Knowledge of the presence of heavy metals in soils of agricultural areas is important to prevent their accumulation in cultivated plants. The objective of the present investigation was to evaluate the total concentrations and fractions of heavy metals Cd, Pb, Zn, Fe, Mn, Ni, Cu, Cr and Co in the tobacco-growing area of Pinar del Río, Cuba and their relationship with the physicochemical properties of soil. For the study, 59 samples of three types of soils were collected at 20 cm depth. The pseudo-total concentrations of metals in the soils are low and lower than the prevention values registered for Cuban soils. In general, the heavy metals studied present a high affinity for the most stable fractions of the soil, which means a low risk of transfer to the tobacco crop or accumulation in groundwater. The pseudo-total concentrations of heavy metals were low, below the alert values established for soils in the region. The heavy metals studied were mainly associated with the residual fraction, the second fraction with the highest association with metals was that linked to manganese and iron oxides. The principal component analysis showed that their main source is pedogenetic and that these elements are closely related to cation exchange capacity and calcium content.

The changes the magnetic flux generated (electric, magnetic and electromagnetic waves) on the surface of earth due to sudden changes is a matter of discussion. These emissions occur along the fault line generated due to geological and tectonic processes. When sudden changes occur in the environment due to seismic and atmospheric variations, these sensing was observed by creatures and human bodies because the animals and trees adopt the abnormal signals and change the behavior. We have analyzed the changing behavior of recorded signal by live sensors (i.e., banyan tree). So we use the deep-rooted and long-aged banyan tree. The root of banyan tree (long-aged) has been working as a live sensor to record the geological and environmental changes. We record the low frequency signals propagated through solar-terrestrial environment which directly affect the root system of the banyan tree and changes that have been observed by live sensors. Then, very low frequency (VLF) signal may propagate to the earth-ionosphere waveguide. We have also analyzed the different parameters of live cells which is inbuilt in latex of the tree, so we record the dielectric parameters of green stem latex and found some parameters i.e., dielectric constant (ε) and dielectric loss (ε’) of various trees to verify these natural hazards and found good correlation. Therefore, we can say by regularly monitoring the bio-potential signal and dielectric properties of banyan tree and we are able to find the precursory signature of seismic hazards and environmental changes.

Flower-visiting insects may be pollinators or, conversely, unrelated to the reproductive process of plants. Interactions between pollinating and non-pollinating flower visitors can negatively influence pollen transfer. Little is known about the effects of bee visits on pollination of squash (Cucurbita spp.) flowers and their interactions with the presence of other floral visitors. The study was conducted at the Facultad de Ciencias Agrarias (Universidad Nacional de Rosario) in the south of Santa Fe (Argentina) and evaluated the effect of the presence of non-pollinating floral visitors on bee foraging in the flowers of two cultivated squash species. Flower sex and squash species C. maxima and C. moschata were included as variables. A total of 937 visitors were recorded in 403 flowers. Bees of the tribes Eucerini and Apini were the most abundant pollinators with an average of 2.3 individuals per flower during 10 minutes of observation. Diptera, flower sex and squash species did not influence the number of bee visits, whereas the prolonged stay of coleoptera and formicids negatively affected the presence of bees on both squash species. The presence of coleoptera reduced bee visits by 38%, while in the presence of ants, bees did not visit the flowers. The theft of nectar and pollen by non-pollinating floral visitors could have a negative effect on the reproductive success of squash.

Forest transition is a trend change process from decreasing to increasing forest area in a country or region. Since the 1990s, ecological and environmental problems such as climate change and loss of biodiversity have received constant attention. The research theory and method of forest transformation has gradually become the frontier and hot topic pursued by international academic circle. With forest transformation as the theme, on the basis of introducing the origin of forest transformation research, along the development vein and internal logic of forest transformation research, this paper reviews the research progress of forest transition theory from the perspectives of Kuznets curve of forest environment and forest transition path, and summarizes the major issues in forest transformation research. The main direction of future research is proposed, including the impact of economic globalization on forest transition, the refinement of research units and the analysis of forest quality transition.

Due to its physicochemical properties, nanoparticles titanium dioxide (nTiO₂) is being put into mass production and widespread applications, which inevitably results in their increasing exposure to the water body. After it entering the water body, the chemical properties of nTiO₂ can be influenced by ion compositions, ion strength and pH, which affects their ecological risk. Excess of ammonium (NH₄⁺) fertilizer has contaminated soil and water environments. In this paper, the Zeta potentials and hydrodynamic radius of nTiO₂ were studied in NH₄⁺ solution compared to those in Na⁺ solution. In addition, the sedimentation rate of nTiO₂ was also investigated. The experiment results show that high pH inhibits the sedimentation of nTiO₂. Moreover, NH₄⁺ increases the stability of nTiO₂ more than Na⁺ at the same IS, which was attributed the more negative Zeta potentials and the smaller hydraulic radius. Our results provide a theoretical basis for evaluating the ecological risk of nTiO₂ in aqueous solution containing NH₄⁺.