The researchers studied three separate locations in Lake Baiyangdian, all at varying distances from major sources of pollution, such as coal emissions, agricultural runoff, and sewage discharge. They found concentrations of arsenic and mercury in fish were above the threshold considered by the U.S. Environmental Protection Agency (EPA) to pose a risk to humans and wildlife.
The findings were published online on Dec. 24, 2007, in the journal Water, Air, and Soil Pollution.
"It's important to study this system because it is typical of many throughout China where human activity and industrialization are having detrimental effects on the environment with major human health implications," says Celia Chen '78, a research associate professor of biological sciences. "It makes perfect sense to apply what we're learning about lakes in the U.S. to other places in the world, like China, that have a growing global impact."
Chen and her team were curious to learn how arsenic and mercury, two toxic environmental metals, moved through the food web in a freshwater ecosystem known to be polluted and contaminated. In a process called bioaccumulation, mercury and arsenic were found throughout the food web, from the water, into the algae, through the tiny algae-eating zooplankton, to the fish. As expected, the researchers found that more nutrient-rich environments supported larger algal blooms, which resulted in lower concentrations of mercury and arsenic in the water due to uptake by the algae.
In their previous work, the researchers found that when there is a lot of algae present, mercury and arsenic are biodiluted, or more dispersed, so zooplankton that eat the algae are exposed to lower levels of the metals and transfer less to fish.
"Despite this potential interaction - a decrease in bioaccumulation due to high algal biomass - the mercury and arsenic in this system are high enough to be of concern to humans and wildlife that drink the water and consume fish," says Chen. "For example, we saw arsenic levels in the water that represent more than fifty times the EPA-recommended limit for consumption of fish and shellfish."
Chen's co-authors include Carol Folt, dean of the faculty and professor of biological sciences at Dartmouth, Paul Pickhardt at Lakeland College, and M.Q. Xu at the Chinese Academy of Sciences in Beijing. Chen and Folt are both affiliated with Dartmouth's Center for Environmental Health Sciences and its Toxic Metals Research Program. Funding from the National Science Foundation and the National Institute of Environmental Health Sciences supported this work.
Sue Knapp | EurekAlert!
The personality factor: How to foster the sharing of research data
06.09.2017 | ZBW – Leibniz-Informationszentrum Wirtschaft
Europe’s Demographic Future. Where the Regions Are Heading after a Decade of Crises
10.08.2017 | Berlin-Institut für Bevölkerung und Entwicklung
At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.
Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
25.09.2017 | Physics and Astronomy
25.09.2017 | Trade Fair News
25.09.2017 | Physics and Astronomy