Influence of additives in the end‐use mixes of tebufenozide on deposition,adhesion and persistence in spruce foliage

Abstract

A commercial flowable formulation of tebufenozide, RH‐5992 2F [N'‐t‐butyl‐N'‐(3,5‐dimethylbenzoyl)‐N‐(4‐ethylbenzoyl) hydrazine], was diluted with water, water and canola oil, and water and the methyl ester of canola oil, to provide six end‐use mixes with concentrations of 35 and 70 g of active ingredient (Al) litre^‐1. The mixes were applied at 70 and 140 g Al ha^‐1 over white spruce [Picea glauca (Moench) Voss] seedlings in a laboratory spray chamber and foliar concentrations of tebufenozide were determined over a 60‐d period. At intervals of time post‐spray, seedlings were sprayed with monosized droplets of Sunspray®11N as rainfall, and the amount of tebufenozide knocked off from foliage was determined. The potential energy of adhesion (PEA) of the Al particles on the foliage increased with time and varied according to the type of end‐use mix, its viscosity and the dosage sprayed.

The end‐use mixes were applied over white spruce trees under field conditions and persistence of tebufenozide was investigated. DT₅₀ values were influenced by the type of mix and dosage sprayed. Oil‐containing mixes and higher dosages increased the PEA of tebufenozide particles.     

Biomass production and carbon sequestration potential in poplar plantations with different management patterns

Biomass production and carbon storage in short-rotation poplar plantations over 10 years were evaluated at the Hanyuan Forestry Farm, Baoying County, China. Experimental treatments applied in a split-plot design included four planting densities (1111, 833, 625 and 500 stems ha(-1)) and three poplar clones (NL-80351, I-69 and I-72). Based on the model of total biomass production developed, total plantation biomass production was significantly different in the plantations. The ranking of the plantation biomass production by planting density was 1111>833 more more than 625>500 stems ha(-1), and by components was stem>root>or=branch>leaf for all plantations. At 10 years, the highest total biomass in the plantation of 1111 stems ha(-1) reached about 146 t ha(-1), which was 5.3%, 11.6% and 24.2% higher than the plantations of 833, 625 and 500 stems ha(-1), respectively. The annual increment of biomass production over 10 years differed significantly among initial planting densities and stand ages (p<0.01), but no significant difference was observed from age 7 to 10. Mean carbon concentration among all biomass components ranged from 42-50%, with the highest carbon concentrations in stems and the lowest in leaves. Over the study period, the dynamic pattern of total plantation carbon storage by planting density was similar to that of total biomass production. At age 10, the highest total plantation carbon storage in the plantation of 1111 stems ha(-1) reached about 72.0 t ha(-1), which was 5.4%, 11.9% and 24.8% higher than in the plantations of 833, 625 and 500 stems ha(-1), respectively. The annual carbon storage increment over 10 years differed significantly among initial planting densities and stand ages (p<0.01), and it showed a pattern similar to the annual biomass production increment of the plantations. The results suggest that biomass production and carbon storage potential were highest for planting densities of 1111 and 833 stems ha(-1) grown over 5- and 6-year cutting cycles, respectively. If 3- or 4-year cutting cycles are used, the planting density should be higher than 1111 stems ha(-1) (e.g., 1667 or 2500 stems ha(-1)). Based on the mean annual carbon storage for the plantation of 625 stems ha(-1), as an estimation, the mean carbon storage in the biomass of poplar plantations (excluding leaves) amounts to 3.75x10(7) t ha(-1)yr(-1) in China.     

