植茶年限对土壤酸度及其团聚体交换性酸分布的影响

为明晰土壤酸度与团聚体交换性酸对植茶年限的响应特征,采用野外实地调查和室内分析相结合的方法,以植茶16、23、31和53 a的土壤为研究对象,开展不同植茶年限对土壤酸度及其团聚体交换性酸分布的影响.结果表明:①随着植茶年限的延长,土壤pH逐渐降低,交换性氢、交换性铝和交换性酸含量均呈升高的趋势.各植茶年限土壤0~20 cm土层pH均低于>20~40 cm土层,而交换性氢、交换性铝和交换性酸含量则表现出相反的变化趋势,且交换性氢含量在植茶23 a后的增幅可达21.29%. ②土壤交换性氢、交换性铝和交换性酸含量均随团聚体粒径的减小而升高,各粒径团聚体交换性氢、交换性铝和交换性酸含量随植茶年限的延长而逐渐升高. ③各植茶年限土壤团聚体交换性氢的分配比例均远低于交换性铝.随团聚体粒径的减小,各植茶年限交换性氢的分配比例均呈升高的趋势,而交换性铝的分配比例则呈降低趋势. 0~20 cm土层各粒径团聚体交换性氢的分配比例均以植茶53 a时较高,为17.97%~19.69%;>20~40 cm土层各粒径团聚体交换性氢的分配比例以植茶16 a时较高,为19.51%~22.77%,而各粒径团聚体交换性铝的分配比例则呈相反的趋势.研究显示,长期植茶会导致土壤酸化,随着植茶年限的延长,土壤pH逐渐降低,交换性氢、交换性铝和交换性酸含量均升高,不同粒径团聚体对交换性酸的保持能力存在明显差异.      

缙云山4种森林植被土壤团聚体有机碳分布特征

以重庆市缙云山的竹林、阔叶林、针叶林和针阔叶混交林这4种亚热带森林植被为研究对象,分析不同林分下土壤团聚体及团聚体有机碳在0～20、20～40、40～60和60～100 cm土壤剖面上的分布规律.结果表明,阔叶林土壤 2 mm粒级团聚体含量、平均重量直径(MWD)、几何平均直径(GMD)及 0. 25 mm团聚体含量(R0. 25)均随土层深度的增加而降低,而其他林分在整个土层中则无明显规律.在各土层中,竹林以 2 mm粒级团聚体为主(30. 73%～53. 08%);阔叶林和混交林的2～0. 25 mm粒级团聚体含量较高,为36. 27%～44. 67%和48. 69%～52. 44%;针叶林的优势粒径为2～0. 25 mm和0. 053 mm.总体上,在各土层中,竹林团聚体的MWD、GMD、R0. 25值均高于其他林分,且其分形维数(D)低于其他林分,可见竹林的土壤团聚体稳定性较好.随着土层深度的增加,不同林分(除针叶林外)土壤团聚体有机碳含量逐渐降低,其中竹林团聚体有机碳含量最高,显著高于针叶林和混交林.就不同团聚体粒级而言,4种林分土壤团聚体有机碳在整个土壤剖面上无明显规律,但各土层均以2～0. 25 mm和0. 053 mm粒级团聚体有机碳含量较高.不同林分下土壤团聚体有机碳相对贡献率存在显著差异,其中针叶林中0. 053 mm粒级团聚体有机碳贡献率最高;竹林的 2 mm粒级团聚体有机碳贡献率高达27. 44%～53. 47%;而阔叶林和混交林则以2～0. 25 mm粒级团聚体有机碳贡献率最高.缙云山的4种林分中,竹林的土壤团聚体稳定性较好,而针叶林的较差;在各土层中,竹林土壤各粒级团聚体有机碳含量最高,针叶林最低.     

Enhancement of phosphorus sorption onto light expanded clay aggregates by means of aluminum and iron oxide coatings

Phosphorus (P) loading from non-point or point sources increases the eutrophication risk of natural waters. The functioning of constructed wetlands (CWs) used as natural water treatment systems can be improved by means of additional materials adsorbing soluble P. In this study, light expanded clay aggregates (LECA) and LECA coated with aluminum (Al) oxide (Al-LECA) or iron (Fe) oxide (Fe-LECA) were tested for their efficiency as P sorbents in the pH range 3–8. The oxide coatings duplicated the actual sorption capacity calculated from the sorption isotherms at the P concentration in the equilibrium solution of 20 μg L⁻¹, assumed to be the allowable P level in purified water. In the oxide-coated LECAs the sorption was fast and followed both the first- and second-order Lagergren kinetic models, suggesting that the formation of a binuclear surface complex was feasible. In LECA, sorption was markedly slower and followed the first-order kinetic model, indicating that retention occurred through a monodentate attachment. These findings were in harmony with the degree of P saturation (DPS) of the sorbent surfaces at the highest P addition level (200 μg L⁻¹), DPS being decisively higher for LECA than for the oxide-coated sorbents. Accordingly, at higher pH values the competition by hydroxyl ions diminished the sorption in LECA relatively more than that in the coated sorbents. In agreement with the acidity of Al³⁺ being 100 times lower than that of Fe³⁺, at elevated pH the sorption by Al-LECA proved to be less reversible than that by Fe-LECA. The results provide evidence that in CWs Al-coated sorbents are superior to Fe-coated ones that are also redox-sensitive and may lose their sorption properties in anoxic conditions.     

