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891.
完善西部地区水资源市场是当务之急 总被引:4,自引:0,他引:4
本文分析了西部地区完善水资源市场的必要性和存在的问题,并提出完善水资源市场的具体措施。 相似文献
892.
VIRGINIA GALLEGOS PÉRULA RAFAEL M. NAVARRO CERRILLO PILAR FERNÁNDEZ REBOLLOo GEMADEL VALLE MURILLO 《Environmental management》2003,31(1):0086-0099
The objective of this study was to examine postfire regeneration of tree, shrub, and dwarf shrub species, in relation to levels
of damage in four planted pine forests (Pinus pinea, Pinus pinaster) in Andalusia. A prefire vegetation map was used for detailing species composition, vertical structure, and density and another
for detailing the extent and intensity of fire damage. Between 3 and 7 years after the fires, an inventory was made of the
vegetation in each area, using the step-point method. The information thus obtained was used to determine the amount of cover
in the dwarf/shrub and tree layers, the frequency of species in each of the layers, floristic richness, and diversity (Shannon
index). The botanical composition of the dwarf and shrub layer was analyzed using TWINSPAN. Variables were poorly correlated
with level of fire damage, which suggests that the forests in this study followed the autosuccession model. Because of the
artificial origin or seminatural condition, regeneration of the dominant tree species is poor, and it seems unlikely that
forests will recover to their prefire state. Therefore action is recommended to restore these ecosystems. 相似文献
893.
Managing the activities of commercial wildlife viewing tends to involve either restricting the number of industry participants
and/or regulating the activities or industry participants. We report on operator compliance with regulations regarding humans
swimming with free-ranging bottlenose dolphins (Tursiops sp.) in Port Phillip Bay, Victoria, Australia. A total of 128 commercial dolphin-swim trips was studied between September
1998 and April 2000. Four permit conditions were investigated: approach type, swim time, time in proximity of dolphins, and
presence of “fetal fold” calves. Results demonstrate noncompliance by operators to all of the four permit conditions studied.
Compliance with temporal conditions was poorer than with other conditions. When conducting studies on the extent to which
tourism affects cetaceans, investigators should consider whether tourist operations comply with existing regulations or guidelines. 相似文献
894.
MARKKU T. KUITUNEN JOHANNA VILJANEN ESKO ROSSI ARTO STENROOS 《Environmental management》2003,31(1):0079-0085
The impact of dense traffic on the breeding success in pied flycatchers (Ficedula hypoleuca) was studied using roadside nest-boxes. Nest site selection and breeding success of flycatchers were observed in relation
to the distance from the road. The number of occupied territories was no higher closer to the road than it was deeper inside
the forest. The distance to the road had no effect on the laying date, clutch size, or brood size. However, nests closer to
the road were more likely to fail at the chick stage. The number of broods that were closer to roads and were lost completely
was significantly higher than those further away. As a consequence, the number of fledglings per breeding attempt decreased
closer to roads. The nestlings typically died as older chicks when the parent birds were providing them with maximum quantities
of food. A possible reason for the declining reproductive success was the traffic-related mortality of parent birds, as weather
conditions were not especially adverse for raising healthy offspring. 相似文献
895.
目的 探究 A517 海工钢在海洋全浸区环境下的腐蚀机理。方法 通过模拟海洋全浸区腐蚀环境,利用失重法、SEM、EDS、XRD、电化学等测试技术,分析A517钢的腐蚀行为历程,并探讨其在全浸区的腐蚀机理。结果A517钢在厚度方向上的最大电位差为 13 mV,小于发生电偶腐蚀的最小电位差50mV,说明材料在厚度方向上的腐蚀敏感性一致。随浸泡时间的延长,腐蚀质量损失量逐渐增加,平均腐蚀速率先降低、后升高、最后趋于稳定,腐蚀速率约为 0.127 mm/a。结论 腐蚀动力初期主要是由溶解氧的极限扩散控制,后期则是腐蚀产物的氧化还原电荷转移控制。腐蚀首先在 Al2O3、MgO 等夹杂物处萌生扩展,腐蚀产物出现明显的分层现象,外锈层主要是疏松易脱落的γ-FeOOH,内锈层主要是致密均匀的 Fe3O4,同时锈层中还检测到了β-FeOOH和α-FeOOH的存在。锈层中存在大量微裂纹,削弱了产物膜的保护作用,促进了腐蚀的进行。 相似文献
896.
微生物是调节土壤磷循环的关键驱动力.阐明土壤解磷菌的微生物矿化过程对于提高植物养分吸收率和作物产量具有重要意义.通过测定柑橘园与毗邻的自然林地土壤编码碱性磷酸酶基因(phoD)丰度、解磷细菌群落多样性和土壤无机磷组分,探究柑橘种植对土壤微生物获取磷策略的影响机制.结果表明,柑橘种植导致土壤pH下降,土壤有效磷累积,ω(有效磷)平均值高达112 mg·kg-1,显著高于毗邻的自然林地(3.7 mg·kg-1).柑橘种植也会影响土壤磷素组成,柑橘土壤含有较高的可溶态磷(CaCl2-P)、柠檬酸提取态磷(Citrate-P)和矿物结合态磷(HCl-P).自然林地土壤各磷组分均显著低于柑橘土壤,而phoD基因丰度和碱性磷酸酶活性显著高于柑橘土壤.高通量测序结果表明,柑橘土壤解磷细菌Shannon指数(4.61)显著低于自然林地(5.35),群落结构也有别于自然林地.柑橘种植改变了土壤解磷菌的群落组成,自然林地变形菌门的相对丰度显著低于柑橘土壤.土壤有效磷含量与碱性磷酸酶活性呈显著负相关,表明土壤高磷累积抑制土壤解磷细菌的活性.柑橘种植改变了土壤微生物对磷的获取策略,在柑橘园中,土壤微生物主要依赖外源磷,而自然林地土壤微生物主要以微生物分泌碱性磷酸酶矿化有机磷来获取磷的方式满足其生长需求. 相似文献
897.
难降解有机物的水解-酸化预处理 总被引:18,自引:0,他引:18
综述了水解-酸化作为难生物降解有机废水预处理工艺的应用情况,介绍了水解-酸化工艺的原理,分析了影响水解-酸化处理效果的部分因素。指出,对于难降解有机废水,水解-酸化是一种有效的预处理手段。 相似文献
898.
899.
阳离子交换树脂生产中废酸的回收利用及树脂质量控制 总被引:3,自引:0,他引:3
采用 酸套洗工艺代替传统的加水稀释洗涤工艺,成功地解决了阳离子交换树脂生产中废酸的回收利用问题,研究了采用新洗涤工艺后树脂变红的机理和防止对策,结果表明,树脂发红帅微生物的参与而引起的。采以完善洗涤 灭菌措施可防止树脂 ,从而确保了稀酸套洗工艺的顺利实施。 相似文献
900.