Using stable isotope tracers to assess hydrological flow paths, residence times and landscape influences in a nested mesoscale catchment

International audience?18O measurements in precipitation and stream waters were used to investigate hydrological flow paths and residence times at nested spatial scales in the mesoscale (233 km2) River Feugh catchment in the northeast of Scotland over the 2001-2002 hydrological year. Precipitation ?18O exhibited strong seasonal variation, which although significantly damped within the catchment, was reflected in stream water at six sampling sites. This allowed ?18O variations to be used to infer the relative influence of soil-derived storm flows with a seasonally variable isotopic signature, and groundwater of apparently more constant isotopic composition. Periodic regression analysis was then used to examine the sub-catchment difference using an exponential flow model to provide indicative estimates of mean stream water residence times, which varied between approximately 3 and 14 months. This showed that the effects of increasing scale on estimated mean stream water residence time was minimal beyond that of the smallest (ca. 1 km2) headwater catchment scale. Instead, the interaction of catchment soil cover and topography appeared to be the dominant controlling influence. Where sub-catchments had extensive peat coverage, responsive hydrological pathways produced seasonally variable ?18O signatures in runoff with short mean residence times (ca. 3 months). In contrast, areas dominated by steeper slopes, more freely draining soils and larger groundwater storage in shallow valley-bottom aquifers, deeper flow paths allow for more effective mixing and damping of ?18O indicating longer residence times (>12 months). These insights from ?18O measurements extend the hydrological understanding of the Feugh catchment gained from previous geochemical tracer studies, and demonstrate the utility of isotope tracers in investigating the interaction of hydrological processes and catchment characteristics at larger spatial scales

Polypremum procumbens L.

https://thekeep.eiu.edu/herbarium_specimens_byname/8066/thumbnail.jp

Polypremum procumbens L.

https://thekeep.eiu.edu/herbarium_specimens_byname/8066/thumbnail.jp

Establishment of Grasses on Sewage Sludge-Amended Strip Mine Spoils

Usefulness of native prairie and domesticated grasses in re-vegetating strip mine spoil and producing biomass was examined on 30-year old, recontoured spoil banks located near Canton, Illinois. Grasses were planted in the spring and fall on strip mine spoil and spoil amended with 333 MT/ha of dry sewage sludge. By the end of the second growing season, indiangrass [Sorghastrum nutans (L.) Nash] produced more biomass than the other warm-season grasses, switchgrass (Panicum virgatum L.) and little bluestem [Schizachyrium scoparium (Michx.) Nash], on the unamended plots, and no warm-season grasses survived on the sludge amended plots. Warm-season grasses were able to compete with weedy species on unamended sites, but two cool-season grasses, reed canarygrass (Phalaris arundinacea L.) and Kentucky 31 tall fescue (Festuca arundinacea Schreb.), produced more biomass on amended sites than on unamended sites

Establishment of Grasses on Sewage Sludge-Amended Strip Mine Spoils

Usefulness of native prairie and domesticated grasses in re-vegetating strip mine spoil and producing biomass was examined on 30-year old, recontoured spoil banks located near Canton, Illinois. Grasses were planted in the spring and fall on strip mine spoil and spoil amended with 333 MT/ha of dry sewage sludge. By the end of the second growing season, indiangrass [Sorghastrum nutans (L.) Nash] produced more biomass than the other warm-season grasses, switchgrass (Panicum virgatum L.) and little bluestem [Schizachyrium scoparium (Michx.) Nash], on the unamended plots, and no warm-season grasses survived on the sludge amended plots. Warm-season grasses were able to compete with weedy species on unamended sites, but two cool-season grasses, reed canarygrass (Phalaris arundinacea L.) and Kentucky 31 tall fescue (Festuca arundinacea Schreb.), produced more biomass on amended sites than on unamended sites

