微塑料对土壤持水性能的影响

为探究微塑料对土壤持水性能的影响,选用粒径为1 mm和25 μm的聚乙烯微塑料（PE—MPs）颗粒进行土培处理后,采用高速离心机法测得不同处理下的土壤水分特征曲线,并使用Gardner模型进行拟合分析。结果表明：（1）土壤中累积少量的PE—MPs （0~5.00 g/kg）能增强土壤持水性,但当累积量超过一定阈值（5.00~50.00 g/kg）会导致土壤持水能力显著降低。（2）1 mm大粒径PE—MPs大量积累对土壤持水性的降低效应更显著;25 μm小粒径PE—MPs少量积累对土壤持水性的提升效应更显著。（3）1 mm大粒径PE—MPs进入土壤后主要影响大孔隙与有效孔隙,对土壤有效含水率的影响较大;25 μm小粒径PE—MPs进入土壤后主要影响微小孔隙,对萎焉系数影响较大。该研究可为高农膜残留地区水分迁移模拟和农业生态风险评价提供理论依据。     

Relaxations Below Glass Transition Temperature in Bread and Its Components

Dry glassy bread, cooked gluten, and gelatinized wheat starch-sucrose mixtures were prepared. Dielectric properties were studied as a function of temperature at different frequencies ranging from 100 to 1,000 kHz. Both bread and starch samples exhibited a tan δ peak at -53°C at 10 kHz, which is associated with a secondary relaxation characterized by an activation energy of 50 kJ/mol. The gluten sample did not show any relaxation in the temperature range studied. The magnitude of the relaxation peak was sensitive to the sucrose concentration of the starch sample. The higher the sucrose content, the greater the amplitude of the peak. Such an effect is attributed to a greater β-relaxation induced by an increasing number of relaxing units or increasing size of the loosely packed regions of the glass. However, it cannot be concluded whether the relaxation is associated with a group present on both starch and sucrose or that the sucrose has an enhancing effect on starch mobility.     

Sodium Chloride Effects on Water and Nutrient Uptake Efficiency in Sarcocornia fruticosa Containerized Production

The ability to produce native plants well adapted to the saline conditions without the production of nutrient-rich runoff will be a boon to nurseries hoping to reduce their environmental contamination impact and water use while at the same time producing quality plants to be used in the restoration of saline lands. Sarcocornia fruticosa plants were grown for 8 weeks in plastic containers with a source of sphagnum peat moss and perlite (80:20 v/v) to evaluate the effect of two salinity levels (2.0 (low-salinity treatment) and 7.5 dS m^?1 (high-salinity treatment)) on plant growth, nutrient concentration in leachate and water and nutrient uptake efficiency and their losses. Leachate was collected to determine the runoff volume and composition, which included nitrate-nitrogen (NO₃^–N), phosphate-phosphorus (PO₄^3–P) and potassium (K⁺) concentrations. Plant dry weight (DW) and nutrient content were determined in plants at the beginning and at the end of the experiment to establish the nutrient balance. Increasing salinity levels of irrigation water did not reduce either the plant DW or the water-use efficiency (WUE), but increased the volume of leachate per plant. The nutrient concentrations in leachates without significant differences between salt treatments exceeded the thresholds established by environmental guidelines, leading to a great risk of pollution. Based on nutrient balance, the irrigation with a higher salinity level reduced the plant nutrient uptake efficiency (10%, 18% and 12% for nitrogen (N), phosphorus (P) and potassium (K), respectively) and increased the nutrient losses (6% N, 7% P and 8% K), resulting in the recommendation to grow this species with the low salinity level based on the highest nutrient-use efficiency and the lowest levels of nutrient losses.     

Effect of Sodium Chloride Levels on Growth,Water Status,Uptake, Transport,and Accumulation Pattern of Sodium and Chloride Ions in Young Sunflower Plants

There is a paucity of information on the critical content, threshold levels, uptake, transport, and accumulation of sodium (Na⁺) and chloride (Cl^?) ions in young sunflower plants. Effect of salinity was analyzed in root, stem, leaves, and buds by raising plants in fine sand irrigated with Hoagland's solution and supplemented with 10–160 mM sodium chloride (NaCl) for 30 days. Maximum sensitivity index, reduction in growth, and water content were observed in buds. Maximum Na⁺ and Cl^? contents were obtained in old leaves and stems under low salinity but in roots at high salinity. Uptake, transport, and accumulation rate of Cl^? were more than those of Na⁺, and for both ions they increased with increasing NaCl concentration but decreased with increasing exposure time. Growth reduction at low salinity seems to be because of Cl^? toxicity, but Na⁺ toxicity and water deficiency could also be the causes at high salinity.     