黄土丘陵区林草退耕年限对土壤团聚体特征的影响

随着国家退耕还林还草战略的实施、植被覆盖的变化,林、草地植被恢复进程中土壤团聚体特征的变化受到广泛关注.本研究以黄土丘陵区西部的官山林场退耕后栽植的刺槐林地、撂荒草地为对象,选取退耕年限为10、25 a的林、草地,采用湿筛法测定各样地0~30 cm土壤的水稳性团聚体组成,比较退耕还林、还草和退耕年限(10、25 a)对土壤水稳性团聚体平均质量直径(MWD)和分形维数(D)的影响.结果表明:退耕10 a的林地0~30 cm土层水稳性大团聚体含量(R0.25)、MWD和D分别为57.60%、1.91 mm和2.73;退耕25 a的林地分别为60.17%、1.88 mm和2.74;退耕10 a的草地分别为59.89%、1.82 mm和2.74;退耕25 a的草地分别为72.69%、2.71 mm和2.61.进一步分析证明,随着退耕年限的增加,土壤团聚性增强;但林草地的变化存在差异:恢复10 a阶段,土壤团聚性林地尚优于草地,25 a后草地优于林地.各样地土壤的SOC含量与R0.25呈显著正相关关系(p0.01),与D呈显著负相关关系(p0.05).退耕类型和退耕年限对土壤团聚性有显著影响.     

土壤团聚体制备方法对其稳定性及固碳潜力评价的影响研究

为探讨不同土壤团聚体制备方法对评价城市土壤固碳潜力的影响,本研究采集北京市两种典型的不同利用类型土壤—城市绿地土壤和城郊农田土壤,分别采用干筛法和湿筛法制备土壤团聚体,对其团聚体组成、有机碳含量以及稳定碳同位素特征进行了解析.结果表明:干筛法制备的机械稳定性团聚体均以>0.25mm的大团聚体为主(城市绿地土壤:69.80%;农田土壤:71.36%);而湿筛法制备的水稳性团聚体均以<0.25mm微团聚体为主(城市绿地土壤:57.70%;农田土壤:52.14%).红外光谱解析发现,不同制备方法下,两类土壤中微团聚体中均是稳定有机碳比活性有机碳相对含量高;北京城郊农田土壤中稳定芳香碳的相对含量较多,而脂肪碳相对含量较少;城市绿地土壤则具有相反特征,说明城市绿地土壤中有机碳具有更高活性易在一定条件下被释放.结合稳定碳同位素比值解析发现,湿筛制备方法下¹³C在<0.053mm团聚体颗粒组中富集,更符合土壤团聚体胚胎发育模型,说明在土壤固碳潜力研究中,湿筛法比干筛法制备团聚体更具有实际评价价值,本研究为进一步评价我国城市土壤的固碳潜力具有参考意义.     

典型湖泊有机聚集体时空特征及驱动因子

有机聚集体(OA)是水体中物质循环和能量流通的重要枢纽,但在不同营养水平湖泊中的比较研究仍相当匮乏.于2019～2021年间,采集了不同季节贫营养抚仙湖、中营养天目湖、中度富营养太湖和重度富营养星云湖表层水样,利用扫描电镜、表面荧光显微镜和流式细胞仪等研究了4个典型湖泊中OA及其附着细菌的时空变化特征.结果表明：(1)抚仙湖、天目湖、太湖和星云湖中,OA丰度的年均值分别为1.4×10⁴、 7.0×10⁴、 27.7×10⁴和16.0×10⁴ind·mL^-1; OA附着细菌丰度的年均值分别为0.3×10⁶、 1.9×10⁶、 4.9×10⁶和6.2×10⁶ cells·mL^-1;附着细菌占总细菌的比值分别为30%、 31%、 50%和38%.(2)夏季OA丰度显著高于秋冬季;但夏季附着细菌占总细菌的比值为26%,显著低于其它3个季节.(3)湖泊营养状态是影响OA及其附着细...     

菲在长期施肥黑土团聚体中的老化行为

在东北黑土区长期肥料试验定位监测田采集[化肥与有机肥配施（NPOM）、不施肥（NF）]的表层（0～20 cm）土壤样品,用室内模拟培养的方法研究了菲在黑土及其不同粒径团聚体中的老化行为及其影响因素的溯源分析.结果表明,老化前期〉2 mm粒径组团聚体是优先吸附剂,而老化后期〈0.053 mm粒径组的团聚体是优先吸附剂.在...     

