Linking Soil Erosion to Instream Dissolved Phosphorus Cycling and Periphyton Growth

Phosphorus (P) is a limiting nutrient in freshwater systems and when present in runoff from agricultural lands or urban centers may contribute to excessive periphyton growth. In this study, we examined the link between soil erosion and delivery of eroded soil to streams during flow events, and the impact of that freshly deposited soil on dissolved reactive P (DRP) concentrations and periphyton growth under baseflow conditions when the risk of stream eutrophication is greatest. A microcosm experiment was designed to simulate the release of P from soil which had been amended with different amounts of P fertilizer to overlying water during baseflow conditions. Unglazed tiles, inoculated for five days in a second order stream, were incubated for seven days in microcosms containing soil with eight levels of soil Mehlich‐3 plant available phosphorus (M3P) ranging from 20 to 679 mg/kg M3P. Microcosm DRP was monitored. Following incubation tiles were scraped and the periphyton analyzed for chlorophyll a. Microcosm DRP concentrations increased with increasing soil M3P and equilibrium phosphorus concentration (EPC₀). Relationships between M3P, EPC₀, and DRP were nonlinear and increases in soil M3P and/or DRP had a greater impact on biomass accumulation when these parameters were above threshold values of 30 mg/kg M3P and 0.125 mg/L DRP. Significantly, this ecological threshold corresponds to the agronomic thresholds above which increased soil M3P does not increase plant response.     

An assessment of the impact of ambient ozone on field-grown crops in New Jersey using the EDU method: part 2-soybean (Glycine max (L.) Merr.)

The yields of eleven commercially grown soybean cultivars were compared in ethylenediurea (EDU)-treated and non-treated field plots in New Brunswick, New Jersey, over a 4 year period. No statistically significant difference between treatments was found for any cultivar; the inference being ambient ozone did not adversely affect soybean yield. Succeeding field experiments supported this interpretation of the data. 'Sanilac' white bean, a legume known to be more sensitive to O(3) than soybean, was found to produce a significantly greater yield in EDU-treated than non-treated plots, unlike a companion planting of 'Williams 82' soybean which did not exhibit the differential response. The results indicated that the specific EDU protocol used in the soybean experiments is capable of detecting an ozone effect in a legume. Moreover, in a concurrent greenhouse experiment the yield of EDU-treated Sanilac white bean was not significantly different from non-treated plants in the absence of ozone pollution. In a dose-response field experiment during a year of unusually high O(3) pollution, yield of 'Williams 82' increased slightly with each EDU increment up to 500 ppm and decreased at 1000 ppm. The difference between non-treated and EDU-treated plants, however, was not statistically significant. There was no evidence to suggest that the EDU concentration (500 ppm) used in previous soybean experiments reduced seed yield. Fortuitously, the tolerance of commercially-grown soybean to ambient ozone is at least partially conditioned by the practce of not irrigating the crop. The New Jersey results are in agreement with reports from Maryland, Georgia and Tennessee in which an adverse impact of ambient O(3) was not found in soybean, but contrary to a current predictive model.     

WATER QUALITY OF AN INTENSWE AGRICULTURAL WATERSHED IN QUEBEC1

ABSTRACT: . Under a watershed based approach being examined by the Quebec Ministry of Agriculture to accelerate the adoption of conservation practices, a study on the impacts of agricultural practices on the St. Esprit watershed was initiated in the fall of 1993. The water quality of this 26 km² intensive agricultural watershed was studied over an 18 month period. Water samples taken at the outlet of the watershed were analyzed for nitrate, phosphate, suspended sediment, and atrazine. Water quality data were analyzed to establish seasonal trends in pollutant concentration and load in the watercourse. Spring snowmelt was identified as a significant period of pollutant material export. All pollutant materials displayed seasonal variability in the export process. Peak pollutant concentrations were associated with high flow events. Mean observed pollutant concentrations did not exceed drinking water quality standards.     

Relationship Between Bird Abundances and Landscape Characteristics: The Influence of Scale

Scale is important to consider when investigating effects of the environment on a species. Breeding Bird Survey (BBS) data and landscape metrics derived from aerial photographs were evaluated to determine how relationships of bird abundances with landscape variables changed over a continuous range of 16 spatial scales. We analyzed the average number of birds per stop (1985–1994) for five songbird species (family Cardinalidae) for each of 50 stops on 198 BBS transects throughout six states in the Central Plains, USA. Land along each transect was categorized into six cover types, and landscape metrics of fractal dimension (a measure of shape complexity of habitat patches), edge density, patch density, and percent area were calculated, with principal components used to construct composite environmental variables. Associations of bird abundances and landscape variables changed in accordance with small scale changes. Abundances of three species were correlated with edge density and one with component I, which subsumes initial variables of patch density for urban, closed forest, open forest, and open country. Fractal dimension and component II (summarizing amount of closed forest versus open country) were associated with the most species. Correlation patterns of fractal dimension with northern cardinal (Cardinalis cardinalis) and painted bunting (Passerina ciris) abundances were similar, with highest correlations at intermediate to small scales, suggesting indirectly that these species thrive in areas where local habitat conditions are most important. Multiscale analysis can provide insight into the spatial scale(s) at which species respond, a topic of intrinsic scientific interest with applied implications for researchers establishing protocols to assess and monitor avian populations.     

Rendering Bio-inert Low-Density Polyethylene Amenable for Biodegradation via Fast High Throughput Reactive Extrusion Assisted Oxidation

Journal of Polymers and the Environment - An energy-efficient high throughput pre-treatment of low-density polyethylene (LDPE) using a fast, reactive extrusion (REX) assisted oxidation technique...     

