开发建设项目主体工程水土保持分析与评价探讨

主体工程水土保持分析与评价是开发建设项目水土保持方案的核心内容之一,具有承前启后的作用,对方案编制的科学性具有重要影响。根据多年从事水土保持方案编制、评审的体会和认识,指出主体工程水土保持分析与评价的基本内容和调查分析要点,并提出了"环境识别—工程建设扰动分析—水土保持措施要求—主体设计与要求比对分析—评价—优化主体设计或方案补充完善"的基本分析评价程序和思路。     

浅谈高速公路水保方案编制中应注意的问题

现行水土保持方案编制主要存在方案编制的滞后、土石方平衡的理想化、图纸的可操作性问题。建议编制公路水土保持方案时应注重收集设计主体工程相应阶段资料、工程周边环境基础资料及行政关系的理顺,方案编制过程中几个技术要点是水土流失预测及土石方平衡、防治责任范围及水土流失防治分区。     

云南生产建设项目水土保持方案编制存在问题及对策

生产建设项目水土保持及其水土流失防治是我国水土保持事业的重要内容之一,其中水土保持方案制度是生产建设项目水土保持工作科学顺利开展的首要保障,然而由于水土保持方案编制的市场性和开放性,造成很多水土保持方案在技术设计、措施布置、语言及逻辑组织方面均存在一些不足。系统阐述了方案编制目前存在的问题,并提出了初步的建议和对策,以供生产建设项目水土保持方案编制从业者和管理者参考。     

对水保方案中工程措施评价的初探

水土流失防治方案是水土保持方案报告书的核心内容,而主体工程设计中具有水土保持功能的措施评价,在水土保持方案报告书中是近年新增加的编制内容,但目前没有相应的编制规范。主体工程设计中具有水土保持功能的措施评价内容应主要从主体工程选方案、主体工程水保措施、渣场及料场、临时占地的防护、施工工艺和时序等方面进行评价。只有全面、细致的评价,才能采取有针对性的水土流失防治方案,与主体工程一起形成有效的水土流失防治体系。     

开发建设项目水土保持措施经济合理性分析

结合部分水土保持方案实例和多年编制及审查方案的经历,就开发建设项目编制水土保持方案的必要性和重要性、水土流失防治责任范围和目标的科学合理性、防治措施设计的经济合理性以及施工组织设计等方面的内容进行了分析探讨。     

加强大型水电站“三通一平”工程与主体工程水土保持方案的策划与衔接

以金沙江中游的阿海和梨园、澜沧江上游的苗尾3座大型水电站为例,在分析三者"三通一平"工程水土保持方案存在问题的基础上,阐述了"三通一平"工程与主体工程水土保持方案策划与衔接的必要性。为保证"三通一平"工程水土保持方案防治措施设计合理、安全、有效运行,提出了3个重点:业主需委托主体工程设计单位(持甲级水土保持方案编制资质)或水利水电行业具有甲级水土保持方案编制资质的单位承担水土保持方案编制任务;认真做好表土资源的剥离、堆存与防护,以保证植物措施覆土量需求和实施效果;做好与后续设计的衔接。     

欢迎订阅《生产建设项目水土保持方案编制指南》

教授级高级工程师范瑞瑜主编、北京林业大学孙保平教授主审的《生产建设项目水土保持方案编制指南》,已由黄河水利出版社出版。《生产建设项目水土保持方案编制指南》,是依据《生产建设项目水土保持技术标准》(GB 50433—2018)进行编写的,是生产建设项目水土保持方案编制的指导书籍。为了使编制单位保质保量地编制生产建设项目水土保持方案,作者在分析研究各类生产建设项目特点、不同水土流失类型区的水土保持要求,并吸收各类方案精华的基础上,结合多年从事水土保持工作的经验和方案编制、审查的实践,以图、文、表并茂的形式,介绍了生产建设项目水土保持方案的结构安排、各章节的内容、编写方法和应注意的问题等,并重点突出了案例分析内容。     

