天然次生林人工更新后对土壤物理性质及碳贮量的影响

天然林被人工林取代后对土壤水文物珲性质及土壤碳贮量有重要的影响.文章以海南天然次生林人工更新为尾细桉(Eucalyptus urophylla×E.tereticornis)和马占相思(Acacia mangium)林前后的土壤为研究对象,研究分析了人工植被更新对土壤水文物理性质和土壤碳贮量的影响.结果表明:天然次生林更新为桉树、马占相思人工林后,土壤容重增加,土壤总孔隙度、毛管孔隙度和非毛管孔隙度减小,0～80 cm土壤的最大贮水量、毛管贮水量和非毛管贮水量降低,桉树和马占相思人工林最大贮水量分别降低19.8 mm和43.3mm,桉树人工林0～40cm土壤碳贮量降低6.77t·hm-2,马占相思人工林的增加14.68t·hm-2.     

综合环境下舰载导弹弹上计算机加速寿命试验研究

目的 研究一种综合考虑陆上环境与舰船环境多应力下的舰载导弹弹上计算机加速寿命试验方法,能更具代表性和真实性地描述产品在综合环境条件下的环境应力,进而为环境应力剖面尽可能准确地折算为加速应力剖面奠定基础。通过加速寿命试验,将产品贮存时间加速至目标年限,验证与评估产品剩余贮存寿命。方法 针对舰船工作环境条件,从搭载研究对象的舰船出海海况入手,利用海况与舰船振动量值的对应关系,确定舰船振动应力。结合考虑综合环境下的其他应力,研究出一种结合温度–振动–电应力等环境条件的加速试验方法,以已经达到设计贮存寿命期限的舰载导弹弹上计算机为试验对象,开展温度–振动–电应力综合加速寿命试验。结果 通过运用温度–振动–电应力的加速寿命试验方法,验证和评估了某型舰载导弹弹上计算机具备延寿至目标年限的剩余贮存寿命,取得了良好的试验效果。结论 根据舰船工作环境对贮存寿命的影响,针对性地研究了舰船振动加速试验,给出一个更加贴合实际寿命的寿命评估结果,为后续延寿研究工作提供了可靠依据。     

Organically modified low-grade kaolin as a secondary containment material for underground storage tanks

Batch scale reactions were conducted to evaluate the efficacy of modified low-grade kaolin for the treatment of petroleum contaminants. Low-grade kaolin, which has been unvalued as material in the mining process because of its low quality for commercial products, was modified with HDTMA (hexadecyl-trimethylammonium), and its efficiency was compared with that of HDTMA-modified bentonite, which is used as a secondary containment barrier for underground storage tanks. The sorption capacity and hydraulic conductivity of both the HDTMA-modified bentonite and low-grade kaolin were investigated and showed distribution coefficients in the sorption of benzene, toluene, ethylbenzene and xylene ranging between 45.7 and 583.7 and 57.0 and 525.1, respectively. The hydraulic conductivities were 2.53 × 10⁻⁸ and 5.62 × 10⁻⁸ cm/s for the HDTMA-modified bentonite and low-grade kaolin, respectively. These results suggest that HDTMA-modified low-grade kaolin could be used as a hydraulic barrier against advection migration of petroleum contaminants. Simulation of the one-dimensional transport of benzene through a liner made of either one of the compounds was also performed. These results also showed that HDTMA-modified kaolin more effectively retards the transport of benzene.     

三江平原湿地沉积有机碳密度和碳储量变异分析

论文研究了东北三江平原3类典型湿地共16个沉积物剖面有机碳的分布特征。结果表明,沼泽化草甸、腐殖质沼泽和泥炭沼泽的储碳层厚度分别为11～29、18～58和70～130cm;其有机碳含量(单个剖面平均)分别为29～75、124～348和187～389g/kg(干物质计);有机碳密度(单个剖面平均)分别为31～48、35～59和49～94kg/m³。3类湿地淀积层的有机碳含量和密度都很低且较稳定。由于有机碳含量的差异,不仅3类湿地之间而且同一类型湿地的不同剖面间有机碳密度的差异也十分明显。储碳层厚度及有机碳密度的空间变异性是导致湿地有机碳储量估算不确定性的主要原因。根据研究结果估算,沼泽化草甸、腐殖质沼泽和泥炭沼泽储碳层单位面积碳储量分别约为8×10³、18×10³和72×10³t/km²,其变异系数分别约为40%、49%和34%;“储碳层+1m淀积层”的单位面积碳储量分别约为17×10³、27×10³和83×10³t/km²,其变异系数分别约为16%、39%和27%。表明以“储碳层+1m淀积层”深度来估算碳储量能较合理地反映湿地沉积物有机碳的蓄积特征。结果还表明,以1m作为统计深度将在很大程度上低估湿地的碳储量。     

水生野生动物自然保护区环境规划指标体系的建立

从水生野生动物自然保护区的特点和实际情况出发,分析了水生野生动物自然保护区环境规划指标体系建立的原则,采用层次分析法筛选指标,建立了基于PSR框架模型的水生野生动物自然保护区环境规划指标体系.应用该指标体系对怀沙河、怀九河水生野生动物保护区进行环境功能区划,得到与实际情况较为符合的区划结果.说明该指标体系能够较为全面、准确地描述保护区的实际情况.     

