Green research and development (R&D) investment and its impact on the market value of firms: evidence from South African mining firms

The importance of global corporate green research and development (R&D) investment is gaining momentum and South Africa is no exception. This paper examines growing economic perceptions that green financial and stock-market systems result in heightened corporate hyperopia and therefore increase long-term and future green investment associated with R&D. It reports on the findings of a survey of 14 South African mining firms listed on the Johannesburg Stock Exchange SRI index. The study found, that, these firms’ market value showed a positive association with Green R&D. It also revealed increased Green R&D activity among large mining firms in the country and that they are highly likely to maintain their level of such investment in the coming years. The study's outcomes thus add to the body of empirical knowledge on firm hyperopia in relation to corporate greening initiatives.     

雾天气下二次气溶胶均质成核生长过程

二次气溶胶的核化过程涉及分子杂乱运动和碰撞,在分子间的范德华力作用下,大气环境系统中产生分子聚合,形成分子团、胚胎和核.基于此建立二次气溶胶核化和生长模型,并且采用颗粒群平衡模拟和多重蒙特卡洛方法,对雾天气下水汽均质同分子核化及H₂O-H₂SO₄均质异分子核化的过程开展热力学和动力学数值研究. 结果表明:在水汽均质核化过程中,当水汽过饱和比从2增至10时,水汽的成核速率增加约73个数量级,形成临界胚胎所需的分子数降低了97.3%. 而对于H₂O-H₂SO₄均质异分子核化过程,在环境温度271.15 K,气态H₂SO₄分子数浓度为5×107cm-3条件下,当RH(相对湿度)由80%增至100%时,二次气溶胶成核速率增加1.4倍;在气态H₂SO₄分子数浓度较高、RH较大时,核化形成的临界胚胎粒径较小. 经过均质核化生长后,二次气溶胶粒径处于1.5～3.5 nm.      

加拿大一枝黄花和小飞蓬叶浸提液对大豆幼苗生长的复合化感效应

加拿大一枝黄花(Solidago canadensis)和小飞蓬(Conyza canadensis)常共同入侵至同一农田生态系统。探究了两者对大豆幼苗生长的复合化感作用。加拿大一枝黄花叶浸提液显著抑制大豆幼苗地上生物量。而小飞蓬叶浸提液也明显抑制大豆幼苗地上生物量(未达到显著水平)。与对照处理相比,两者复合叶浸提液处理未显著影响大豆幼苗地上生物量。两者复合叶浸提液处理下大豆幼苗地上生物量显著大于加拿大一枝黄花叶浸提液单一处理,同时也大于小飞蓬叶浸提液单一处理(未达到显著水平)。两者叶浸提液单一处理均明显降低大豆幼苗株高(未达到显著水平)。与对照处理相比,两者复合叶浸提液处理未显著影响大豆幼苗株高。两者复合叶浸提液处理下大豆幼苗株高明显大于两者叶浸提液单一处理(未达到显著水平)。因此,两者叶浸提液对大豆幼苗的生长均具有一定程度的抑制效应,且加拿大一枝黄花叶浸提液对大豆幼苗产生的化感作用(尤其是地上生物量)明显大于小飞蓬。两者复合化感作用明显低于两者单一化感作用,尤其是两者对大豆幼苗地上生物量的复合化感作用显著低于加拿大一枝黄花的单一化感作用。所以,化感效应可能在两者共同入侵(即两者复合作用)进程中所起的贡献低于在两者单一入侵进程中所起的作用。     

In vitro toxic effects of heavy metals on fungal growth and phosphate-solubilising abilities of isolates obtained from Phragmites australis rhizosphere

In this research, we evaluated the toxic effect of metal ions on mycelial growth and phosphate-solubilising activity of soil-borne micromycetes isolated from the Phragmites australis rhizosphere using Pikovskaya-agar plates supplemented with four metal concentrations. The diameter growth rate (DGR) decreased as the metal concentration rise for all tested fungi. Trichoderma atroviride had the fastest growth rate (1.48?cm²?day^?1) and was the least susceptible to Al³⁺, Cd²⁺, Cr³⁺, Cu²⁺ and Pb²⁺ with a median effective concentration (MEC₅₀) of 12.19, 0.48, 4.51, 11.44 and 50.05?mM, respectively. Aspergillus japonicus was the most tolerant to Co²⁺, Ni²⁺ and Zn²⁺, with MEC₅₀ values of 3.36, 1.095 and 2.34?mM, respectively. Penicillium italicum was the most tolerant to Cr6⁺ (MEC₅₀?=?0.677?mM). The ability to solubilise phosphate remained, despite the decrease in the DGR, and P. italicum and Penicillium dipodomyicola had the highest Phosphate Solubilisation Indexes (PSIs) at 1.97 and 2.12, respectively. In particular, P. italicum recorded the highest PSI of all the studied isolates at 0.62?mM Cr³⁺ (PSI?=?4.74). A. japonicus and T. atroviride were the most tolerant isolates to all tested metals, which suggests that these isolates are promising candidates for further study with regard to mycoremediation and biofertilisation of metal-polluted soils.     

