Livestock Hormones in the Environment

Livestock manure may contain both endogenous and synthetic steroid hormones. The latter are used as growth hormones in livestock. This presentation reviews hormone use in livestock, transport, and fate of hormones to the environment, effects of hormones in humans and wildlife, and future research needs. The growth hormones approved for use are trenbolone acetate, zeranol, and melegestrol acetate. Hormones are excreted in the feces or urine and are transported to aquatic environments through run-off of land-applied manure. Sorption and degradation are the primary mechanisms of removal of hormones from the environment. Endogenous hormones sorb strongly to soils and degrade quickly under aerobic conditions, while synthetic growth hormones are persistent in the environment. Both types of hormones are extremely potent and may cause adverse reproductive effects at concentrations less than 10 ng/L. Future research emphasis should include the effects of sediments on aquatic species and the occurrence of growth hormones and testosterone in the environment and meat products

Nutrient Flux, Uptake, and Transformation in a Spring-fed Stream in the Missouri Ozarks, USA

We examined nutrient flux, uptake, and transformation along a spring-fed stream in the Ozark region of Missouri, USA, over the year 2006. Water in Mill Creek originates from several springs, with a single spring contributing over 90% of the stream discharge during much of the year of study. Soluble reactive phosphate concentrations were usually low (\u3c10 μg L−1) along Mill Creek, but peaked during high discharge. Concentrations of dissolved inorganic nitrogen (DIN) were relatively high in the spring water, mainly as nitrate, but usually declined across a small pond and the 10-km length of Mill Creek. During low flows in summer and early autumn, the stream removed over 300 μg L−1 of DIN over its 10-km length, or about 80% of the initial amount. DIN retention along the stream, as a percentage of the DIN upstream, was related mainly to discharge, with higher flows having much higher DIN concentrations. The net uptake rate of DIN uptake was 0.91 μg m−2 s−1 in the stream during summer baseflow. The uptake rate declined downstream for different reaches and was closely related to DIN concentration. In experimental channels, uptake by epilithic algae was one significant sink for nitrate-N in Mill Creek. In 2006, inorganic nutrient export during a single day after a spring storm was similar to export during 40-100 days of low flow conditions in summer and early autumn. Our results suggest that significant nutrient retention can occur during baseflow periods via biological uptake, whereas substantial export occurs during high flow conditions

Livestock Hormones in Aquatic Ecosystems

We begin this article with a general description of sources of hormones followed by their transport and fate in the environment. We then focus on occurrences and effects of livestock estrogens in aquatic ecosystems. Two case studies from our research are presented in details to contrast levels of estrogens in a concentrated animal farming area in northern Missouri with those in a relatively pristine area in southern Missouri. Estimation of human exposure to estrogenic compounds from various sources would be informative to the general public. Thus, we estimate exposures from environmental estrogens, medicinal estrogens, and dietary phytoestrogens. Estimation of exposure via these three sources was made using 17β-estradiol equivalent concentrations. Finally, we discuss the limited available data on other livestock hormones and then conclude with future research that should be conducted to further understand the impact of livestock hormones on aquatic ecosystems

Overstory community composition and elevated atmospheric CO \u3c inf\u3e 2 and O \u3c inf\u3e 3 modify understory biomass production and nitrogen acquisition

Elevated atmospheric CO2 and O3 have the potential to affect the primary productivity of the forest overstory, but little attention has been given to potential responses of understory vegetation. Our objective was to document the effects of elevated atmospheric CO2 and O 3 on understory species composition and biomass and to quantify nitrogen (N) acquisition by the understory vegetation. The research took place at the aspen free-air CO2 and O3 enrichment (FACE) experiment, which has four treatments (control, elevated CO2, elevated O3, and elevated CO2+O3) and three tree communities: aspen, aspen/birch, and aspen/maple. In June 2003, each FACE ring was uniformly labeled with 15N applied as NH4Cl. Understory biomass was harvested in June of 2004 for productivity, N, and 15N measurements, and photosynthetically active radiation (PAR) was measured below the canopy. The understory was divided into five species groups, which dominate in this young aggrading forest: Taraxacum officinale (dandelion), Solidago sp. (goldenrod), Trifolium repens and T. pretense (clover), various species from the Poaceae family (grass), and composited minor components (CMC). Understory species composition, total and individual species biomass, N content, and 15N recovery showed overstory community effects, but the direct effects of treatments was masked by the high variability of these data. Total understory biomass increased with increasing light, and thus was greatest under the open canopy of the aspen/maple community, as well as the more open canopy of the elevated O3 treatments. Species were different from one another in terms of 15N recovery, with virtually no 15N recovered in clover and the greatest amount recovered in dandelion. Thus, understory species composition and biomass appear to be driven by the structure of the overstory community, which is determined by the tree species present and their response to the treatments. However, N acquisition by the understory does not appear to be affected by either the overstory community or the treatments at this point. © Springer 2006

Occurrence of Organic Chemicals in Two Rivers Inhabited by Ozark Hellbenders (Cryptobranchus Alleganiensis Bishopi)

Ozark Hellbender (Cryptobranchus alleganiensis bishopi) populations are in decrease throughout their native range with rare recruitment of young. Increased estrogenic chemical levels and alterations of physicochemical properties in their habitat may play a significant role in this phenomenon. We report here the first systematic, comprehensive study of organic chemical concentrations and physical and nutrient parameters in two rivers containing Ozark hellbender populations. Water samples were collected monthly from August 2003 to November 2004. Concentrations of 21 organic chemicals were determined using gas chromatography-mass spectrometry. Nine organic chemicals were detected. Benzyl butyl phthalate, dibutyl phthalate, bisphenol A, and β-sitosterol were all detected \u3e 85% of the time, with median concentrations of 18 to 234 ng/L and maximum concentrations of 198 to 4141 ng/L. Individually, concentrations of nutrients and organic chemicals were much lower than those shown previously in laboratory and field experiments to have reproductive effects on amphibians. Nevertheless, hellbenders are exposed to a variety of chemicals with potential estrogenic effects. Our study establishes the basis to examine the specific effects of the detected concentrations, alone and in combination, on the Ozark hellbenders