铜处理对菠菜幼苗矿质营养吸收和细胞超微结构的影响

土壤重金属积累严重影响植物生长和生态系统平衡,探寻植物对重金属的耐性机理尤为重要.菠菜可能具有一定的耐铜性,但Cu对其矿质元素吸收、细胞超微结构等方面的耐性机理尚不明确.本研究以菠菜幼苗为研究对象,通过盆栽试验,探究不同浓度铜处理对菠菜幼苗生长、矿质元素吸收、叶片细胞超微结构等指标的影响.结果表明: 100 mg·L^-1 CuSO₄处理浓度时,菠菜幼苗根Cu²⁺积累量小于地上部,其根系生长量增加,地上部生长量稍有下降,继续增加铜处理浓度,植物体各器官生长参数均呈下降趋势.低浓度铜处理时(<400 mg·L^-1 CuSO₄),菠菜幼苗叶N、K、Ca、Mg、Fe含量增加,P含量减少;根N、P、K含量减少,Ca、Mg、Fe含量增加;叶片细胞内各细胞器清晰可见,基粒片层排列仍较为整齐,叶绿体内外膜完整.高浓度铜处理时(>600 mg·L^-1 CuSO₄),菠菜幼苗叶N含量增加,P、K、Ca、Mg、Fe含量减少;根N、P、K、Ca、Mg、Fe含量均减少;叶片细胞内叶绿体变圆,叶绿体膜变薄,基质、基粒片层变少,层堆积高度下降,细胞核解体,液泡、细胞壁中有黑色小点分布,可能是大量Cu²⁺聚集导致细胞内膨压增大所致.低浓度铜处理并未对菠菜幼苗的生长生理特性产生明显的负面影响,而高浓度铜处理并未终止菠菜幼苗的生长.说明菠菜幼苗具有一定的耐铜性.     

丝绸之路经济带核心区新疆城镇建设用地扩展的时空演变特征及影响机理

将丝绸之路经济带核心区新疆城镇建设用地扩展作为一个时空变化系统进行分析,提取1980—2015年7个年份用地演变信息,结合10 km×10 km方格网构建,从总量趋势、分地州市级区域、分用地类型及特殊性全面认知扩展的时空演变特征,采用地理探测器模型,在县域尺度定量诊断城镇建设用地扩展的人文要素和自然要素的影响程度及各要素间的交互影响作用,进而识别其主控要素并探讨其作用机理,对比分析天山北坡城市群和喀什都市圈两个重点发展区域的分异性。研究结果表明:近35年以来,丝绸之路经济带核心区新疆城镇建设用地扩展约2.9倍,扩展强度波动增长且以分散小斑块为主,各地州市扩展规模和强度的时空差异性显著,次一级城镇建设用地类型扩展呈现动态变化特征,用地扩展受自然本底胁迫条件和经济社会发展过程多重影响有其特殊性;全域城镇建设用地在县域尺度以低水平扩展与各级人文要素和自然要素水平的耦合匹配关系为主;综合地理探测器因子分析模块和交互作用模块的探测结果,判定地形位指数、城镇化率、地形起伏度、二三产业比重为影响丝绸之路经济带核心区新疆县域城镇建设用地扩展的主控要素,并探寻各主控要素的作用机理;在重点发展区域天山北坡城市群和喀什都市圈的驱动要素有共性也有明显分异性。该研究为丝绸之路经济带核心区新疆城镇建设用地因地因城因类的差别化调控及区域可持续发展提供科学支撑和决策依据。     

青藏高原山水林田湖草生态保护修复模式——以拉萨河流域为例

山水林田湖草生态保护与修复是推进生态文明建设的必然要求。青藏高原是我国生态屏障区、水源涵养区和生态脆弱区,生态地位独特、生态保护责任重大。为此,中央及地方政府高度重视青藏高原生态文明建设,积极开展山水林田湖草生态保护修复试点工程。从青藏高原山水林田湖草生态保护与修复试点的特殊性出发,以拉萨河流域为例梳理了其主要的生态保护修复工程项目,提炼了青藏高原山水林田湖草生态保护与修复的技术路线,从参与主体、整合要素、运行保障、实施目标等方面总结了青藏高原多部门跨区、多要素综合、多渠道协作、多目标耦合的山水林田湖草联动治理模式,从山、水、林、田、湖、草六大生态要素出发归纳了青藏高原生态保护修复的分类指导-精准施策的实践框架,以期对青藏高原山水林田湖草生态建设情况有一个清晰的认识,并为全国其他地区系统开展山水林田湖草生态保护修复工作提供借鉴。     

福建梅花山自然保护区蕨类植物区系研究

通过野外调查和资料整理,统计分析梅花山自然保护区蕨类植物区系组成和分布区类型,比较其与周边相邻4个自然保护区的蕨类植物区系的相似性。结果表明:(1)梅花山自然保护区共有蕨类植物42科83属189种,科、属组成优势现象明显,区系起源古老。(2)分布区类型在科、属级水平上以泛热带分布和世界分布为主,种级水平以热带亚洲分布、东亚分布和中国特有分布为主,热带亲缘明显,具有由热带向温带过渡的性质。(3)在地理亲缘关系上,梅花山与梁野山的蕨类植物区系联系最为紧密,与圭龙山的关系次之,与热带区系性质较强的南靖南亚热带雨林自然保护区和典型的中亚热带性质的武夷山自然保护区的种子植物区系联系较为疏远,具有从南亚热带向中亚热带过渡的明显特点。     

Exposure assessment of potentially toxic trace elements via consumption of fruits and vegetables grown under the impact of Alaverdi's mining complex

This study is aimed to investigate the transfer of potentially toxic trace elements from soils to plants grown under the impact of Alaverdi's mining complex and assess the related dietary exposure to local residents. Contamination levels of potentially toxic trace elements (Cu, Ni, Pb, Zn, Hg, As, Cd) in soils and plants were determined and afterwards, transfer factors, estimated daily intakes, target hazard quotients, and hazard indexes were calculated.

