鄂尔多斯高原沙地柏液流通量及其影响因子

[目的]分析沙地柏液流通量变化特征及主要影响因子,为沙地植被的保护提供理论依据。[方法]以鄂尔多斯高原沙地植被的优势种沙地柏为研究对象,利用热扩散(TDP)技术监测生长季沙地柏的液流动态,通过相关分析和回归分析等研究其与气象因子的关系。[结果]晴天沙地柏的液流通量为单峰曲线,干旱时为双峰曲线。雨天沙地柏的液流通量为单峰或双峰曲线。晴天沙地柏液流通量的最大值是2.30～23.38 g/(cm~2·h)。沙地柏液流通量对降雨的响应具有1～4 d的时滞。生长季沙地柏液流通量与光合有效辐射、水汽压亏缺、气温和风速均呈显著正相关,而与相对湿度和降雨量呈显著负相关。[结论]鄂尔多斯高原沙地柏的液流通量随天气而变化。太阳辐射和水分是沙地柏液流通量的主要影响因子。建议当地加强对沙地柏灌丛的保护,防止由于过度水分消耗导致的植被退化。     

基于格网的石漠化地区生态系统服务与经济空间耦合

[目的]分析石漠化地区生态系统服务价值与经济的空间耦合关系,为石漠化地区生态环境保护与社会经济协调发展提供依据。[方法]以贵州省盘州市为例,基于格网尺度,计算了研究区生态服务价值(ESV)与国内生产总值GDP,并利用耦合协调模型,对两者间的耦合协调发展程度进行定量评估。[结果]①盘州市ESV热点区主要分布在东北部的几个少数民族乡镇,冷点区主要分布在经济发展较快且城市化率较高的区域;②盘州市GDP在空间上呈现出局部高的特点,高值区主要集中在石桥镇、亦资街道、翰林街道等工业镇和政治、经济、文化中心;③盘州市ESV与GDP耦合协调度值较低,空间上存在明显的自相关性,耦合协调度较低的区域主要分布在盘州市东南部、北部以及中部;④盘州市ESV与GDP耦合协调度类型以严重失调衰退经济损益型为主,占区域总面积的79.95%。[结论]盘州市ESV与GDP在空间上存在一定矛盾,耦合协调度较低,兼顾生态环境保护与经济发展有助于提升协调度。     

稀土元素示踪法探究坡面侵蚀进展与热点——基于CiteSpace计量分析

稀土元素示踪法从上世纪90年代开始逐渐被相关学者重视,并在坡面土壤侵蚀的研究中得到越来越广泛的应用。笔者采用CiteSpace软件和文献计量学方法,以Web of Science数据库核心合集和中国知网(CNKI)数据库核心期刊为数据源,分析了近30年国内外稀土元素示踪法在坡面侵蚀研究的发展历程。研究发现:①总体而言,国内稀土元素示踪法在坡面侵蚀中的应用在理论和实践层面已经从初步探索走向了成熟;②随着研究的深入,稀土元素示踪法的研究与相关学科交叉更加密切,并在微观探索和宏观调控方面取得一定进展;③未来发展趋势来看,宏观方面趋向和生态系统、气候变化等互相作用机理的研究,微观方向趋向对团聚体等微观颗粒的迁移研究;④在国际相关研究方面,对于稀土元素示踪法在坡面侵蚀的应用从多个方面和角度做了大量的研究,我国的相关研究相较于国外顶尖水平的研究仍存在一定差距。     

基于中高职衔接背景下中职人才培养导向研究--以四川省为例

中等职业学校是职业教育重要的组成部分,主要培养技术技能型人才,目前许多产业结构的调整对技术技能人才提出了更高的要求。基于此,本文以四川省为例,通过对四川省中职毕业生去向、走访和调查部分中职学校的人才培养导向和毕业生在企业中的工作岗位等进行分析,提出了应该结合当下发展状况,采用就业和升学双导向的人才培养模式,提高中职人才培育质量。     

Effects of ferulic acid on growth performance,immunity and antioxidant status in genetically improved farmed tilapia (Oreochromis niloticus) fed oxidized fish oil

A study was conducted to characterize the effects of dietary oxidized fish oil on the growth performance, immunity and antioxidant status of genetically improved farmed tilapia (Oreochromis niloticus) and to determine the role of ferulic acid on the oxidative damage induced by the oxidized fish oil. The tilapia (13.73 ± 0.31 g) were fed four experimental diets containing untreated (peroxide value, POV: 2.2 meq/kg) and highly oxidized (POV: 120.6 meq/kg) fish oil either with or without ferulic acid (0 or 400 mg/kg) supplementation for 12 weeks. From the results, the oxidized fish oil treatments increased antioxidant enzyme activities and MDA values but decreased the weight gain and the immunological parameters in tilapia. Meanwhile, the serum biochemical indices were significantly affected by the oxidized fish oil. Besides, the addition of ferulic acid partially counteracted the free radical‐induced damage and improved the health status of tilapia. In conclusion, the oxidized fish oil may induce oxidative stress, destroy liver, dysregulate lipid metabolism as well as reduce non‐specific immunity, and eventually result in growth inhibition of tilapia. The ferulic acid supplementation partially offset the negative effects of the oxidized fish oil on tilapia.     

