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81.
PDCA循环模式是HSE管理体系运行的最基本方式,也是实现体系绩效螺旋式上升的重要手段.在体系运行的过程中,经过PDCA等各个环节以及各环节涉及到的诸多要素的不断发展与完善,体系的目标与方针得以实现.从管理体系实际运行的角度来看,整个体系运行过程中的PDCA循环又可以分为以下层次:单要素间某几个管理方面的相互影响与作用;几个要素之间形成的PDCA循环;大部分要素(关键要素)之间的作用;整个体系的PDCA循环.这几层次的循环模式也是相互交叉相互作用的.现以表1所涉及的工作为例,探讨这几个层次PDCA循环的相关性. 相似文献
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基于2009年4月28日、5月4日、5月5日及5月6日在太湖梅梁湾的栈桥头、直湖港的河口区、太湖中心及胥口湾中心测定的初级生产力及水下光场数据,计算了各测点的藻类光量子产额和P-I曲线,并分析了其空间差异的特征.太湖栈桥头的P-I曲线呈现出明显的光抑制现象;在胥口湾中心和直湖港河口,P-I曲线呈现出弱的光抑制现象;而在太湖中心区域,P-I曲线只达到了光饱和状态,并未出现光抑制现象.单位叶绿素a的最大光量子产额的大小顺序为太湖中心区域、梅梁湾的栈桥头、直湖港的河口区及胥口湾的湖心区. 相似文献
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Sedimentary record of polycyclic aromatic hydrocarbons in Lake Erhai,
Southwest China 总被引:1,自引:0,他引:1
Jianyang Guo Zhang Liang Haiqing Liao Zhi Tang Xiaoli Zhao Fengchang Wu 《环境科学学报(英文版)》2011,23(8):1308-1315
The temporal distribution of polycyclic aromatic hydrocarbons (PAHs) was investigated in a sediment core from Lake Erhal in Southwest China using gas-chromatography/mass spectrometry (GC/MS) method.The total organic carbon (TOC) normalized total PAHs concentrations (sum of US Environmental Protection Agency proposed 16 priority PAHs) ranged from 31.9 to 269 μg/g dry weight (dw),and were characterized by a slowly increasing stage in the deeper sediments and a sharp increasing stage in the upper sediments.The PAHs in the sediments were dominated by low molecular weight (LMW) PAHs,suggesting that the primary source of PAHs was low- and moderate temperature combustion processes.However,both the significant increase in high molecular weight (HMW) PAHs in the upper sediments and the vertical profile of diagnostic ratios pointed out a change in the sources of PAHs from low-temperature combustion to high-temperature combustion.The ecotoxicological assessment based on consensus-based sediment quality guidelines implied that potential adverse biological impacts were possible for benzo(ghi)perylenelene and most LMW PAHs.In addition,the total BaP equivalent quotient of seven carcinogenic polycyclic aromatic hydrocarbons (BaA,CHr,BbF,BkF,BaP,DBA and INP) was 106.1 ng/g,according to the toxic equivalency factors.Although there was no great biological impact associated with the HMW PAlls,great attention should be paid to these PAH components based on their rapid increase in the upper sediments. 相似文献
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Adsorption and degradation of levonorgestrel (LNG) by two hydrophytes, Cyperus alternfolius (CA) and Eichhornia crassipes (EC), were investigated under light-shielding conditions in the water column. Variations of LNG concentrations in water, plant root epidermis, root, stem and leaf of the plants were analyzed. The results indicated that the removal efficiency of LNG by hydrophytes over the period of 50 days was significantly greater than the blank control (p 〈 0.05), with the removal rates of 79.80%± 3.10% and 78.86% ± 2.55% for CA and EC, respectively. Compared with bio-adsorption, bio-conversion of LNG was found to be the dominant elimination pathway, evidenced by relatively high conversion rates (77.31% ±2.68% for CA and 77.82% ± 2.95% for EC), while the adsorption rates were lower (1.77% ± 0.90% for CA and 1.05% ± 0.40% for EC). The bio-adsorption and conversion of LNG showed no significant differences between the two hydrophytes. Additionally, the mineralization on root epidermis played an important role in the reduction of LNG in water. 相似文献
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