Dietary strategies for reduced phosphorus excretion and improved water quality

Cost effective feeding strategies are essential to deal with P surpluses associated with intensive animal agriculture and the consequent impact on water quality. Reduction of P overfeeding, use of feed additives to enhance dietary P utilization, and development of high available phosphorus (HAP) grains have all been shown to decrease fecal P excretion without impairing animal performance. Much progress has been made, but more research will be needed to refine these strategies to maximize reductions in P excretion while maintaining animal performance. Recent research has focused on the impact of modifying dietary P on the forms of P excreted and the mobility of P in soils amended with these manures, with strong treatment trends becoming evident in the literature. In general, dietary strategies have been developed that can effectively reduce the total P concentration in manures produced, and combining strategies usually leads to greater reductions than individual practices. However, the impact of different approaches on the solubility of P in manures and amended soils has been more variable. Soluble P remains of particular concern due to links between solubility of P in manure and P losses from manure-amended soils. In this paper, we outline the major strategies for reducing dietary P in different species, review the literature on the impact of these approaches on P forms in manures and amended soils, and discuss the potential beneficial effects on animal agriculture and the environment.     

Commentary: assessment of past infiltration fluxes through Yucca Mountain on the basis of the secondary mineral record-is it a viable methodology?

Two papers recently published in the Journal of Contaminant Hydrology by Marshall et al. [Marshall, B.D., Neymark, L.A., Peterman, Z.E., 2003. Estimation of past seepage volumes from calcite distribution in the Topopah Spring Tuff, Yucca Mountain, Nevada. J. Contam. Hydrol. 62-63, 237-247] and Xu et al. [Xu, T., Sonnenthal, E., Bodvarsson, G., 2003. A reaction-transport model for calcite precipitation and evaluation of infiltration fluxes in unsaturated fractured rock. J. Contam. Hydrol. 64, 113-127] attempt to assess past volumes of seepage and infiltration fluxes through the vadose zone of Yucca Mountain, Nevada, on the basis of the modeling of the spatial distribution of secondary calcite. In this commentary, we argue that the employed methodology is not viable. In addition, the thermal boundary conditions used in simulations do not correspond to the temperatures of the mineral forming fluids established on the basis of the fluid inclusion studies.     

Methodological scheme for designing the monitoring of genetically modified crops at the regional scale

According to EC regulations the deliberate release of genetically modified (GM) crops into the agro-environment needs to be accompanied by environmental monitoring to detect potential adverse effects, e.g.unacceptable levels of gene flow from GM to non-GM crops, or adverse effects on single species or species groups thus reducing biodiversity. There is, however, considerable scientific and public debate on how GM crops should be monitored with sufficient accuracy, discussing questions of potential adverse effects, agro-environmental variables or indicators to be monitored and respective detection methods; Another basic component, the appropriate number and location of monitoring sites, is hardly considered. Currently, no consistent GM crop monitoring approach combines these components systematically. This study focuses on and integrates spatial agro-environmental aspects at a landscape level in order to design monitoring networks. Based on examples of environmental variables associated with the cropping of Bt-Maize (Zea maize L.), herbicide-tolerant (HT) winter oilseed rape (Brassica napus L.), HT sugar beet (Beta vulgaris L.), and starch-modified potato (Solanum tuberosum L.), we develop a transferable framework and assessment scheme that comprises anticipated adverse environmental effects, variables to be measured and monitoring methods.These we integrate with a rule-based GIS (geographic information system) analysis, applying widely available spatial area and point information from existing environmental networks. This is used todevelop scenarios with optimised regional GM crop monitoring networks.     

Promotive effect of diethylstilbestrol on urethan-induced mouse lung tumorigenesis

The effect of diethylstilbestrol (DES) on urethan-induced mouse lung tumorigenesis was assessed by a single intraperitoneal injecting of urethan (50 mg/kg) or/and multi intramuscular injecting of DES (5 or 50 mg/kg). All mice were sacrificed 18 weeks after administration, and the lung tumors were examined histopathologically. DES did not produce an elevated lung tumor response when administered alone, but it produced a statistically significant enhancement of incidence of tumors, average number of tumors, incidence of cancers and constituent ratio of malignant tumors when given in conjunction with urethan. The results indicated that DES may be a promoter in lung tumor formation.     