Some trace elements (Pb, Zn, Cd) exceeded the maximum allowable levels. EDIs of Cu, Ni, Hg for the majority of studied fruits and vegetables exceeded the health-based guideline values. Meanwhile, in case of combined consumption of the studied food items, the estimated cumulative daily intakes exceeded health-based guideline values not only for the aforementioned trace elements but also for Zn in the following sequence: Zn > Hg > Ni > Cu. HI > 1 values highlighted the potential adverse health effects for local population through more than one trace element.

Detailed investigations need to be done for the overall assessment of health risks, taking into consideration not only adverse health effects posed by more than one toxic trace element but also through other exposure pathways.     

Spatiotemporal evaluation of trace elements in river water using multivariate methods

The multivariate statistical methods (cluster analysis and discriminant analysis [DA]) are used to evaluate the quality of water spatiotemporally in the Brahmani River basin. A total of 15 water quality indicators (pH, Chloramines, Sodium, Sulfate, Phosphate, Potassium, Boron, Fluoride, Cadmium, Copper, Lead, Nickel, Zinc, Iron, and Total Chromium) are collected for 13 years in two seasons (the dry and the wet season) from nine sampling stations. These stations are grouped into four clusters (Considerable [Co], Low Pollution [LP], Moderate Pollution [MP], and Extreme Pollution [(EP]) by hierarchical agglomerative cluster analysis based on the similarities of water quality characteristics. The nine important influencing discriminating water quality indicators are extracted by stepwise method of temporal DA,where as eight important influencing indicators for dry season and eight indicators (Potassium, Phosphate, Fluoride, Copper, Lead, Nickel, Iron, and Total Chromium) for wet season are found out by the spatial DA. The pollution status in the river basin was observed from overall trend in (Considerable) Co to (Extreme Pollution) EP regions. The study could be very useful in prioritizing the important sites for water resources and pollution management.     

Hox genes: Downstream “effectors” of retinoic acid signaling in vertebrate embryogenesis

One of the major regulatory challenges of animal development is to precisely coordinate in space and time the formation, specification, and patterning of cells that underlie elaboration of the basic body plan. How does the vertebrate plan for the nervous and hematopoietic systems, heart, limbs, digestive, and reproductive organs derive from seemingly similar population of cells? These systems are initially established and patterned along the anteroposterior axis (AP) by opposing signaling gradients that lead to the activation of gene regulatory networks involved in axial specification, including the Hox genes. The retinoid signaling pathway is one of the key signaling gradients coupled to the establishment of axial patterning. The nested domains of Hox gene expression, which provide a combinatorial code for axial patterning, arise in part through a differential response to retinoic acid (RA) diffusing from anabolic centers established within the embryo during development. Hence, Hox genes are important direct effectors of retinoid signaling in embryogenesis. This review focuses on describing current knowledge on the complex mechanisms and regulatory processes, which govern the response of Hox genes to RA in several tissue contexts including the nervous system during vertebrate development.     

Essential Elements as a Distinguishing Factor between Mycorrhizal Potentials of Two Cohabiting Truffle Species in Riparian Forest Habitat in Serbia

True truffles (Tuber sp.) that establish ectomycorrhizal symbiosis (ECM) with trees in the Mediterranean and temporal regions have species specific abilities to assimilate soil born elements. Suitable habitats are usually inhabited by few truffle species, while distinguishing their symbiotic potentials appeared very difficult. Two species that commonly inhabit riparian forests in Serbia are the most prized one, Tuber magnatum Pico (Piedmont white truffle) and not so highly valued Tuber brumale Vitt . In order to assess potential differences between their assimilation and accumulation abilities, the differences between contents of elements that may be the subjects of the symbiotic trade between the host plant and fungi were evaluated in accumulation target (ascocarps) and their source (the soil). Essential (K, Na, Ca, Mg, Fe, P, S, and Zn) and essential trace elements (Co, Cr, Cu, Mn, and Se) in truffles and soil samples were determined by means of inductively coupled plasma with optical emission spectrometry (ICP‐OES). Their concentrations (mg/kg) in ascocarps were in the range from 1.364±0.591 (Cr) to 10760.862±16.058 (K), while in soil ranged from 23.035±0.010 (Cr) to 20809.300±122.934 (Fe). Element accumulation potential (bioaccumulation factor) was calculated in the system truffle/soil. The statistical approaches were used for establishing the differences, while the possible differentiation between symbiotic potentials of two mycelia in the defined soil conditions was discussed.