Depletable externalities and pigouvian taxation

In their book Baumol and Oates [“The Theory of Environmental Policy: Externalities, Public Outlays, and the Quality of Life,” Prentice-Hall, Englewood Cliffs, N.J. (1975).] argue that whether an externality is depletable (private) or undepletable (public) is the key characteristic in determining the optimal pricing pattern. They argue that unlike the undepletable case a negative depletable externality requires not only a charge or tax on the generator of the externality but a payment or compensation to the victim in order to achieve Pareto optimality. It is shown that the key characteristic determining whether compensation of victims is required for efficiency is not the depletability of the externality but whether the victim can costlessly control or limit the amount of the damaging substance received.     

Flexible foraging strategies in a diving seabird with high flight cost

How central-place foragers change search strategy in response to environmental conditions is poorly known. Foragers may vary the total distance travelled and how far they range from the central place in response to variation in the distribution of their prey. One potential reason as to why they would extend the length of their foraging trip and its distance from the colony would be to increase prey quality or quantity, despite incurring higher transit costs. To test this trade-off hypothesis in a species with high flight costs, we recorded the foraging behaviour of razorbills (Alca torca) using state-of-the-art techniques that log both individual horizontal (flight activity) and vertical (dive activity) movements. We show that the distance that razorbills travelled to foraging locations increased with sea-surface temperature, which may relate to higher prey quality or quantity. This relation is supported by an indirect index of patch quality, based on dive profiles, which also increased with travel distance from the colony. Furthermore, we show that this index was highest during the daily peak in diving activity, around midday. Taken together, these results suggest that razorbills are capable of adjusting their search strategies sensitively in response to proximate environmental cues.     

Frequency analysis of hazardous material transportation incidents as a function of distance from origin to incident location

According to the United States Department of Transportation (USDOT), more than 3.1 billion tons of hazardous materials (HazMat) are shipped within the United States annually. This averages to about 800,000 individual shipments of HazMat per day, of which 300,000 are shipments of petroleum/flammable–combustible liquids. This paper presents a temporal trend study (1995–2004) of 2145 HazMat incidents occurring through the transportation of flammable/combustible liquids. The study also correlates between HazMat incidents and distances between shipment origin and incident location. These distances attained through great circle calculations since the data compilation did not allow for the identification of specific routes taken in commodity transport. Findings of this study illustrate a bimodal distribution of frequency as a function of the logarithm of the Distance with first mode (less than 105 miles) mean of 24 [km] and second mode mean of 1061 [km]. Additionally, transport phase introduced no significance to the distribution of frequencies.     

Prenatal ascertainment of triploidy by maternal serum alpha-fetoprotein screening

We report our experience in ascertaining fetal triploidy during routine maternal serum alpha-fetoprotein (MSAFP) screening. Three cases were identified after elevated MSAFP tests. Two of the three had normal amniotic fluid alpha-fetoprotein (AFAFP). The third had amniocentesis too late for AFAFP interpretation. Three additional cases were detected by amniocentesis without prior MSAFP screening and none had an elevated AFAFP. A literature review revealed eight triploid fetuses detected as a result of an elevated MSAFP. Of the five with AFAFP quantitation, only one had an abnormal value and the elevation was minimal. In these 14 cases from our own and other reports, ultrasound findings of placental and fetal abnormalities were often noted, but a pattern diagnostic of triploidy was not present. We conclude that, for optimal prenatal detection of triploidy, fetal karyotyping should be included when an amniocentesis is performed for elevated MSAFP.     

Reduction in residential chromium following site remediation

The purpose of this study was to determine the influence of chromate production waste site remediation on residential Cr concentrations in house dust. Twenty-three homes in Jersey City, NJ, were identified as having had high (> 500 micrograms/gm, median 739 micrograms/gm), medium (100-400 micrograms/gm, median 245 micrograms/gm), or low (< 100 micrograms/gm, median 48 micrograms/gm) Cr in house dust during a study conducted in 1992-1993 prior to site remediation. House dust samples were collected on four visits from each home between November 1996 and February 1998, extracted with HNO3, and analyzed for Cr with an inductively coupled plasma-mass spectrometer. Homes that had low Cr concentrations in 1992-1993 continued to have low Cr concentrations (median 1 microgram/g). In contrast, substantial declines in Cr concentrations were found in the house dust collected from homes located near the remediated waste sites: previously high-level homes had a median of 50 micrograms/g and mid-level homes had a median of 34 micrograms/g. Site remediation had a beneficial effect on household loadings of Cr, since no differences in post-remediation house dust Cr concentrations were found among the three groups.     