Nitrogen superfractionation in dense cloud cores

We report new calculations of interstellar 15N fractionation. Previously, we have shown that large enhancements of 15N/14N can occur in cold, dense gas where CO is frozen out, but that the existence of an NH + N channel in the dissociative recombination of N2H+ severely curtails the fractionation. In the light of recent experimental evidence that this channel is in fact negligible, we have reassessed the 15N chemistry in dense cloud cores. We consider the effects of temperatures below 10 K, and of the presence of large amounts of atomic nitrogen. We also show how the temporal evolution of gas-phase isotope ratios is preserved as spatial heterogeneity in ammonia ice mantles, as monolayers deposited at different times have different isotopic compositions. We demonstrate that the upper layers of this ice may have 15N/14N ratios an order of magnitude larger than the underlying elemental value. Converting our ratios to delta-values, we obtain delta(15N) > 3,000 per mil in the uppermost layer, with values as high as 10,000 per mil in some models. We suggest that this material is the precursor to the 15N `hotspots' recently discovered in meteorites and IDPsComment: accepted by MNRA

Using stable isotope tracers to identify hydrological flow paths, residence times and landscape controls in a mesoscale catchment

International audience?18O tracer measurements of precipitation and stream waters were used to investigate hydrological flow paths and residence times at nested spatial scales in the mesoscale (233 km2 River Feugh catchment in the northeast of Scotland over the 2001-2002 hydrological year. Precipitation ?18O exhibited strong seasonal variation, which although significantly damped by catchment mixing processes, was reflected in stream water outputs at six sampling sites. This allowed ?18O variations to be used to infer the relative influence of soil-derived storm flows with a seasonally variable isotopic signature, and groundwater of more constant isotopic composition. Periodic regression analysis was then used to examine the sub-catchment differences in the mixing of these two main hydrological sources processes more quantitatively, using an exponential flow model to provide preliminary estimates of mean stream water residence times, which varied between 0.4-2.9 years. This showed that the effects of increasing scale on estimated mean stream water residence time was minimal beyond the smallest (ca. 1 km2 headwater catchment scale. Instead, the interaction of catchment soil cover and topography acted as the dominant influence. Responsive hydrological pathways, associated with peat soils in the headwater sub-catchments, produced seasonally variable ?18O signatures in runoff with short mean residence times (0.4-0.8 years). In contrast, areas dominated by more freely draining soils and larger groundwater storage in shallow aquifers appear to provide effective mixing and damping of variable precipitation inputs implying longer residence times (1.4-2.9 years). These insights from ?18O measurements extend the hydrological understanding of the Feugh catchment gained from previous geochemical tracer studies, and demonstrate the utility of isotope tracers in investigating the interaction of hydrological processes and catchment characteristics at the mesoscale

Obtaining Personal Jurisdiction over Alien Corporations--A Survey of U.S. Practice

With the increase in international trade, civil litigation between persons of different nationalities has become increasingly important. Today alien and foreign corporations are being brought before American courts to defend actions arising out of products liability, contract, and tort. There is considerable authority holding alien and foreign corporations amenable to jurisdiction on the basis of a single act or business transaction. The states themselves are affecting international trade since state law is chosen to determine the amenability of alien and foreign corporations to suit in diversity actions in federal court. This survey presents a cross-section of recent cases and attempts to distinguish the treatment given alien corporations from the treatment given foreign corporations. While a variety of actions is represented, the majority of the cases deal with products liability. Generally, these cases concern an alien corporation\u27s contacts with a particular state, although some courts might look to contacts with the United States as a whole in determining whether to assume jurisdiction in some types of cases. Recurrent considerations which appear throughout include: (1) whether the corporation has availed itself of the privilege of conducting business within the forum state; (2) whether the corporation knew its product was destined for the forum state; (3) whether the assumption of jurisdiction would violate traditional notions of fair play; (4) whether the plaintiff could realistically bring suit in the alien forum; (5) whether the alien corporation set its product in the normal stream of commerce; and (6) whether an American corporation is an alter ego of the alien corporation. While these considerations are largely derived from the major cases in which suit was brought against foreign corporations in a particular state, the courts balance the same considerations and apply the same standards to alien corporations in determining whether jurisdiction is proper. However, it has been advocated that a different standard should be applied in cases where alien corporations are involved