Height growth of northern red oak in relation to site and atmospheric deposition in Pennsylvania

A forest tree growth-response to atmospheric deposition is expected to arise indirectly through soil chemical changes and would probably be observable only in the long term. We examined this hypothesis by evaluating the relationship between periodic height growth of mature northern red oak (Quercus rubra L.) trees and soil, physiography and atmospheric sulfate deposition along a 170-km west-to-east gradient of decreasing sulfate deposition in north central Pennsylvania, USA. Height increments for three common 20-year periods beginning in 1929, 1949 and 1969 were estimated from exponential-monomolecular growth functions fitted to stem analysis data for each of 45 trees in 13 ecologically analogous stands along the deposition gradient. Canonical analysis was used to identify a statistically manageable subset of the original 48 independent soil, site and tree (age, crown width) variables strongly associated with height growth. Predictive models relating total (60-year) and the three 20-year height increments to the reduced variable set plus estimated average sulfate and nitrate deposition were derived by best subsets multiple regression. An inherent spatial gradient of decreasing height growth from western to eastern sites was apparent in even the earliest (1929-1948) increment. This inferred non-deposition-related spatial growth trend was accounted for in the 1949-1968 growth increment by introduction of the earliest (1929-1948) growth increment as a significant covariate in the regression model. The inherent growth largely disappeared by the 1969-1988 period as a probable consequence of converging growth rates reported to occur in oaks after age 60 years regardless of site quality. The 1969-1988 growth increment was not as strongly correlated with site factors as was growth in preceding periods, nor was early growth or sulfate deposition significantly related to this height increment. Growth effects from sulfate deposition, if any, would most likely occur within the recent (1969-1988) increment coincident with the period of naturally decreasing growth rate, when site differences and possibly environmental factors would have less influence on growth. Our results give no indication that wet sulfate inputs are affecting northern red oak height growth across the atmospheric deposition gradient.     

Nitrogen fertilizer recommendations for corn grown on soils amended with oily food waste

Soil and plant indices of soil fertility status have traditionally been developed using conventional soil and crop management practices. Data on managing N fertilizer for corn (Zea mays L.) produced on soils amended with C-rich organic materials, such as oily food waste (OFW) is scarce. Identification of a reliable method for making N fertilizer recommendations under these conditions is imperative. The objective of this research was to evaluate soil NO(3)-N (0- to 30-cm depth) at preplant and presidedress (PSNT) times of sampling for predicting N requirements for corn grown on fields receiving OFW. Experiments were conducted at two locations in Ontario, Canada over 3 yr (1995-1997) where OFW was applied at different rates (0, 10, and 20 Mg ha(-1)), times (fall and spring), and slope positions (upper, mid, and lower) within the same field. Presidedress soil NO(3)-N contents were higher compared with preplant time of sampling under all OFW management conditions. Corn grain yields were significantly affected by OFW management and N fertilizer application rates. Maximum economic rate of N application (MERN) varied depending on OFW management conditions. Presidedress soil NO(3)-N contents had a higher inverse relationship with MERN (r = -0.88) compared with soil NO(3)-N at preplant (r = -0.74) time of sampling. A linear regression model (Y = 180.1 - 8.22 NO(3)-N at PSNT) is proposed for making N fertilizer recommendations to corn grown on soils amended with OFW in this geographical region.     

Microbial response to heavy metal-polluted soils: community analysis from phospholipid-linked fatty acids and ester-linked fatty acids extracts

Heavy metal pollution of soil is of concern for human health and ecosystem function. The soil microbial community should be a sensitive indicator of metal contamination effects on bioavailability and biogeochemical processes. Simple methods are needed to determine the degree of in situ pollution and effectiveness of remediating metal-contaminated soils. Currently, phospholipid-linked fatty acids (PLFAs) are preferred for microbial profiling but this method is time consuming, whereas direct soil extraction and transesterification of total ester-linked fatty acids (ELFAs) is attractive because of its simplicity. The 1998 mining acid-metal spill of >4000 ha in the Guadiamar watershed (southwestern Spain) provided a unique opportunity to study these two microbial lipid profiling methods. Replicated treatments were set up as nonpolluted, heavy metal polluted and reclaimed, and polluted soils. Inferences from whole community-diversity analysis and correlations of individual fatty acids with metals suggested Cu, Cd, and Zn were the most important in affecting microbial community structure, along with pH. The microbial stress marker, monounsaturated fatty acids, was significantly lower for reclaimed and polluted soil over nonpolluted soils for both PLFA and ELFA extraction. Another stress marker, the monounsaturated to saturated fatty acids ratio, only showed this for the PLFA. The general fungal marker (18:2omega6c), the arbuscule mycorrhizae marker (16:1omega5c), and iso- and anteiso-branched PLFAs (gram positive bacteria) were suppressed with increasing pollution whereas 17:0cy (gram negative bacteria) increased with metal pollution. For both extraction methods, richness and diversity were greater in nonpolluted soils and lowest in polluted soils. The ELFA method was sensitive for reflecting metal pollution on microbial communities and could be suitable for routine use in ecological monitoring and risk assessment programs because of its simplicity and reproducibility.     