铁电絮凝去除磷酸盐性能及影响因素研究

不同水质条件下,铁板作为阳极电絮凝时会产生不同形态的絮体,而絮体种类对磷酸盐去除效果尚不明确.利用铁板作为阳极进行电絮凝,考察溶解氧对电絮凝过程中生成絮体种类的影响,进一步研究电流密度和初始pH值对磷酸盐去除效果的影响.结果表明,低溶解氧（DO）条件下絮体成分主要为磁铁矿,高DO条件下可能为无定型三价铁氧化物/氢氧化物;电流密度越大(2.5、5和10 mA·cm^-2),磷酸盐去除效率越高,同时,低DO条件下磷酸盐去除效率高于高DO条件;而初始pH值（4、5、6、7和8）虽不影响不同溶解氧条件下所产絮体的除磷效果,但DO浓度高时,酸性条件下磷酸盐去除效率更高.当前污水处理厂二级出水存在磷浓度较高的问题(TP> 0.5 mg·L^-1),采用实际污水在2.5 mA·cm^-2电流密度下进行电絮凝,10 min后,初始浓度为1.307 mg·L^-1磷酸盐去除效率达98%以上.研究结果将为电絮凝产不同形态铁去除磷酸盐提供理论支持.     

深圳市大气颗粒物分粒径有效密度及影响因素

为探究深圳市大气颗粒物分粒径有效密度变化特征及其影响因素,本文将离心颗粒物质量分析仪(CPMA)与差分电迁移粒径分析仪(DMA)联用,通过粒径筛分测定了2020年9月~2021年2月粒径范围为50~500nm的深圳市大气颗粒物分粒径有效密度.结果表明:深圳市大气颗粒物的中值有效密度范围在1.29~1.53g/cm³,颗粒物有效密度均随颗粒物粒径增加而增大,秋季有效密度略低于冬季.清洁时期,有效密度较低且观察到双峰分布,低密度颗粒物中值有效密度在0.70~0.80g/cm³范围内,表明存在新鲜排放的黑碳颗粒物,高密度颗粒物中值有效密度在1.3~1.5g/cm³范围内,介于二次无机颗粒物和有机物的材料密度之间,推测为二者混合状态.污染时期,不同粒径有效密度值增加且呈现单峰分布,表明颗粒物呈现内混态.在新粒子生成事件中,气态硝酸凝结可能是大气颗粒物后续粒径增长和有效密度增加的主要原因.     

泥石流浆体屈服应力综合表达式的研究

根据野外泥石流浆体观测试验分析,通过对不同料径沙颗粒的甘油沙浆流变试验,以及动摩擦临界浓度和极限浓度的实验研究,导出了反映泥石流浆体结构强度的屈服应力综合表达式,以便为泥石流高浓度,高速机理探讨和泥石流防治工作的设计提供科学依据的参数。     

Edge Effects and Isolation: Red-Backed Voles Revisited

Abstract:  We examined demographic responses of California red-backed voles ( Clethrionomys californicus ) to forest fragmentation in southwestern Oregon at sites where this species has previously shown negative responses to fragmentation. Voles were captured in live traps and released. Voles were rarely caught in clearcuts surrounding 11 forest fragments, but relative vole density did not decrease from the forest-fragment interiors to edges. The first result agrees with previous findings at these sites 6 years earlier, but the latter result does not. There was no evidence that vole response to edge changes with fragment age. Two years of intensive mark-recapture efforts at two forest-fragment sites and two unfragmented (control) sites did not show negative effects of fragmentation on vole survival, an important demographic rate. Vole capture probabilities varied greatly across space and time on these four sites, which may explain the differences in vole responses to edge seen between this and the previous study. These results suggest that reliable appraisal of edge effects may be difficult for many species on small fragments because the data necessary to apply population estimators require great efforts to obtain and the use of indices leads to a confounding of detection probabilities with demographic change.     

