Effect of bottom conditions on eutrophy of impoundments

Cover title.Includes bibliographical references (p. 57-58)

Acute Toxicity of Residual Chlorine and Ammonia to Some Native Illinois Fishes

Ninety-six hour residual chlorine bioassays were conducted on bluegill and channel catfish. In 96-hr acute toxicity studies with ammonia (NH3 -N) bass, in addition to bluegill and channel catfish, were included. The studies were performed in waters typical of most lakes and streams in midwestern states, i.e., relatively high in alkalinity and the salts of and magnesium. Observations of the characteristics and reaction of the fishes to each toxicant were noted. The 96-hr median tolerance limits for residual chlorine were: from 0.18 to 0.33 mg/1 for bluegill depending on temperature and fish weight; about 0.09 mg/1 for channel catfish with temperature not a factor. For ammonia the 96-hr median tolerance limits were: from 0.40 to 1.3 mg/1 for bluegill depending on temperature and fish weight; from 0.72 mg/1 at 22° C to 1.2 mg/1 at 30°C for bass and 1.5 mg/1 at 22°C to 3.0 mg/1 at 28° C for channel catfish with size not a factor. For the protection of the fishes investigated, and consistent with Illinois water pollution regulations, residual chlorine should not be detectable and NH3-N should not exceed a concentration of 0.04 mg/1.publishedpeer reviewedOpe

Effect of agriculture on Cedar Lake water quality

Cover title.Includes bibliographical references (p. 56-59)

Appendices for An Inventory of Court Creek Watershed Characteristics That May Relate to Water Quality in the Watershed

published or submitted for publicationis peer reviewedOpe

The Influences of Land Uses and Stream Modifications on Water Quality in the Streams of the Court Creek Watershed

published or submitted for publicationis peer reviewedOpe

Radio galaxies in the 2SLAQ Luminous Red Galaxy survey: II. The stellar populations of radio-loud and radio-quiet LRGs

We present an analysis of the optical spectra of a volume-limited sample of 375 radio galaxies at redshift 0.4<z<0.7 from the 2dF-SDSS Luminous Red Galaxy and QSO (2SLAQ) redshift survey. We investigate the evolution of the stellar populations and emission-line properties of these galaxies. By constructing composite spectra and comparing with a matched sample of radio-quiet sources from the same survey, we also investigate the effect on the galaxy of the presence of an active nucleus. The composite spectra, binned by redshift and radio luminosity, all require two components to describe them, which we interpret as an old and a younger population. We found no evolution with redshift of the age of the younger population in radio galaxies, nor were they different from the radio-quiet comparison sample. Similarly, there is no correlation with radio power, with the exception that the most powerful radio sources (P(1.4) > 10^26 W/Hz) have younger stars and stronger emission lines than the less powerful sources. This suggests that we have located the threshold in radio power where strong emission lines "switch on", at radio powers of around 10^26 W/Hz. Except for the very powerful radio galaxies, the presence of a currently-active radio AGN does not appear to be correlated with any change in the observed stellar population of a luminous red galaxy at z~0.5.Comment: 10 pages, 10 figures and 2 tables, accepted for publication in MNRA

The 2dF-SDSS LRG and QSO Survey: The Star Formation Histories of Luminous Red Galaxies

We present a detailed investigation into the recent star formation histories of 5,697 Luminous Red Galaxies (LRGs) based on the Hdelta (4101A) and [OII] (3727A) lines. LRGs are luminous (L>3L*), galaxies which have been selected to have photometric properties consistent with an old, passively evolving stellar population. For this study we utilise LRGs from the recently completed 2dF-SDSS LRG and QSO survey (2SLAQ). Equivalent widths of the Hdelta and [OII] lines are measured and used to define three spectral types, those with only strong Hdelta absorption (k+a), those with strong [OII] in emission (em) and those with both (em+a). All other LRGs are considered to have passive star formation histories. The vast majority of LRGs are found to be passive (~80 per cent), however significant numbers of k+a (2.7 per cent), em+a (1.2 per cent) and em LRGs (8.6 per cent) are identified. An investigation into the redshift dependence of the fractions is also performed. A sample of SDSS MAIN galaxies with colours and luminosities consistent with the 2SLAQ LRGs is selected to provide a low redshift comparison. While the em and em+a fractions are consistent with the low redshift SDSS sample, the fraction of k+a LRGs is found to increase significantly with redshift. This result is interpreted as an indication of an increasing amount of recent star formation activity in LRGs with redshift. By considering the expected life time of the k+a phase, the number of LRGs which will undergo a k+a phase can be estimated. A crude comparison of this estimate with the predictions from semi-analytic models of galaxy formation shows that the predicted level of k+a and em+a activity is not sufficient to reconcile the predicted mass growth for massive early-types in a hierarchical merging scenario.Comment: Accepted for publication in MNRAS, 13 pages, 10 figure

The 2dF-SDSS LRG and QSO survey: evolution of the clustering of luminous red galaxies since z = 0.6

We present an analysis of the small-to-intermediate scale clustering of samples of Luminous Red Galaxies (LRGs) from the Sloan Digital Sky Survey and the 2dF-SDSS LRG and QSO (2SLAQ) survey carefully matched to have the same rest-frame colours and luminosity. We study the spatial two-point auto-correlation function in both redshift-space and real-space of a combined sample of over 10,000 LRGs, which represent the most massive galaxies in the universe with stellar masses > 10^11 h^-1 M_sun and space densities 10^-4 h^-3 Mpc^-3. We find no significant evolution in the amplitude r_0 of the correlation function with redshift, but do see a slight decrease in the slope with increasing redshift over 0.19 < z < 0.55 and scales of 0.32 < r < 32 h^-1 Mpc. We compare our measurements with the predicted evolution of dark matter clustering and use the halo model to interpret our results. We find that our clustering measurements are inconsistent (>99.9% significance) with a passive model whereby the LRGs do not merge with one another; a model with a merger rate of 7.5 +/- 2.3% from z = 0.55 to z = 0.19 (i.e. an average rate of 2.4% Gyr^-1) provides a better fit to our observations. Our clustering and number density measurements are consistent with the hypothesis that the merged LRGs were originally central galaxies in different haloes which, following the merger of these haloes, merged to create a single Brightest Cluster Galaxy. In addition, we show that the small-scale clustering signal constrains the scatter in halo merger histories. When combined with measurements of the luminosity function, our results suggest that this scatter is sub-Poisson. While this is a generic prediction of hierarchical models, it has not been tested before.Comment: 20 pages, replaced with version accepted for publication in MNRA

Pilot Lake Restoration Investigations--aeration and Destratification in Lake Catherine

published or submitted for publicationis peer reviewedOpe

Pilot Lake Restoration Investigations in the Fox Chain of Lakes

published or submitted for publicationis peer reviewedOpe