保水剂对土壤持水性状的影响

测定了保水剂对土壤持水性状的影响。保水剂拌入土壤后,其吸水能力明显降低,表现为理论含水量明显低于实测含水量。加入保水剂后,壤土水分的蒸发率比不加保水剂时壤土中水分的蒸发率高,沙土水分的蒸发率比不加保水剂时低。加入保水剂还明显减缓了水分向土壤深层的入渗,使水分滞留于土体近表层,使用不当会加大土壤无效蒸发的潜力。     

Hydraulic Retention Time Influence on Improving Flocculation in the Activated Sludge Processes Through Polyelectrolytes

Hydraulic retention time (HRT) influence improving sludge flocculation with adding the polyelectrolytes (non-ionic, anionic, and cationic) was studied on an activated sludge (AS) system fed with synthetic domestic wastewater (SDW), dairy industry wastewater (DIW), and caramel industry wastewater (CIW). The sludge volumetric index, food/microorganism ratio (F/M), and mixed liquor volatile suspended solids at different HRTs (6, 8 and 10 h) were monitored on an experimental model. Results showed that both SDW and IW had the best sludge flocculation conditions at 8 h and 100 mL of non-ionic polyelectrolyte (0.2 mg L^?1). In addition, this phenomenon reached the organic matter removal efficiencies of 95.9, 95.7, and 94.2% for SDW, DIW, and CIW, respectively. Therefore, optimum HRT increased the organic matter removal efficiencies by 10%, sludge concentration by 37% (22–55%), and F/M ratio by 70%. Moreover, the polyelectrolytes used in AS improved the sludge flocculation by 2.9 times.     

Development of a Model to Predict Runoff Water Headloss Through Compost Filter Berms

As a part of a larger study designed to develop compost filter berms i.e., an unsupported mound of compost that intercepts surface runoff from a site, suitable for removing nutrients and sediment from agricultural operations, we evaluated the hydraulic behavior of compost buffers with different masses and particle size distributions subjected to varying water flow rates using flume experiments. For each berm combination, the maximum flow rate the compost berm could sustain before a structural failure occurs was determined for different compost particle sizes. These data were used to develop models to predict headloss through a compost berm as a function of the flow rate per unit width, the median particle size of the compost media, and the buffer dimensions. The developed models perform well with R² values ranging from 0.64 to 0.97 with the majority of values greater than 0.9. The effect of presence of sediments in the flow was also quantified. The results show that headloss increased by 1–2 cm as a result of sediment removal, ranging from 5 to 35%, taking up pore space in the compost berm.     

城市绿地的持水性能以及影响因素研究

以黑龙江省齐齐哈尔市街道绿地为例,运用土壤理化分析手段研究了城市绿地土壤的持水性能。结果表明:研究区城市绿地土壤孔隙度以非毛管孔隙为主,非毛管孔隙所占比例在85%以上。受踩踏较轻的草坪地带土壤以及公园表层土壤的饱和含水率较高,最高可达50%。经常处于践踏的城市绿地土壤紧实,容重在1.5 g cm~(-3)以上。受到压实的土壤地表的植被缺失,土壤的饱和含水率和渗透速率都显著的小于没有压实的土壤(P0.05)。相关分析和主成份分析的结果表明,容重和电导率与城市绿地土壤的渗透性成显著负相关的关系,有机质量、孔隙度以及饱和含水率则与土壤渗透系数成显著性正相关。研究区单位面积(1 m~2)地表枯落物最大持水量高达5.75 kg,对于保持城市绿地的持水效应有十分重要的作用。适当保持城市绿地地表的枯枝落叶,减少绿地踩踏,适当增加草坪面积对于保持城市绿地土壤的水分和改善局地生态环境具有十分重要的意义。     

