Study of chest injuries to 3-year-old child occupants seated in impact shield and 5-point harness CRSs

Objective: The objective of this study was to investigate whether the 5-point harness or the impact shield child restraint system (CRS) or both have the potential to cause chest injuries to children. This is determined by examining whether the loading to the chest reaches the internal organ injury threshold for children.

Method: The chest injury risk to a child occupant in a CRS was investigated using Q3 dummy tests, finite element (FE) simulations (Q3 dummy and human models), and animal tests. The investigation was done for 2 types of CRSs (i.e., the impact shield CRS and 5-point harness CRS) based on the UN R44 dynamic test specifications.

Results: The tests using a Q3 dummy indicated that although the chest deflection of the dummy in the impact shield CRS was large, it was less than the injury threshold (40 mm). Computational biomechanics simulations (using finite element FE analysis) showed that the Q3 dummy's chest is loaded by the shield and deforms substantially under this load. To clarify whether chest injuries due to chest compression can occur with an impact shield or with the 5-point harness CRS, 7 experiments were performed using Tibetan miniature pigs with weights ranging from 9.7 to 13 kg. Severe chest and abdominal injuries (lung contusion, coronary artery laceration, liver laceration) were found in the tests using the impact shield CRS. No chest injuries were present when using the 5-point harness CRS.

Conclusion: When using the impact shield CRS, the chest deformed substantially in dummy tests and FE simulations, and chest and abdominal injuries were observed in pig tests. It is possible that these chest injuries could also occur to child occupants sitting in the impact shield CRS.     

Organochlorine pesticides in the dust fall around Lake Chaohu, the fifth largest lake in China

The residual levels of organochlorine pesticides (OCPs) in the dust fall around Lake Chaohu were measured using gas chromatography mass spectrometry from April 2010 to March 2011. The fluxes, components, temporal–spatial variations, and sources of OCPs were also analyzed. Twenty-one types of OCPs were detected in the dust fall samples around Lake Chaohu, with a total concentration of 51.54?±?36.31 ng/g and a total flux of 10.01?±?13.69 ng/(m² day). Aldrin (35.3 %), endosulfan (39.1 %), dichlorodiphenyltrichloroethanes (DDTs) (49.8 %), and isodrin (37.1 %) were the major OCPs in the spring, summer, autumn, and winter, respectively. Both the residual level and the flux were higher in the spring than in other seasons and higher at the outer lake sampling sites than inner lake sampling site. The potential source of the hexachlorcyclohexanes in the dust fall may be recent lindane usage. The DDTs mainly came from historical dicofol usage, and a significant input of DDT was found during April and June. The presence of endosulfan may be due to the present use of technical endosulfan. The aldrin in the dust might be due to its occasional usage, and isodrin may be a result of long-distance transport from other countries.     

Polycyclic aromatic hydrocarbons in urban soils of Beijing: status, sources, distribution and potential risk

We studied the source, concentration, spatial distribution and health risk of 16 polycyclic aromatic hydrocarbons (PAHs) in urban soils of Beijing. The total mass concentration of 16 PAHs ranged from 93 to 13 141 μg kg⁻¹ with a mean of 1228 μg kg⁻¹. The contour map of soil PAH concentrations showed that the industrial zone, the historical Hutong district and the university district of Beijing have significantly higher concentrations than those in remainder of the city. The results of sources identification suggested that the primary sources of PAHs were vehicle exhaust and coal combustion and the secondary source was the atmospheric deposition of long-range transported PAHs. The incremental lifetime cancer risks (ILCRs) of exposing to PAHs in the urban soils of Beijing for adult were 1.77 × 10⁻⁶ and 2.48 × 10⁻⁵, respectively under normal and extreme conditions. For child, they were 8.87 × 10⁻⁷ and 6.72 × 10⁻⁶, respectively under normal and extreme conditions.     

我国燃煤电厂除尘技术路线选择问题分析

通过文献调研分析了影响我国燃煤电厂除尘技术路线选择的主要问题,从煤质含硫量、粉尘比电阻、粉尘粒径分布三方面研究结果表明电除尘技术对我国煤种的适应性较差,无法满足严格的排放标准;另外,通过前人对比不同除尘方式协同脱汞效果和对下游设备保护作用的研究成果,结果表明袋式除尘器具有更好的协同脱汞作用,更高的除尘效率并赋予湿法脱硫设备长期可靠运行。     

Evaluation of the economic and environmental impact of converting cropland to forest: a case study in Dunhua county, China

The Sloping Land Conversion Program (also known as "Grain for Green" or the Upland Conversion Program) for converting cropland to forest is one of China's most ambitious environmental initiatives, and is one of the world's largest land-conservation programs with a budget of RMB 337 billion (over US$ 40 billion). Although environmental impacts have played a vital role in the general reasoning and argumentation for forest plantations, environmental impact analyses have often received less attention than economic analyses in the planning of plantation forestry projects. The overall goal of this paper is to evaluate the program's environmental impact considering the farmer's interests and the potential social benefits due to carbon sequestration in different scenarios based on household and field survey data in Dunhua County. Our findings are that: (1) in many cases, the program did not give adequate consideration to land productivity and environmental heterogeneity when selecting plots; (2) more than half of the reforestation plots were on flat cropland (slopes of less than 5 degrees ); (3) in five of the eight townships, net incomes on reforested land were substantially above or below previous crop incomes, raising questions about the efficiency of the allocation of compensation to farmers participating in the program; (4) the potential carbon co-benefit increased the NPV of the program by 5954-7009 RMB/ha. In conclusion, we recommend that more attention should be paid to the quality of reforestation programs rather than just their scale and note that consideration of potential carbon sequestration co-benefits enhances the benefits of cropland conversion programs.     