铜胁迫对3种草本植物生长和重金属积累的影响

采用盆栽试验,研究了不同浓度Cu胁迫对3种草本植物弯叶画眉草、象草和苏丹草生物量、根系耐性指数、Cu积累量、富集系数、转运系数的影响。结果表明,弯叶画眉草和象草生长随着Cu胁迫浓度的升高呈现"上升-下降"趋势,胁迫浓度低于100 mg·kg~(-1)时促进生长;苏丹草生长随着Cu胁迫浓度的增加而下降;弯叶画眉草、象草和苏丹草的Cu耐性指数分别是130.63、149.15和75.81。3种植物对重金属Cu均以根系积累为主,积累量随着Cu处理浓度的增加显著升高;对Cu的吸收和富集能力为象草苏丹草弯叶画眉草,Cu从根系转运到地上部的能力为弯叶画眉草象草苏丹草,转运系数均小于1。可见,象草耐性较强,可用于Cu污染土壤植物修复;弯叶画眉草转运能力较强,可用于Cu污染土壤生物净化。     

吡草醚原药对大鼠胚胎及胎仔发育的影响

经口染毒大鼠检测妊娠动物接触吡草醚原药后引起致畸的可能性,初步评价吡草醚原药致畸危害程度。依据《GB15670-1995农药登记毒理学试验方法》,选用的大鼠按雄、雌2:1比例同笼交配,次日清晨阴道涂片检查雌鼠,发现精子即确定为受孕第0天,设低、中、高三个剂量组(18.56、92.80、464.00 mg·(kg·d)-1)、一个阴性对照组和一个阳性对照组。在雌鼠受孕第6~15天灌胃给予受试物,连续共10天,在妊娠第19.5天,处死孕鼠检查胚胎发育情况。高剂量组和阳性对照组大鼠孕期体重增重值降低,差异有显著性(p0.05);中、高剂量组和阳性对照组大鼠吸收胎率与阴性对照组比较差异有显著性(p0.05);中、高剂量组和阳性对照组胎鼠重量与阴性对照组比较,差异有显著性(p0.01);阳性对照组胎鼠外观畸形明显,与阴性对照组比较差异有显著性(p0.01);各剂量组胎鼠外观畸形与阴性对照组比较,差异均无显著性(p0.05);中、高剂量组组和阳性对照组胎鼠骨骼及内脏畸形例数明显增多,差异有显著性(p0.01)。实验结果表明吡草醚原药中、高剂量组可明显影响雌鼠体重增长及其胚胎的发育。     

Project Tocoen. the fate of selected pollutants in the environment. Part XIX. the phytotoxicity of organic and inorganic pollutants‐cadmium. The effect of cadmium on the growth of germinating maize plants

The effect of increasing cadmium concentration (10, 100 and 1000 μmol dm^‐3) on the growth, leaf area, content of assimilation pigments, cadmium content and the regulatory ability of the tissue of maize plants was investigated.

The results obtained document, already after 6 days, a significant decrease of dry weight, reduction of leaf area, chlorophyll a and b as well as carotenoids in plants grown in the nutrient solution containing 1000 μmol dm ^‐3 of cadmium. A highly significant inhibition of growth, leaf area and assimilation pigments in plants growing in the nutrient solutions with 100 and 10 μmol dm^‐3 of cadmium was registered after 17 days of cultivation. In plants growing in the nutrient solution containing 100 μmol dm^‐3 of cadmium a demonstrable reduction of the content of assimilation pigments was registered after 11 days of culture.

With increasing cadmium concentration in the nutrient solution as well as in the plant tissue after 6 and 17 days of culture both the range of the regulatory zone and the extent of optimum pH increased into the acid region. The pH values of the isoelectric point decreased with increasing cadmium content in the solution.     

