Sediment toxicity and stormwater runoff in a contaminated receiving system: consideration of different bioassays in the laboratory and field.

Several field and laboratory assays were employed below an urban storm sewer outfall to define the relationship between stormwater runoff and contaminant effects. Specifically, two bioassays that measure feeding rate as a toxicological endpoint were employed in the field and in the laboratory, along with bioassays measuring survival and growth of test organisms. In 7 to 10 d in situ exposures, amphipod leaf disc processing, growth and survival were monitored. Different exposure scenarios were investigated by varying the mesh size (74 microns or 250 microns mesh) and method of deployment (water column, sediment surface, or containing sediment) of in situ exposure chambers. Hyalella azteca, Daphnia magna, and Pimephales promelas survival were monitored in 48 h in situ exposures. Feeding inhibition was investigated via enzyme inhibition of H. azteca and D. magna and via leaf disc processing measurements of the detritivore H. azteca. Additionally, we investigated the extent of phototoxicity at this site via field exposures in sun and shade and laboratory exposures with and without UV light. The measurement of detritivore leaf disc processing, and thus its usefulness as an endpoint, was hindered by individual variability in the amount of leaf consumed and by leaf weight gain during the summer field exposures. For D. magna, enzyme inhibition measured in a laboratory exposure did not reveal the toxicity observed in field exposures. For H. azteca, enzyme inhibition measured in the laboratory indicated toxicity similar to that observed in short term chronic in situ exposures. Enzyme inhibition also did not detect differences in toxicity due to variations in flow conditions. There were no statistically significant effects of any exposure on P. promelas survival or H. azteca growth, and there were no statistically significant effects due to mesh size or sun exposure. Survival of H. azteca was the most sensitive and the least variable endpoint. Effects on survival were noted in the same treatments over short-term chronic exposures in the laboratory and in situ. Significant differences in survival were noted due to the method of deployment under low flow conditions. In situ chambers containing sediment resulted in greater mortality in the 10 d low flow in situ experiments. Under high flow conditions, significant reductions in survival and leaf disc processing were noted under all methods of deployment at the two impacted sites over a 7 d exposure. Also under high flow conditions, significantly greater mortality of H. azteca was reported at the downstream field site when sediment was included in the chamber at deployment. These results suggest that significant toxicity at this site is due to accumulation of contaminants in the sediment and the mobilization of these contaminants during a storm event. In situ exposures detected toxicity not observed in laboratory exposures. These results suggest that a combination of laboratory and field bioassays is most useful in defining field effects.     

Genetic heterogeneity among adult and recruit red sea urchins, Strongylocentrotus franciscanus

Allozyme electrophoresis was used to characterize genetic variation within and among natural populations of the red sea urchin Strongylocentrotus franciscanus. In 1995 to 1996, adult urchins were sampled from twelve geographically separated populations, seven from northern California and five from southern California (including Santa Rosa Island). Significant population heterogeneity in allelic frequencies was observed at five of six polymorphic loci. No geographic pattern of differentiation was evident; neighboring populations were often more genetically differentiated than distant populations. Northern and southern populations were not consistently distinguishable at any of the six loci. In order to assess within-population genetic variation and patterns of recruitment, large samples were collected from several northern California populations in 1996 and 1997, and were divided into three size classes, roughly representing large adults (>60 mm), medium-sized individuals (31 to 60 mm, “subadults”) and individuals <2 yr of age (≤30 mm test diam, referred to as “recruits”). Comparisons of allelic counts revealed significant spatial and temporal differentiation among size-stratified population samples. Recruit samples differed significantly from adult samples collected at the same locale, and showed extensive between-year variation. Genetic differentiation among recruit samples was much higher in 1997 than in 1996. Between-year differences within populations were always greater for recruits than for adults. Potential explanations for the differentiation of recruit samples include pre- and post-settlement natural selection and high interfamily variance in reproductive success or “sweepstakes” recruitment. Unless recruit differentiation can be attributed to an improbable combination of strong and spatially diverse selection, such differentiation across northern California populations indicates that the larval pool is not well mixed geographically (even on spatial scales <20 km), despite long planktonic larval duration. Received: 6 July 1999 / Accepted: 25 January 2000     

THE IMPACT OF HIGHWAY CONSTRUCTION ON A NORTH FLORIDA WATERSHED1

ABSTRACT A 20 month study of some effects of highway construction on water quality was conducted during construction of Interstate 10 at Tallahassee, Florida. Highway construction resulted in significant increases in turbidity, suspended solids, total phosphorus, and dissolved silicon in downstream waters despite use of recommended procedures for erosion control. Highway construction did not result in significant increases in dissolved phosphorus or nitrogen.     