The contribution of azo dyes to the mutagenic activity of the Cristais River

To verify whether dyes emitted within the discharge of a dye processing plant were contributing to the mutagenicity repeatedly found in the Cristais River, Sao Paulo, Brazil, we chemically characterized the following mutagenic samples: the treated industrial effluent, raw and treated water, and the sludge produced by a Drinking Water Treatment Plant (DWTP) located approximately 6 km from the industrial discharge. Considering that 20% of the dyes used for coloring activities might be lost to wastewaters and knowing that several dyes have mutagenic activity, we decided to analyze the samples for the presence of dyes. Thin layer chromatographic analysis indicated the presence of three prevalent dyes in all samples, except for the drinking water. This combination of dyes corresponded to a commercial product used by the industry, and it tested positive in the Salmonella assay. The structures of the dye components were determined using proton magnetic resonance and mass spectrometric (MS) methods, and the dyes were tested for mutagenicity. The blue component was identified as the C.I. Disperse Blue 373, the violet as C.I. Disperse Violet 93, and the orange as C.I. Disperse Orange 37. The dyes showed mutagenic responses of 6300, 4600, and 280 revertants/microg for YG1041 with S9 respectively. A bioassay-directed fractionation/chemical analysis showed that the C.I. Disperse Blue 373 contributed 55% of the mutagenic activity of the DWTP sludge. We showed that these dyes contributed to the mutagenic activity found in the Cristais River environmental samples analyzed and are indirectly affecting the quality of the related drinking water. Therefore, we believe that this type of discharge should be more thoroughly characterized chemically and toxicologically. Additionally, human and ecological risks associated with the release of dye processing plant effluents should be more fully investigated, especially where the resultant water is taken for human consumption.     

Polychlorinated biphenyls, organochlorine pesticides and chlorobenzenes content of livers from Atlantic cod (Gadus morhua) caught off Halifax Nova Scotia

The mean levels ± s.d., (ranges) of organochlorines, pesticides, chlorobenzenes and polychlorinated biphenyl were determined in the livers of 100 Atlantic cod (Gadus morhua) caught off the east coast of Canada in 1980 and were as follows: PCB 1.71±0.90 (0.24–4.33); p,p-DDE 0.28±0.15 (0.01–0.84); p,p-DDD 0.10±0.09 (trace-0.84); p,p-DDT 0.15±0.09 (ND-0.58); -HCH 0.06±0.02 (trace-0.10); -HCH (ND-trace); heptachlor 0.02±0.01 (ND-0.04); heptachlor epoxide 0.15±0.37 (ND-2.16); dieldrin 0.06±0.11 (ND-0.71); hexachlorobenzene 0.02±0.01 (trace-0.05) mg kg^–1 (wet wt.). The levels of these compounds in 1980 have not changed over the previous eight years with the exception of PCB and the DDT group where there appears to be a general decline between 1972 and 1975 with no significant change thereafter.     

Methods for joint inference from panel survey and demographic data

A number of methods for joint inference from animal abundance and demographic data have been proposed in recent years, each with its own advantages. A new approach to analyzing panel survey and demographic data simultaneously is described. The approach fits population-dynamics models to the survey data, rather than to a single index of abundance derived from them and thus avoids disadvantages inherent in analyzing such an index. The methodology is developed and illustrated with British Lapwing data, and the results are compared with those obtained from existing approaches. The estimates of demographic parameters and population indices are similar for all methods. The results of a simulation study show that the new method performs well in terms of mean squared error.     

The effect of the corticosteroid hormone cortexolone on the metabolites produced during phenanthrene biotransformation in Cunninghamella elegans

The metabolism of phenanthrene and the mammalian corticosteroid hormone cortexolone by the fungus Cunninghamella elegans was studied. The amounts of the cortexolone transformation products, cortisol and epicortisol, were affected by the presence of phenanthrene. Approximately 40% more cortisol was produced by C. elegans in cultures with phenanthrene. In contrast, epicortisol formation decreased. C. elegans transformed phenanthrene to phenanthrene trans-1,2-,3,4-, and 9,10-dihydrodiols, phenols, diphenols (diols) and glucoside conjugates of 1-, 2-, 3-, 4-, and 9-phenanthrols. Almost all of the phenanthrene initially added was metabolized to ethyl acetate extractable metabolites. In the mycelia and culture medium extracts, phenanthrol glucosides represented 80% and 94% of the total metabolites, respectively. The major metabolite was the glucoside conjugate of 1-phenanthrol. The presence of cortexolone affected the biodegradation of phenanthrene by decreasing the amounts of phenanthrene metabolites compared to control cultures.     

Forecasting air quality time series using deep learning

This paper presents one of the first applications of deep learning (DL) techniques to predict air pollution time series. Air quality management relies extensively on time series data captured at air monitoring stations as the basis of identifying population exposure to airborne pollutants and determining compliance with local ambient air standards. In this paper, 8 hr averaged surface ozone (O₃) concentrations were predicted using deep learning consisting of a recurrent neural network (RNN) with long short-term memory (LSTM). Hourly air quality and meteorological data were used to train and forecast values up to 72 hours with low error rates. The LSTM was able to forecast the duration of continuous O₃ exceedances as well. Prior to training the network, the dataset was reviewed for missing data and outliers. Missing data were imputed using a novel technique that averaged gaps less than eight time steps with incremental steps based on first-order differences of neighboring time periods. Data were then used to train decision trees to evaluate input feature importance over different time prediction horizons. The number of features used to train the LSTM model was reduced from 25 features to 5 features, resulting in improved accuracy as measured by Mean Absolute Error (MAE). Parameter sensitivity analysis identified look-back nodes associated with the RNN proved to be a significant source of error if not aligned with the prediction horizon. Overall, MAE's less than 2 were calculated for predictions out to 72 hours.

Implications: Novel deep learning techniques were used to train an 8-hour averaged ozone forecast model. Missing data and outliers within the captured data set were replaced using a new imputation method that generated calculated values closer to the expected value based on the time and season. Decision trees were used to identify input variables with the greatest importance. The methods presented in this paper allow air managers to forecast long range air pollution concentration while only monitoring key parameters and without transforming the data set in its entirety, thus allowing real time inputs and continuous prediction.