Modeling Watershed‐Scale Impacts of Stormwater Management with Traditional versus Low Impact Development Design

Stormwater runoff and associated pollutants from urban areas in the greater Chesapeake Bay Watershed (CBW) impair local streams and downstream ecosystems, despite urbanized land comprising only 7% of the CBW area. More recently, stormwater best management practices (BMPs) have been implemented in a low impact development (LID) manner to treat stormwater runoff closer to its source. This approach included the development of a novel BMP model to compare traditional and LID design, pioneering the use of comprehensively digitized storm sewer infrastructure and BMP design connectivity with spatial patterns in a geographic information system at the watershed scale. The goal was to compare total watershed pollutant removal efficiency in two study watersheds with differing spatial patterns of BMP design (traditional and LID), by quantifying the improved water quality benefit of LID BMP design. An estimate of uncertainty was included in the modeling framework by using ranges for BMP pollutant removal efficiencies that were based on the literature. Our model, using Monte Carlo analysis, predicted that the LID watershed removed approximately 78 kg more nitrogen, 3 kg more phosphorus, and 1,592 kg more sediment per square kilometer as compared with the traditional watershed on an annual basis. Our research provides planners a valuable model to prioritize watersheds for BMP design based on model results or in optimizing BMP selection.     

Potential for rainwater use in high-rise buildings in Australian cities

Rainwater is a traditional but underutilized water resource that has today had a resurgence due to the worldwide water crisis. This paper demonstrates the outcomes of research on the feasibility of rainwater use in high-rise residential envelopes for four Australian cities of Melbourne, Sydney, Perth and Darwin. Different climate patterns and various levels of water demand management were established for determination of storage dimensions; annual tank water use; reduction in both imported water flow and stormwater disposal; and water spillage from tanks. High level water demand management was a profoundly effective tool for reducing potable water supply, especially in combination with rainwater use. The economic feasibility of rainwater use systems were estimated; with Sydney having the shortest payback period compared to other cities either both with 3A rated appliances (8.6 years) or 5A ones installed (10.4 years). That was due to the higher and more consistent rainfall in Sydney. An outcome of this study was that Sydney was likely most suited to rainwater use, followed by Perth, Darwin, and then Melbourne. The objective of this study was to fill in the gap in estimating feasibility of rainwater use in various Australian cities. This investigation endeavors to provide assistance to water authorities and urban planners of Australian cities with the consideration of the potential of rainwater harvesting.     

Metallic and organic contaminants in sediments of Sydney Harbour, Australia and vicinity-- a chemical dataset for evaluating sediment quality guidelines

An internally consistent dataset comprising 103 surficial estuarine sediment samples were collected from Sydney Harbour, Australia and locations south of Sydney. This paper describes the chemical characteristics of the dataset and evaluates its suitability for use in evaluating biological effects-based sediment quality guidelines (SQGs). The sediments contained mixtures of chemicals, the most prevalent chemical classes being metals and polycyclic aromatic hydrocarbons, whereas sediments from coastal lakes/estuaries south of Sydney had low concentrations of contaminants. Maximum concentrations of the prevalent contaminants zinc, lead, copper and pyrene were 11,300, 1,420, 1,060 mg kg(-1) and 23,300 microg kg(-1), respectively. For the majority of samples, concentrations of individual chemicals exceeded most effects-based SQGs that have been adopted for use in Australia, implying occasional or frequent adverse biological effects are expected. Comparing mixtures of contaminants to ranges in numbers of SQGs exceeded and mean SQG quotients showed that most samples (57% to 68%) had contamination characteristics associated with moderate probabilities (30% to 52%) of acute toxicity, based on North American data. A smaller proportion of samples (15% to 17%) had contamination characteristics associated with high probabilities (74% to 85%) of toxicity. The wide range of chemicals and concentrations, associated with low, medium and high probabilities of toxicity, indicated that the dataset was suitable for future use in evaluating predictive abilities of SQGs. This is relevant, given the recent introduction of North American-derived SQGs for Australia.     

Differences in sensitivity to the fungal pathogen Batrachochytrium dendrobatidis among amphibian populations

Contributing to the worldwide biodiversity crisis are emerging infectious diseases, which can lead to extirpations and extinctions of hosts. For example, the infectious fungal pathogen Batrachochytrium dendrobatidis (Bd) is associated with worldwide amphibian population declines and extinctions. Sensitivity to Bd varies with species, season, and life stage. However, there is little information on whether sensitivity to Bd differs among populations, which is essential for understanding Bd‐infection dynamics and for formulating conservation strategies. We experimentally investigated intraspecific differences in host sensitivity to Bd across 10 populations of wood frogs (Lithobates sylvaticus) raised from eggs to metamorphosis. We exposed the post‐metamorphic wood frogs to Bd and monitored survival for 30 days under controlled laboratory conditions. Populations differed in overall survival and mortality rate. Infection load also differed among populations but was not correlated with population differences in risk of mortality. Such population‐level variation in sensitivity to Bd may result in reservoir populations that may be a source for the transmission of Bd to other sensitive populations or species. Alternatively, remnant populations that are less sensitive to Bd could serve as sources for recolonization after epidemic events.     