铜绿微囊藻生长代谢的密度依赖性特征及分子机制

蓝藻水华是淡水湖库普遍面临的水环境问题,目前水华形成机制研究大多关注外界环境因素而忽略了藻类自身及群体的关键调节作用.因此,本文以初始细胞密度为单一变量,考察了不同初始细胞密度条件下蓝藻生长、营养物质利用、叶绿素、藻毒素、胞外分泌物随时间的变化情况.结果发现,初始细胞密度会影响铜绿微囊藻的环境适应性和生长情况,当接种密度≥1×10⁶ cell·mL^-1,铜绿微囊藻适应期消失,初始细胞密度从1×10⁵ cell·mL^-1增加至1×10⁷ cell·mL^-1,最高细胞密度增加了68%,生长速率提高了21%,并且叶绿素变化趋势与生长情况一致.胞外分泌物随初始细胞密度增加而逐渐增加,有利于蓝藻细胞聚集成膜.当初始细胞密度较低（1×10⁵ cell·mL^-1）时,单细胞藻毒素分泌量反而增加,以提高蓝藻的环境适应能力.在高初始密度（1×10⁷ cell·mL^-1）条件下,铜绿微囊藻主要通过上调丙酮酸代谢和碳代谢,促进细胞生长增殖.因此,细胞密度是影响铜绿微囊藻生长代谢的重要因素,在蓝藻水华形成过程中可能发挥重要作用,水华防治应当在细胞密度较低的阶段进行.     

济南市大气颗粒物背景值确定方法

城市大气颗粒物背景值的确定能够为制订城市大气颗粒物污染防治目标提供重要基础支撑,探索大气颗粒物背景值确定方法对于大气污染防治具有重要意义.以济南市清洁对照点跑马岭监测数据为基础,直接采用概率密度法计算得到的ρ（PM₁₀）和ρ（PM_2.5）背景值范围分别是100~110和40~50 μg/m3.综合应用空气质量模型模拟法和概率密度法,提出基于数值模拟的城市大气颗粒物环境背景值确定方法,并在此基础上确定了济南市大气颗粒物背景值.结果表明:济南市ρ（PM₁₀）和ρ（PM_2.5）背景值范围分别是30~35和15~20 μg/m3,其中ρ（PM₁₀）环境背景值秋季（40~45 μg/m3）最高、夏季（25~30 μg/m3）最低;ρ（PM_2.5）环境背景值秋季（25~30 μg/m3）最高、冬季（10~15 μg/m3）最低.研究显示,基于数值模拟计算得到的颗粒物背景值明显低于直接采用概率密度法得到的结果,表明跑马岭受人为因素影响明显,监测结果已不能完全代表济南市大气颗粒物背景值水平;而数值模拟法可以完全剔除了人为源的贡献,计算得到较为准确的ρ（PM₁₀）和ρ（PM_2.5）背景值.      

1973~2013年黑龙江省森林碳储量及其动态变化

基于1973~2013年8次省森林清查数据以及实测数据改进的生物量蓄积量转换参数,利用生物量转换因子连续函数法,研究了近40a黑龙江省森林碳储量及其动态变化.结果表明：黑龙江省森林碳储量从1973~1976年的1159.35 TgC下降到2009~2013年的833.99 TgC,其中天然林减少387.51 TgC,人工林增加62.15 TgC;森林总体表现为碳源（-10.88 TgC/a）,主要归因于天然林面积的减少.不同森林类型的碳储量存在较大差异,桦木、落叶松和阔叶混是碳储量的主要贡献者;大多数森林类型的碳密度呈上升趋势.森林以中、幼龄林为主,中龄林碳储量占同期全省总量的27.9%~46.6%,其他龄组的碳储量均呈减少趋势,以成熟林最为明显（201.17 TgC）;幼龄林、中龄林和近熟林的碳密度分别增加2.20、3.21和3.43MgC/hm²,成熟林和过熟林则有所下降;不同龄组森林面积和碳密度的变化是导致其碳储量变化的主要原因.     

Effects of urbanization on heavy metal accumulation in surface soils, Beijing

Urbanization processes affect the accumulation of heavy metals in urban soils. Effects of urbanization on heavy metal accumulation in soils were studied using Beijing as an example. It has been suggested that the ecological function of vegetation covers shifting from natural to agricultural settings and then to urban greenbelts could increase the zinc(Zn) concentrations of soils successively. The Zn concentration of urban soils was significantly correlated to the percentage of the impervious land surface at the500 m × 500 m spatial scale. For urban parks, the age or years since the development accounted for 80% of the variances of cadmium(Cd) and Zn in soils. The population density,however, did not affect the heavy metal distributions in urban soils. To conclude, the urban age turned out to be a notable factor in quantifying heavy metal accumulation in urban soils.