An FTIR investigation of isocyanate skin absorption using in vitro guinea pig skin

Isocyanates may cause contact dermatitis, sensitization and asthma. Dermal exposure to aliphatic and aromatic isocyanates can occur in various exposure settings. The fate of isocyanates on skin is an important unanswered question. Do they react and bind to the outer layer of skin or do they penetrate through the epidermis as unreacted compounds? Knowing the kinetics of these processes is important in developing dermal exposure sampling or decontamination strategies, as well as understanding potential health implications such exposure may have. In this paper the residence time of model isocyanates on hairless guinea pig skin was investigated in vitro using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrometry. Model isocyanates tested were octyl isocyanate, polymeric hexamethylene diisocyanate isocyanurate (pHDI), polymeric isophorone diisocyanate isocyanurate (pIPDI) and methylenediphenyl diisocyanate (MDI). Isocyanates in ethyl acetate (30 microL) were spiked directly on the skin to give 0.2-1.8 micromol NCO cm(-2) (NCO = -N=C=O), and absorbance of the isocyanate group and other chemical groups of the molecule were monitored over time. The ATR-FTIR findings showed that polymeric isocyanates pHDI and pIPDI may remain on the skin as unreacted species for many hours, with only 15-20% of the total isocyanate group disappearing in one hour, while smaller compounds octyl isocyanate and MDI rapidly disappear from the skin surface (80+% in 30 min). Isocyanates most likely leave the skin surface by diffusion predominantly, with minimal reaction with surface proteins. The significance of these findings and their implications for dermal exposure sampling and isocyanate skin decontamination are discussed.     

磁铁矿金属化焙烧高温捕集催化剂浸出渣回收铂族金属研究

针对汽车催化剂氧化浸出渣,开展磁铁矿金属化焙烧高温捕集回收铂族金属研究。重点研究捕集剂、还原剂、助熔剂、反应温度、反应时间对铂族金属捕集率的影响。试验结果表明,捕集剂配比20%,还原剂配比12%、助熔剂配比25%、焙烧温度1 400℃、恒温反应时间4 h条件下,铂族金属铂、钯、铑的捕集率分别可达97.19%、92.88%、97.08%。     

Links among nitrification, nitrifier communities, and edaphic properties in contrasting soils receiving dairy slurry

Soil biotic and abiotic factors strongly influence nitrogen (N) availability and increases in nitrification rates associated with the application of manure. In this study, we examine the effects of edaphic properties and a dairy (Bos taurus) slurry amendment on N availability, nitrification rates and nitrifier communities. Soils of variable texture and clay mineralogy were collected from six USDA-ARS research sites and incubated for 28 d with and without dairy slurry applied at a rate of ~300 kg N ha(-1). Periodically, subsamples were removed for analyses of 2 M KCl extractable N and nitrification potential, as well as gene copy numbers of ammonia-oxidizing bacteria (AOB) and archaea (AOA). Spearman coefficients for nitrification potentials and AOB copy number were positively correlated with total soil C, total soil N, cation exchange capacity, and clay mineralogy in treatments with and without slurry application. Our data show that the quantity and type of clay minerals present in a soil affect nitrifier populations, nitrification rates, and the release of inorganic N. Nitrogen mineralization, nitrification potentials, and edaphic properties were positively correlated with AOB gene copy numbers. On average, AOA gene copy numbers were an order of magnitude lower than those of AOB across the six soils and did not increase with slurry application. Our research suggests that the two nitrifier communities overlap but have different optimum environmental conditions for growth and activity that are partly determined by the interaction of manure-derived ammonium with soil properties.     

Development and application of a video-mosaic survey technology to document the status of coral reef communities

The recent decline in the condition of coral reef communities worldwide has fueled the need to develop innovative assessment tools to document coral abundance and distribution rapidly and effectively. While most monitoring programs rely primarily on data collected in situ by trained divers, digital photographs and video are used increasingly to extract ecological indicators, provide a permanent visual record of reef condition, and reduce the time that divers spend underwater. In this study, we describe the development and application of a video-based reef survey methodology based on an algorithm for image registration and the estimation of image motion and camera trajectory. This technology was used to construct two-dimensional, spatially accurate, high-resolution mosaics of the reef benthos at a scale of up to 400 m². The mosaics were analyzed to estimate the size and percent cover of reef organisms and these ecological indicators of reef condition were compared to similar measurements collected by divers to evaluate the potential of the mosaics as monitoring tools. The ecological indicators collected by trained divers compared favorably with those measured directly from the video mosaics. Five out of the eight categories chosen (hard corals, octocorals, Palythoa, algal turf, and sand) showed no significant differences in percent cover based on survey method. Moreover, no significant differences based on survey method were found in the size of coral colonies. Lastly, the capability to extract the same reef location from mosaics collected at different times proved to be an important tool for documenting change in coral abundance as the removal of even small colonies (<10 cm in diameter) was easily documented. The two-dimensional video mosaics constructed in this study can provide repeatable, accurate measurements on the reef-plot scale that can complement measurements on the colony-scale made by divers and surveys conducted at regional scales using remote sensing tools.     

