We conducted statistical analyses of a 10-year record of stream nutrient and sediment concentrations for 17 streams in the greater Seattle region to determine the impact of urban non-point-source pollutants on stream water quality. These catchments are dominated by either urban (22–87%) or forest (6–73%) land cover, with no major nutrient point sources. Stream water phosphorus concentrations were moderately strongly (r2=0.58) correlated with catchment land-cover type, whereas nitrogen concentrations were weakly (r2=0.19) and nonsignificantly (at < 0.05) correlated with land cover. The most urban streams had, on average, 95% higher total phosphorus (TP) and 122% higher soluble reactive phosphorus (SRP) and 71% higher turbidity than the most forested streams. Nitrate (NO3), ammonium (NH4), and total suspended solids (TSS) concentrations did not vary significantly with land cover. These results suggest that urbanization markedly increased stream phosphorus concentrations and modestly increased nitrogen concentrations. However, nutrient concentrations in Seattle region urban streams are significantly less than those previously reported for agricultural area streams. 相似文献
Ecological risk assessment (ERA) evaluates potential causal relationships between multiple sources and stressors and impacts on valued ecosystem components. ERAs applied at the watershed scale have many similarities to the place-based analyses that are undertaken to develop Total Maximum Daily Loads (TMDLs), in which linkages are established between stressors, sources, and water quality standards, including support of designated uses. TMDLs focus on achieving water quality standards associated with attainment of designated uses. In attempting to attain the water quality standard, many TMDLs focus on the stressor of concern rather than the ecological endpoint or indicators of the designated use that the standard is meant to protect. A watershed ecological risk assessment (WERA), at least in theory, examines effects of most likely stressors, as well as their probable sources in the watershed, to prioritize management options that will most likely result in meeting environmental goals or uses. Useful WERA principles that can be applied to TMDL development include: development and use of comprehensive conceptual models in the Problem Identification step of TMDLs; use of a transparent process for selecting Numeric Targets for TMDLs based on assessment endpoints derived from the management goal or designated use under consideration; analysis of co-occurring stressors likely to cause beneficial use impairment based on the conceptual model; use of explicit uncertainty analyses in the Linkage Analysis step of TMDL development; and frequent stakeholder interactions throughout the process. WERA principles are currently most applicable to those TMDLs in which there is no numeric standard and, therefore, indicators and targets need to be developed, such as many nutrient or sediment TMDLs. WERA methods can also be useful in determining TMDL targets in situations where simply targeting the water quality standard may re-attain the numeric criterion but not the broader designated use. Better incorporation of problem formulation principles from WERA into the TMDL development process would be helpful in improving the scientific rigor of TMDLs. 相似文献
OBJECTIVE: The objective of this study was to quantify the occupant response variability due to differences in vehicle and seat design in low-speed rear-end collisions. METHODS: Occupant response variability was quantified using a BioRID dummy exposed to rear-end collisions in 20 different vehicles. Vehicles were rolled rearward into a rigid barrier at 8 km/h and the dynamic responses of the vehicle and dummy were measured with the head restraint adjusted to the up most position. In vehicles not damaged by this collision, additional tests were conducted with the head restraint down and at different impact speeds. RESULTS: Despite a coefficient of variation (COV) of less than 2% for the impact speed of the initial 8 km/h tests, the vehicle response parameters (speed change, acceleration, restitution, bumper force) had COVs of 7 to 23% and the dummy response parameters (head and T1 kinematics, neck loads, NIC, N(ij) and N(km)) had COVs of 14 to 52%. In five vehicles tested multiple times, a head restraint in the down position significantly increased the peak magnitude of many dummy kinematic and kinetic response parameters. Peak head kinematics and neck kinetics generally varied linearly with head restraint back set and height, although the neck reaction moment reversed and increased considerably if the dummy's head wrapped onto the top of the head restraint. CONCLUSIONS: The results of this study support the proposition that the vehicle, seat, and head restraint are a safety system and that the design of vehicle bumpers and seats/head restraint should be considered together to maximize the potential reduction in whiplash injuries. 相似文献
Environmental Information Services, Inc. (EIS) publishes detailed reports and offers custom research related to the full spectrum of environmental issues facing corporations. In this article, EIS reports on the compliance performance of the Ford Motor Company, focusing on the five key environmental concerns: toxic waste management, air pollution, water pollution, spills, and Superfund. 相似文献
In this article, environmental management programs of Standard & Poors (S&P) 500 companies were evaluated using a series of industry and size-adjusted environmental trend indicators. The statistical analysis shows that a handful of corporate policy, governance, human resources, auditing, and financial parameters are highly relevant to improving corporate environmental performance. The results have implications for corporate environmental efforts as well as future government policies to foster environmental improvement. 相似文献