自然循环式污水处理系统及应用实例研究

自然循环污水处理系统(naturalcirculationsystem,NC)是日本研究开发的一种新型的污水人工渗滤处理系统,该技术将落叶、木屑、木炭和石头等自然材料作为填料,并通过各处理单元的有效组合,使该装置内的生物净化功能达到最佳效果。在江苏省宜兴市建立的示范工程显示:NC系统对污水中几个代表性水质指标有较好的去除,CODCr、BOD5、TP和NH+4N等指标基本去除率分别为4951%~9513%、50%~80%、3560%~7813%和7198%~9844%。     

Profiling unauthorized natural resource users for better targeting of conservation interventions

Unauthorized use of natural resources is a key threat to many protected areas. Approaches to reducing this threat include law enforcement and integrated conservation and development (ICD) projects, but for such ICDs to be targeted effectively, it is important to understand who is illegally using which natural resources and why. The nature of unauthorized behavior makes it difficult to ascertain this information through direct questioning. Bwindi Impenetrable National Park, Uganda, has many ICD projects, including authorizing some local people to use certain nontimber forest resources from the park. However, despite over 25 years of ICD, unauthorized resource use continues. We used household surveys, indirect questioning (unmatched count technique), and focus group discussions to generate profiles of authorized and unauthorized resource users and to explore motivations for unauthorized activity. Overall, unauthorized resource use was most common among people from poor households who lived closest to the park boundary and farthest from roads and trading centers. Other motivations for unauthorized resource use included crop raiding by wild animals, inequity of revenue sharing, and lack of employment, factors that created resentment among the poorest communities. In some communities, benefits obtained from ICD were reported to be the greatest deterrents against unauthorized activity, although law enforcement ranked highest overall. Despite the sensitive nature of exploring unauthorized resource use, management‐relevant insights into the profiles and motivations of unauthorized resource users can be gained from a combination of survey techniques, as adopted here. To reduce unauthorized activity at Bwindi, we suggest ICD benefit the poorest people living in remote areas and near the park boundary by providing affordable alternative sources of forest products and addressing crop raiding. To prevent resentment from driving further unauthorized activity, ICDs should be managed transparently and equitably.     

Simulating on rollover phenomenon in LNG storage tanks and determination of the rollover threshold

Rollover is a potential risk to the safety of LNG storage tanks during the LNG storage process, so study of its prevention method is very important. In this paper, rollover phenomenon in a liquefied natural gas (LNG) storage tank is modeled physically and mathematically. Its evolution is simulated using FLUENT™ software from the breakdown of stratification to the occurrence of rollover. Results show that the evolution consists of three phases: the initial phase where rollover occurs near the side wall of the storage tank; the turbulent phase where rollover transfers to the center of the tank; and the final phase where new layers evolve. Based on these phases, rollovers in 160,000, 30,000, and 5000 m³ LNG storage tanks are simulated at varying initial density differences, and a rollover coefficient is defined to describe rollover intensity. The simulations show that the rollover coefficient initially increases within a small scope and then increases rapidly with the increment of initial density difference. This turning point is chosen to be the rollover threshold, which is regarded as the critical density difference in this study. The critical density differences obtained from the simulation results of the 160,000, 30,000, and 5000 m³ LNG storage tanks are 3, 5, and 7 kg/m³, respectively, which can be used as their rollover criteria to ensure the safety of LNG storage tanks.     

Population Growth,Available Resources,and Quality of Life:China’s Post-Reform Economic Development

Two opposing intellectual traditions and their contem-porary developments regarding the relations among population, available resources, and quality of life as reflected in economic growth are reviewed. What is at issue is whether population growth is detrimental to or beneficial for economic development. Neither of the extreme views gives a complete picture of the interplay among population, resources, and quality of life. Following previous literature on the topic, this paper establishes a more balanced approach that considers the function linking population and quality of life not constant but variable and regards the limitedness of resources as not absolute but relative to regions and societies. The proposed approach is more flexible in better explaining the relation between population and economic growth. China is examined as a case in point to shed light on the interaction of population growth, economic development, and available resources, and its recent post-economic reform experiences showcase the appropriateness of the synthetic approach.     

Assessment of mammal reproduction for hunting sustainability through community‐based sampling of species in the wild

Wildlife subsistence hunting is a major source of protein for tropical rural populations and a prominent conservation issue. The intrinsic rate of natural increase. (r_max) of populations is a key reproductive parameter in the most used assessments of hunting sustainability. However, researchers face severe difficulties in obtaining reproductive data in the wild, so these assessments often rely on classic reproductive rates calculated mostly from studies of captive animals conducted 30 years ago. The result is a flaw in almost 50% of studies, which hampers management decision making. We conducted a 15‐year study in the Amazon in which we used reproductive data from the genitalia of 950 hunted female mammals. Genitalia were collected by local hunters. We examined tissue from these samples to estimate birthrates for wild populations of the 10 most hunted mammals. We compared our estimates with classic measures and considered the utility of the use of r_max in sustainability assessments. For woolly monkey (Lagothrix poeppigii) and tapir (Tapirus terrestris), wild birthrates were similar to those from captive populations, whereas birthrates for other ungulates and lowland‐paca (Cuniculus paca) were significantly lower than previous estimates. Conversely, for capuchin monkeys (Sapajus macrocephalus), agoutis (Dasyprocta sp.), and coatis (Nasua nasua), our calculated reproductive rates greatly exceeded often‐used values. Researchers could keep applying classic measures compatible with our estimates, but for other species previous estimates of r_max may not be appropriate. We suggest that data from local studies be used to set hunting quotas. Our maximum rates of population growth in the wild correlated with body weight, which suggests that our method is consistent and reliable. Integration of this method into community‐based wildlife management and the training of local hunters to record pregnancies in hunted animals could efficiently generate useful information of life histories of wild species and thus improve management of natural resources.