农村工业化进程中的土地资源优化配置研究——以浙江永康市为例

在阐述农村工业化与土地资源优化配置关系问题的基础上，以浙江永康市为例，对当前我国农村工业化过程中土地资源优化配置问题进行了研究。研究表明，永康目前处于工业化中期阶段，工业用地扩张趋势明显，但同时也存在用地结构布局不甚合理、集约利用程度较低以及环境影响等问题。解决这些问题可通过切实保护耕地，合理安排建设用地规模与布局，提高土地集约利用率和控制环境污染等有效途径。     

Plutonium in groundwater at the 100K-Area of the U.S. DOE Hanford Site

We examined the concentration, size distribution, redox state and isotopic composition of plutonium (Pu) in groundwater at the 100K-Area at the U.S. Department of Energy's (DOE) Hanford Site. Total concentrations of Pu isotopes were extremely low (10(-4) to 10(-6) pCi/kg, approximately 10(4) to 10(6) atoms/kg) but measurable for the first time in the 100K-Area wells using mass spectrometric analyses that are much more sensitive than alpha spectroscopy methods used previously. Size fractionation data from two wells suggest that 7-29% of the Pu is associated with colloids, operationally defined here as particles between 1 kDa-0.2 microm in size. These colloids were collected using a 1 kDa cross-flow ultrafiltration (CFF) system developed specifically for groundwater actinide studies to include careful controls both in the field and during processing to ensure in situ geochemical conditions are maintained and size separations can be well characterized. Pu in this colloidal fraction was exclusively in the more reduced Pu(III/IV) form, consistent with the higher affinity of Pu in the lower oxidation states for particle surfaces. While the overall concentrations of Pu were low, the Pu isotopic composition suggests at least two local sources of groundwater Pu, namely, local Hanford reactor operations at the 100K-Area and spent nuclear fuel from the N-reactor, which was stored in concrete pools at this site. Differences between this site and the Savannah River Site (SRS) are noted, since groundwater Pu at the F-Area seepage basin at SRS has been found using these same methods, to be characterized by lower colloidal abundances and higher oxidation states. This difference is not directly attributable to groundwater redox potential or geochemical conditions, but rather the physical-chemical difference in Pu sources, which at SRS appear to be dominated downstream from the seepage basins by decay of 244Cm, resulting in more oxidized forms of 240Pu. There is no clear evidence for colloid facilitated transport of Pu in groundwater at the Hanford Site, since downstream wells have both an order of magnitude lower concentrations of Pu and a lower fractional colloidal distribution.     

低瓦斯综采放顶煤工作面通风除尘的研究

通过对低瓦斯综采放顶煤工作面的研究,选择了合理的通风方式和最优排风速和,即有利于工作面降温,保证了工作面安全生产.     

Adsorption and desorption of iodine by various Chinese soils: I. Iodate

In order to assess the adsorption of iodate by different soils from China, a series of batch experiments were conducted. It was found that soils rich in iron oxide had high affinity for iodate. Iodate adsorption isotherms could be well fitted with both Langmuir and Freundlich equations. Iodate adsorption by 20 different soils from China revealed that iodate adsorption was significantly correlated with soil organic matter negatively and positively with free iron oxide contents. At initial concentration of 4 mg I L(-1), iodate adsorption ranged between 9 and 34 mg kg(-1) soil. No correlation between iodate adsorption and cation exchange capacity and soil pH was found. For a single soil, there was a significant linear relationship between the amounts of iodate adsorbed and desorbed, but for a group of different soils, the relationship between the amounts of iodate adsorption and desorption followed a nonlinear relationship, the deviation mainly occurred at high adsorption side. The relationship between K(d) and free aluminum oxide and free iron oxide contents showed an exponential relationship for various soils with exception of the soil from Hetian in Xinjiang.     

2,3,7,8-四氯代二苯并噻吩在锦鲫不同组织中的生物富集及对肝脏的氧化损伤

研究了含硫"类二噁英"化合物多氯代二苯并噻吩(PCDTs)中的2,3,7,8-四氯代二苯并噻吩(2,3,7,8-TCDT)在锦鲫(Carassius auratus)不同组织中的生物富集规律和对肝脏的氧化损伤.结果表明,2,3,7,8-TCDT在锦鲫各组织中的富集能力表现为肝脏>鳃>肌肉.2,3,7,8-TCDT在锦鲫...     

基于动态贝叶斯网络的石化装置火灾事故动态风险分析

为揭示石油炼化装置事故风险动态特性和事故情景演变路径,在对石化装置进行风险因素分析的基础上构建石化装置火灾事故故障树,基于贝叶斯网络非常规突发事故的演变过程,构建情景演变下的动态贝叶斯网络模型,在综合考虑应急措施的基础上,利用MATLAB软件和联合概率公式计算出各种事故场景的状态概率.以丙烯精馏装置火灾事故为例,结果表...     

乙醛清洁生产工艺的模拟研究

在对乙醇路线制备乙醛生产过程中乙醛分离提纯工艺进行分析的基础上,提出废水循环回用的乙醛清洁生产工艺,运用序贯模块法建立系统的数学模型。通过计算机求解,得出一系列参数。研究结果表明,该工艺可以达到减少废水排放量、提高非目标产物出口浓度的目的。     

半经验生物滴滤器模型研究

生物滴滤(BTF)净化有机废气是一个复杂的过程,其数学模型往往形式繁琐、参数众多,实际应用比较困难.半经验生物滴滤模型是基于生物酶促反应基本原理(米-门方程),并在含苯废气的生物滴滤净化动态实验和生物膜静态实验等研究的基础上建立和完善的一个应用模型.为了符合生物滴滤器内的实际状况,在建模过程中引入了微生物质量浓度沿床层深度变化的函数等合理假设.模型的检验采用将静态实验所得参数代入模型计算,并与生物滴滤动态实验结果进行对比的方法.检验结果表明:在较宽的负荷、表观过滤气速范围内,该模型对滴滤器的模拟值均较符合实验值.该模型的数学形式简单,参数也较少,且主要参数,如生物膜最大净化速率,K值及微生物质量浓度分布等均可通过生物膜静态实验测得.      

SJ10000风机出口气流强烈脉动现象初探

通过对 SJ10 0 0 0风机运行工况进行监测 ,对管网系统进行校验 ,以此为依据对风机出口强烈脉动现象进行了分析。采取降低管道阻力或提高风机静压力等措施来消除风机出口气流强烈脉动。     

典型醛类污染物与细胞DNA分子的结合作用

为了研究甲醛、乙醛和丙烯醛等 3种典型醛类污染物与细胞DNA的结合作用 ,探讨其遗传毒性效应和机制 ,采用体外测试系统 ,应用紫外光谱移动法和高效液相色谱法研究结合位点 .结果表明 ,醛类污染物染毒细菌DNA紫外吸收峰位移不显著 ;但提取的细菌DNA与甲醛进行试管反应体系紫外位移显著 ;醛类污染物染毒真核细胞致DNA分子紫外吸收峰位移显著 ;乙醛与脱氧鸟苷酸的试管反应经NaBH₄ 还原后经HPLC分离检测 ,产物初步定性为N2-乙基鸟苷加合物 .说明 3种醛类污染物能够与细胞DNA结合而体现遗传毒性 ,鸟苷的N2位可能是共价加合的位点 .