Stable lead isotope profiles in smelter and general urban communities: a comparison of environmental and blood measures

High-precision lead isotope ratios and lead concentrations have been compared statistically and graphically in women of child-bearing age (n = 77) from two smelter communities and one general urban community to evaluate the relative contributions to blood lead of tissue lead stores and lead from the contemporaneous environment (soil, floor dust, indoor airborne dust, water, food). Blood lead (PbB) contents were generally low (e.g. <10 g dL^–1). Statistically significant isotopic differences in blood and environmental samples were observed between the three cities although isotopic differences in blood for individual subjects living in close proximity (200 m radius) was as large as the differences within a city. No single environmental measure dominated the biological isotope profile and in many cases the low levels of blood lead meant that their isotopic profiles could be easily perturbed by relatively small changes of environmental exposure. Apportioning of sources using lead isotopes is possibly not feasible, nor cost effective, when blood lead levels are <5 g dL^–1. Interpretations based on statistical analyses of city-wide data do not give the same conclusions as when the houses are considered individually. Aggregating data from multiple subjects in a study such as this obscures potentially useful information. Most of the measures employed in this study, and many other similar studies, are markers of only short-to-medium integration of lead exposure. Serial sampling of blood and longer sampling times, especially for household variables, should provide more meaningful information.     

Assessment of patch quality by ladybirds: relative response to conspecific and heterospecific larval tracks a consequence of habitat similarity?

Summary. Aphid colonies can reach high levels of abundance but last for short periods of time. The larvae of aphidophagous ladybirds (Coleoptera: Coccinellidae) that feed on these colonies might therefore suffer from starvation, which favours the occurrence of cannibalism and intraguild predation. Thus, the assessment of patch quality becomes crucial and it has been shown that female ladybirds refrain from laying eggs in the presence of an oviposition deterring semiochemical deposited by their larvae. Adalia bipunctata (L.), Adalia decempunctata (L.) and Coccinella septempunctata L. are 3 sympatric species of ladybirds, which can co-occur in aphid colonies. As a consequence, their eggs and larvae are under threat, not only from cannibalism but also intraguild predation. Females should, therefore, also use the tracks deposited by heterospecific larvae to assess the quality of aphid colonies as oviposition sites. The expectation is that: 1- the strength of the reaction to each other’s larval tracks should be correlated with percentage habitat overlap and that 2- the reaction to conspecific larval tracks should be stronger than to heterospecific tracks. In order to test these hypotheses, females’ oviposition behaviour was analysed and a chemical analysis of the tracks of their larvae undertaken. The results show that oviposition behaviour is not related to habitat overlap. Both species of Adalia react to tracks of their own larvae and those of C. septempunctata, but A. decempunctata reacted more strongly than A. bipunctata. C. septempunctata reacted very slightly to its own tracks but not to those of either species of Adalia. The larval tracks are mainly composed of alkanes. Those of the two species of Adalia are qualitatively 100% similar and 60% so when the quantitative results are compared. They are, however, only 24–29% similar to those of Coccinella septempunctata.     

Behaviour and physiology of sockeye salmon homing through coastal waters to a natal river

Adult sockeye salmon (Oncorhynchus nerka, N = 179) from six Fraser River populations (British Columbia) were intercepted in continental shelf waters ∼215 km from the Fraser River mouth, gastrically implanted with acoustic transmitters, non-lethally biopsied for blood biochemistry, gill Na⁺,K⁺-ATPase activity and somatic energy density and then released. Migration behaviour and travel times to the river mouth and into the river were monitored by underwater telemetry receivers positioned at the river mouth and in the river. Post-release survival of salmon was excellent, with 84% (N = 150) of fish reaching the furthest receiving station ∼85 km upriver. Fish from Late-summer run populations (Adams and Weaver Creek) averaged a migration rate of ∼20 km day⁻¹ through the marine area and held at the river mouth and adjacent areas for 7–9 days before entering the river. Summer-run populations (Birkenhead, Chilko, Horsefly and Stellako) had a migration rate ∼33 km day⁻¹ and held for only 1–3 days. Once in river, similar patterns were observed: Late-run populations migrated at ∼28 km day⁻¹ and Summer-run populations at ∼40 km day⁻¹. From point of release to the river mouth, males migrated faster than females, but once in river migration rates did not differ between sexes. Among all females, a correlation was discovered between levels of circulating testosterone and river entry timing. This correlation was not observed among males. Plasma K⁺, Cl⁻, glucose, lactate and osmolality were also correlated with entry timing in both sexes.     

用Autospec-Ultima NT气相色谱-高分辨质谱分析二噁英及相关的持久性有机污染物

"二噁英"是指一类化学结构和生物特征均有某些相似之处的化合物.这些有毒化合物有几百种,可分为相关的三大类:氯代二苯并-对-二噁英(CDDs),氯代二苯并呋喃(CDFs)和某些多氯代联苯(PCBs).CDDs和CDFs并非与生具有,而是由于人类活动不注意而生成的.天然过程也会产生CDDs和CDFs.     