Multi-generational effects of four selected environmental oestrogens on Daphnia magna

The objective of this study was to determine whether vertebrate-type oestrogens have ecotoxicological effects on a crustacean species. The effects of 17beta-oestradiol (E2), diethylstilbestrol (DES), bisphenol A (BPA) and 4-nonylphenol (4-NP) on the freshwater invertebrate Daphnia magna were assessed over first and second generations. The acute EC(50) 48 h, based on immobilisation, for E2, DES, BPA and 4-NP were 2.87 mg/l, 1.55 mg/l, 7.75 mg/l and 0.13 mg/l, respectively. The impact of the test chemicals on moulting frequency was also assessed. The EC(50) 48 h, based on the inhibition of moult number for E2, DES and 4-NP were 2.04 mg/l, 1.87 mg/l and 0.14 mg/l, respectively. BPA was not observed to impact the moulting frequency of D. magna at concentrations tested. In a series of separate studies, the effects of the four selected test compounds on the survival, moulting frequency and reproduction of first and second generational D. magna were assessed over a period of 21 d. Exposure of D. magna to 4-NP decreased the number of offspring produced in both first and second generation testing. DES proved to have no significant (p0.05) inhibition of fecundity in first generation but when second generation daphnids were exposed to DES, a significant (p0.05) reduction in the number of offspring was recorded. When D. magna were exposed to E2 or BPA, no statistically significant (p0.05) inhibition in the number of moults or offspring produced was observed.     

Quantifying driver cell phone use at signalized intersections using software-defined radio

Objective: This article outlines a data collection process that quantifies driver cell phone use using a software-defined radio (SDR) at a signalized intersection. Cell phone use while driving has been shown to be factor that increases the risk of a crash incident. Both operational and enforcement strategies can be applied at locations where high driver cell phone use is identified.

Methods: A baseline driver cell phone use observation was made at the intersection, where 9,699 vehicles were observed at the intersection of Carlton Road and State Route 31 (Pennington Road) in Ewing, New Jersey. An SDR cell phone detection device created as part of this study was then deployed at the same intersection to determine whether the SDR device could detect an active cell phone signal. The identification of vehicle cell phone activity using the SDR was conducted a sample of 4,000 vehicles. A visual observation, along with a motion detection camera, was made alongside the SDR to visually confirm cell phones use.

Results: Of the 4,000 vehicles sampled using the SDR cell phone detection device, 6.1% of the a.m. peak travel time and 7.6% of the p.m. peak travel time had an active cellular device. A concurrent visual field verification of driver cell phone use showed that approximately 57% (a.m. peak) and 67% (p.m. peak) of the SDR-detected cell phones were visually confirmed to be associated with distracted cell phone use.

Conclusions: Once characterized, the frequency of driver cell phone use can be used to justify changes to signal timing protocols. These adjustments could include extending the signal’s “all-red time” or holding “yellow time” longer in order to properly clear the intersection. These data can also be used to identify locations that may require more enforcement measures to dissuade driver cell phone use. Furthermore, the impact of anti–cell phone campaigns or new laws can be quantified by measuring before and after cell phone use in the near term rather than waiting for crash studies at intersections to be completed and analyzed.     

Considering extinction of dependent species during translocation, ex situ conservation, and assisted migration of threatened hosts

Translocation, introduction, reintroduction, and assisted migrations are species conservation strategies that are attracting increasing attention, especially in the face of climate change. However, preventing the extinction of the suite of dependent species whose host species are threatened is seldom considered, and the effects on dependent species of moving threatened hosts are unclear. There is no published guidance on how to decide whether to move species, given this uncertainty. We examined the dependent-host system of 4 disparate taxonomic groups: insects on the feather-leaf banksia (Banksia brownii), montane banksia (B. montana), and Stirling Range beard heath (Leucopogon gnaphalioides); parasites of wild cats; mites and ticks on Duvaucel's gecko (Hoplodactylus duvaucelii) and tuatara (Sphenodon punctatus); and internal coccidian parasites of Cirl Bunting (Emberiza cirlus) and Hihi (Notiomystis cincta). We used these case studies to demonstrate a simple process for use in species- and community-level assessments of efforts to conserve dependents with their hosts. The insects dependent on Stirling Range beard heath and parasites on tigers (Panthera tigris) appeared to represent assemblages that would not be conserved by ex situ host conservation. In contrast, for the cases of dependent species we examined involving a single dependent species (internal parasites of birds and the mite Geckobia naultina on Duvaucel's gecko), ex situ conservation of the host species would also conserve the dependent species. However, moving dependent species with their hosts may be insufficient to maintain viable populations of the dependent species, and additional conservation strategies such as supplementing populations may be needed.     

THE STATE OF LOUISIANA SUPERPORT AUTHORITY ENVIRONMENTAL PROTECTION PLAN – OIL AND OYSTERS1

ABSTRACT: The State of Louisiana created in 1972 the Deep Draft Harbor and Terminal Authority (commonly called Superport Authority) to plan, promote, and develop a deepwater (crude oil) terminal off the coast of Louisiana, and empowered it to establish an Authority development program to promote the economic and social welfare of its citizens. Simultaneously, the Authority was also charged with developing an environmental protection plan to preserve the environmental values of Louisiana's unique coastal marshland while permitting beneficial industrial and economic development. Consequently, in January 1974, an Environmental Protection Plan was promulgated, consisting of a series of regulations, design standards, and operating procedures aimed specifically at protecting the fragile estuarine environment of coastal Louisiana during the construction and ultimate operation of the superport. The paper describes the development of the Superport Authority's Environmental Protection Plan and the current status of the superport project.