United States Environmental Protection Agency

About: United States Environmental Protection Agency is a government organization based out in Washington D.C., District of Columbia, United States. It is known for research contribution in the topics: Population & Environmental exposure. The organization has 13873 authors who have published 26902 publications receiving 1191729 citations. The organization is also known as: EPA & Environmental Protection Agency.

Mixing models in analyses of diet using multiple stable isotopes: a critique

Abstract: Stable isotope analysis is used frequently to determine the relative contributions of different food sources to an animal’s diet (Hobson 1999). Isotopic ratios for the animal tissues and each of its potential food sources are determined. The similarity of the ratios for the animal tissues with those of individual food sources (after correcting for fractionation during digestion and assimilation) gives an idea of their relative importance in the diet; in other words “you are what you eat” (DeNiro and Epstein 1978). Two food sources can be partitioned using the isotopic ratio for a single element (e.g., δ13C), or three food sources can be partitioned using isotopic ratios for two elements (e.g., δ13C and δ15N) (Kwak and Zedler 1997). A number of recent papers have used geometric procedures to quantify the contributions of three food sources to the diet using δ13C and δ15N (Ben-David et al. 1997a, 1997b; Kline et al. 1993; Szepanski et al. 1999; Whitledge and Rabeni 1997). However, these methods do not provide correct solutions to this three-endmember mixing problem. The purpose of this paper is to point out the shortcomings of these methods and to propose an alternative procedure which avoids them. Figure 1 shows a graphical representation of the analytical situation. The dietary isotopic composition is represented by point D within the triangle bounded by the points for the adjusted food source isotopic compositions A′, B′, and C′. In the geometric procedures, Euclidean distances are calculated for line segments DA′, DB′, and DC′ and are used to compute the dietary contributions. Several variations of this calculation have been utilized. Kline et al. (1993) used the following equation:

Characterization of the dust/smoke aerosol that settled east of the World Trade Center (WTC) in lower Manhattan after the collapse of the WTC 11 September 2001.

Abstract: The explosion and collapse of the World Trade Center (WTC) was a catastrophic event that produced an aerosol plume impacting many workers, residents, and commuters during the first few days after 11 September 2001. Three bulk samples of the total settled dust and smoke were collected at weather-protected locations east of the WTC on 16 and 17 September 2001; these samples are representative of the generated material that settled immediately after the explosion and fire and the concurrent collapse of the two structures. We analyzed each sample, not differentiated by particle size, for inorganic and organic composition. In the inorganic analyses, we identified metals, radionuclides, ionic species, asbestos, and inorganic species. In the organic analyses, we identified polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, polychlorinated dibenzodioxins, polychlorinated dibenzofurans, pesticides, phthalate esters, brominated diphenyl ethers, and other hydrocarbons. Each sample had a basic pH. Asbestos levels ranged from 0.8% to 3.0% of the mass, the PAHs were > 0.1% of the mass, and lead ranged from 101 to 625 microg/g. The content and distribution of material was indicative of a complex mixture of building debris and combustion products in the resulting plume. These three samples were composed primarily of construction materials, soot, paint (leaded and unleaded), and glass fibers (mineral wool and fiberglass). Levels of hydrocarbons indicated unburned or partially burned jet fuel, plastic, cellulose, and other materials that were ignited by the fire. In morphologic analyses we found that a majority of the mass was fibrous and composed of many types of fibers (e.g., mineral wool, fiberglass, asbestos, wood, paper, and cotton). The particles were separated into size classifications by gravimetric and aerodynamic methods. Material 53 microm in diameter. The results obtained from these samples can be used to understand the contact and types of exposures to this unprecedented complex mixture experienced by the surviving residents, commuters, and rescue workers directly affected by the plume from 11 to 12 September and the evaluations of any acute or long-term health effects from resuspendable dust and smoke to the residents, commuters, and local workers, as well as from the materials released after 11 September until the fires were extinguished. Further, these results support the need to have the interior of residences, buildings, and their respective HVAC systems professionally cleaned to reduce long-term residential risks before rehabitation.

Linking Agricultural Biodiversity and Food Security: the Valuable Role of Agrobiodiversity for Sustainable Agriculture

Abstract: Agricultural biodiversity is critical for food security throughout the world. At the genetic, species, and farming systems levels, biodiversity provides valuable ecosytems services and functions for agricultural production. How can the erosion of agrobiodiversity be halted? How can it effectively be conserved and enhanced? This article highlights key principles, policies, and practices for the sustain-able use, conservation and enhancement of agrobiodiversity for sustaining food security. After clarifying the serious threats from the global loss of agrobiodiversity, the article summarizes practical guidelines and lessons for biodiversity management in farming systems and landscapes. Such strategies build upon valuable local experiences and knowledge in traditional farming practices, and they also take advantage of recent scientific findings in agroecology and ecosystem health. There is an urgent need to adopt an agroecosytems approach, beyond a focus on genetic resource conservation alone, to implement other biodiversity-enhancing methods in farms, such as integrated ecological pest and soil management. Conflicting agricultural politics that promote monocultural industrial farming models and uniform technology packages need to be eliminated. In addition, the protection of intellectual property rights is vital for those who have knowledge of the values and uses of such biodiversity, particularly for indigenous peoples and small farmers. The approaches reviewed in this analysis show effective ways to conserve, use and enhance biodiversity that will encourage sustainable food security.