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131.
ABSTRACT: Rosgen analysis, developed for assessing channel stability in streams from the western United States, is applied to the Oswego River watershed in the New Jersey Pine Barrens. The Rosgen method requires calibration to local conditions due to the impact of peat substrates on channel morphology. In particular, the presence of peat induces low width to depth ratios and greater channel confinement, reversing typical downstream morphologic trends observed in other rivers. Therefore peat is added to those substrates already evaluated by Rosgen. A consistent sequence of Rosgen stream types develops along the Oswego River and its tributaries created by spatially overlapping processes of water table emergence, peat development, and channel formation. This sequence delineates a “natural” transition of stream channel morphology downslope through the watershed. First, as the water table reaches the surface of dry sloughs, Sphagnum growth is stimulated and peat substrates result. These substrates have lower permeability than the underlying gravelly sands. Next, surface runoff, through braided pathways over the peat, eventually erodes mainly anastomosing channels into the peat. Finally, single‐thread channels develop in underlying gravelly sands further downslope. This downslope sequence, expressed as Rosgen stream types, begins generally with DA7 streams arising from dry sloughs. These pass to E7, C7 or DA5 stream types that in turn pass to B5c, C5 and C4 stream types. Departures from the “natural” stream type sequence occur along the course of the Oswego and its tributaries due to human activities such as the construction of dams, bridges and drainage ditches, stream bank erosion at streamside camping and picnic areas and the clear‐cutting of adjacent stands of Atlantic white cedar. 相似文献
132.
An investigation of the impacts from elevated intertidal Pacific oyster culture in a New Zealand estuary showed enhanced sedimentation
beneath culture racks compared with other sites. Seabed elevation beneath racks was generally lower than between them, suggesting
that topographic patterns more likely result from a local effect of rack structures on hydrodynamic processes than from enhanced
deposition. Compared with control sites, seabed sediments within the farm had a greater silt/clay and organic content, and
a lower redox potential and shear strength. While a marked trend in macrofaunal species richness was not evident, species
composition and dominance patterns were consistent with a disturbance gradient, with farm effects not evident 35 m from the
perimeter of the racks. Of the environmental variables measured, sediment shear strength was most closely associated with
the distribution and density of macrofauna, suggesting that human-induced disturbance from farming operations may have contributed
to the biological patterns. To evaluate the taxonomic sufficiency needed to document impacts, aggregation to the family level
based on Linnean classification was compared with an aggregation scheme based on `general groups' identifiable with limited
taxonomic expertise. Compared with species-level analyses, spatial patterns of impact were equally discernible at both aggregation
levels used, provided density rather than presence/absence data were used. Once baseline conditions are established and the
efficacy of taxonomic aggregation demonstrated, a `general group' scheme provides an appropriate and increasingly relevant
tool for routine monitoring. 相似文献
133.
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135.
龚平 《铁路节能环保与安全卫生》2020,(2):1-4,9
分析了铁路建设项目种类多样化、投资建设主体多元化的新业态,以及新版环境评价技术导则、生态环境领域深化"放管服"改革对铁路建设项目环评的新要求,阐述项目合规性分析是环境评价开展的前提,对工程概况、工程方案环境影响比选,以及生态、声、地表水、地下水、土壤等环境要素评价的技术要点,改建铁路"以新带老"和工程变更环评管理提出了建议。 相似文献
136.
Introduction: Adolescents engaging in school-sponsored work experiences may be at risk of injury due to factors such as inexperience. This article examines trends in 20 years of reported injuries among New Jersey (NJ) adolescents engaging in school-sponsored work experiences, and compares a transition from paper to online reporting format. Methods: New Jersey requires reporting of injuries occurring during school-sponsored work experiences to the NJ Department of Education. Injuries reported by NJ schools from 1999 to 2018 (n = 2,119) were examined; incidence rates for 2008 to 2018 (n = 743) were calculated using publicly available NJ Department of Education enrollment data for the denominator, including for specific groups of students: career and technical education; special healthcare needs. Results: A downward trend in reported injuries in NJ schools was observed. However, the year online reporting became required by code (2013), an increase of nearly 50% was seen from 2012 (59–89), followed by a decline in reported incidents 2014 to 2018 (mean = 65, range 76 down to 47). Injury rate trends over time paralleled those of reported incidents. Conclusions: This study suggested worker safety and public health benefits of improvements from State of NJ code required training programs and online injury surveillance report form. Practical Applications: One potential method to address the safety and health of adolescents engaging in work experiences is the use of online reporting forms, to aid in surveillance efforts, coupled with occupational safety and health training specifically geared toward teachers and administrators who both supervise young, relatively inexperienced and vulnerable workers and who make relatively frequent worksite visits. Incorporation of specific details of the instructions on the use of a reporting form into required trainings, in addition to providing a clear, accessible guidance manual online, could further help improve youth worker safety surveillance efforts. 相似文献
137.
