Statewide Survey of Hormones and Antibiotics in Surface Waters of Delaware

Water‐quality surveys have confirmed the presence of hormones and antibiotics in surface waters of the United States, which may be of concern to aquatic life. We investigated the concentrations of hormones and antibiotics in surface waters of the state of Delaware to determine – how they compared against environmental thresholds, how they varied across the state, and if they were correlated with land use type. Fifty surface water locations were sampled during early spring and late summer. Water samples were initially screened with ELISA followed by analysis with LC/MS/MS. The measured ranges of hormone concentrations were: 0‐3.71 ng/l for estrone, 0‐4.65 ng/l for estrone‐3‐sulfate, and 0‐6.27 ng/l for 17β‐estradiol. The measured ranges of antibiotics were: 0‐3.30 ng/l for sulfamerazine, 0‐10.74 ng/l for sulfamethoxazole, and 0‐2.29 ng/l for tetracycline. The predicted no‐effect concentration (PNEC) for estrone was exceeded for three samples and the PNEC for 17β‐estradiol was exceeded for 11 samples. In general, concentrations and detection frequencies were lower in the summer than the spring. The highest concentrations of hormones and antibiotics were spatially distributed in agricultural and urban areas; however, the correlations between land use type and the concentrations were weak. This study was the first statewide survey of hormones and antibiotics for Delaware and provided important baseline data on these emerging contaminants.     

Selection of a suitable mobile phase for the speciation of four arsenic compounds in drinking water samples using ion-exchange chromatography coupled to inductively coupled plasma mass spectrometry

The performance of two mobile phase buffers, phosphate and TRIS, were compared for the speciation of four arsenic species: arsenate (As(V)), arsenite (As(III)), mono methylarsonic acid (MMA), and dimethyl arsinic acid (DMA) in drinking water, using ion-exchange chromatography inductivelycoupled plasma mass spectrometry (IEC-ICP-MS). The mobile phase containing TRIS acetate buffer ("TRIS") demonstrated superior perfomance in baseline separation of all four arsenic species and the internal standard. It is also applicable to high-throughput sample analysis as it minimized the frequency required to clean the sampling interface due to salt build-up when compared to the phosphate mobile phase. The method was evaluated for its precision, accuracy, linearity and detection limits. The method was successfully applied for the analysis of drinking water samples.     

Development of Indicators to Assess Economic Vulnerabilities to Changes in Ecosystem Services: Case Study of Counties in Maryland,USA

We develop indicators showing the relative environmental burdens that human activities place on locales for a given level of economic benefits. The main purpose is to develop tools that allow us to examine the potential vulnerabilities within economies to changes in resource conditions. The indicators of pollution emission or resource consumption per job can be used to identify potential challenges to resource and industry managers and to compare areas in terms of their ability to adapt to change. For example, if a large number of area jobs are dependent on abundant water, this indicates a vulnerability to a reduction in water availability for industrial use. We develop a case study for 23 counties and 1 city in Maryland to examine the usefulness and limitations of the indicators. Our case study demonstrates that the indicators provide an informative view into patterns of local economic activity and use of an area’s environmental goods and services. In contrast to patterns for total environmental burdens (e.g., total SO₂ emissions) that are typically reported, the rates of environmental burden per job are not simply correlated with high or low economic output. Thus, the indicators represent distinct patterns of environmental burdens per job that reflect reliance on environmental services. The indicators have some limitations when used at this fine scale because they can misrepresent conditions in counties in which economic sectors are dominated by one or a few businesses. For this reason, the indicators are best used as a regional screening tool.     

Are methylmercury concentrations in the wetlands of Kejimkujik National Park, Nova Scotia, Canada, dependent on geology?

