沙漠光伏的热力平衡效应及其防沙治沙的生态学意义

以甘肃古浪振发光伏电场为例,对比分析了光伏电场内外气温、风速、太阳辐射等的差异及其变化特征。结果表明:(1)沙漠光伏可大量转化太阳辐射,有效调节沙漠地表热力平衡,消减沙尘暴发生的动力(即地表热力);(2)河西走廊沙尘暴主要发生在春季,沙漠光伏对春季10 m高度降温作用较明显;(3)沙漠光伏主要是通过转换太阳辐射降低沙面气温和自身的沙障作用以及改善植物生长条件3种方式达到防沙治沙和消减沙尘暴的目的。

沙漠光伏电场的光伏转换及能量传递效应——以甘肃古浪振发光伏电场为例

为了揭示沙漠光伏的热能转换及其传递效应,以甘肃古浪振发光伏电场为例,运用2018年5月—2019年10月的观测数据进行了分析。结果表明:(1)沙漠光伏的能量传递过程表现为太阳辐射的减少导致光伏电场及其周围气温降低,进而影响光伏电场及其周围气压和风速、风向,古浪振发沙漠光伏年发电量20947.66×10^4 kW•h,转换的太阳辐射相当于每天可将2.35 km3的空气温度降低0.5℃。(2)当月平均气温高于11℃时,光伏转换的太阳辐射能小于由于光伏设施影响空气对流而滞留的热量;沙漠光伏电场对2 m高度气温的影响主要在夏季,对10 m高度气温的影响主要在冬季。(3)光伏电场对上风2 m高度气温的影响距离大于300 m,对10 m高度气温的影响距离小于300 m;对上风向风速和风向的影响距离分别为大于1000 m和小于1000 m。(4)我国沙漠、戈壁面积广大,发展沙漠、戈壁光伏产业前景广阔。

盐生植物盐爪爪种子营养成分评价

为更好地发掘和利用治理土壤盐渍化的优良盐生植物盐爪爪(Kalidium foliatum),采用离子交换色谱仪法、火焰原子吸收光谱法等测定方法,分析评价了盐爪爪种子营养物质组成及食用价值。结果表明,盐爪爪种子主要营养物质含量分别为蛋白质204 g·kg^(-1)、脂肪54 g·kg^(-1)、粗纤维45 g·kg^(-1)、碳水化合物379 g·kg^(-1)。含18种氨基酸,氨基酸总含量为205.8 g·kg^(-1),其中必需氨基酸占氨基酸总量的26.82%,赖氨酸含量最高为11.3 g·kg^(-1),必需氨基酸指数为120.40,蛋白质营养价值较高。微量元素含量分别为铁332 mg·kg^(-1),锌44.1 mg·kg^(-1),钙1590 mg·kg^(-1)。脂肪酸主要成分为亚油酸、油酸和亚麻酸,人体必需脂肪酸为73.91%。综上所述,盐爪爪种子有益营养成分种类丰富,可作为高蛋白、高粗纤维、富铁功能型食品加工的理想原料。

Effects of sand-fixing and windbreak forests on wind flow:a synthesis of results from field experiments and numerical simulations

Sand-fixing and windbreak forests are widely used to protect or/and improve the ecological environments in arid and semi-arid regions. A full understanding of wind flow characteristics is essential to arranging the patterns of these protective forests for enhancing the effectiveness. In this study, the wind velocity over the underlying surface with sand-fixing forests and windbreak forests at the heights of 1–49 m was monitored from two 50-m high observation towers in an oasis of Minqin, Gansu Province of China. The wind velocities were simulated at different locations over these protective forests between those two towers by a two-dimensional Computational Fluid Dynamics（CFD） model. The results showed that at the heights of 1–49 m, the wind velocity profiles followed a classical logarithm law at the edge of the oasis and a multilayer structure inside the oasis. With increasing number of sand-fixing forest and windbreak forest arrays, the wind velocity at the heights of 1–49 m generally decreased along the downstream direction of the prevailing wind. Specifically, below the height of windbreak forests, the wind velocity decelerates as the airflow approaches to the windbreak forests and then accelerates as the airflow passes over the windbreak forests. In contrast, above the height of windbreak forests, the wind velocity accelerates as the airflow approaches to the windbreak forests and then generally decelerates as the airflow passes over the windbreak forests. Both the array number and array spacing of sand-fixing and windbreak forests could influence the wind velocity. The wind protection effects of sand-fixing forests were closely related to the array spacing of windbreak forests and increased with the addition of sand-fixing forests when the array of the forests was adequately spaced. However, if the array spacing of windbreak forests was smaller than seven times of the heights of windbreak forests, the effects were reduced or completely masked by the effects of windbreak forests. The results could offer theoretical guidelines on how to systematically arrange the patterns of sand-fixing and windbreak forests for preventing wind erosion in the most convenient and the cheapest ways.

