The copper tolerance strategies and the role of antioxidative enzymes in three plant species grown on copper mine

This study was undertaken to identify the strategies and the status of antioxidant enzyme activities involved in three plant species tolerance against Cu-toxicity in copper mine. The following methods were used for evaluations in three wild type species; Datura stramonium, Malva sylvestris and Chenopodium ambrosioides. The level of chlorophyll and the activities of superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase (CAT) by spectrometry, malondialdehyde (MDA) and dityrosine by HPLC and the levels of Cu in tissues and soils by atomic absorption spectrometry (AAS).

Analysis showed that total and available copper were at toxic levels for plants growing on contaminated soil (zone 1). However, there were not any visual and conspicuous symptoms of Cu toxicity in plant species. Among three species, excess copper was transferred only into the D. stramonium and C. ambrosioides tissues. The C. ambrosioides accumulated Cu in roots and then in leaves, in which the leaves chloroplasts stored Cu around two times of vacuoles. In D. stramonium most of Cu was accumulated in leaves in which the storage rate in vacuoles and chloroplasts were 42% and 8%, respectively. In zone 1, the chlorophyll levels increased significantly in leaves of C. ambrosioides with respect to the same plant growing on uncontaminated soil (zone 2). There was insignificant decrease in chlorophyll content of D. stramonium leaves, collected from zone 1 with respect to zone 2. The D. stramonium and C. ambrosioides in zone 1, both revealed significant increase in their tissues antioxidant enzyme activities in comparison with the same samples of zone 2. There was significant elevation in oxidative damage biomarkers; MDA and dityrosine, when the aerial parts of D. stramonium in zone 1 were compared with the same parts of zone 2.

We concluded that there were different tolerance strategies in studied plant species that protected them against copper toxicity. In M. sylvestris, exclusion of Cu from the roots or its stabilization in the soil restricted Cu toxicity effects. On the other hand D. stramonium and C. ambrosioides, elevated their antioxidative enzyme activities in response to cu-toxicity. In addition, the species D. stramonium accumulated excess of Cu in leaves vacuoles.     

川藏铁路沿线地区夏季气温日较差的影响因素研究

利用ERA5再分析资料,分析了1979—2018年川藏铁路沿线区域气候特征.研究了2014—2018年夏季气温日较差(DTR)的变化趋势,以及2014—2018年夏季DTR与地面太阳辐射(SSR)、总降水量(TP)、总云量(TCC)、海拔(DEM)和地表平均蒸发率(MER)的相关性.结果表明:研究区域气温呈上升趋势,2...     

振动环境试验控制允差的剪裁应用

从工程应用的角度,本文分析讨论了GJB 150.16A对振动环境试验控制允差的要求。结果表明,GJB150.16A对控制允差的要求是灵活的,但是未规定RMS允差,容易造成过试验或欠试验,且对加速度谱密度的控制允差要求的表述存在着一定的模糊。文中给出了解决建议。     

Tropical amphibians in shifting thermal landscapes under land‐use and climate change

Land‐cover and climate change are both expected to alter species distributions and contribute to future biodiversity loss. However, the combined effects of land‐cover and climate change on assemblages, especially at the landscape scale, remain understudied. Lowland tropical amphibians may be particularly susceptible to changes in land cover and climate warming because many species have narrow thermal safety margins resulting from air and body temperatures that are close to their critical thermal maxima (CT_max). We examined how changing thermal landscapes may alter the area of thermally suitable habitat (TSH) for tropical amphibians. We measured microclimates in 6 land‐cover types and CT_max of 16 frog species in lowland northeastern Costa Rica. We used a biophysical model to estimate core body temperatures of frogs exposed to habitat‐specific microclimates while accounting for evaporative cooling and behavior. Thermally suitable habitat area was estimated as the portion of the landscape where species CT_max exceeded their habitat‐specific maximum body temperatures. We projected changes in TSH area 80 years into the future as a function of land‐cover change only, climate change only, and combinations of land‐cover and climate‐change scenarios representing low and moderate rates of change. Projected decreases in TSH area ranged from 16% under low emissions and reduced forest loss to 30% under moderate emissions and business‐as‐usual land‐cover change. Under a moderate emissions scenario (A1B), climate change alone contributed to 1.7‐ to 4.5‐fold greater losses in TSH area than land‐cover change only, suggesting that future decreases in TSH from climate change may outpace structural habitat loss. Forest‐restricted species had lower mean CT_max than species that occurred in altered habitats, indicating that thermal tolerances will likely shape assemblages in changing thermal landscapes. In the face of ongoing land‐cover and climate change, it will be critical to consider changing thermal landscapes in strategies to conserve ectotherm species.     