Effects of Sodium Chloride and Mineral Nutrients on Initial Stages of Development of Sunflower Life

Abstract

The effects of three levels of salinity [0, 50, and 100 mM of sodium chloride (NaCl)] and the addition of potassium, calcium, nitrogen, phosphorus, iron, manganese, and boron (K, Ca, N, P, Fe, Mn, and B) on seed germination and survival of Helianthus annuus L. plants grown in an inert medium were studied. Increasing levels of salinity significantly decreased germination percentage. The presence of NaCl affected seedling survival rather than germination. Nitrogen addition damaged seedling growth, especially in high saline conditions. Addition of some nutrients may alleviate the effects induced by NaCl. Calcium additions to the culture medium significantly improved germination percentage and seedling survival, which markedly decreased after addition of K and B under saline conditions. Iron addition, especially in the ferrous form, counteracted the effects of salinity on seed germination and seedling survival. Phosphorus addition showed detrimental effects on germination and especially in seedling survival; however, it benefited the surviving seedling's growth.     

Influence of Sodium Chloride Salt Stress on Growth and Nutrient Acquisition of Sour Orange In Vitro

Abstract

Growth and nutrient acquisition in sour orange (Citrus aurantium L.) were studied under salt stress in vitro. Microshoots were transferred to Murashige and Skoog (MS) solid proliferation media containing 8.9 µM BA (6‐Benzyladenine) and 0.5 µM NAA (naphthaline acetic acid). Salinity was induced by incorporating different concentrations [0.0 (control), 50, 100, 150, 200, or 300 mM] of sodium chloride (NaCl) to the culture media. Microshoots were exposed to direct or gradual salinity shock. Slight reduction was obtained in growth (shoot length, shoot number, leaf number, and dry weight) when microshoots were directly exposed to NaCl stress from 0.0 to 150 mM. At 200 and 300 mM NaCl, growth parameters were adversly affected and microshoots died thereafter. Gradual NaCl shock was studied by transferring microshoots sequentialy every week to different NaCl concentraions (0.0, 50, 100, 150, 200, or 300 mM). Growth was monitored at each concentration until the end of the last week of incubation at 300 mM NaCl. Growth (shoot length, shoot number or leaf number, and dry weight) generally decreased with elevated salinity level, but was less impaired than the direct shock. The percentage of shoot content of phosphorus (P), potassium (K), and iron (Fe) in the direct Nail shock experiment were reduced with elevated salinity level. This reduction was less in the gradual shock treatments. Sodium Chloride level strongly reduced Fe acquisition under both direct and gradual salinity stress. Tissue contents of sodium (Na), zinc (Zn), and manganese (Mn) were increased with the imposed salinity treatments in both experiments.     

Relationship of Gelatinization and Recrystallization of Cross‐Linked Rice to Glass Transition Temperature

Nonwaxy rice starch was cross‐linked with sodium trimetaphosphate and sodium tripolyphosphate to obtain different degrees of cross‐linking (9.2, 26.2, and 29.2%). The objective was to investigate the influence of cross‐linking on thermal transitions of rice starch. Starch suspensions (67% moisture) were heated at 2°C/min using differential scanning calorimetry (DSC) to follow melting transition of amylopectin. Biphasic transitions were observed at ≈60–95°C in all samples. Melting endotherms of amylopectin shifted to a higher temperature (≤5°C) with an increasing degree of cross‐linking, while there was no dramatic change in enthalpy. Recrystallization during aging for 0–15 days was significantly suppressed by cross‐linking. The delayed gelatinization and retrogradation in crosslinked starch were evident due to restricted swelling and reduced hydration in starch granules. Glass transition temperature (T_g) measured from the derivative curve of heat flow was ‐3 to ‐4°C. No significant change in T_g was observed over the storage time studied.     