青藏高原东北缘祁连山区现代孢粉空间分布与搬运过程

孢粉在揭示过去不同时间尺度气候和生态变化方面发挥了重要作用,然而目前对干旱区盆-山复杂地形下现代孢粉分布特征、搬运和沉积过程还缺乏系统的认识,在一定程度上影响了孢粉在干旱区的适用性以及重建结果的准确性。本研究以垂直地带性明显的青藏高原东北缘祁连山区为对象,基于现代空气孢粉收集器的分析结果,同时结合河流水体和表土孢粉数据,讨论了风力和河流对不同类型孢粉的搬运作用,进而确定了盆地沉积物孢粉的来源及对区域植被和气候的指示意义。研究结果表明:1)区域现代空气孢粉收集器样品孢粉组合以近源和区域植被类型为主,未发现外源长距离搬运对观测结果的明显影响;2)河流对山地木本类型孢粉有较强的搬运能力,但随着河流搬运距离的增加,木本类型孢粉的比例减少,所携带的山地植被信息被削弱;河流孢粉组合特征与取样点周围植被状况密切相关,且在不同的时段孢粉组合特征有明显的差异;3)在利用盆地沉积物孢粉序列重建过去植被和气候时,要充分考虑径流量及河道变迁引起孢粉沉积过程的改变,区分山地和盆地的不同信息,构建适用于干旱区复杂地形的孢粉-植被-气候关系,提高重建的准确性。

风沙活动对人工梭梭(Haloxylon ammodendron)林土壤碳氮含量的影响

风沙活动及其物质输移是关键的陆地地表过程,对沙地生态系统影响显著。以石羊河下游民勤县不同林龄人工梭梭(Haloxylon ammodendron)林为研究对象,研究了固沙造林对0—1 m深度土壤碳氮含量的影响以及风蚀和降尘引起的碳氮含量变化特征,探讨了风沙活动对人工梭梭林土壤碳氮库的影响。结果表明:35 a人工梭梭林0—1 m和0—5 cm土壤有机碳储量较流动沙丘分别增长2.5倍和4.6倍,土壤氮储量分别增长3.3倍和5.3倍。地表风沙流被人工梭梭林截留引起的碳氮输入速率5年平均值分别为1.12 g∙m^(-2)∙a^(-1)和0.15 g∙m^(-2)∙a^(-1),占35 a林地0—1 m土壤有机碳氮固定速率的2.2%和1.8%,占0—5 cm土壤有机碳氮固定速率的21.5%和24.9%。在人工梭梭林下垫面上,降尘引起的碳氮输入速率5年平均值分别为2.47 g∙m^(-2)∙a^(-1)和0.29 g∙m^(-2)∙a^(-1),占到35 a林地0—1 m土壤有机碳氮固定速率的4.7%和3.5%,占0—5 cm土壤有机碳氮固定速率的45.7%和48.1%,是地表风沙流的近2倍。人工梭梭林对风沙流活动的削减作用显著促进了沙漠土壤有机碳氮的积累,在0—5 cm层更为明显。

Characteristics of the lower layer of sandstorms in the Minqin desert-oasis zone

By measuring the sand-dust flux,vertical deposition,and the wind velocity throughout 19 sandstorms in the Minqin region,we quantitatively analyzed the horizontal distribution and vertical variation in sandstorm characteristics under different land cover conditions.The effect of different land cover on mitigating sandstorms was also investigated.The results indicated that,in the surface layer ranging from 0-50 m,the intensity of sand-dust horizontal flux and concentration of sand-dust decreased with the increase of the height in the desert and the edge of oasis,whereas the two physical quantities increased slightly with the increase of the height in the oasis.The two physical quantities obey power function well under all three cover conditions.Moreover,in the desert and at the edge of oasis,the sand-dust vertical deposition decreased with the increase of the height.But a partial unimodal distribution at the oasis site and the maximum deposition occurred at the height of 9 m,which corresponds to the middle height of farmland protection forest.The annual flux that passed through a section of 1 m in width and 50 m in height was 9169 kg in the desert,5318 kg at the edge of oasis,and 2345 kg in the oasis.And the annual fluxes at the edge of oasis and in the oasis are 42% and 74% less,respectively,than that in the desert.This implies that the wind break forest significantly reduced the intensity of sandstorms.