Polychlorierte Naphthaline

Measurements show that PCN may occur in industrial waste and residues in the mg/kg range. Investigations were carried out with optimized parameters for GC and MS using two different GC/MS-systems. Chromatograms were obtained for a variety of chlorination degrees using capillary columns of different polarities. It is proposed to quantify PCN using relevant single compounds comparable to the analysis of polychlorinated biphenyls.     

Seasonal differences in citrate synthase and digestive enzyme activity in larval and postlarval antarctic krill, Euphausia superba

Antarctic krill maintain large population sizes despite dramatic seasonal fluctuations in food availability, but the mechanisms for this are still debated. The aim of this study was to compare seasonal differences in enzyme activity and respiration rates of larval and postlarval krill to provide insights into their overwintering strategies. Respiration rates, activity of the metabolic enzyme citrate synthase (CS), and those of the digestive enzymes laminarinase and total proteinase were measured in austral summer west of the Antarctic Peninsula, and in autumn in the southwestern Lazarev Sea. The 100-fold difference in chlorophyll a concentrations between the two studies is representative of the classic transition from a summer bloom to sparse winter conditions. Correspondingly, adult krill showed reduced respiration rates and CS activity in autumn. However, their digestive enzyme activity was significantly higher, suggesting more efficient assimilation of food at low food levels. Similar-sized larvae showed no summer-autumn differences in respiration rates and enzyme activity, supporting suggestions that they need to feed and grow year-round. However, trends in enzymatic activity varied between the larval stages measured, implying ontogenetic changes in body structure and function. Published online: 1 August 2002     

Genetic monogamy in the common loon (Gavia immer)

We conducted behavioral observations and genetic analysis on breeding pairs of common loons in the upper Great Lakes region from 1993 through 1995 to look for behavioral evidence of extrapair copulations (EPCs) and to determine parentage of young. Pairs remained close to each other (usually within 20 m) during the pre-laying period, leaving little opportunity for EPCs to occur. Males and females both maintained physical proximity by approaching each other when they became separated. Copulations were obvious but infrequent, occurring about once every other day during the pre-laying period. Multilocus DNA fingerprinting was consistent with behavioral findings: 58 young from 47 different families were all genetic offspring of parents that raised them. Perfect genetic monogamy (genetic parentage of young by parents that rear them) in loons might arise as a consequence of the need for vigorous territorial defense to prevent territorial takeover. Received: 8 August 1996 / Accepted after revision: 22 March 1997     

A non-motorized dye ejector for visualization of flow in situ and its use with coral reef crinoids

We describe a portable, non-motorized device for delivering a tracer dye into seawater under field conditions. Dye is ejected at a constant flow rate over a period of tens of minutes. The ejector works in a wide range of ambient pressures without external energy requirements. The flow rate is adjusted simply by varying the length of the delivery tube. The dye streams permitted observations of the upcurrent and downcurrent flow regimes for a filter-feeding crinoid (Comanthus bennetti) living at a depth of 8 m on a coral reef. The results indicate that the crinoid may enhance the rate of particle capture by changing the scale of turbulence in the water passing through the mesh of the filtration fan.     

Possibilities for improving nitrogen use from organic materials in agricultural cropping systems

Nitrogen release from organic nutrient sources in soil is influenced by a range of factors such as soil temperature and moisture, and chemical composition of the organic material. Chemical composition can, to a certain degree, be controlled to increase the synchronization of nitrogen (N) release with plant N demand, whereas climatic factors cannot be controlled and so must be taken into account when planning management measures. In this paper, we discuss different ways to affect N release through manipulation of the chemical composition of fresh or pretreated plant materials and animal manures, timing of incorporation, and intentional distribution during application. We conclude by giving an overview of off-farm options that may need to be implemented to achieve improved use of N, especially in agricultural systems with surplus N.     

Comparison of a novel passive sampler to standard water-column sampling for organic contaminants associated with wastewater effluents entering a New Jersey stream

Four water samples collected using standard depth and width water-column sampling methodology were compared to an innovative passive, in situ, sampler (the polar organic chemical integrative sampler or POCIS) for the detection of 96 organic wastewater-related contaminants (OWCs) in a stream that receives agricultural, municipal, and industrial wastewaters. Thirty-two OWCs were identified in POCIS extracts whereas 9-24 were identified in individual water-column samples demonstrating the utility of POCIS for identifying contaminants whose occurrence are transient or whose concentrations are below routine analytical detection limits. Overall, 10 OWCs were identified exclusively in the POCIS extracts and only six solely identified in the water-column samples, however, repetitive water samples taken using the standard method during the POCIS deployment period required multiple trips to the sampling site and an increased number of samples to store, process, and analyze. Due to the greater number of OWCs detected in the POCIS extracts as compared to individual water-column samples, the ease of performing a single deployment as compared to collecting and processing multiple water samples, the greater mass of chemical residues sequestered, and the ability to detect chemicals which dissipate quickly, the passive sampling technique offers an efficient and effective alternative for detecting OWCs in our waterways for wastewater contaminants.     

Development of a sample equilibration system for the TEOM continuous PM monitor

In recent years, scientific discussion has included the influence of thermodynamic conditions (e.g., temperature, relative humidity, and filter face velocity) on PM retention efficiency of filter-based samplers and monitors. Method-associated thermodynamic conditions can, in some instances, dramatically influence the presence of particle-bound water and other light-molecular-weight chemical components such as particulate nitrates and certain organic compounds. The measurement of fine particle mass presents a new challenge for all PM measurement methods, since a relatively greater fraction of the mass is semi-volatile. The tapered element oscillating microbalance (TEOM) continuous PM monitor is a U.S. Environmental Protection Agency (EPA) PM10 equivalent method (EQPM-1090079). Several hundred of these monitors are deployed throughout the United States. The TEOM monitor has the unique characteristic of providing direct PM mass measurement without the calibration uncertainty inherent in mass surrogate methods. In addition, it provides high-precision, near-real-time continuous data automatically. Much attention has been given to semi-volatile species retention of the TEOM method.     

Analysis of 2,3,7,8-Tetrachlorodibenzo-p-dioxin in Great Lakes fish

In fish samples from Lake Ontario and Lake Huron 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was found at concentrations from 2 to 162 pg/g (ppt) and from 2.5 to 29 ppt respectively. Fish from the other Great Lakes (Lake Superior, Lake Michigan and Lake Erie) generally had no detectable signals for TCDD although a few samples had < 3 ppt.