Cadmium accumulation in deer tongue grass (Panicum clandestinum L.) and potential for trophic transfer to microtine rodents

Site 36 at the Crab Orchard National Wildlife Refuge includes a Cd-contaminated soil dominated by deer tongue grass (Panicum clandestinum L.). Analysis of deer tongue grass from this site indicated that biomass and leaf surface area were reduced and that there was a linear relationship between both plant bioavailable soil Cd and total soil Zn and tissue Cd concentration. The Cd concentrations in stems and leaves were also used to estimate the dietary Cd exposures that might be experienced by prairie voles (Microtus ochrogaster) and pine voles (M. pinetorum) consuming deer tongue grass. Renal and hepatic Cd burdens predicted from exclusive consumption of deer tongue grass would be comparable to those that have resulted in chronic toxicity in rodents. The results suggest that for the contaminated soil at Site 36, conditions could allow for the accumulation of Cd in deer tongue grass to concentrations that may pose an ecological risk.     

Loss of volatile hydrocarbons from an LNAPL oil source

The light nonaqueous phase liquid (LNAPL) oil pool in an aquifer that resulted from a pipeline spill near Bemidji, Minnesota, was analyzed for volatile hydrocarbons (VHCs) to determine if the composition of the oil remains constant over time. Oil samples were obtained from wells at five locations in the oil pool in an anaerobic part of the glacial outwash aquifer. Samples covering a 21-year period were analyzed for 25 VHCs. Compared to the composition of oil from the pipeline source, VHCs identified in oil from wells sampled in 2008 were 13 to 64% depleted. The magnitude of loss for the VHCs analyzed was toluene?o-xylene, benzene, C(6) and C(10-12)n-alkanes>C(7)-C(9)n-alkanes>m-xylene, cyclohexane, and 1- and 2-methylnaphthalene>1,2,4-trimethylbenzene and ethylbenzene. Other VHCs including p-xylene, 1,3,5- and 1,2,3-trimethylbenzenes, the tetramethylbenzenes, methyl- and ethyl-cyclohexane, and naphthalene were not depleted during the time of the study. Water-oil and air-water batch equilibration simulations indicate that volatilization and biodegradation is most important for the C(6)-C(9)n-alkanes and cyclohexanes; dissolution and biodegradation is important for most of the other hydrocarbons. Depletion of the hydrocarbons in the oil pool is controlled by: the lack of oxygen and nutrients, differing rates of recharge, and the spatial distribution of oil in the aquifer. The mass loss of these VHCs in the 5 wells is between 1.6 and 7.4% in 29years or an average annual loss of 0.06-0.26%/year. The present study shows that the composition of LNAPL changes over time and that these changes are spatially variable. This highlights the importance of characterizing the temporal and spatial variabilities of the source term in solute-transport models.     

Direct comparison of 210Po, 234Th and POC particle-size distributions and export fluxes at the Bermuda Atlantic Time-series Study (BATS) site

Particle-reactive, naturally occurring radionuclides are useful tracers of the sinking flux of organic matter from the surface to the deep ocean. Since the Joint Global Ocean Flux Study (JGOFS) began in 1987, the disequilibrium between ²³⁴Th and its parent ²³⁸U has become widely used as a technique to measure particle export fluxes from surface ocean waters. Another radionuclide pair, ²¹⁰Po and ²¹⁰Pb, can be used for the same purpose but has not been as widely adopted due to difficulty with accurately constraining the ²¹⁰Po/²¹⁰Pb radiochemical balance in the ocean and because of the more time-consuming radiochemical procedures. Direct comparison of particle flux estimated in different ocean regions using these short-lived radionuclides is important in evaluating their utility and accuracy as tracers of particle flux. In this paper, we present paired ²³⁴Th/²³⁸U and ²¹⁰Po/²¹⁰Pb data from oligotrophic surface waters of the subtropical Northwest Atlantic and discuss their advantages and limitations. Vertical profiles of total and particle size-fractionated ²¹⁰Po and ²³⁴Th activities, together with particulate organic carbon (POC) concentrations, were measured during three seasons at the Bermuda Atlantic Time-series Study (BATS) site. Both ²¹⁰Po and ²³⁴Th reasonably predict sinking POC flux caught in sediment traps, and each tracer provides unique information about the magnitude and efficiency of the ocean's biological pump.