玻璃温室和塑料大棚内逐时气温模拟模型

2014-2016年在江苏省不同地区选择塑料大棚和玻璃温室进行设施内气温监测,基于设施内日最高和最低气温,采用余弦分段函数、正弦分段函数、正弦-指数分段函数、一次分段函数和神经网络模型分别模拟不同季节和不同天气状况（晴天和阴雨天）下的逐时气温日变化,探究利用室内最高和最低气温模拟计算逐时气温的方法,以及设施内逐时气温日变化规律。结果表明：5种模型均可通过当日最高、最低气温模拟逐时气温变化,其中神经网络模拟精度较高（RMSE=0.69℃）,并且受温室类型、天气状况和季节变化的影响较小,普适性较高;正弦-指数分段函数模拟效果最好（RMSE=0.43℃）,且受天气和季节的影响较小,但其受温室本身特性和地区的影响较大;余弦分段函数（RMSE=0.85℃）和正弦分段函数（RMSE=0.78℃）模拟效果相近,且受天气和地区的影响;一次分段函数准确度较低（RMSE=0.90℃）且误差变化较大。各方法对塑料大棚内逐时气温的模拟精度均高于玻璃温室。模型模拟精度的季节变化因模型和温室类型有一定差异,但通常情况下,春季和冬季的模拟误差大于秋季,夏季误差最小。     

Influence of Soil Moisture and Salinity on the Carbon Dioxide Emission and Water Consumption during Germination of Cereal Seeds

The influence of moisture and salinity of quartz sand on activation of the CO₂ emission and water consumption by seeds of spring wheat (Triticum), winter rye (Secále cereále), triticale (Triticosecale), and spring barley (Hórdeum) treated by a stimulant was studied under conditions of a model experiment. It was found that the seeds treated with a stimulant get advantages in the development upon a decrease in the water content of quartz sand. However, in the case of sand salinization, stimulant application did not lead to acceleration of seed development. The deficiency of moisture in saline sand also resulted in the increase of stimulant application efficiency. It was supposed that optimum moisture contents of quartz sand for seed germination and for the development of endophytic microorganisms do not coincide: active development of endophytic microorganisms stimulating seed development began under a lower moisture in comparison with that of the active seed development. Thus, active development of endophytic microorganisms upon the low moisture content mitigates the deceleration of seed development in the case of water deficiency. Hence, application of the microbial stimulant for seeds should be efficient in the cases, when germination of seeds proceeds under conditions of possible moisture deficiency, i.e., in the regions, where early spring droughts are frequent.     

Variation and Heritability of Sodium Chloride Tolerance in Spring Wheat at Early Stage of Plant Development

The response of 5‐week‐old wheat seedlings of 68 genotypes was assessed in three salinity levels (i.e., control, 12, and 24 dS/m^?1) developed in solution cultures on the basis of fresh root and shoot weight. The 68 genotypes responded differently to increasing salinity levels in the growing medium. The genotypes S‐24 and DN‐33, which produced greater root weights than those of DN‐30, appeared as the most tolerant, whereas WC‐78, DN‐27, and DN‐32 were the most sensitive genotypes. The estimates of broad sense heritability (h² _B) for absolute fresh root weight were 0.35, 0.038, and 0.018 in the control, 12, and 24 dSm^?1, respectively, whereas those for relative fresh root weight were 0.08 and 0.05 in low and high salinities, respectively.     

未来气候及土地利用变化对水源涵养量的影响

“四水四定”背景下,科学量化变化环境下城镇或小流域未来水源涵养量是水资源管理、水利规划和水生态保护等工作的重要基础。水源涵养量尺度转化是目前生态水文学研究的难点之一,较高精细尺度研究是尺度转化的重要切入点。以秦岭北麓灞河流域为研究区,应用SWAT模型、CA-Markov模型、ArcGIS、RClimDex等分析工具,评估NEX-GDDP-CMIP6高分辨率数据集对灞河流域月流量模拟能力,选取最优气候模式,模拟未来土地利用变化,分析灞河流域未来30年水源涵养量演变趋势,旨在为秦岭生态保护、水资源管理、土地利用保护等提供基础数据。结果表明：(1)NEX-GDDP-CMIP6高分辨率数据集ACCESS-CM2、ACCESS-ESM1-5、CanESM5等9个气候模式对月平均流量均值模拟效果较好,对极端流量模拟效果较差,NESM3气候模式相比其他8个气候模式有较好的流量模拟效果。(2)NESM3气候模式低估极端降水情况,高估持续干燥天数,月尺度降水数据模拟能力高于年尺度和日尺度。(3)通过Kappa系数检验CA-Markov模型在灞河流域土地利用变化方面具有较好的适用性。(4)在土地利用和气候...     

