Analysis of polychlorobiphenyls from used transformers for polychlorodibenzofurans

The results of analyses for polychlorodibenzofuran (PCDF) content in two samples of polychlorobiphenyl (PCB) from used electrical transformers are presented and discussed. In neither sample was there evidence for enhanced PCDF concentrations even though one of them had been subjected to overheating while in service.     

Polychlorodibenzo-p-dioxins and dibenzofurans in technical pentachlorophenol - results of a collaborative analytical exercise

Results of analyses of eight samples of technical pentachlorophenol conducted by three different analytical methods are presented and discussed.     

Vicarious sampling: the use of personal and public information by starlings foraging in a simple patchy environment

Group foragers may be able to assess patch quality more efficiently by paying attention to the sampling activities of conspecifics foraging in the same patch. In a previous field experiment, we showed that starlings foraging on patches of hidden food could use the successful foraging activities of others to help them assess patch quality. In order to determine whether a starling could also use another individual’s lack of foraging success to assess and depart from empty patches more quickly, we carried out two experimental studies which compared the behaviour of captive starlings sampling artificial patches both when alone and when in pairs. Solitary starlings were first trained to assess patch quality in our experimental two-patch system, and were then tested on an empty patch both alone and with two types of partner bird. One partner sampled very few holes and thus provided a low amount of public information; the other sampled numerous holes and thus provided a high amount of public information. In experiment 1, we found no evidence of vicarious sampling. Subjects sampled a similar number of empty holes when alone as when with the low and high information partners; thus they continued to rely on their own personal information to make their patch departure decisions. In experiment 2, we modified the experimental patches, increasing the ease with which a bird could watch another’s sampling activities, and increasing the difficulty of acquiring accurate personal sampling information. This time, subjects apparently did use public information, sampling fewer empty holes before departure when with the high-information partner than when with the low-information partner, and sampling fewer holes when with the low-information partner than when alone. We suggest that the degree to which personal and public information are used is likely to depend both on a forager’s ability to remember where it has already sampled and on the type of environment in which foraging takes place. Received: 31 January 1995/Accepted after revision: 11 September 1995     

Usefulness and uses of climate forecasts for agricultural extension in South Carolina,USA

Farmers and extensionists can use forecasts about agro-climatic conditions to reduce risks of agricultural production. Eighteen extension agents, researchers, consultants, and farmers provided feedback about decision support tools that utilize such forecasts during focus groups that were conducted in Florence, South Carolina on January 14, 2011. Climate Risk and County Yield Database were the tools most selected as potentially useful for agricultural extension in South Carolina. An irrigation scheduler was the most frequently mentioned tool to be developed. Also, a survey of Clemson University’s extension personnel was conducted in January and February 2011 to assess interest of South Carolina’s growers and producers in using climate forecasts, eleven potential uses of climate forecasts by extension’s clientele, and potential usefulness to extensionists of twelve specific forecasts. Clemson’s extensionists represent approximately 97 % of the state’s agricultural extensionists. They are more likely than not to agree that growers and producers are interested in using climate forecasts. Most of the state’s extension personnel also think that farmers could use a climate forecast to improve irrigation management and planting schedules. A majority of the state’s extensionists thinks that a freeze alert could be useful to them and the proportion that thinks the forecast could be useful exceeds the proportion that thinks any other forecast could be useful. Most extensionists also think that a forecast of plant moisture stress could be useful to help farmers schedule irrigation. The key survey results are remarkably similar to those from surveys of extension personnel at North Carolina State University in early 2009 and University of Florida in late 2004.     

Long term changes in polychlorodibenzo-p-dioxin concentrations in wood treated with technical pentachlorophenol

Wood samples treated with technical pentachlorophenol (PCP), technical sodium pentachlorophenoxide (NaPCP) and octachlorodibenzo-p-dioxin have been exposed outdoors for periods up to $\text{2}\text{1}\text{2}$ years. Analysis of extracts from the samples show that photolytic reductive dechlorination of highly chlorinated dibenzo-p-dioxins to less chlorinated isomers occurs. However there is no discernible increase in polychlorodibenzo-p-dioxin concentrations in the technical PCP treated wood presumably because further photolytic reactions and volatilisation compete effectively with the photolytic formation. There is no evidence for formation of octachlorodibenzo-p-dioxin (OCDD) in technical PCP treated wood in this study, probably because photolytic destruction and volatilisation compete effectively with formation reactions when the initial OCDD concentration is relatively high.     

Formation of nitrogenous disinfection by-products from pre-chloramination

A sampling survey investigated the formation of nitrogenous disinfection by-products (N-DBPs) and carbonaceous DBPs (C-DBPs) from pre-chloramination, an increasingly common treatment strategy in China for regulated C-DBP control, followed by subsequent conventional water treatment processes, i.e., coagulation, sedimentation, and filtration. Dihalogenated N-DBPs typically peaked in the summer and early autumn with a relatively higher temperature, with the maximum levels of dichloroacetamide (DCAcAm), dichloroacetonitrile (DCAN), bromochloroacetonitrile, dibromoacetonitrile and dichloroacetone at 1.8, 6.3, 6.0, 2.6 and 1.8 μg L⁻¹ in the finished water, respectively. Also, the levels of all the dichlorinated N-DBPs were correlated with the ratio of dissolved organic nitrogen (DON) to dissolved organic carbon, implying autochthonous DON played an essential role in the formation of these DBPs. In contrast, the yields of trihalogenated DBPs [chloroform (CF), trichloronitromethane (TCNM) and trichloroacetone (TCAce)] appeared not to be significantly affected by seasons. CF and DCAN were the dominant species in trihalomethanes (THMs) and dihaloacetonitriles (DHANs), respectively. Bromine was more readily incorporated into DHANs to form brominated DBPs than THMs during pre-chloramination. Although pre-chloramination can ensure the finished water to meet with the current Chinese THM regulatory limits, the increased levels of TCNM and TCAce may be a new water quality concern.