生产建设项目水土保持方案技术审查工作探讨

水土保持方案技术审查是水行政主管部门批复水土保持方案的重要技术支撑。根据多年从事水土保持方案技术审查的工作实践,归纳总结了水土保持方案技术审查的任务、内容、标准和方法,并结合实际,提出了做好水土保持方案技术审查工作的几点意见,对水土保持方案的指导性和控制性、编制阶段和深度、典型设计等目前方案编报及审批中存在的主要问题进行了分析。     

开发建设项目土壤侵蚀模数确定初探

开发建设项目水土流失预测是编制开发建设项目水土保持方案的关键,是水土保持措施布局和设计的基础,其重要内容就是项目区背景及扰动后土壤侵蚀模数的确定。本文通过对现有土壤侵蚀模数确定的方法进行总结,分析其不足,并提出相应建议,以促进开发建设项目水土流失预测,同时为开发建设项目水土保持方案编制人员提供参考。     

分阶段编制水土保持方案的建议

依法编制的生产建设项目水土保持方案,对防治工程建设过程中可能产生的水土流失发挥了重要作用,但部分项目依旧存在水土保持措施和资金不到位的情况,原因是目前水土保持方案与主体工程可行性研究报告在编报方式及审批流程上结合度较弱。通过梳理长期的工作经验,并结合新出台的相关法律法规,研究认为应分阶段编制水土保持方案。可行性研究阶段,编制水土保持可行性分析报告,水行政主管部门及专家参与项目决策;初步设计阶段,根据可研批复的水土保持投资及主体工程设计内容相应开展水土保持设计工作,这样可以使水土保持措施设计更加合理,做到投资有来源,验收有依据。同时,建议增加编制中止机制和多部门协同审查机制,使水土保持方案更好地服务于项目建设。     

Charge characteristics and exchangeable cation status of Korean Ultisols and Alfisols and Thai Ultisols and Oxisols

The charge characteristics of A₁ or Ap and B₂ horizon samples of total 23 Ultisols, Alfisols and Oxisols in Korea and Thailand were studied by measuring the retention of NH₄⁺ and NO₃^? at different pH values (4–8) and NH₄NO₃ concentrations (0.1–0.005 m ). The magnitude of their negative charge (σ^?; meq/100g) was dependent on pH and NH₄NO₃ concentration (C; m ) as represented by a regression equation: log σ^?=apH +blogC +c. The values of the coefficient a (0.04–0.226), b (0.03–0.264) and c (–0.676–1.262) were correlated with the kinds of the soil and horizon and with the region where the soil exists. The retention of NO₃^? was less than 1 and 2–3 meq/100 g for the A₁ or Ap and B₂ horizon samples, respectively. The sum of exchangeable base and Al (‘effective’ CEC) was close to and higher than the magnitude of permanent charge (=σ^? measured at pH = 4.3 and at C = 0.005 m ) for one-third and two-thirds of samples, respectively. A σ^? value of 16 meq/100 g clay at pH = 7 and C = 0.01 m was found appropriate to separate the B₂ horizons of Thai Ultisols and Oxisols from those of Korean Ultisols and Alfisols. Korean Alfisols and Ultisols and Thai Ultisols were distinguished from each other on the status of exchangeable base and Al     

Forest soil respiration and its heterotrophic and autotrophic components: Global patterns and responses to temperature and precipitation

