Dendroremediation of trinitrotoluene (TNT) part 1: Literature overview and research concept

BACKGROUND, AIM AND SCOPE: For decades, very large areas of former military sites have been contaminated diffusely with the persistent nitroaromatic explosive 2,4,6-trinitrotoluene (TNT). The recalcitrance of the environmental hazard TNT is to a great extent due to its particulate soil existence, which leads to slow but continuous leaching processes. Although improper handling during the manufacture of TNT seems to be a problem of the past in developed countries, environmental deposition of TNT and other explosives is still going on unfortunately, resulting from thousands of unexploded ordnance or low order explosions at munitions test areas and at current battlefields. OBJECTIVE: Sustainable phytoremediation strategies for explosives in Germany, which intend to use trees to decontaminate soil and groundwater ('dendroremediation'), have to consider that most of the former German military sites are already covered with woodlands, mainly with conifer stands. Therefore, parallel investigation of the remediation potential is necessary for both of the selected hybrids of fast growing broadleaf trees, which are waiting for planting and forest conifers, which have already proven for decades that they are able to grow on explosive contaminated sites. MAIN FEATURES: A short literature review is given regarding phytoremediation of TNT with herbaceous plants and some general aspects of dendroremediation are discussed. Furthermore, an overview of our TNT-dendroremediation research network is introduced, which has the strategic goal to make dendroremediation more calculable for a series of potent trees for site-adapted in situ application and for the assessment of tree remediation potentials in natural attenuation processes. RESULTS AND DISCUSSION: Some of our methods, results and conclusions yet unpublished are presented. For a preliminary calculation of area-related annual TNT dendroremediation potential of five-year-old trees, the following values were assessed: Salix EW-13 6.0, Salix EW-20 8.5, Populus ZP-007 4.2, Betula pendula 5.2, Picea abies 1.9 and Pinus sylvestris 0.8 g m(-2) a(-1). For a 45-year-old spruce forest, an annual natural attenuation potential of 4.2 g TNT m(-2) a(-1) was found. CONCLUSION, RECOMMENDATIONS AND PERSPECTIVE: Our main results deliver quantitative proposals for dendroremediation strategies in situ and provide decision aids. Also aspects of growth of raw materials for energy production are considered. Our dendroremediation research concept for TNT and its congeners can be easily completed for other trees of interest and it can also be applied to herbaceous plants. Knowing the current bottlenecks of phytoremediation and considering the known environmental behaviour of other contaminants, elements of our methodological approach may be easily adapted to those pollutant groups, e.g. for pesticides, pharmaceuticals, PAHs, chlorinated recalcitrants and, with some restrictions, to inorganics and to multiple contaminations. Our dynamical dendrotolerance test systems will help to predict tree growth on polluted areas. To provide some light into the black box of TNT dendroremediation, experimental data regarding the uptake, distribution and degradation of [14C]-TNT in mature tree tissues will be reported in the second part of this publication.     

铁铝吸附剂对起爆药污染土壤中锑的稳定化研究

采用3种铁基吸附剂（FeSO₄•7H₂O、针铁矿、Fe⁰）和铝基吸附剂（Al（OH）₃）,对某起爆药污染场地土壤中锑（Sb）进行稳定化处理,通过等温吸附实验、批量浸出实验、比表面积测定以及BCR分析,研究了铁、铝单一和混合吸附剂的稳定化效果以及稳定化前后土壤比表面积及Sb形态的变化.结果表明：不同铁基吸附剂对Sb的等温吸附符合Freundlich模型,FeSO₄ （log K_f= 5.85）的吸附能力明显高于Fe⁰ （log K_f = 3.21）和针铁矿（log K_f = 4.32）;稳定时间为10d的条件下,不同铁基吸附剂对Sb的稳定化效率随添加量的增大而提高,且10%FeSO₄（97.1%） > 10% Fe⁰（72.3%） > 针铁矿（41.0%）;FeSO₄的添加明显促进了土壤中Zn、Cu、Pb的浸出,达到原土壤浸出浓度的1990.2、2.8倍和21.6倍,添加Al（OH）₃后能够显著降低Zn、Cu、Pb的浸出浓度,添加量为4%时,稳定化效率分别达到93.8%（Zn）、93.5%（Cu）和98.3%（Pb）;5%FeSO₄和4% Al（OH）₃混合吸附剂对Sb及Zn、Cu、Pb的综合稳定化效率最好,处理10d后稳定化效率最高可达94.6%、74.2%、82.2%和97.6%;进一步分析表明,混合吸附剂添加后比表面积能够达到原土壤的1.31~1.67倍,残渣态Sb比例增加0.037~0.197倍,与稳定化效果相一致,表明铁铝混合吸附剂是处理起爆药污染场地复合重金属污染土壤的有效途径.     