Metal contents of fish from cultureponds near scrap metal reclamation facilities

Milkfish (Chanos chanos) from four fish-culture ponds adjacent to different metal recovery facilities along the Er-Jen River area, Tainan, Taiwan, were sampled to determine their metal contents. Chemical analysis showed that fish tissue contained different concentrations of Cu: 0.71-6.37 micrograms/g, Pb: ND (not detectable) approximately 41.04 micrograms/g, Cd: ND approximately 0.41 microgram/g, Al: 6.75-64.11 micrograms/g, Ni: 0.062-0.504 microgram/g and Zn: 16.11-41.86 micrograms/g. The average concentrations of Cu, Al, Zn, Cd and Pb in fish samples from some of the ponds were significantly higher than those from the reference pond. In addition, there were variations in metal concentrations of fish collected from different ponds. Pond D had the highest mean values of Cu, Cd and Zn, and Pond B of Al and Pb. Further investigations are needed to determine the source of metal contamination in the fish.     

Ecological effects of various toxic agents on the aquatic microcosm in comparison with acute ionizing radiation

The purpose of this study was an evaluation of the effect levels of various toxic agents compared with acute doses of ionizing radiation for the experimental model ecosystem, i.e., microcosm mimicking aquatic microbial communities. For this purpose, the authors used the microcosm consisting of populations of the flagellate alga Euglena gracilis as a producer, the ciliate protozoan Tetrahymena thermophila as a consumer and the bacterium Escherichia coli as a decomposer. Effects of aluminum and copper on the microcosm were investigated in this study, while effects of gamma-rays, ultraviolet radiation, acidification, manganese, nickel and gadolinium were reported in previous studies. The microcosm could detect not only the direct effects of these agents but also the community-level effects due to the interspecies interactions or the interactions between organisms and toxic agents. The authors evaluated doses or concentrations of each toxic agent which had the following effects on the microcosm: (1) no effects; (2) recognizable effects, i.e., decrease or increase in the cell densities of at least one species; (3) severe effects, i.e., extinction of one or two species; and (4) destructive effects, i.e., extinction of all species. The resulting effects data will contribute to an ecological risk assessment of the toxic agents compared with acute doses of ionizing radiation.     

Comparison of the Chemical Composition of Mineral Particles Collected in Dunhuang,China and those Collected in the Free Troposphere over Japan: Possible Chemical Modification during Long-Range Transport

The Asian continent is recognized as one of the most important sources of mineral (or soil) particles. These particles have a large potential to effect global changes through the biogeochemical cycle of particulates and through radiative balance (IPCC Third Assessment Report, 2001). Therefore, comparison of particle compositions near the source region and those after long-range transport is important in understanding the long-range particle transport phenomenon. Individual aerosolparticles were collected in Dunhuang (40°09N; 94°41E), China. Particles were collected at the campus of the Meteorological Bureau of Dunhuang City (17 August 2001) and near the Mogao Grots, located approximately 30 km from Dunhuang (18 August 2001, 18 October 2001 and 13 January 2002) using a two-stage low-volume impactor. The morphology of individual aerosol particles and their elemental compositions were examined via a scanning electron microscope (Hitachi, S-3000N) equipped with an energy dispersive X-ray (EDX) analyzer (Horiba, EMAX-500). The particles collected at these locations were comprised primarily of minerals, with the exception of sulphateparticles in the submicron range that were contained in thesample collected on 18 October 2001 (likely, ammonium sulphate). The most abundant elements were found to be Si and Al. Approximately 46–77% of the collected particles were Si-richparticles (composed primarily of quartz and aluminosilicate),and 13–41% of the collected particles were Ca-rich particles,such as calcite (CaCO₃), dolomite (CaMg(CO₃)₂),and gypsum (CaSO₄2H₂O). The fractions of Fe-rich, Mg-rich, Ti-rich, K-rich, and Cl-rich were 3–10, 0–7, 0–3, 0–1, and 0–1%, respectively. Similar types of mineral particles were found in the free troposphere over Japan(Trochkine et al., 2002). A number of differences were found to exist between the particles collected in China and thosecollected in Japan, and these differences can be explained bychemical modification of the particles during transport fromChina to Japan.     

