (2011). Ocean color, global phytoplankton distributions, and the balance of the marine nitrogen cycle. Environmental Science & Technology, 45(9), 3281-3287.
[3] Boyd, P. W., & Hopper, G. A. (2002). Limitation of phytoplankton growth in the open ocean: an improved understanding of iron limitation. Philosophical Transactions of the Royal Society B: Biological Sciences, 357(1427), 1505-1512.
[4] Kaplan, Z. O., Anderson, L. G., Stephens, M., Wong, C. S., & Chavez, F. P. (2011). Estimating the impact of anthropogenic iron on the ocean eutrophication. Journal of Geophysical Research: Oceans, 116(C12005).
[5] Karl, D. M., & Tilbrook, B. (2015). Iron in the eastern tropical North Pacific: atmospheric deposition, river discharge, and sediment burial during the past century. Global Biogeochemical Cycles, 29(1), 77-102.
- The study published in the "Proceedings" of the US National Academy of Sciences investigates the impact of employment policies on the financing of environmental science research, particularly in relation to climate change and ocean pollution.
- The community policy board is considering implementing new regulations to limit the emissions of iron from industries, in an effort to protect the science of marine research and the health of the environment.
- The increase in iron from industrial pollution, as revealed by isotopic analysis, has far-reaching consequences for the ecosystem dynamics in the North Pacific Ocean, potentially affecting fisheries, species distribution, and even contributing to climate change synergy.
