WASHINGTON, April 11 (Xinhua) -- The Walden Pond, a once-pristine lake that inspired naturalist Henry David Thoreau's best-known work "Walden", is being befouled by swimmers' urine, a new study has showed.
In the book, first published in 1854, Thoreau recounted his stay at the pond, celebrating simple living in natural surroundings. Referring to the "crystalline purity" of the pond, he described it as "so transparent that the bottom can easily be discerned at the depth of 25 or 30 feet."
"Heaven is under our feet as well as over our heads," he famously wrote.
Following publication of Thoreau's works, the Walden Pond became a tourist attraction. Swimming, walking and hiking are some of the activities offered at the lake.
Scientists analyzing the Massachusetts waterway discovered a surge in the lake's level of nitrogen and phosphorous, which are found in human waste. These chemicals feed the algae, which mars the water and blocks the rays of the sun, threatening the lake's ecosystem.
"These findings suggest that, although mitigation effort have curtailed anthropogenic nutrient inputs to Walden Pond, the Lake has not returned to the pre-impact condition described by Henry David Thoreau," warned Dr. Jay Curt Stager, a researcher at Paul Smith's College and one of the authors of the study.
"If we're not careful, this beautiful, iconic lake... could easily become more like a murky, green stew of algae," he said.