Quantifying global patterns of forest soil respiration (SR), its components of heterotrophic respiration (HR) and belowground autotrophic respiration (AR), and their responses to temperature and precipitation are vital to accurately evaluate responses of the terrestrial carbon balance to future climate change. There is great uncertainty associated with responses of SR to climate change, concerning the differences in climatic controls and apparent Q₁₀ (the factor by which respiration increases for a 10 °C increase in temperature) over HR and AR. Here, we examine available information on SR, HR, AR, the contribution of HR to SR (HR/SR), and Q₁₀ of SR and its components from a diverse global database of forest ecosystems. The goals were to test how SR and its two components (AR and HR) respond to temperature and precipitation changes, and to test the differences in apparent Q₁₀ between AR and HR. SR increased linearly with mean annual temperature (MAT), but responded non-linearly to mean annual precipitation (MAP) in naturally-regenerated forests. For every 1 °C increase in MAT, overall emissions from SR increased by 24.6 g C m⁻² yr⁻¹. When MAP was less than 813 mm, every 100 mm increase in MAP led to a release of 75.3 g C m⁻² yr⁻¹, but the increase rate declined to 20.3 g C m⁻² yr⁻¹ when MAP was greater than 813 mm. MAT explained less variation in AR than that in HR. The overall emissions in AR and HR for every 1 °C increase in MAT, increased by 12.9 and 16.1 g C m⁻² yr⁻¹, respectively. The AR emissions for every 100 mm increase in MAP, increased by 44.5 g C m⁻² yr⁻¹ when MAP less than 1000 mm. However, above the threshold, AR emissions stayed relatively constant. HR increased linearly by 15.0 g C m⁻² yr⁻¹ with every 100 mm increased in MAP. The Q₁₀ value of SR increased with increasing depth at which soil temperature was measured up to 10 cm and was negatively correlated with HR/SR. Our synthesis suggests AR and HR differ in their responses to temperature and precipitation change. We also emphasized the importance of information on soil temperature measurement depth when applying field estimation of Q₁₀ values into current terrestrial ecosystem models. Q₁₀ values derived from field SR measurements including AR, will likely overestimate the temperature response of HR on a future warmer earth.     

Interactions between azospirillum and va mycorrhiza and their effects on growth and nutrition of maize and ryegrass

Interactions between the N₂-fixing bacterium Azospirillum brasilense and the mycorrhizal fungus Glomus mosseae were studied in relation to their effects on the growth and nutrition of Zea mays (C₄) and Lolium perenne (C₃) plants. Although roots from plants inoculated with Azospirillum exhibited C₂H₂ reduction activity no significant effect of inoculation on N concentration in the plant shoots was found. With non-mycorrhizal plants, inoculation with Azospirillum resulted in increased dry matter production at the first harvest compared to the effect achieved by supplying N as fertilizer, but this trend was reversed at the last harvest. However, with mycorrhizal maize plants, Azospirillum, which stimulated the development of VA mycorrhiza, was still effective in improving plant growth and nutrient uptake at the last harvest. Azospirillum and N behaved similarly in enhancing the growth and nutrition of mycorrhizal maize. The dual inoculation of maize by Azospirillum and Glomus produced plants of a similar size, N content, and a higher P content, than those supplied with N and P.     

Influence of Puroindolines A and B Individually and in Combination on Wheat Milling and Bread Traits

Endosperm texture in wheat (Triticum aestivum L.) is determined by the Pina and Pinb genes located within the Hardness (Ha) locus on chromosome 5D. We have previously shown that Pina and Pinb can act alone to produce intermediate-textured grain or act together to produce soft grain. The objective here was to isolate the role of PINA and PINB individually and in combination on milling and bread traits by analyzing F₃ recombinant lines created by crosses between PINA and PINB null cultivars with Pina-D1a and Pinb-D1a overexpressing transgenic lines. Homozygous lines that contained either the Pina-D1b/Pinb-D1a (Pina null) or Pina-D1a/Pinb-D1e (Pinb null) Ha locus with or lacking transgenically added Pina or Pinb were analyzed for milling and bread traits. Addition of Pina-D1a to Pina-D1b/Pinb-D1a and addition of Pinb-D1a to Pina-D1a/Pinb-D1e Ha locus genotypes gave soft grain with lower flour yield, flour ash, and a higher proportion of small flour particles. Addition of Pinb-D1a produced greater negative effects on loaf volume than addition of Pina-D1a. Grain hardness, flour protein, flour ash, and mixograph water absorption were positively correlated, which is indicative of the complex phenotype conditioned by PINs. The results demonstrate that PIN overexpression leads to a reduction in grain hardness and reduced flour yield, flour ash, and flour particle size. PIN expression also results in reduced loaf volume and flour water absorption.     