火炸药装药实验室寿命评估标准体系研究

为解决我国火炸药装药寿命评估标准工作滞后、体系缺失等问题,规范和指导火炸药装药寿命评估工作,提升寿命评估结果的准确性和认可度,从火炸药装药实验室寿命评估技术体系出发,探讨了火炸药装药寿命评估的流程及技术要求。参照北约弹药装药安全性及寿命评估的相关标准情报资料,构建了我国火炸药装药实验室寿命评估标准体系框架,明确了标准体系建设内容。提出我国火炸药装药实验室寿命评估标准体系按照系统科学、层次分明、综合开放的思路进行构建,分为顶层规范类标准、设计类标准、操作类标准3个层次。     

Research on the critical temperature of thermal decomposition for large cartridge emulsion explosives

Emulsion explosives are one type of main industrial explosives. The emergence of the large cartridge emulsion explosives has brought new security incidents. The differential scanning calorimeter (DSC) and the accelerating rate calorimeter (ARC) were selected for the preliminary investigation of the thermal stability of emulsion explosives. The results showed that the initial thermal decomposition temperatures were in the range of 232–239 °C in nitrogen atmosphere (220–232 °C in oxygen atmosphere) in DSC measurements and 216 °C in ARC measurements. The slow cook-off experiments were carried out to investigate the critical temperature of the thermal decomposition (T_c) of the large cartridge emulsion explosives. The results indicated that the larger the diameter of the emulsion explosives, the smaller the T_c is. For the large cartridge emulsion explosives with diameter of 70 mm, the T_c was 170 °C at the heating rate of 3 °C h⁻¹. It is a dangerous temperature for the production of the large cartridge emulsion explosives and it should cause our attention.     

不敏感装药高温相变影响机制研究进展与思考

综述了HMX、CL-20以FOX-7等未来不敏感装药主要候选组分的相变研究进展,归纳了高温相变对安全性带来影响的几个原因,主要包括炸药本身的稳定性下降、炸药密度改变及炸药内部缺陷增加的原因。针对如何降低高温相变对不敏感装药安全性的影响进行了初步思考,认为目前为了降低高温相变对炸药安全性的影响,主要手段仍是对相变进行一定程度的抑制,而共晶技术、包覆技术、晶型控制剂抑制技术和配方抑制相变技术是未来相变抑制技术的主要研究方向。     

炸药缓慢加热条件实验技术进展

为降低炸药装药意外热刺激起爆后对武器平台、后勤系统和人员损伤的严重程度及概率,适应不敏感弹药发展过程中对炸药热危险性综合评定的需要,有针对性地分析了以美国为主的炸药和弹药装药慢烤燃实验相关文献、STANAG 4382《北约弹药缓慢加热测试标准》调查报告以及西安近代化学研究所开展的密闭系统的模拟弹慢速烤燃实验研究成果。分析结果发现,尚需解决的问题为3.3℃/h温升速率条件起源未知,小型模型实验技术是目前开展的重点,可视化/量化反应状态的实验技术及仿真预测试验反应剧烈程度的模型研究是发展重点,试验反应剧烈性抑制技术研究是未来的发展趋势。     

某RDX基浇注PBX的加速老化规律与寿命评估

目的掌握环三亚甲基三硝胺(RDX)基浇注高聚物黏结炸药(PBX)的加速老化规律,分析老化机理和关键敏感参量,并探讨加速老化寿命评估方法。方法针对RDX基浇注PBX开展60、70、80℃等恒定温度下的加速贮存老化试验,采用微焦点X射线计算机断层扫描仪(微焦点CT)、核磁共振、气相色谱等方法,分析浇注炸药在老化过程中微孔隙率、交联密度以及增塑剂含量等结构参量的变化规律,通过对这几种参量的对比,分析其老化机理,并进一步对加速老化寿命评估方法进行初步探讨。结果浇注PBX在加速老化过程中会出现明显的孔隙率逐渐增加、交联密度逐渐增加以及增塑剂逐渐降低等问题,且表现为温度越高,相关性能参量变化得越快。鉴于增塑剂含量的降低理论上会导致孔隙率增加,且增塑剂具有降低感度的作用,对于侵彻安定性具有较大的影响,且增塑剂含量的表征方法简便,以增塑剂含量作为浇注PBX的敏感参量,采用阿伦尼乌斯模型,对浇注PBX的寿命进行了评估。结论RDX基浇注PBX在加速老化过程中孔隙率、交联密度以及增塑剂含量会出现较为明显的变化,可作为性能评价的敏感参量。以增塑剂含量作为敏感参量,以增塑剂含量降低10%为判据,推导出RDX基浇注PBX的寿命约为14.5 a(25℃)和23.8 a(21℃)。     

某市小型民用爆炸物品地面储存库安全现状调查

主要依据国家关于民用爆炸物品地面储存库的有关法律法规、标准规范,对某市辖区内的47家小型民用爆炸物品地面储存库的安全现状进行了调查分析。通过调查发现当地小型民用爆炸物品地面储存库主要存在内外部安全距离不足,建筑结构不合格,防雷设施不合格,雷管库的保险柜未作防静电接地,民用爆炸物品未按规定安全摆放,安全管理不到位等6个方面的问题。对发现的问题,简要分析了原因,并提出了针对性的措施和建议,为某市民用爆炸物品地面储存库安全管理的标准化和规范化提供参考。     

基于可变模糊集理论的硫化矿炸药自爆危险性评价

为了判定某高硫矿山的炸药自爆危险性,采用可变模糊集理论对矿山中的黄铁矿含量、装药时间等8个影响炸药自爆的因素进行评价。根据可变模糊评价模型确定指标评价区间矩阵Iab、可变范围评价区间Icd和点值矩阵M,利用熵权法确定各影响因素权重,并根据指标特征值xij,Mih得到综合相对隶属度矩阵,结合判断准则得出该矿山炸药自爆危险性等级。研究结果表明:该矿山的炸药自爆危险等级为Ⅱ级,自爆危险性一般,与实际生产情况相符,可变模糊集理论在评价炸药自爆危险性时具有有效性。