Relation between Occupancy and Abundance for a Territorial Species,the California Spotted Owl

Land and resource managers often use detection–nondetection surveys to monitor the populations of species that may be affected by factors such as habitat alteration, climate change, and biological invasions. Relative to mark‐recapture studies, using detection–nondetection surveys is more cost‐effective, and recent advances in statistical analyses allow the incorporation of detection probability, covariates, and multiple seasons. We examined the efficacy of using detection–nondetection data (relative to mark‐recapture data) for monitoring population trends of a territorial species, the California Spotted Owl (Strix occidentalis occidentalis). We estimated and compared the finite annual rates of population change (λ_t) and the resulting realized population change (Δ_t) from both occupancy and mark‐recapture data collected over 18 years (1993–2010). We used multiseason, robust‐design occupancy models to estimate that territory occupancy declined during our study (Δ_t = 0.702, 95% CI 0.552–0.852) due to increasing territory extinction rates ( = 0.019 [SE 0.012]; = 0.134 [SE 0.043]) and decreasing colonization rates ( = 0.323 [SE 0.124]; = 0.242 [SE 0.058]). We used Pradel's temporal‐symmetry model for mark‐recapture data to estimate that the population trajectory closely matched the trends in territory occupancy (Δ_t = 0.725, 95% CI 0.445–1.004). Individual survival was constant during our study ( = 0.816 [SE 0.020]; = 0.815 [SE 0.019]), whereas recruitment declined slightly ( = 0.195 [SE 0.032]; = 0.160 [SE 0.023]). Thus, we concluded that detection–nondetection data can provide reliable inferences on population trends, especially when funds preclude more intensive mark‐recapture studies. Relación entre Ocupación y Abundancia en una Especie Territorial, el Búho Moteado de California     

Allelopathic effect of Cylindrospermopsis raciborskii extracts on the germination and growth of several plant species

Cylindrospermopsis raciborskii is an invasive cyanobacterium and a potential producer of the alkaloid toxin cylindrospermopsin (CYN). Extracts of two strains of C. raciborskii were tested for their effects on the germination and growth of Lactuca sativa, Phaseolus vulgaris, Pisum sativum and Solanum lycopersicum. Germination was not significantly inhibited for any of the plant species tested, but growth was affected, depending on the species. Root and stem growth in L. sativa was generally stimulated by both strains. Ph. vulgaris root growth was stimulated by both strains but no effect was visible in stem growth. S. lycopersicum root growth was inhibited by both strains and stem growth was inhibited only by the CYN strain. P. sativum root growth was also inhibited by both strains but stem growth was stimulated. CYN accumulation was also differential with toxin transfer to the stem. Ph. vulgaris accumulated the highest CYN concentration. This study suggests that plants behave differently in their response to this toxin and that roots and stems also show different abilities to react and accumulate the toxin. Knowledge of the impact of CYN- and non-CYN-producing cyanobacteria in different plant species and translocation of the toxin to different plant parts is essential for the avoidance of human as well as environmental health hazards.     

Rice seedlings under cadmium stress: effect of silicon on growth,cadmium uptake,oxidative stress,antioxidant capacity and root and leaf structures

In this study, the effect of silicon (Si) addition on cadmium (Cd) toxicity in rice seedlings was investigated. After a series of screening experiments, 50 μmol·L^?1 of Cd and 10 μ mol·L^?1 of Si were selected. Treatment of rice seedlings with Cd (50 μ mol·L^?1) resulted in significant accumulation of this metal in roots and shoots. The data revealed that accumulation of Cd resulted in oxidative stress in rice seedlings as evidenced by increased accumulation of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA; a peroxidation product of lipids). However, addition of Si (10 μ mol·L^?1) together with Cd prevented accumulation of Cd, H₂O₂ and MDA. Antioxidant capacity was decreased by Cd but enhanced by Si addition. Cd decreased the length and frequency of root hairs, stomatal frequency, and distorted leaf mesophyll cells and vascular bundles. However, addition of Si together with Cd reduced these abnormalities. The results showed that addition of exogenous Si protected rice seedlings against Cd toxicity by preventing Cd accumulation and oxidative stress (H₂O₂ and MDA accumulation) by increasing Si accumulation and antioxidant capacity, which maintained the structure and integrity of leaf and root.