In the relatively pristine ecosystem in Kejimkujik Park, Nova Scotia, methylmercury (MeHg) concentrations in loons, Gavia immer, are among the highest recorded anywhere in the world. This study investigated the influence of bedrock lithology on MeHg concentrations in wetlands. Twenty-five different wetland field sites were sampled over four different bedrock lithologies; Kejimkujik monzogranite, black sulfidic slate, gray slate, and greywacke. Soil samples were analyzed for ethylmercury (EtHg), MeHg, total Hg, acid-volatile sulfides (AVS), organic matter, and water content as well as the biological parameters, mercury methyltransferase (HgMT) activity, sulfate reduction rates, fatty acid methyl ester (FAME) composition, and acidity. Methylmercury concentrations in the wetlands were highly dependent (P < 0.08) on lithology with no significant difference between bogs, fens, and swamps. Methylmercury concentrations in wetland soils developed on Kejimkujik monzogranite averaged 900 ng kg(-1) compared with only 300 ng kg(-1) in wetland soils developed on black sulfidic slate. Fatty acid methyl ester composition was also lithologically dependent (P < 0.001) with biomarkers for Desulfobulbus spp. discriminating between sites containing high and low MeHg concentrations. Levels of MeHg in wetlands were predicted mainly (41% of the sum of squares) by HgMT activity that differed (P < 0.009) between wetlands, with activity in bogs almost three times that present in swamps. Wetland MeHg concentrations are highly dependent on the lithology on which they have developed for largely biological reasons.     

A Method for Constructing a Social Vulnerability Index: An Application to Hurricane Storm Surges in a Developed Country

An important goal of vulnerability assessment is to create an index of overall vulnerability from a suite of indicators. Constructing a vulnerability index raises several problems in the aggregation of these indicators, including the decision of assigning weights to them. The purpose of this paper is to demonstrate a method of aggregating vulnerability indicators that results in a composite index of vulnerability, but that avoids the problems associated with assigning weights. The investigators apply a technique based on Pareto ranking to a complex, developed socioeconomic landscape exposed to storm surges associated with hurricanes. Indicators of social vulnerability to this hazard are developed and a principal components analysis is performed on proxies for these indicators. Overall social vulnerability is calculated by applying Pareto ranking to these principal components. The paper concludes that it is possible to construct an effective index of vulnerability without weighting the individual vulnerability indicators.     

Prenatal diagnosis of fragile X syndrome: Management of the male fetus with a premutation

Direct detection of the fragile X mutation by DNA analysis has greatly simplified prenatal diagnosis of this disease. However, women carrying a fragile X premutation may pass their expanded trinucleotide repeat to sons without expansion to a full mutation. Such sons are predicted to be intellectually normal. In this situation, the accuracy with which the fetal status can be inferred from analysis of chorionic villus sample (CVS) DNA is unclear. We describe such a case, in which it was felt necessary to proceed to fetal blood sampling despite technically unambiguous DNA results from the CVS. The lack of prospective data means that this dilemma may be expected to recur over the next few years when performing prenatal diagnosis on fragile X premutation carriers.     

Experimentally induced polygyny in a monogamous bird species: prothonotary warblers and the polygyny threshold

Summary Hypotheses regarding evolution of polygyny were tested using prothonotary warblers (Protonotaria citrea), through experimental manipulations of habitat quality. Two experiments were performed. Experiment 1 involved supplying nest boxes in different breeding habitats: flooded riparian areas (high food availability) and adjacent dry bottomland (low food availability). Nine bigamous matings were induced in this experiment, all occurring in flooded habitats even though monogamous mating opportunities existed in dry areas. Costs of polygyny for secondary females in flooded habitat were similar to costs incurred by monogamous females in dry habitat. Thus, a polygyny threshold apparently existed, possibly based on differences in food abundance in the two habitats. However, male quality covaried with habitat quality, as males in flooded areas were older and larger than males in dry habitat. Secondary females may have chosen polygyny in the best breeding situation, a combination of male and territory quality. In Experiment 2 nest box density was varied within flooded habitat to allow males to monopolize different numbers of nest-sites. Monogamous females settled earlier on territories with a large number of nest-sites, and males that defended many nest-sites were more likely to become polygynous. Male physical characteristics were not related to occurrence of polygyny in flooded habitat. Limitation of suitable nest-holes ultimately constrains occurrence of polygyny in prothonotary warblers.