HISTORY OF THE FEDERAL-STATE COOPERATIVE WATER RESOURCES RESEARCH INSTITUTE PROGRAM1

ABSTRACT: This paper presents a condensed history of the State Water Resources Research Institute Program, which evolved from the Water Resources Research Act of 1964, as amended, the Water Research and Development Act of 1978, Public Law (P.L.) 96–457, and the Water Research and Development Act of 1984. These laws authorized the following components of the Institute Program: (1) the annual allotment and matching grants program for the Institutes, and (2) the additional and saline water research programs for organizations in addition to the State Water Resources Research Institutes. The paper covers the legislative history of the Institute Program and reviews authorized and appropriated funds for the program from fiscal year 1965 to fiscal year 1986. It also discusses the Institutes’role in conducting and sponsoring water-resources research and development, training of scientists and engineers, and coordinating, disseminating, and transferring water-research results. The State Water Resources Research Program has been administered by the Office of Water Resources Research (OWRR) (1964–1974), the Office of Water Research and Technology (OWRT) (1974–1982), the Office of Water Policy (OWP) (1982–1983), and the U.S. Geological Survey (USGS) (1983-present).     

Environmental degradation and remediation: is economics part of the problem?

It is argued that standard environmental economic and 'ecological economics', have the same fundamentals of valuation in terms of money, based on a demand curve derived from utilitymaximization. But this approach leads to three different measuresof value. An invariant measure of value exists only if the consumer has 'homothetic preferences'. In order to obtain a numerical estimate of value, specific functional forms are necessary, but typically these estimates do not converge. This is due to the fact that the underlying economic model is not structurally stable.According to neoclassical economics, any environmental remediation can be justified only in terms of increases in consumer satisfaction, balancing marginal gains against marginal costs. It is not surprising that the optimal policy obtained fromthis approach suggests only small reductions in greenhouse gases.We show that a unidimensional metric of consumer's utility measured in dollar terms can only trivialize the problem of global climate change.     

Assessment of denitrification gaseous end-products in the soil profile under two water table management practices using repeated measures analysis

The denitrification process and nitrous oxide (N2O) production in the soil profile are poorly documented because most research into denitrification has concentrated on the upper soil layer (0-0.15 m). This study, undertaken during the 1999 and 2000 growing seasons, was designed to examine the effects of water table management (WTM), nitrogen (N) application rate, and depth (0.15, 0.30, and 0.45 m) on soil denitrification end-products (N2O and N2) from a corn (Zea mays L.) field. Water table management treatments were free drainage (FD) with open drains and subirrigation (SI) with a target water table depth of 0.6 m. Fertility treatments (ammonium nitrate) were 120 kg N ha(-1) (N120) and 200 kg N ha(-1) (N200). During both growing seasons greater denitrification rates were measured in SI than in FD, particularly in the surface soil (0-0.15 m) and at the intermediate (0.15-0.30 m) soil depths under N200 treatment. Greater denitrification rates under the SI treatment, however, were not accompanied with greater N2O production. The decrease in N2O production under SI was probably caused by a more complete reduction of N2O to N2, which resulted in lower N2O to (N2O + N2) ratios. Denitrification rate, N2O production and N2O to (N2O + N2) ratios were only minimally affected by N treatments, irrespective of sampling date and soil depth. Overall, half of the denitrification occurred at the 0.15- to 0.30- and 0.30- to 0.45-m soil layers, and under SI, regardless of fertility treatment level. Consequently, sampling of the 0- to 0.15-m soil layer alone may not give an accurate estimation of denitrification losses under SI practice.     