Efficacy of Two Lion Conservation Programs in Maasailand,Kenya

Lion (Panthera leo) populations are in decline throughout most of Africa. The problem is particularly acute in southern Kenya, where Maasai pastoralists have been spearing and poisoning lions at a rate that will ensure near term local extinction. We investigated 2 approaches for improving local tolerance of lions: compensation payments for livestock lost to predators and Lion Guardians, which draws on local cultural values and knowledge to mitigate livestock‐carnivore conflict and monitor carnivores. To gauge the overall influence of conservation intervention, we combined both programs into a single conservation treatment variable. Using 8 years of lion killing data, we applied Manski's partial identification approach with bounded assumptions to investigate the effect of conservation treatment on lion killing in 4 contiguous areas. In 3 of the areas, conservation treatment was positively associated with a reduction in lion killing. We then applied a generalized linear model to assess the relative efficacy of the 2 interventions. The model estimated that compensation resulted in an 87–91% drop in the number of lions killed, whereas Lion Guardians (operating in combination with compensation and alone) resulted in a 99% drop in lion killing. Eficacia de Dos Programas de Conservación de Leones en Maasailand, Kenia     

外来入侵假臭草在中国分布区的预测

假臭草原产南美洲,上世纪80年代首次记载传入中国,是潜在的恶性杂草.为提供其在中国分布区的预测资料,采用397个采集数据和已有的146个分布点数据,利用生态位模型(GARP)和Domain模型对分布区进行预测分析,并通过AUC与MaxKappa进行模型评价.结果显示:近十年,假臭草入侵记录增多,入侵扩散加剧;太阳辐射、水汽压、极端高温、霜日频率和水流方向对假臭草的分布限制较小,雨日频率、坡向、坡度、海拔、年降水、年均温、地形指数和极端低温等8个环境因子对其分布影响显著;入侵的主要植被类型是农田、灌木或草类覆盖嵌合区,常绿、落叶灌木地带,栽培植被及相关联地带等.模型评价表明两种模型预测能力为较好及以上,预测结果显示:假臭草在西藏(除东南小块区域)、新疆、青海、内蒙古、宁夏,陕西和山西北部地区,黑龙江、吉林、辽宁(除辽东半岛小块区域)是不宜生长区;最易入侵广东、广西、海南等地区,其中华中部分省份、华北平原为适生区,还未见有假臭草入侵的报道,相关部门应引起重视,严防入侵.     

Estimating animal densities and home range in regions with irregular boundaries and holes: A lattice-based alternative to the kernel density estimator

Density estimates based on point processes are often restrained to regions with irregular boundaries or holes. We propose a density estimator, the lattice-based density estimator, which produces reasonable density estimates under these circumstances. The estimation process starts with overlaying the region with nodes, linking these together in a lattice and then computing the density of random walks of length k on the lattice. We use an approximation to the unbiased crossvalidation criterion to find the optimal walk length k. The technique is illustrated using walleye (Sander vitreus) radiotelemetry relocations in Lake Monroe, Indiana. We also use simulation to compare the technique to the traditional kernel density estimate in the situation where there are no significant boundary effects.     