Temperature Effects on Retention of Atrazine and Imazapyr on Soils

Water, Air, &; Soil Pollution -     

Effect of Sodium Chloride Salinity on Growth and Ion Accumulation in Some Halophytes

Abstract

Effects of salinity on biomass production, water content, and ion accumulation pattern in Atriplex amnicola P. G. Wilson, Atriplex calotheca L., Atriplex hortensis L., Chenopodium album L., Salsola kali L., and Suaeda nudiflora Moq. (all Chenopodiaceae) have been studied. The plants survived and exhibited no toxicity symptoms up to 6000 mg L^?1 NaCl treatment. Ion composition was variable in plants grown under different salinity treatments. Salinity, except in Suaeda nudiflora where the least biomass was produced in control, affected all other species negatively, and they produced the least biomass at high salinity treatment. Shoot water content of Suaeda nudiflora and Chenopodium album increased significantly in response to salinity. Among all the species examined here, maximum sodium (Na⁺) accumulation was recorded for Suaeda nudiflora, and it increased with the increasing salinity. This study concluded that among all the species tested, Suaeda nudiflora was most suitable plant for bioremediation of salt‐contaminated soils.     

Soil Organic C Development in Cereal and Ley Systems. Data from 20 Years Old Swedish Field Experiments

In four Swedish long-term field experiments in cereals and in four with mixed ley production the top soil organic C changes with time were investigated at different N levels. In the cereals treatments with all straw removed and all straw chopped and ploughed into the soil were compared. The experiments were started 20 years or more ago at 4 contrasting sites from south to north and they are still running. In the cereal system the C content decreased from 2.3 to 1.9% on average over the sites. The decline was the biggest where the initial content was the highest. Straw returned increased the C content with 0.1 percentage unit compared with straw removed. N also increased the C content in the cereal system but not in the ley system. The change with time was also insignificant in the ley part. Estimated rate constants for C decomposition varied from 0.1 to 1.66% yr m 1 in cereals. It decreased usually with increasing N level. When straw was returned at the high N level the rate constant also decreased. The rate constants corresponded to C break down of 610-740kg ha m 1 at the northernmost site and 250-270kg ha m 1 at the southernmost. With the assumed humification factor of 15% the gross supply of C was not high enough to maintain present C content at the northern site but at the southern site it was. In the ley systems steady state levels seemed almost to be established.     

玉米田间微集水种植的水温效应及其对植株生长发育的影响

以常规覆膜为对照,探讨了玉米采取4种集水种植模式的水温效应及其对玉米生长发育的影响。结果表明,4种集水种植模式都具有不同程度的集水增墒效应和降低地表温度的作用。集水效应以宽垄式＞硬覆盖＞膜内式＞膜侧式,依次是对照的2.36、2.07、1.88和1.69倍。降温效应以硬覆盖＞宽垄式＞膜侧式＞膜内式,依次较对照低1.6 ℃、1.4 ℃、0.8 ℃和0.5 ℃。水温效应的协调作用不仅可控制植株营养生长,促进生殖生长,而且还延长了生育期,使生殖生长与雨季更加吻合,因而穗大、粒饱,增产效果显著。硬覆盖、宽垄式、膜内     

水温对虹鳟血清中血糖含量的影响

本研究设置8个处理,水温分别控制为12．0℃、13．5℃、15．0℃、16．5℃、18．0℃、19．5℃、21．0℃和22．5℃,每个处理有3个重复实验,恒温饲养虹鳟一周后使用DS-2000全自动生化分析仪检测虹鳟血清中血糖含量,探讨水温对虹鳟血清中血糖含量的影响。结果表明：虹鳟血清中血糖含量在水温12．0～18．0℃阶段保持相对稳定;水温18．0～19．5℃阶段,血糖含量随水温上升而显著升高,升高变化率为63．72％;水温19．5～22．5℃阶段,血糖含量随水温上升而急著下降。虹鳟血清中血糖含量在不同温度下的动态变化对虹鳟南移温水驯化养殖具有参考价值。