Effects of bioflocs with different C/N ratios on growth,immunological parameters,antioxidants and culture water quality in Opsariichthys kaopingensis Dybowski

Biofloc technology (BFT) is a new ecological aquaculture technology that is intended not only to eradicate pollutants and elevate feed utilization but also to enhance immunity and antioxidant activity in aquatic animals. A 28‐day feeding trial was implemented to evaluate the effects of promoted bioflocs on the water quality, growth performance, immunological parameters and antioxidant status of Opsariichthys kaopingensis Dybowski juveniles in low exchange culture tanks. Three hundred sixty healthy O. kaopingensis juveniles (7.1 ± 0.02 g) were irregularly distributed among 12 tanks. Four C:N ratios in triplicate tanks were tried: C/N = 10.8:1 with a commercial diet (control), C/N = 15:1, C/N = 20:1 and C/N = 25:1. Anhydrous glucose (99.97%) was added to the commercial diet to maintain elevated carbon ratio in the three treatments. Uninterrupted 24‐hr aeration was supplied during the test by using an air‐stone connected to an air pump to develop the bioflocs in the water column. The results indicated that BFT significantly reduced total ammonia nitrogen (TAN), nitrite (NO2^?‐N), total phosphorus (TP) concentrations and water transparency (Secchi depth) in C/N 15, C/N 20 and C/N 25 (p < .05), whereas the chemical oxygen demand (COD) and nitrate nitrogen (NO3^?‐N) concentrations gradually increased over time. In addition, weight gain, specific growth rate (SGR), survival and protein efficiency ratio (PER) were significantly elevated in C/N 20, while food conversion rate (FCR) was considerably decreased (p < .05) in C/N 20, compared with the control. Significant increases in lysozyme (LSZ), glutamic pyruvic transaminase (GPT), glutamic oxaloacetic transaminase (GOT) and alkaline phosphatase (AKP) activities of O. kaopingensis were found in the C/N 20 group after a 28‐day feeding trial (p < .05). Comparing the antioxidant capacity of O. kaopingensis in gills, brains, kidneys, hepatopancreas, intestines and serum of juveniles from the four experimental groups, the activity of superoxide dismutase (SOD), total antioxidant capacity (T‐AOC), catalase (CAT) activity and glutathione peroxidase (GSH‐PX) activity of juveniles in the C/N 20 group were significant higher (p < .05), and the content of malondialdehyde (MDA) was considerably lower, than in the control. Overall, these findings suggest that BFT not only can enhance O. kaopingensis growth performance and strengthen antioxidant status but also can upgrade immune response, ensuring the sustainable development of aquaculture.     

基于遥感数据的大尺度区域水田空间格局及生态服务价值变化分析

受经济和气候驱动，长江经济带水田空间格局发生了显著变化，影响区域粮食安全与生态安全。本研究基于1990-2015年土地利用遥感监测数据，利用GIS的空间分析功能，探究长江经济带水田空间格局动态变化特征，采用当量因子法计算生态系统服务价值（ESV），分析了水田变化的综合影响。结果表明：1）1990-2015年长江经济带水田规模持续缩减，共减少了17390km²，减幅呈增长态势具有显著地域差异，长江中上游与下游的水田减幅相差约为9.56%。其中下游减幅较大，水田占区域比例随之降低，中上游恰好相反。2）由于经济建设及水产养殖的发展，水田主要转化为建设用地和水系，水田主要由水系、旱地和湿地等转化而来。长江三角洲城市群、长江中游及成渝城市群的水田变化最为剧烈，建设用地侵占水田扩张的现象分布广泛，水田转为水系主要在两湖平原局部地区。3）水田与其他生态系统的转化对ESV是正影响，水田转为水系对此贡献最大，其转化规模决定了不同时期ESV净增量的大小，水系转化为水田损失的价值最多，建设用地侵占水田次之。不同市域的水田变化情况不一致，因此ESV增减情况具有明显差异。4）生态系统服务中水文调节、水资源供给增强的同时，食物生产、气体调节受到严重损害，与水资源规模扩大和水田资源大量流失有直接关系。研究结果有助于揭示长江流域水田的时空变化过程及其对各项生态系统服务的影响，可为区域土地利用规划、农业政策与生态可持续发展提供理论支持。