Contribution of a New PCR assay to the prenatal diagnosis of congenital toxoplasmosis

A polymerase chain reaction (PCR) assay has been developed for the detection of Toxoplasma gondii. The target sequence (88 bp) is part of a rDNA repetitive gene. A signal can be observed with only one parasite. It is directly and rapidly detected by electrophoresis and ethidium bromide staining. We report a prospective study of 80 documented cases of toxoplasmic seroconversions during pregnancy. The PCR assay of the amniotic fluids was compared with the current standard methods for diagnosis of fetal infection. Seventy specimens gave no PCR signal, and were negative according to prenatal tests and postnatal examinations. The presence of T. gondii was detected in ten specimens by PCR analysis. Four were confirmed by isolation of the parasite from the amniotic fluid; four by biological study of the fetal blood. For the remaining two, infection was diagnosed after birth. Together with ultrasonographic and biological data, this technique permits prenatal diagnosis within 1 day.     

A revised stratigraphic framework for Later Cenozoic sequences in the northeastern Mediterranean region

This study describes the lithostratigraphic character of mid-Cenozoic (Oligocene–Pliocene) sequences in different parts of the northeastern Mediterranean area and offers a detailed stratigraphic correlation for this region. The sequences concerned are drawn from the Camardi area (south–central Anatolia), the Adana Basin, the Misis Mountains and the Kyrenia Range (northern Cyprus) and the submerged Florence Rise (west of Cyprus). The stratigraphic relationships identified here indicate the following: (a) Following the middle Eocene (Lutetian) regression there was uplift throughout the entire region; (b) Episodes of fluvial and lacustrine deposition in intramontane settings ensued in most of this region during the late Eocene/early Miocene interval; (c) Following a regionally extensive phase of tectonic compression, major marine transgression commenced in the late Oligocene in northern Cyprus and in the early Miocene in adjacent southern Turkey, with the exception of the Ecemis Fault Zone where continental deposition continued; (d) These Oligo-Miocene transgressive sequences comprise a broadly diachronous complex of both shallow and deeper marine facies, including reefal carbonates, littoral clastics, basinal shales and fan-turbidites; (e) Deeper marine Miocene facies persisted longer in the Misis area and in northern Cyprus; (f) A regional regression occurred throughout most of the area during the late Serravallian to Tortonian interval and is marked by the abrupt, locally discordant appearance of extensive shallow marine, deltaic and fluvial deposits; (g) Continued regression in the Messinian led to the formation of significant evaporite deposits in the western and southern parts of the region, but localized uplift of the Misis area is attested by the initial deformation of the Neogene rocks there and the absence of Messinian sediments from this area; (h) In the Pliocene there was extensive emergence of the northern parts of the region interrupted by brief marine incursions. The present-day drainage pattern was established at this time; (i) Marine conditions persisted longer in northern Cyprus, where emergence occurred only in the latest Pliocene.     

An experimental set up of a PAH vapour generator and its use to test an annular denuder

The aim of this work is to develop and test a dynamic gas generator for semi-volatile organic compounds (SVOC). A single compound, naphthalene, is used as a surrogate PAH to test the system. The dynamic generation of PAH is based on the permeation technique [Analyst 106 (1981) 817; Am. Ind. Hyg. Assoc. J. 38 (1977) 712]. Monitoring the temperature and measuring the mass of PAH present in the permeation chamber every 48 h gives a direct measurement of the sublimation rate of the PAH. Knowing the flow rate, gives an accurate value of the concentration of PAH from the generator. It was found stable over a period of time under constant operating conditions. This concentration is diluted down to between 0.3 and 30 ppbv by a controlled flow of pure air. The diluting airflow is a mixture of dry and wet air, making it possible to control the relative humidity of the flow from the generator as well as its concentration in PAH. We used this generator to calibrate an annular denuder tube, based on the study by Gundel et al. [Atmos. Environ. 29 (1995) 1719]. Although this technique has been shown to be artefact-free for sampling gaseous PAH [Polycyclic Aromatic Compounds 9 (1996) 67; Atmos. Environ. 28 (1994) 3083], its trapping efficiency still depends on environmental parameters (temperature, relative humidity and sampling duration). Accordingly, we used our generator to calibrate a single annular denuder under controlled conditions (T degrees C, HR%, CPAH, sampling duration). The trapping efficiency of the denuder was calculated by two independent methods. Firstly, by comparing the amount trapped on a denuder with the measured mass sublimated in the generator. Secondly, by putting two denuders in series and comparing the mass collected on the first and the second tube. These two methods gave similar results, within the 10% relative uncertainties of both methods. The first results obtained show that, in environmental conditions, the efficiency ranges between 90 and 100%.     

Detection of Cryptosporidium parvum oocysts in sediment and biosolids by immunomagnetic separation.

A method for the detection of Cryptosporidium parvum oocysts in sediment and wastewater biosolids has been developed using immunomagnetic separation kits that were designed for use with water. This method requires no pretreatment of the sediment or biosolids samples before the commercial kit application. Oocyst recovery efficiencies from sediment and biosolids using the modified Dynal (Lake Success, New York) and Crypto-Scan commercial methods (Immucell Corporation, Portland, Maine) ranged from 20 to 60%. While the sensitivity of the method is dependent on the amount of sediment processed and the equivalent volume examined under the microscope, it was able to detect 0.48 oocysts per gram dry weight sediment. Using this method, Cryptosporidium parvum oocysts were found at levels as high as 97 oocysts/g of primary biosolids and at levels up to 4 oocysts/g in polluted sediment.