Effects of sampling,preparation and defecation on metal concentrations in selected invertebrates at urban sites

In order to obtain basic information for designing standardized test preparation methods, the heavy metals Zn, Cu, Cd and Pb were measured in gastropods (Xerolenta obvia), oligochaetes (Lumbricus terrestris), isopods (Armadillidium vulgare, Trachelipus rathkei) and carabids (Harpalus rubripes, Calathus fuscipes) using different sampling methods and different modes of sample treatment. In some of the experiments, higher Zn, Cd and Pb, and lower Cu-contents were observed in isopods and carabids trapped with formalin-pitfalls compared to manually collected specimens (which were allowed to defecate). Defecation had marked effects on the levels of all four metals investigated in oligochaetes, and on Cd and Pb in gastropods and isopods. Cellulose was fed as an accelerator of gut passage and showed a significant effect on the Pb concentration in the soft body of gastropods. Deionate-washed isopods (A. vulgare) showed higher Cd concentrations than ultrasonic-cleaned individuals. No marked differences were observed between heat-dried and freeze-dried isopods. Carabids showed strong sex-specific differences in metal concentrations. Based on these and previous results, invertebrates should be: collected in vivo, allowed to defecate, be freeze-fixed and (at least in arthropods) ultrasonic-cleaned, determined to species level and in certain groups (carabids) also to sex, and then be sized or sorted by size (age) before further preparation and analysis. If any of these treatments is impractical, comparable sampling and preparation methods are recommended as a minimum requirement in order to avoid bias in the results and/or interpretation.     

Cesium-134 and strontium-85 in strawberry plants following wet aerial deposition

The understanding of the processes that control the behavior of radionuclides in crops can support policymakers to take actions to protect the environment and safeguard human health. Data concerning the behavior of radionuclides in fruits are limited. Strawberry (Fragaria x ananassa Duchesne) plants were contaminated on the aboveground part by sprinkling an aqueous solution of 134Cs and 85Sr at three growing stages: predormancy, anthesis, and beginning of ripening. Intercepted activity was more affected by the posture and physical orientation of leaves rather than by leaf area or biomass. Fruit interception ranges from 0.2 to 1.2% of the sprinkled activity. Translocation coefficients from leaf to fruit are on the order of 10(-4) for 134Cs and 10(-5) for 85Sr. Translocation reaches its highest intensity between anthesis and ripening. If deposition occurs when plants are bearing fruits, the fruit activity will be affected by the activity initially deposited on the fruit surfaces. This is important for 85Sr as it is not translocated in the phloem. The loss of the dead leaves at the resumption of growth causes high plant decontamination, but a fraction of both radionuclides remains in the storage organs, roots, and shoots, which is retranslocated to fruits in the following spring. The values of the environmental half-time, t(w), after deposition at predormancy are 114 d for 134Cs and 109 d for 85Sr. Cesium-134 tends to be allocated to fruits, while 85Sr remains in leaves and crowns. Translocation of radionuclides to roots results in soil contamination.     

Features in Number Concentration-Size Distributions of Aerosols in the Free Atmosphere over the Desert Areas in the Asian Continent: Balloon-Borne Measurements at Dunhuang,China

Vertical changes of aerosol concentration and size in the freetroposphere over the Asian desert areas were firstly observed using a balloon-borne optical particle counter at DunHuang, China (40°00N, 94°30E) (17 August and 17 October 2001, and 11 January 2002). In the free troposphere highly concentrated aerosol layers were frequentlyobserved, suggesting the importance of regional scale particletransportation over the Asian continent. Concentration ofparticles with a diameter larger than 0.15 m was about 5–10particles cm^-3 in the free troposphere.Particle number-size distribution in the free troposphereshows important contribution of super micron particles. Regionalscale transportation, in addition to diffusion of soil particlesfrom the lower atmosphere to the free troposphere through localand small scale air motions, is suggested by backward trajectoryanalysis of air masses containing super micron particles. The importance of horizontal transport of coarse size particles in the free troposphere was strongly suggested.Thickness of the boundary mixing layer, from distributions ofparticle concentration, was about 4 km in summer (17 August 2001)and apparently higher than the height of layers in fall (17 October2001) and in winter (11 January 2002), which suggest an active mixingof particles near the boundary in summer. In winter measurement(11 January 2002), strong inversion was found in the vertical profile of temperature, suggesting cold ground surface and vertically stable atmosphere near the ground.