Recently in Wildlife habitat Category

Desalination of salt water and brackish water is becoming a critical issue as inland lakes and ponds suffer from droughts and water relocation projects.

Ecosystems suffer first. Terminus lakes could benefit from a new desalination system being developed at the University of Nevada, Reno.

Terminus lakes are located in closed-basin regions where there is no outflow for the water and a high evaporation rate, leaving a high concentration of minerals and salts.

This new, low cost way to desalinate water uses a specialized low-cost solar pond and patented membrane distillation system powered by renewable energy.

Hundreds of terminus lakes worldwide such as the Great Salt Lake, the Salton Sea in California, the Aral Sea and Nevada's  Walker Lake are experiencing a decline in water levels and an increase in salinity from both human and natural processes," says Francisco Suarez, a doctoral student in hydrological sciences.

Suarez is developing an artificial salt-gradient stratification process that traps solar heat at the bottom of the solar pond and uses the collected energy to power the membrane distillation system recently patented by the University. The hot brine in the lower storage zone of the pond, which can reach temperatures greater than 195 degrees Fahrenheit, may be used directly for heating, thermal desalination, or for other low-temperature thermal applications.

The process has been highly successful in the lab in a small-scale experiment using a 400-gallon tank, where dissolved solids and precise fiber-optic temperature sensing are being used to track the process as it desalinates the water. The next step for Suarez and the research group is to build a pilot-project, demonstration-scale, low-temperature desalination system in an open environment.

This desalination system is designed to help sustain the ecosystems of these closed-basin regions.

Read more about this desalination system at the University of Nevada

Did you know... 65% of new impervious cover can be classified as car habitat!

What is "car habitat"?  

"...the geometry of roads, parking lots, sidewalks, cul-de-sacs and other new development infrastructure."  That's car habitat.

Local development codes enforce how much impervious surface is allowed.  They take into consideration how water drains and is absorbed by local soil conditions, as well as the level of development already affecting the watershed.

Better site design can reduce flooding by improving absorption of heavy water deluges into nature's groundwater infrastructure.  Snowpack might be nature's LARGEST water reservoir, but groundwater is also a very valuable service provided by nature in lowlands. 

Better Site Design (BSD), can include greater use of

• swales
• relaxed lot geometry
• natural area conservation
• open-space subdivisions
• pervious paving
• and other site design techniques

Several dozen communities across the country have changed their local codes and ordinances to promote BSD through a roundtable process to gain consensus among development stakeholders.

Better Site Design Can Reduce Development Costs

The strength of the BSD approach is that numerous modeling studies have demonstrated it can reduce impervious cover, pollutants and development costs by as much as 10 to 40% at individual development sites.

The weakness of BSD is that it lacks a watershed context and therefore reductions in site IC may be not be enough to meet subwatershed objectives.

SOURCE:
Chesapeake Stormwater Network, CSN Technical Bulletin No. 3, "Implications of the Impervious Cover Model".

Spiders that live near water may be an effective warning system for contaminants in aquatic ecosystems, according to a new USGS and U.S. Environmental Protection Agency study.

PCB Contamination in Aquatic Habitat

Scientists examined PCB (polychlorinated biphenyls) levels in shoreline-living spiders at Lake Hartwell, a Superfund site in South Carolina, and used this information to map contaminant concentrations in lake sediment.

Future monitoring studies will use the spiders as indicators of ecosystem recovery from PCB contamination.

Researchers also made risk maps for a spider-eating bird, the Carolina wren, which could be exposed to PCBs through eating spiders. These spiders rely heavily on adult aquatic insects for food and play a key ecological role in the transfer of contaminants between water and land ecosystems. In spite of this, they are underused as a sentinel species at contaminated sediment sites.

This study, "Using riparian spiders as sentinels of PCB export and risk" was conducted by USGS at the Society of Environmental Toxicology and Chemistry and the EPA.  

Wading through the sources of lake contamination

Contamination of urban lakes and streams by polycyclic aromatic hydrocarbons (PAHs) is widespread and has been increasing over the last 40 years in the United States.

PAHs are Toxic to Fish Humans and Other Organisms

These PAHs can be toxic to bottom-dwelling organisms, can cause tumors in fish, and several are believed to cause cancer in humans. 

In this study, researchers examined five sources of PAHs in 40 urban lakes from across the United States, including coal-tar-based pavement sealcoat, coal combustion, oil combustion, vehicle emissions and wood combustion.

Sealcoat Contributes to PAH Contamination

Of the five sources studied, sealcoat was the strongest contributor to PAH contamination in lake sediment. This research can help those trying to reduce pollution levels in the urban environment by providing them with a better understanding of PAH sources. 

This study, "Sources of PAHs to urban lakes in the United States," was conducted by USGS at the Society of Environmental Toxicology and Chemist  

Elevated concentrations of pesticides in streams can affect aquatic organisms in streams as well as the quality of drinking water in some high-use areas where surface water is used for municipal supply.

Decreasing Usage Decreases Stream Contamination...???!

Concentrations of several major pesticides mostly declined or stayed the same in "Corn Belt" rivers and streams from 1996 to 2006, according to a new U.S. Geological Survey study.

The declines in pesticide concentrations closely followed declines in their annual applications, indicating that reducing pesticide use is an effective and reliable strategy for reducing pesticide contamination in streams.