Through discussion of causative factors and examination of historical data, petrochemical spill prevention in US waters is reviewed. Unintentional petrochemical outflow is analyzed in a comprehensive manner and presented as a hierarchical sequence of antecedent events to reveal the trends of causative factors leading to release. Specifically, a seaborne petrochemical spill is examined in terms of four basic, antecedent events: (1) an underway source, (2) a failure incident, (3) a marine accident capable of breaching the hull and cargo block, and (4) the onset of outflow. These events are further subdivided into underlying, contributing events to form a causative framework for spill prevention. While a hierarchical review is not necessary to uncover the elements of causation, it does provide a comprehensive and logical structure that clearly defines these elements in terms of occurrence frequency and contribution to resulting outflow. It is found that relatively small, frequent spills less than 40,000 liters (10,567 gallons), attributable to human operator failures, leading to grounding, and cargo transfer system failure accidents, dominate US seaborne petrochemical outflow from 1992 to 1999. Given the frequency of groundings, structural reinforcement regulations such as those contained in the Oil Pollution Act of 1990 (requiring double hulls) appear well justified. However, passive restraint systems are secondary to the need for vigilant training and licensing of tank vessel operators. 相似文献
Objective: Although advanced restraint systems, such as seat belt pretensioners and load limiters, can provide improved occupant protection in crashes, such technologies are currently not utilized in military vehicles. The design and use of military vehicles presents unique challenges to occupant safety—including differences in compartment geometry and occupant clothing and gear—that make direct application of optimal civilian restraint systems to military vehicles inappropriate. For military vehicle environments, finite element (FE) modeling can be used to assess various configurations of restraint systems and determine the optimal configuration that minimizes injury risk to the occupant. The models must, however, be validated against physical tests before implementation. The objective of this study was therefore to provide the data necessary for FE model validation by conducting sled tests using anthropomorphic test devices (ATDs). A secondary objective of this test series was to examine the influence of occupant body size (5th percentile female, 50th percentile male, and 95th percentile male), military gear (helmet/vest/tactical assault panels), seat belt type (3-point and 5-point), and advanced seat belt technologies (pretensioner and load limiter) on occupant kinematics and injury risk in frontal crashes.
Methods: In total, 20 frontal sled tests were conducted using a custom sled buck that was reconfigurable to represent both the driver and passenger compartments of a light tactical military vehicle. Tests were performed at a delta-V of 30 mph and a peak acceleration of 25 g. The sled tests used the Hybrid III 5th percentile female, 50th percentile male, and 95th percentile male ATDs outfitted with standard combat boots and advanced combat helmets. In some tests, the ATDs were outfitted with additional military gear, which included an improved outer tactical vest (IOTV), IOTV and squad automatic weapon (SAW) gunner with a tactical assault panel (TAP), or IOTV and rifleman with TAP. ATD kinematics and injury outcomes were determined for each test.
Results: Maximum excursions were generally greater in the 95th percentile male compared to the 50th percentile male ATD and in ATDs wearing TAP compared to ATDs without TAP. Pretensioners and load limiters were effective in decreasing excursions and injury measures, even when the ATD was outfitted in military gear.
Conclusions: ATD injury response and kinematics are influenced by the size of the ATD, military gear, and restraint system. This study has provided important data for validating FE models of military occupants, which can be used for design optimization of military vehicle restraint systems. 相似文献
This article describes new field-based technologies that support the Dynamic Workplan/Adaptive Sampling and Analysis Program employed to better characterize hazardous waste sites at lower cost. A laser-induced fluorescence (LIF) probe was designed and field-tested with a cone penetrometer (CP) for investigating petroleum contaminants present at under-ground tank farms. The LIF produced real-time quantitative data for naphthalene and semiquantitative results for total petroleum hydrocarbons and diesel range organics. Two different projects are described employing fast gas chromatography/mass spectrometry (GC/MS) in the field. A 70-foot heated transfer line and probe were used in combination with a cone penetrometer to thermally extract (TE) subsurface soil-bound semivolatile organics. In the second project, soil samples were collected by a GeoprobeTM and brought to the surface for analysis. The direct measurement TECP data produced semiquantitative results while the more conventional means of collecting and analyzing samples produced risk analysis quality data in the field. A new set of mass spectrometry algorithms provided the technology breakthrough for identifying and quantifying a wide range of Environmental-Protection-Agency-listed target compounds in the presence of high levels of matrix (petroleum) interferents under fast, 7 min/sample, GC conditions. 相似文献
Environmental Information Services Inc. (EIS) publishes detailed reports and offers custom research related to the full spectrum of environmental issues facing corporations. This article highlights several key sections from EIS's new 1997 Chemical Industry Report. It details the environmental performance, policies, and expenditures of the largest companies in the chemical industry. EIS industry reports contain data on five key performance criteria—toxic waste management, hazardous waste generation, penalties, spills, and Superfund sites. Here we examine one of those—penalties—and the policies of three of the largest companies in the chemical industry. In the full report, which can be obtained from EIS, 15 corporations are analyzed based on all the performance criteria. 相似文献
Congenital bronchopulmonary malformations detectable on prenatal ultrasound include cystic adenomatoid malformation (CAM), lobar sequestration, and upper airway atresia. We describe three fetuses with prenatally detected intrathoracic lesions in which the associated pulmonary hyperechogenicity disappeared before delivery. In the first case of pulmonary sequestration, the infant was asymptomatic after birth. However, in a case of CAM and another with laryngeal atresia, respiratory distress developed after delivery, despite recent scans showing apparently normal lung fields. This experience suggests that ultrasonic resolution of hyperechogenic lung lesions in utero does not necessarily indicate resolution of the underlying pathology. 相似文献