Phytotoxicity of fresh and weathered diesel and gasoline to willow and poplar trees

The toxicity of fresh and weathered gasoline and diesel fuel to willow and poplar trees was studied using a tree transpiration toxicity test. Soils were taken from an abandoned filling station. Concentrations in the samples were measured as the sum of hydrocarbons from C₅ to C₁₀ (gasoline) and C₁₂ to C₂₈ (diesel). Concentrations ranged from 145 to 921 mg/kg gasoline and 143 to 18231 mg/kg diesel. The correlation between log soil concentration and toxicity to willows(Salix viminalis x schwerinii) was highly significant for the diesel fraction (r²=0.81, n=19) and for the sum of hydrocarbons (r²=0.84, n=19). The EC₅₀ (50% inhibition of transpiration) for the sum of hydrocarbons was determined at 3910 mg/kg (95% C.I., 2900 to 5270 mg/kg) and followed a log-normally distributed sigmoidal curve. The EC₁₀ was 810 mg/kg (95% C.I., 396 to 1660 mg/kg). The results were verified with artificially mixed diesel and gasoline contaminated soils, and two willow and one poplar species(S. viminalis, S. alba and Populus nigra). Fresh diesel at about 1000 mg/kg showed no effect onS. alba, althoughP. nigra was more sensitive. 10000 mg/kg seriously affected the transpiration of all species, silver willow(S. alba) being the least sensitive. Free phase diesel killed all trees within six weeks. Fresh gasoline at 1000 mg/kg was deadly for all trees, hence was more toxic than weathered gasoline. Survival of poplars and willows planted at the abandoned filling station was compared to the laboratory findings. There was some correlation, but in the field, trees also suffered from other stress factors than fuel pollution.     

Comparison of Arsenic and Phosphate Uptake and Distribution in Arsenic Hyperaccumulating and Nonhyperaccumulating Fern

Abstract

Uptake of arsenic (As) and its distribution in Chinese Brake fern (Pteris vittata L.), an As hyperaccumulator, and Boston fern (Nephrolepis exaltata L.), a nonhyperaccumulator, in the presence of phosphorus (P), were characterized by employing a hydroponic experiment with a complete three-factorial design. Two levels of As (100 and 1000 µM) and four levels of P (0, 100, 500, and 1000 µM) were used in this study. Arsenic uptake rates on the basis of root fresh weight for the two ferns were similar at low As concentration (100 µM). At high As concentration (1000 µM), however, As uptake rates (373–987 nmol g^?1 f wt h^?1) of P. vittata were significantly greater than those of N. exaltata (164–459 nmol g^?1 f wt h^?1). In both ferns, addition of P reduced their As uptake rate as well as accumulation. Pteris vittata had a greater As TF (Translocation factor = concentration ratio of fronds to roots) than N. exaltata. On the contrary, N. exaltata displayed a greater P TF than P. vittata. As a result, high P/As ratio was observed in the roots of P. vittata, whereas high P/As ratio was observed in the fronds of N. exaltata. The study illustrated that As hyperaccumulation by P. vittata may be facilitated by its high As influx rate and its high molar P/As ratio in the roots resulting from both high As TF and low P TF.     

