Coastal Louisiana recent land loss and canal impacts

Annual coastal land loss in the sedimentary deltaic plain of southern Louisiana is 102 km², which is correlated with man-made canal surface area. The relationships between land loss and canals are both direct and indirect and are modified by the deltaic substrate, distance to the coast, and availability of new sediments. Loss rates are highest in the youngest of the former deltas nearest the coast; they are lowest in the more consolidated sediments far from the coast. The average estimate for land loss at zero canal density in the six regression equations developed was 0.09%±0.13% annually, the present land loss rates approach 0 8% annually Although additional analyses are needed, we conclude that canals are causally related to a significant portion of the total coastal land loss rates The relation probably involves an interruption of local and regional hydrologic regimes. Reduction of the present acceleration in land loss rates is possible by managing present canals more effectively, by not permitting new ones, and by changing the design of new canals to allow more natural water flow     

Broiler diet modification and litter storage: impacts on phosphorus in litters, soils, and runoff

Modifying broiler diets to mitigate water quality concerns linked to excess phosphorus (P) in regions of intensive broiler production has recently increased. Our goals were to evaluate the effects of dietary modification, using phytase and reduced non-phytate phosphorus (NPP) supplementation, on P speciation in broiler litters, changes in litter P forms during long-term storage, and subsequent impacts of diets on P in runoff from litter-amended soils. Four diets containing two levels of NPP with and without phytase were fed to broilers in a three-flock floor pen study. After removal of the third flock, litters were stored for 440 d at their initial moisture content (MC; 24%) and at a MC of 40%. Litter P fractions and orthophosphate and phytate P concentrations were determined before and after storage. After storage, litters were incorporated with a sandy and silt loam and simulated rainfall was applied. Phytase and reduced dietary NPP significantly reduced litter total P. Reducing dietary NPP decreased water-extractable inorganic phosphorus (IP) and the addition of dietary phytase reduced NaOH- and HCl-extractable organic P in litter, which correlated well with orthophosphate and phytic acid measured by 31P nuclear magnetic resonance (NMR), respectively. Although dry storage caused little change in P speciation, wet storage increased concentrations of water-soluble IP, which increased reactive P in runoff from litter-amended soils. Therefore, diet modification with phytase and reduced NPP could be effective in reducing P additions on a watershed scale. Moreover, efforts to minimize litter MC during storage may reduce the potential for dissolved P losses in runoff.     

Self-reported driving under the influence of alcohol and cannabis among Ontario students: Associations with graduated licensing,risk taking,and substance abuse

Objective: This article describes the patterns of self-reported driving under the influence of alcohol (DUIA) and driving under the influence of cannabis (DUIC) among licensed Ontario students in 2009 and examines their associations with graduated licensing, risk taking, and substance use problems for understanding DUIA and DUIC behaviors. Ontario's graduated licensing system requires new drivers to hold a G1 license for a minimum of 8 months and a G2 license for a minimum of 12 months before a full and unrestricted G license can be obtained. Among other restrictions, G1 drivers must maintain a 0 blood alcohol content (BAC), have an experienced driver in the passenger seat, not drive on any high-speed expressways, and not drive between the hours of midnight and 5 a.m. A G2 license is more similar to a G license, with fewer restrictions.

Method: This study analyzed data from the 2009 Ontario Student Drug Use and Health Survey (OSDUHS). The OSDUHS is a biennial population-based survey of students (grades 7 to 12) in Ontario, Canada.

Results: The results showed that 16.3% of licensed students in Ontario reported DUIC and 11.5% reported DUIA during the past year. After controlling for the effect of age, type of license emerged as a robust predictor for both DUIA and DUIC behavior, because students with a G2 and full license were significantly more likely to report DUIA and DUIC than drivers with a G1 license. Multivariate analyses suggested that risk-seeking behaviors were more important for understanding DUIA behavior than for DUIC behavior. Elevated problem indicators for alcohol and for cannabis were associated with DUIA and DUIC, respectively.

Conclusions: Though much attention has been paid to drinking and driving among adolescents, this research shows that more Ontario students now report driving after cannabis use than after drinking alcohol. The results identify important correlates of both behaviors that may be useful for prevention purposes.     