Declines in concentrations of the agricultural herbicides cyanazine, alachlor and metolachlor show the effectiveness of U.S. Environmental Protection Agency (EPA) regulatory actions as well as the influence of new pesticide products.

In addition, declines from 2000 to 2006 in concentrations of the insecticide diazinon correspond to the EPA's national phase-out of nonagricultural uses. The USGS works closely with the EPA, which uses USGS findings on pesticide trends to track the effectiveness of changes in pesticide regulations and use.

Stream Pollutants in llinois, Indiana, Iowa, Nebraska and Ohio

Scientists studied 11 herbicides and insecticides frequently detected in the Corn Belt region, which generally includes Illinois, Indiana, Iowa, Nebraska and Ohio, as well as parts of adjoining states.

This area has among the highest pesticide use in the nation -- mostly herbicides used for weed control in corn and soybeans. As a result, these pesticides are widespread in the region's streams and rivers, largely resulting from runoff from cropland and urban areas.

Four of the 11 pesticides evaluated for trends were among those most often found in previous USGS studies to occur at levels of potential concern for healthy aquatic life. Atrazine, the most frequently detected, is also regulated in drinking water.

"Pesticide use is constantly changing in response to such factors as regulations, market forces, and advances in science," said Dan Sullivan, lead scientist for the study. "For example, acetochlor was registered by the EPA in 1994 with a goal of reducing use of alachlor and other major corn herbicides -- acetochlor use rapidly increased to a constant level by about 1996, and alachlor use declined. Cyanazine use also decreased rapidly from 1992 to 2000, as it was phased out because of environmental concerns. Metolachlor use did not markedly decrease until about 1998, when S-metolachlor, a more effective version that requires lower application rates, was introduced. Each of these declines in use was accompanied by similar declines in concentrations."

Although trends in concentration and use almost always closely corresponded, concentrations of atrazine and metolachlor each declined in one stream more rapidly than their estimated use. According to Skip Vecchia, senior author of the report on this analysis, "The steeper decline in these instances may be caused by agricultural management practices that have reduced pesticide transport, but data on management practices are not adequate to definitively answer the question. Overall, use is the most dominant factor driving changes in concentrations."

Simazine Shows Increased Usage

Only one pesticide -- simazine, which is used for both agricultural and urban weed control -- increased from 1996 to 2006. Concentrations of simazine in some streams increased more sharply than its trend in agricultural use, suggesting that non-agricultural uses of this herbicide, such as for controlling weeds in residential areas and along roadsides, increased during the study period.

The USGS study is based on analysis of 11 pesticides for 31 stream sites in the Corn Belt for two partially overlapping time periods: 1996 to 2002 and 2000 to 2006. Pesticides included in the trend analyses were the herbicides atrazine, acetochlor, metolachlor, alachlor, cyanazine, EPTC, simazine, metribuzin and prometon, and the insecticides chlorpyrifos and diazinon. Additional detailed analyses of relations between concentrations and use focused on four herbicides mainly used for weed control in corn (atrazine, acetochlor, metolachlor and alachlor) at a subset of 11 sites on the main rivers and selected large tributaries in the Ohio, Upper Mississippi and Missouri River basins.

Concentrations of many other pesticides that were less prevalent than the 11 included in the study were below analytical detection limits in most samples and thus could not be analyzed for trends.

Glyphosate, the most heavily used herbicide in the US

Glyphosate, an herbicide which has had rapidly increasing use on new genetically modified varieties of soybeans and corn, and which now is the most heavily used herbicide in the nation, was not measured until late in the study and thus had insufficient data for analysis of trends.

A USGS Scientific Investigations Report, "Trends in Pesticide Concentrations in Corn-Belt Streams, 1996-2006," (Analysis of concentration trends for 11 pesticides at 31 stream and river sites) and a journal article in the Environmental Science and Technology journal, "Trends in Concentrations and Use of Agricultural Herbicides for Corn Belt Rivers" (Analysis of concentration and use trends for 4 herbicides at 11 major river sites) is available online. Additional information, including data, reports and maps on pesticide status, trends and use may be found at the USGS Pesticide National Synthesis Project Web site.

USGS provides science for a changing world. For more information, visit www.usgs.gov.

The rite of passage for young coho salmon is a glorious rendezvous with the sea, but three years of drought have left many migrating fish marooned in the drying tributaries of Marin County's San Geronimo Valley, according to a recent study.

Many of these trapped juvenile fish, commonly known as smolts, have either been plucked out of isolated pools by birds and other predators or died from lack of nutrients, biologists with the Salmon Protection and Watershed Network said.

The stranding of smolt trying to reach the ocean is one of a litany of problems facing the endangered Central California coho population, which registered the lowest number of egg-laying adults in the normally bountiful Lagunitas watershed in recorded history last winter.

It is unique in that the primary spawning grounds are in the middle of developed communities. Some 40 percent of the coho in the watershed are hatched in tributaries surrounded by homes, golf courses, roads and horse corrals in the 9-square-mile San Geronimo Valley, according to the study.

It is estimated that between 3,000 and 6,000 coho swim down the waterway back to the ocean every year. The plummeting coho numbers exacerbate a near-catastrophic decline in the overall population of salmon along the West Coast. The coho population around the state has declined precipitously over the years and so few chinook salmon returned to spawn in the Sacramento-San Joaquin River system the past two years that ocean fishing had to be banned in California and Oregon.