Soil microbial and extractable C and N after wildfire

 The effect of wildfire on soil microbes and extractable C (C_ext) and N (N_ext) changed with respect to the time from burning and soil depth. Initially, microbial biomass C (C_mic) and N (N_mic) were drastically reduced in the soil surface layer (0–5 cm) and reduced by 50% in the subsurface (5–10 cm), whereas C_ext increased by 62% in the surface layer and did not significantly change in the subsurface. These parameters were affected for the following 4 years, during which the average reductions in the soil surface and subsurface layers were, respectively, 60% and 50% for C_mic, 70% and 45% for N_mic, 60% and 40% for the ratio C_mic: organic C (C_org) and 70% and 30% for the ratio N_mic: total N (N_tot), while for C_ext the surface layer was the only zone consistently affected and C_ext decreased by up to 59%. Immediately after a fire, the C_ext : C_org ratio increased by 3.5-fold and 2-fold in the surface and subsurface layers, respectively; thereafter for 2 years, it decreased in the surface layer (by up to 45%) while the effect on the subsurface layer was not consistent. The effect of burning on N_ext lasted 1 year, in which N_ext increased by up to 7- and 3-fold in the surface and subsurface layers, respectively, while the average N_ext : N_tot ratio doubled in the surface layer and increased by 34% in the subsurface. During the time in which each parameter was affected by burning, the soil factor explained a high percentage of variance in the fluctuations of C_mic, N_mic, C_mic : C_org and N_mic : N_tot, while those of N_ext and N_ext : N_tot, but not those of C_ext and C_ext : C_org depended on both the soil and its depth. In the burned soils similar patterns of response were found between the following parameters listed in pairs: C_mic and N_mic; C_mic : C_org and N_mic : N_tot; C_ext and N_ext; and C_ext : C_org and N_ext : N_tot. However, after the fire relationships found previously between the parameters studied and many other soils properties were either no longer evident, or were inverted. Although the addition of cellulose to the burned soil favoured fungal mycelium development and increased C_mic and C_ext contents, the negative effect of burning on the microbial biomass and the C_ext was not counteracted even under incubation conditions suitable for both microbial growth and C mineralization. Received: 28 May 1997     

水稻根际和周围土壤中微生物功能基因丰度与碳、氮状况及其通量之间的关系

Rapid nitrogen（N） transformations and losses occur in the rice rhizosphere through root uptake and microbial activities. However,the relationships between rice roots and rhizosphere microbes for N utilization are still unclear. We analyzed different N forms（NH＋4,NO-3, and dissolved organic N）, microbial biomass N and C, dissolved organic C, CH4 and N2O emissions, and abundance of microbial functional genes in both rhizosphere and bulk soils after 37-d rice growth in a greenhouse pot experiment. Results showed that the dissolved organic C was significantly higher in the rhizosphere soil than in the non-rhizosphere bulk soil, but microbial biomass C showed no significant difference. The concentrations of NH＋4, dissolved organic N, and microbial biomass N in the rhizosphere soil were significantly lower than those of the bulk soil, whereas NO-3in the rhizosphere soil was comparable to that in the bulk soil. The CH4 and N2O fluxes from the rhizosphere soil were much higher than those from the bulk soil. Real-time polymerase chain reaction analysis showed that the abundance of seven selected genes, bacterial and archaeal 16 S rRNA genes, amoA genes of ammonia-oxidizing archaea and ammonia-oxidizing bacteria, nosZ gene, mcrA gene, and pmoA gene, was lower in the rhizosphere soil than in the bulk soil, which is contrary to the results of previous studies. The lower concentration of N in the rhizosphere soil indicated that the competition for N in the rhizosphere soil was very strong, thus having a negative effect on the numbers of microbes. We concluded that when N was limiting, the growth of rhizosphere microorganisms depended on their competitive abilities with rice roots for N.     

