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At least 739 records · Page 41Linked to original sources
USGS1991

Agricultural research to improve water quality

ime courses for ingest~on, retention and release via feces of microbial food was investigated using 2 b~valves w~th d~fferent feeding strategies, Potamocorbula amurensis and Macoma balthica. The results showed 2 pathways for the uptake of food material in these clams. The first is represented by an initlal label pulse in the feces. The second pathway operates over longer time periods. Inert "Cr-labeled beads were used to determine time frames for these pathways. The first pathway, involving extracellular digestion and intestinal uptake, is relatively inefficient In the digestion of bacter~al cells by P amurensis but more efficient in M. balthica. The second pathway, involving intracellular digestion withln the digestive gland of both clams, was highly efficient in absorb~ng bacterial carbon, and was responsible for most chromium uptake. Differences in the overall retention of microbial "Cr and I4C relate not to gut-passage times but to the processing and release strategies of the food material by these 2 clams.

Journal of Soil and Water Conservation↗
USGS2005

Shorebird habitat availability assessment of agricultural fields using a digital aerial video system

Field and wetland conditions in the rice prairies of Louisiana and Texas are highly dynamic habitats. Rice prairies are important habitat for many species of migratory birds, including shorebirds, wading birds, and waterfowl. Ground sampling a variety of fields to assess habitat availability is very labor intensive, and accessibility to private lands makes statistical habitat sampling almost impossible. Aerial video is a tool we can use for assessing availability of these highly ephemeral habitats because of the short-duration repeatability of the surveys. The strong statistical basis of line transect theory allows quantitative estimation of habitat availability. We used ground surveys of field conditions and shorebird ground counts to correlate spectral signatures with shorebird habitat availability. This video system can also be used to identify and map distribution of invasive plant species known to affect suitability of stopover habitat for shorebirds and landbirds.

Louisiana↗
USGS2019

Stream corridor sources of suspended sediment and phosphorus from an agricultural tributary to the Great Lakes

Fine-grained sediment and phosphorous are major contaminants in the Great Lakes and their tributaries. Plum Creek, Wisconsin (92 km2), a tributary to the Lower Fox River, has a Total Maximum Daily Load (TMDL) requiring reductions of suspended sediment and phosphorus loading by 70% and 77%, respectively. In 2016-18, an integrated sediment fingerprinting and stream corridor-based sediment budget study was conducted to help quantify upland and stream corridor sources of suspended sediment and phosphorus at a loads monitoring station on Plum Creek. Sediment fingerprinting results indicated that the proportion of upland and stream corridor sources of suspended sediment in Plum Creek varied by season and the amount of runoff; however, bank and gully erosion accounted for 51% and 24% of the suspended sediment annual load, with one or both sources present in all seasons. The next most common source was roadside ditches (11%), which was also present in all seasons. Cropland and woodland sources accounted for small proportions of the suspended sediment, with cropland mainly in summer and woodland in winter, spring, and summer. Relative source proportions for sediment-bound phosphorus were similar to suspended sediment but made up less of the overall loading because on average 27% of the phosphorus load resides in the dissolved phase. Soft fine-grained streambed sediment had source signatures of mainly bank, gully, and ditches (ordered by decreasing proportion). Results from the field-based rapid geomorphic assessment supported the sediment fingerprinting results and in general showed that the amount of bank erosion increases in a downstream direction. The high proportion of sources from banks and gullies is due, in part, to a 20-km long, deeply entrenched valley and steep eroding bluffs between the majority of cropland and the Plum Creek water monitoring station.

Wisconsin↗