水盐梯度对闽江河口湿地土壤水稳性团聚体分布及稳定性的影响

为了揭示水盐梯度对河口湿地土壤水稳性团聚体分布及稳定性的影响,对闽江河口不同淹水环境和盐度下短叶茳芏(Cyperus malaccensis)湿地土壤水稳性团聚体进行了测定与分析.结果表明:①闽江河口半咸水湿地和淡水湿地0～30 cm土壤粉+黏团聚体、微团聚体和大团聚体的含量分别为63.12%～77.49%、6.82%～31.64%、4.38%～22.63%.除20～30 cm土层外,高潮滩0～20 cm土壤粉+黏团聚体和大团聚体含量均随盐度的增加而增加,增幅分别为8.74%～9.85%和105.54%～144.40%;0～20 cm土壤微团聚体含量均随盐度的增加而降低,高潮滩降幅为59.56%～65.20%,低潮滩降幅为55.65%～60.92%.②高潮滩土壤团聚体稳定性随盐度的增加而增加,盐度对微团聚体、大团聚体含量(DR_(0.25))和平均重量直径(MWD)的作用力在不同土层均影响显著,盐度和淹水的交互作用对各级土壤水稳性团聚体分布及稳定性的影响均不显著.③土壤团聚体稳定性与土壤TC含量呈倒"U"型关系.综上,淹水环境变化对土壤水稳性团聚体分布及稳定性的影响较小,盐度和有机碳含量是影响闽江河口湿地土壤水稳性团聚体分布及稳定性的重要限制性参数.     

Short-term Model of the Production of Construction Aggregates in Taiwan Based on Artificial Neural Networks

BACKGROUND: Taiwan's geography and limited stock of sandstone have caused sandstone resources to gradually decline to the point of exhaustion after long-term excavation. Moreover, the Taiwanese government has continuously increased the amount of land area near rivers that cannot be excavated to facilitate riverbed remediation and promote conservation of water resources. Accordingly, predicting and managing the annual production of construction aggregates in future construction projects, and dealing appropriately with some thorny problems, for instance, demand that excess supply, excessive excavation, unregulated excavation, and the consequent environmental damage, will significantly affect the efficient use of natural resources in a manner that accords with the national policy of Sustainable Development (SD). METHODS:. This study establishes an empirical model for forecasting the annual production of future construction aggregates using Artificial Neural Networks (ANN), based on 15 relevant socio-economic indicators, such as indicator of annual consumption of cement. A sensitivity analysis is then performed on these indicators. RESULTS AND DISCUSSION: This work applies ANN to estimate the annual production of construction aggregates; the estimates, the verification of the model and the sensitivity analysis are all acceptable. Furthermore, sensitivity analysis results indicate that the annual consumption of cement is the indicator that most strongly influences the production of construction aggregates, as well as whether construction waste can be recycled and steel structures can be used in buildings, helping to reduce the future production of construction aggregates in Taiwan. CONCLUSIONS: The elaborate prediction methodology presented in this study avoids some of the weaknesses or limitations of conventional linear statistics, linear programming or system dynamics. Additionally, the results not only provide a short-term prediction of the production of construction aggregates in Taiwan, but also provide a viable and flexible means of verifying quality certification of the production data of construction aggregates in the future by incorporating those relevant socio-economic indicators. RECOMMENDATIONS AND OUTLOOK: The continuity and quality of the database of relevant indicators used in this study should be closely scrutinized in order to ensure the SD means of exploiting resources.     

西藏退化高寒草原土壤团聚体有机碳的变化特征

为进一步了解高寒草原土壤碳动态变化特点与变化过程,采用湿筛法对藏北高原未退化、轻度退化和严重退化高寒草原表层（0~10 cm）、亚表层（>10~20 cm）不同粒级w（SAOC）（SAOC为土壤团聚体有机碳）进行研究.结果表明,与未退化草地相比,不同程度退化草地w（SAOC）均呈下降趋势,但严重退化草地表层、亚表层中w（SAOC）、>0.25 mm粒级w（SAOC）、 < 0.25 mm粒级w（SAOC）降幅均显著低于轻度退化草地;不同程度退化草地表层、亚表层中>0.25、 < 0.25 mm粒级w（SAOC）在总体上趋于下降,且亚表层的降幅明显高于表层的降幅,但退化草地亚表层中w（SAOC）仍高于表层（未退化草地、轻度和严重退化草地亚表层较表层分别增加51.84%、31.34%、6.83%）,w（SAOC）的土层差异随草地退化加剧而大幅缩小;轻度、严重退化草地不同粒级w（SAOC）的土层分布特征仍与未退化草地一致,其表层、亚表层中>0.25 mm粒级w（SAOC）均明显较高;与未退化草地相同,退化草地表层、亚表层w（SAOC）贡献率亦均呈|2~0.25 mm| > | < 0.25~0.053 mm| > | > 2 mm| > | < 0.053 mm|粒级;退化草地环境对团聚体与w（SAOC）,以及w（SOC）（SOC为土壤有机碳）与w（SAOC）间的关系具有重要影响.研究显示,高原冷干环境下不同粒级SAOC及其变化受草地退化程度、土层深度等的深刻影响,需要从影响土壤有机碳形成与转化的土壤机制等方面进行深入研究.