Wood density and carbon and nitrogen concentrations in deadwood of Chamaecyparis obtusa and Cryptomeria japonica

Estimating carbon (C) and nitrogen (N) stocks in deadwood in forests nationwide is required for understanding large-scale C and N cycling. To do so requires estimated values of wood density and C and N concentrations. Additionally, parameters that show variation should be examined. In this study, we clarified the estimated values and the variation in three parameters in each decay class of each of two tree species and examined whether dead log diameter and region contribute to variation in the parameters. Data were collected from 73 Chamaecyparis obtusa (Sieb. et Zucc.) Endl. plantations and 66 Cryptomeria japonica D. Don plantations throughout Japan. Wood densities decreased from 386 to 188?kg?m^?3 for C. obtusa and from 334 to 188?kg?m^?3 for C. japonica in decay classes 1–4. The variation in wood density increased with decay class, and the coefficient of variance increased from 13.9% to 46.4% for C. obtusa and from 15.2% to 48.1% for C. japonica. The N concentrations increased from 1.04 to 4.40?g?kg^?1 for C. obtusa and from 1.11 to 2.97?g?kg^?1 for C. japonica in decay classes 1–4. The variation in N concentration increased with decay class, and the coefficient of variance increased from 51.9% to 76.7% for C. obtusa and from 50.3% to 70.4% for C. japonica. Log diameter and region contributed to variations in wood density and N concentration in decay classes 1 and 2 for C. obtusa and C. japonica. However, no relationship was observed between regional climates and the two parameters. In contrast, C concentrations ranged from 507 to 535?g?kg^?1 and were stable with much lower coefficients of variance throughout the decay classes for both tree species. Thus, we recommend that the same C concentration can be adapted for all decay classes of both tree species.     

Spatial and temporal variation of nitrous oxide and methane flux between subtropical mangrove sediments and the atmosphere

We quantified spatial and temporal variations of the fluxes of nitrous oxide (N₂O) and methane (CH₄) and associated abiotic sediment parameters across a subtropical river estuary sediment dominated by grey mangrove (Avicennia marina). N₂O and CH₄ fluxes from sediment were measured adjacent to the river (“fringe”) and in the mangrove forest (“forest”) at 3-h intervals throughout the day during autumn, winter and summer. N₂O fluxes from sediment ranged from an average of −4 μg to 65 μg N₂O m⁻² h⁻¹ representing N₂O sink and emission. CH₄ emissions varied by several orders of magnitude from 3 μg to 17.4 mg CH₄ m⁻² h⁻¹. Fluxes of N₂O and CH₄ differed significantly between sampling seasons, as well as between fringe and forest positions. In addition, N₂O flux differed significantly between time of day of sampling. Higher bulk density and total carbon content in sediment were significant contributors towards decreasing N₂O emission; rates of N₂O emission increased with less negative sediment redox potential (E_h). Porewater profiles of nitrate plus nitrite (NO_x⁻) suggest that denitrification was the major process of nitrogen transformation in the sediment and possible contributor to N₂O production. A significant decrease in CH₄ emission was observed with increasing E_h, but higher sediment temperature was the most significant variable contributing to CH₄ emission. From April 2004 to July 2005, sediment levels of dissolved ammonium, nitrate, and total carbon content declined, most likely from decreased input of diffuse nutrient and carbon sources upstream from the study site; concomitantly average CH₄ emissions decreased significantly. On the basis of their global warming potentials, N₂O and CH₄ fluxes, expressed as CO₂-equivalent (CO₂-e) emissions, showed that CH₄ emissions dominated in summer and autumn seasons (82-98% CO₂-e emissions), whereas N₂O emissions dominated in winter (67-95% of CO₂-e emissions) when overall CO₂-e emissions were low. Our study highlights the importance of seasonal N₂O contributions, particularly when conditions driving CH₄ emissions may be less favourable. For the accurate upscaling of N₂O and CH₄ flux to annual rates, we need to assess relative contributions of individual trace gases to net CO₂-e emissions, and the influence of elevated nutrient inputs and mitigation options across a number of mangrove sites or across regional scales. This requires a careful sampling design at site-level that captures the potentially considerable temporal and spatial variation of N₂O and CH₄ emissions.