Macrobenthic species assemblages in Ellis Fjord,Vestfold Hills,Antarctica

A study was made of the sub-littoral benthic environment of Ellis Fjord, a 10 km-long fjord located near Davis Station, in the Vestfold Hills, Antarctica, over a 15 mo period (November 1984 to February 1986). Data were collected by SCUBA diving and underwater photography and were inhitially analysed by ordination techniques (non-metric multidimensional scaling). Ordinations showed substratum type to be the factor most strongly associated with changes in the distribution and abundance of macrobenthic species within the fjord. Other factors shown to be associated with changes in macrobenthic species assemblages were depth, distance from the fjord mouth, bottom slope, shoreline characteristics, current speed, and the presence of low-salinity water at shallow depths during the summer melt. The four major substratum types in Ellis Fjord were sand, rock, Serpula narconensis colonies and Phyllophora antarctica thalli. S. narconensis colonies supported the most species and sand substrate supported the least. P. antarctica is the only macrophyte species which occurred in the fjord. S. narconensis colonies in Ellis Fjord from one of the largest known tubeworm reefs in the world. The assemblages of benthic species in Ellis Fjord were different from those seen at other sub-littoral benthic sites off the Vestfold Hills, and at other Antarctic sites. There was a far greater proportion of filter-feeding species in the fjord than at other sub-littoral benthic sites off the Vestfold Hills. Factors which are thought to have caused these differences are the high level of organic but low level of inorganic input into the benthic system of the fjord, and the absence of anchor ice from the fjord.     

PCB, PCDF, and PCDD exposure following a transformer fire: Chicago

On September 28, 1983, an electrical fire in a transformer vault resulted in the loss of 15 gallons of transformer oil composed of 65% PCBs (Aroclor 1260) and 35% trichlorobenzene and forced the precautionary evacuation of a major Chicago office building. A square foot wipe sample of soot on the vault ceiling contained 28,000 ng total TCDFs, 3,800 ng 2,3,7,8-TCDF, 40,000 ng PCDFs, 33,000 ng HxCDFs, 11,200 ng HpCDFs, 1,238 ng OCDFs, 314 ng HpCDDs, and 127 ng OCDDs. No PCDFs or PCDDs were detected in the blood (detection limit 3–40 ppt) of two fire fighters hospitalized with smoke inhalation nor of two office employees similarly exposed.     

No evidence that chronic nitrogen additions increase photosynthesis in mature sugar maple forests

Atmospheric nitrogen (N) deposition can increase forest growth. Because N deposition commonly increases foliar N concentrations, it is thought that this increase in forest growth is a consequence of enhanced leaf-level photosynthesis. However, tests of this mechanism have been infrequent, and increases in photosynthesis have not been consistently observed in mature forests subject to chronic N deposition. In four mature northern hardwood forests in the north-central United States, chronic N additions (30 kg N ha(-1) yr(-1) as NaNO3 for 14 years) have increased aboveground growth but have not affected canopy leaf biomass or leaf area index. In order to understand the mechanism behind the increases in growth, we hypothesized that the NO3(-) additions increased foliar N concentrations and leaf-level photosynthesis in the dominant species in these forests (sugar maple, Acer saccharum). The NO3(-) additions significantly increased foliar N. However, there was no significant difference between the ambient and +NO3(-) treatments in two seasons (2006-2007) of instantaneous measurements of photosynthesis from either canopy towers or excised branches. In measurements on excised branches, photosynthetic nitrogen use efficiency (micromol CO2 s(-1) g(-1) N) was significantly decreased (-13%) by NO3(-) additions. Furthermore, we found no consistent NO3(-) effect across all sites in either current foliage or leaf litter collected annually throughout the study (1993-2007) and analyzed for delta 13C and delta 18O, isotopes that can be used together to integrate changes in photosynthesis over time. We observed a small but significant NO3(-) effect on the average area and mass of individual leaves from the excised branches, but these differences varied by site and were countered by changes in leaf number. These photosynthesis and leaf area data together suggest that NO3(-) additions have not stimulated photosynthesis. There is no evidence that nutrient deficiencies have developed at these sites, so unlike other studies of photosynthesis in N-saturated forests, we cannot attribute the lack of a stimulation of photosynthesis to nutrient limitations. Rather than increases in C assimilation, the observed increases in aboveground growth at our study sites are more likely due to shifts in C allocation.