宝山堇菜多金属吸收特征和耐性策略

宝山堇菜Viola baoshanensis Shu,Liu et Lan是一种Cd超富集植物,但它对不同重金属的吸收和转运能力有待进一步研究。从湖南桂阳宝山多金属矿区中筛选4个宝山堇菜优势分布的小生境,分析这些生境中宝山堇菜及其根区土壤的重金属质量分数。化学分析结果显示,宝山堇菜优势分布土壤中Cd、Pb、Zn、Cu、Mn和Fe的平均质量分数(mg/kg)分别为471、15 044、8 273、1 776、4 702和69 054。宝山堇菜地上部Cd、Pb、Zn、Cu、Mn和Fe的平均质量分数(mg/kg)分别为387、1 077、1 037、99、379和1 812,其中Cd、Pb超过超富集植物标准,Zn、Cu的平均质量分数大约是Zn、Cu超富集植物标准的10%,Mn的平均质量分数低于Mn超富集植物标准的5%,Fe的平均质量分数高于1 000 mg/kg。上述结果表明,宝山堇菜可以超富集Cd和Pb,富集Zn、Cu和Fe以及低积累Mn。此外,宝山堇菜对不同重金属差别化吸收模式可能也代表了超富集植物适应重金属复合污染土壤的一种策略。     

会泽铅锌尾矿区自然生长的3种豆科植物铅锌耐性的研究

为了解会泽铅锌尾矿区自然发生的豆科植物对重金属的耐性,研究了该地区自然发生的3种豆科植物在Pb2＋/Zn2＋单盐和双盐胁迫下种子萌发及其幼苗生长的情况。研究表明：在本实验所设的浓度范围内,Pb2＋/Zn2＋单独胁迫时,对供试植物种子及幼苗的生长主要表现为抑制作用,除苕子（Vicia Cracca L.）外,金属离子的质量浓度越大抑制作用越强;Pb2＋/Zn2＋共同胁迫时出现复杂的交互作用。对于苕子的种子及幼苗的生长,Pb2＋/Zn2＋呈现明显的相互加强抑制作用;对于其它2种植物,当Zn2＋浓度在低质量浓度时,Pb2＋似乎对Zn2＋抑制有缓解作用,同样当Pb2＋浓度在低质量浓度时,Zn2＋似乎对Pb2＋抑制有缓解作用,但是当Pb2＋/Zn2＋高浓度时,Pb2＋/Zn2＋呈现明显的相互加强抑制作用。不论是单盐还是双盐,苕子对的耐性最强,其次为白三叶（Trifolium repens L.）,紫花苜蓿（Medicago sativa L.）最弱。会泽铅锌尾矿区重金属含量高是该区植被恢复的最大障碍,进一步研究植物对Pb2＋及Zn2＋的耐受性对于铅锌尾矿区的植被恢复有极其重要的意义。     

温度与营养盐耐受藻种筛选及其群落氮磷去除研究

为筛选出能适应不同温度与营养条件的污水处理优势藻种,探究其混合培养所形成微藻群落的污水处理效果,本文在实验室条件下,选择淡水小球藻、斜生栅藻、菱形藻、莱茵衣藻和小环藻,设置10,20,30℃ 3种不同温度,3种不同营养条件,TN、TP浓度分别为8.40与1.97mg/L,12.97与5.70mg/L,60.22与18.19mg/L,筛选出3种在不同温度和营养条件下耐受性和氮磷去除效果较好的优势藻种.进一步将筛选出的优势藻种分别进行藻类群落搭配,基于不同藻类群落对于人工废水中氮磷污染物的去除效果与稳定性确定优势藻种群落.结果表明：在3种不同温度下,小环藻和菱形藻的生长状况较稳定且氮磷去除率一般为80%以上;在3种不同的营养状况下,仅有斜生栅藻的生长速率和氮磷去除率较高,斜生栅藻、菱形藻与小环藻具有更好的环境耐受性与去除率.将上述3种藻分别进行群落搭配组合,发现菱形藻和小环藻的群落组合对TN和TP的去除率一般在80%～90%左右,没有异常变化;斜生栅藻、菱形藻与小环藻的群落组合生长状况较稳定.