Ancillary benefits of reduced air pollution in the US from moderate greenhouse gas mitigation policies in the electricity sector

Actions to slow atmospheric accumulation of greenhouse gases also would reduce conventional air pollutants yielding “ancillary” benefits that tend to accrue locally and in the near-term. Using a detailed electricity model linked to an integrated assessment framework to value changes in human health, we find a tax of $25 per metric ton of carbon emissions would yield NO_x-related health benefits of about $8 per metric ton of carbon reduced in the year 2010 (1997 dollars). Additional savings of $4–$7 accrue from reduced investment in NO_x and SO₂ abatement in order to comply with emission caps. Total ancillary benefits of a $25 carbon tax are $12–$14, which appear to justify the costs of a $25 tax, although marginal benefits are less than marginal costs. At a tax of $75, greater total benefits are achieved but the value per ton of carbon reductions remains roughly constant at about $12.     

Subsistence over symbolism: the role of transnational municipal networks on cities’ climate policy innovation and adoption

Urban areas account for the majority of global greenhouse gas emissions, and increasingly, it is city governments that are adopting and implementing climate mitigation policies. Many municipal governments have joined two different global city networks that aim to promote climate policy development at the urban scale, and there is qualitative evidence that such networks play an important role in motivating cities to adopt climate policies and helping them to implement them. Our study objective is to test this proposition quantitatively, making use of a global database on cities’ environmental policy adoption, and also taking into account a large number of other factors that could play a role in climate policy adoption. Controlling for these other factors, we find that network membership does make a significant difference in the number of different measures that city governments adopt. We also find that there are significant differences between the two different networks, suggesting that the nature of the services that such networks offer their members can play an important role. Our findings lead to the provision of a set of global mitigation strategies: First of all, joining the city networks can lead to a generation of global strategies which can result into climate mitigation benefits. However, cities are required to select the network which provides proper tailor made policies. Second, in the absence of concrete international commitments at the local level, city networks lay the ground for global governance and enable cities to adopt policies independently and proactively. Third, consideration of co-benefits of climate policies can optimize the development of global strategies.     

Nutrient compensatory foraging in a free-living social insect

The geometric framework model predicts that animal foraging decisions are influenced by their dietary history, with animals targeting a combination of essential nutrients through compensatory foraging. We provide experimental confirmation of nutrient-specific compensatory foraging in a natural, free-living population of social insects by supplementing their diet with sources of protein- or carbohydrate-rich food. Colonies of the ant Iridomyrmex suchieri were provided with feeders containing food rich in either carbohydrate or protein for 6 days, and were then provided with a feeder containing the same or different diet. The patterns of recruitment were consistent with the geometric framework: while feeders with a carbohydrate diet typically attracted more workers than did feeders with protein diet, the difference in recruitment between the two nutrients was smaller if the colonies had had prior access to carbohydrate than protein. Further, fewer ants visited feeders if the colony had had prior access to protein than to carbohydrates, suggesting that the larvae play a role in worker foraging behaviour.     

Making index insurance attractive to farmers

There are several factors that influence whether people will want to participate in index insurance programs. A number of these influence their attractiveness on economic grounds, including both the size and timing of the premium and potential payouts, and the degree of risk aversion of the potential customers. Other factors make programs attractive for reasons that are not economic, but no less valid. These have to do with the trust that people have in the insurance product and the organizations involved in selling and managing it. Indeed, data from India, Africa, and South America show that these factors may be more important than the economic ones in influencing demand. Index insurance pilot projects, in order to estimate demand for alternative products, have typically involved a great deal of interaction with potential customers. It is important to recognize that such interaction is crucial not just as a research tool, but also as a means to build understanding and trust in the products. When scaling up from isolated pilots to operational programs, it is vital to recognize this trust building function by replicating participation efforts in every community. In this paper, we examine the role of field games in establishing and building trust in three important aspects of these projects for participants: trust in the insurance product, trust in the participating organizations, and trust in their own ability to make good decisions. While games have previously been used as a way to gauge interest in the product and to identify design features, we argue that these games are also valuable tools for constructing these kinds of trust.     

Climate and Land Use Effects on Hydrologic Processes in a Primarily Rain‐Fed,Agricultural Watershed

Anticipating changes in hydrologic variables is essential for making socioeconomic water resource decisions. This study aims to assess the potential impact of land use and climate change on the hydrologic processes of a primarily rain‐fed, agriculturally based watershed in Missouri. A detailed evaluation was performed using the Soil and Water Assessment Tool for the near future (2020–2039) and mid‐century (2040–2059). Land use scenarios were mapped using the Conversion of Land Use and its Effects model. Ensemble results, based on 19 climate models, indicated a temperature increase of about 1.0°C in near future and 2.0°C in mid‐century. Combined climate and land use change scenarios showed distinct annual and seasonal hydrologic variations. Annual precipitation was projected to increase from 6% to 7%, which resulted in 14% more spring days with soil water content equal to or exceeding field capacity in mid‐century. However, summer precipitation was projected to decrease, a critical factor for crop growth. Higher temperatures led to increased potential evapotranspiration during the growing season. Combined with changes in precipitation patterns, this resulted in an increased need for irrigation by 38 mm representing a 10% increase in total irrigation water use. Analysis from multiple land use scenarios indicated converting agriculture to forest land can potentially mitigate the effects of climate change on streamflow, thus ensuring future water availability.