Stormwater runoff quality from different surfaces in an urban catchment in Beijing, China

Urban stormwater runoff quality, widely investigated around the world, has been monitored less in Beijing, China, which impedes the municipal government to use best management practices to protect surface water. In this study, rainwater and stormwater runoff samples from roofs, roads, and a lawn on the campus of the Research Center for Eco-Environmental Sciences (RCEES) (Beijing, China) and from a ring road, with heavy traffic, have been sampled and analyzed for 31 storm events from June 2004 to August 2005. Total suspended solids (TSS), chemical oxygen demand (COD), 5-day biochemical oxygen demand (BOD5), total nitrogen, and total phosphorus concentrations in rainwater and runoff ranged over 2 or more orders of magnitude, meaning that the highest concentration of a certain pollutant did not always occur in a certain kind of runoff. Runoff contained significantly higher concentrations of pollutants than rainwater. On the campus of RCEES, TSS and total phosphorus in runoff samples from the lawn and roads were significantly higher than those from roofs, while the COD, BOD5, and total nitrogen concentrations were not significantly different in runoff among surfaces. Compared with runoff from the roads on campus, runoff from the ring road contained more COD and total nitrogen, but less TSS, BOD5, and total phosphorus. All pollutants measured in runoff from roofs on campus and from the ring road showed a peak concentration in starting runoff, which then decreased sharply. The peak concentrations of COD, BOD5, total nitrogen, and total phosphorus in the roof runoff increased with the increase in time of the antecedent dry period. Thus, urban stormwater pollution control, especially for first-flush control, is of great importance for the full use of rainwater and prevention of water pollution.     

改良型A2／O-MBR工艺的反硝化除磷性能研究

重点考察了-种改良型膜生物反应器（A2／O—MBR）的脱氮除磷性能。该工艺主要特点在于对膜池硝化回流液进行了固液分离，并将上清液和浓缩污泥分别回流至缺氧池和厌氧池，这种改进提高了系统对氮、磷的同步去除效率。实验结果表明，在水力停留时间（HRT）为12h，污泥龄（SRT）为30d，混合液回流比为200％的运行条件下，进水COD、NH4＋-N、TN和TP平均浓度分别为（225±38）、（24．8±3．9）、（26．7±2．9）和（2．90±0．53）mg／L时，增加膜池硝化回流液固液分离装置前后，系统对COD和NH4＋-N的去除都维持在较高水平，而系统对TN和TP的去除效果显著提高，出水TN和TP平均浓度分别由（14．9±3．3）mg／L和（1．95±0．72）mg／L下降到（9．4±1．9）mg／L和（0．91±0．38）mg／L，表明增加膜池硝化回流液固液分离装置显著改善了A2／O-MBR系统的脱氮除磷效果。反硝化除磷活性实验结果进一步表明，改进后系统中反硝化除磷活性占总除磷活性的比例由51．5％上升至61．7％，说明增加膜池硝化回流液固液分离装置强化了系统的反硝化除磷性能。     

Simulation of phytoremediation of a TNT-contaminated soil using the CTSPAC model

Knowledge of water movement in the plant-xylem system and contaminant bioavailability in the soil environment is crucial to evaluate the success of phytoremediation practices. This study investigated the removal of 2,4,6-trinitrotoluene (TNT) from a contaminated sandy soil by a single poplar (Populus fastigiata) tree through the examinations of temporal variations of xylem water potential, root water uptake, and soil TNT bioavailability. A mathematical model, CTSPAC (Coupled Transport of water, heat, and solutes in the Soil-Plant-Atmosphere Continuum), was modified for the purpose of this study. The model was calibrated using laboratory measurements before its application. Our simulations show that the xylem water potential was high in the roots and low in the leaves with a potential head difference of 3.55 cm H2O, which created a driving force for water flow and chemical transport upward from the roots through the stem to the leaves. The daily average root water uptake rate was 25 cm3 h(-1) when an equilibrium condition was reached after 24 h. Our simulations further reveal that no TNT was found in the stem and leaves and only about 1% of total TNT mass was observed in the roots due to the rapid biodegradation and transformation of TNT into its daughter products. About 13% of the soil TNT was removed by the poplar tree, resulting mainly from root uptake since TNT is a recalcitrant compound. In general, the soil TNT bioavailability decreased with time due to the depletion of soil solution TNT by the poplar tree. A constant bioavailability (i.e., 3.1 x 10(-6)) was obtained in 14 d in which the soil TNT concentration was about 10 mg L(-1). Our study suggests that CTSPAC is a useful model to simulate phytoremediation of TNT-contaminated sites.     

THREE‐DIMENSIONAL KRIGING ANALYSIS OF SEDIMENT MERCURY DISTRIBUTION: A CASE STUDY1

ABSTRACT: This study presents an application of a three‐dimensional kriging technique to estimate spatial distribution of total mercury (Hg) in the Cedar‐Ortega Rivers watershed located in the lower St. Johns River basin, Florida. The kriging procedures, including preliminary data analysis, structural data analysis and the log kriging estimation, are presented. Results show watershed wide Hg contamination of river sediment to a depth of 1.0 m. A three‐dimensional plot of Hg against the Florida Sediment Assessment Guidelines (i.e., the probable effect level or PEL) demonstrates that the Cedar River is more contaminated with Hg than the rest of the watershed. The maximum sediment depth with Hg concentrations above PEL value (0.696 mg/kg) is 1.5 m. Hg concentrations at or above this level could pose a significant hazard to aquatic organisms. Analysis of the spatial distribution of Hg in the watershed finds multiple input sources. This study suggests that there is a need to identify the major sources of Hg in the watershed, and to determine the pathways that allow Hg to enter the river.