Tea-like substances formed from forests and wetlands stain many lakes brown, such as Elbow Pond, an acidic brown water lake in New Hampshire. Both natural and human activities can cause changes in lake color and clarity. The development of communities or the use of agricultural fertilizers around lakes often reduces water clarity and adds nutrients, shifting lakes from blue water to green water.
Lakes can also naturally become more eutrophic and green over time. As lakes age over centuries, nutrients, sediment and plant material slowly build up. This natural process is much slower than changes caused by human impacts. While human impacts often change lakes from blue to green, conservation and protection can improve the clarity and color of lakes. In areas where water quality has been degraded by pollution, eutrophication, or changes in land use, community action to improve water quality through enhanced laws and zoning can improve water quality and shift lakes from green water to blue water.
This process is often difficult, however, as lakes tend to remain in the color state in which they currently exist. Seasonally, lakes can change in color. In many lakes, rapid algal growth in the spring months produces a green color. However, this period is usually followed by a clear water phase i. The length of clear water phases can vary and is determined by the ecological interactions among aquatic organisms.
In addition, sunlight can bleach organic matter in the same way that materials left outside for too long become bleached and faded. The bleaching typically follows day length and lakes can be most transparent e. Ever wondered how those pretty waters flanked by towering mountains get to be such unbelievable shades of turquoise?
Also known as rock flour or glacial silt, glacial flour is the sediment from ground up rock and gravel particles produced during glacial erosion. A glacier grows and moves when the accumulation of snow in the winter exceeds the snow melt in the summer, and snow piles up layer by layer each year.
As more and more snowflakes pile on top of each other, they transform into smaller grains of snow all packed together.
Many years later these layers of crystallized snow will become glacial ice. Besides melting, long-term stresses and pressure on the glacier of bearing its own weight force of gravity can bend and deform the ice without actually breaking it. Kind of like how a metal worker can bend and shape cooling metal without snapping it.
As pressure increases the melting point decreases, and once the ice is below its melting point the molecular bond between ice crystals in this zone become malleable. When the moving ice approaches obstacles like boulders, the pressure increases allowing it to melt and then refreeze once it has moved over the other side. How cool is that?! This occurrence is known as glacial retreat, and it has been occurring ever since the end of the Little Ice Age in approximately A glacier does not move uphill, it only moves downhill.
However, factors such as climate change can cause the lowest point of the glacier to melt faster than new snow can be replaced at the top, resulting in it advancing downhill more slowly. Or even retreating. This explains why there is evidence of many glaciers covering less and less ground as the years go by, with some disappearing altogether.
Of those 30, most have shrunk in area by two-thirds. Glacial flour, however, is suspended in the water column and is the reason for the cloudy or murky appearance of glacially fed waters. Clear water in the sea or non-glacial lakes absorbs longer wavelengths of visible light yellow, orange and red and strongly reflects shorter blue and blue-green wavelengths.
Because algae abundance strongly depends on the amount of phosphorus available, the best long-term strategy is to improve land-use practices to prevent phosphorus and other nutrients from getting into our lakes and ponds. News What causes some lakes to turn green? Answer: By mid Suggested Articles. Government and Politics.
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