对加拿大东南部湖泊从酸沉降效应中恢复的评价

北美洲SO2排放量的减少激起了人们对加拿大东南部的水生态系统能迅速摆脱酸化的状态的期待.但是只有那些明显减少了排放量的冶炼厂附近的湖泊达到了这种期望值.在临近大西洋的省份魁北克和安大略,受远程污染源影响的湖泊的硫酸根离子(SO2- 4)浓度都有一定降低,但pH和碱度则仅有较少量的提高.对于这种延迟的酸度响应,有如下几种因素可以解释:碱基阳离子含量的下降,干旱加速SO2- 4的迁移,水体内部碱性物质生成机制遭到破坏;同时硝酸盐和有机阴离子含量的提高也可能是其中的原因.对加拿大东南部生物恢复的监测资料非常有限,即使有的话,在萨德伯里(Sudbury)和基拉尼(Killarney)地区以外也很难找到恢复的证据.比如,尽管除了酸化作用外其他因素也对上述现象有一定影响,新思科舍河中的大西洋鲑鱼出现率和安大略湖潜鸟的繁殖成功率实际上正在下降.化学和生物学模型预测,只有比目前法规要求严格的多的SO2排放削减额才能促进广泛的化学恢复和其后的生物恢复,而在加拿大东南部的众多湖泊中重建工业化前的化学与生物学条件或许很难实现.     

Monitoring global change: Comparison of forest cover estimates using remote sensing and inventory approaches

Satellite-based remote sensing offers great potential for frequent assessment of forest cover over broad spatial scales, however, calibration and validation using ground-based surveys are needed. In this study, forest cover estimates for the United States from a recently developed land surface cover map generated from satellite remote sensing data were compared to state-level inventory data from the U.S. National Resources Planning Act Timber Database. The land cover map was produced at the U.S. Geological Survey EROS Data Center and is based on imagery from the AVHRR sensor (spatial resolution 1.1 km). Vegetation type was classified using the temporal signal in the Normalized Difference Vegetation Index derived from AVHRR data. Comparisons revealed close agreement in the estimate of forest cover for extensively forested states with large polygons of relatively similar vegetation such as Oregon. Larger forest cover differences were observed in other states with some regional patterns in the level of agreement apparent.Comparisons in inventory- and remote sensing-based estimates of current forested area with potential vegetation maps indicated the magnitude of past land use change and the potential for future changes. The remote sensing approach appears to hold promise for conducting surveys of forest cover where inventory data are limited or where rates of vegetation change, due to human or climatic factors, are rapid.     

Use of historical assessment for evaluation of process-based model projections of future environmental change: Lake acidification in the Adirondack mountains, New York, USA

Because of the considerable uncertainties associated with modeling complex ecosystem processes, it is essential that every effort be made to test model performance prior to relying on model projections for assessment of future surface water chemical response to environmental perturbation. Unfortunately, long-term chemical data with which to validate model performance are seldom available. The authors present here an evaluation of historical acidification of lake waters in the northeastern United States, and compare historical changes in a set of lakes to hindcasts from the same watershed model (MAGIC) used to estimate future changes in response to acidic deposition. The historical analyses and comparisons with MAGIC model hindcasts and forecasts of acid-base response demonstrate that the acidic and low-ANC lakes in this region are responsive to strong acid inputs. However, the model estimates suggest lakewater chemistry is more responsive to atmospheric inputs of sulfur than do the estimates based on paleolimnological historical analyses. A 'weight-of-evidence approach' that incorporates all available sources of information regarding acid-base response provides a more reasonable estimate of future change than an approach based on model projections alone. The results of these analyses have important implications for predicting future surface water chemical change in response to acidic deposition, establishing critical loads of atmospheric pollutants, and other environmental assessment activities where natural variation often exceeds the trends under investigation (high noise-to-signal ratio). Under these conditions, it is particularly important to evaluate future model projections in light of historical trends data.     

Sensitivity to change for low-ANC eastern US lakes and streams and brook trout populations under alternative sulfate deposition scenarios

A weight-of-evidence approach was used by the US National Acid Precipitation Assessment Program (NAPAP) to assess the sensitivity of chemistry and biology of lakes and streams to hypothesized changes in sulfate deposition over the next 50 years. The analyses focused on projected effects in response to differences in the magnitude and the timing of changes in sulfate deposition in the north-eastern United States, the Mid-Appalachian Highlands, and the Southern Blue Ridge Province. A number of tools was used to provide the weight of evidence that is required to have confidence in an assessment that has many uncertainties because of the complexity of the systems for which the projections of future conditions were made and because of limited historical data. The MAGIC model provided the projections of chemical changes in response to alternative deposition scenarios. Projected chemical conditions were input into biological models that evaluate effects on fish populations. The sensitivity of water chemistry and brook trout resources to the hypothesized changes in deposition was found to be greatest in the Adirondacks and Mid-Atlantic Highlands. Under the hypothesized sulfur deposition reduction scenarios, chemical conditions suitable for fish were projected to improve 20-30 years sooner than with the scenario that assumed no new legislated controls. Other lines of evidence, e.g. other models, field observations, and paleolimnological findings, were used to evaluate uncertainty in the projections. Model parameter/calibration uncertainty for the chemical models and population sampling uncertainty were explicitly quantified. Model structural uncertainties were bracketed using model comparisons, recent measured changes, and paleolimnological reconstructions of historical changes in lake chemistry.