Heather E. Golden Elizabeth W. Boyer Michael G. Brown S. Thomas Purucker René H. Germain 《Journal of the American Water Resources Association》2009,45(4):945-962
Abstract: Nitrate‐nitrogen (NO3‐N) concentrations in stream water often respond uniquely to changes in inter‐annual conditions (e.g., biological N uptake and precipitation) in individual catchments. In this paper, we assess (1) how the spatial distribution of NO3‐N concentrations varies across a dense network of nonnested catchments and (2) how relationships between multiple landscape factors [within whole catchments and hydrologically sensitive areas (HSAs) of the catchments] and stream NO3‐N are expressed under a variety of annual conditions. Stream NO3‐N data were collected during two synoptic sampling events across >55 tributaries and two synoptic sampling periods with >11 tributaries during summer low flow periods. Sample tributaries drain mixed land cover watersheds ranging in size from 0.150 to 312 km2 and outlet directly to Cayuga Lake, New York. Changes in NO3‐N concentration ratios between each sampling event suggest a high degree of spatial heterogeneity in catchment response across the Cayuga Lake Watershed, ranging from 0.230 to 61.4. Variations in NO3‐N concentrations within each of the large synoptic sampling events were also high, ranging from 0.040 to 8.7 mg NO3‐N/l (March) and 0.090 to 15.5 mg NO3‐N/l (October). Although Pearson correlation coefficients suggest that this variability is related to multiple landscape factors during all four sampling events, partial correlations suggest percentage of row crops in the catchments as the only similar factor in March and October and catchment area as the only factor during summer low flows. Further, the strength of the relationships is typically lower in the HSAs of catchment. Advancing current understanding of such variations and relationships to landscape factors across multiple catchments – and under a variety of biogeochemical and hydrological conditions – is important, as (1) nitrate continues to be employed as an indicator of regional aquatic ecosystem health and services and (2) a unified framework approach for understanding individual catchment processes is a rapidly evolving focus for catchment‐based science and management. 相似文献
138.
我国水污染物排放标准评析 总被引:2,自引:0,他引:2
司蔚 《环境监测管理与技术》2010,22(4):7-9
简述了国家污染物排放标准制定的发展历程及未来规划,对已发布和即将发布的国家水污染物排放标准特点及与国家环境保护标准制修订有关的法律法规、规范性文件进行了分析,提出了在标准实施中加大监督执法、掌控标准实施效果、加强标准基础性研究和健全污染排放标准体系的建议。 相似文献
139.
借鉴国内外 I/ M制度的经验 ,运用系统论、控制论的观点 ,创造性地提出有效治理城市汽车尾气污染应建立的六大体系 ,强调城市汽车尾气污染的控制应以尾气污染预前控制和过程控制为主 ,并以此构筑城市汽车尾气污染治理的新模式 相似文献
140.
Impact of poor solid waste management on ground water 总被引:1,自引:0,他引:1
Eight sediment cores recovered from Tamaki Estuary were analysed for Cu, Pb, Zn, and Cd using downward cored sub-samples.
The results indicate a significant upward enrichment in heavy metals with the highest concentrations found in the uppermost
0–10 cm layer. Assessment of heavy metal pollution in marine sediments requires knowledge of pre-anthropogenic metal concentrations
to act as a reference against which measured values can be compared. Pristine values for the cored sediments were determined
from flat “base-line” metal trends evident in lower core samples. Various methods for calculating metal enrichment and contamination
factors are reviewed in detail and a modified and more robust version of the procedure for calculating the degree of contamination
is proposed. The revised procedure allows the incorporation of a flexible range of pollutants, including various organic species,
and the degree of contamination is expressed as an average ratio rather than an absolute summation number. Comparative data
for normalized enrichment factors and the modified degree of contamination show that Tamaki Estuary sediments have suffered
significant systematic heavy metal contamination following catchment urbanization. Compared to baseline values the uppermost
sediment layers show four-fold enrichment averaged across eight cores and four analysed metals. 相似文献