Seasonality and forest edge as drivers of Tradescantia zebrina Hort. ex Bosse invasion in the Atlantic Forest

As a result of biodiversity and ecosystem service losses associated with biological invasions, there has been growing interest in basic and applied research on invasive species aiming to improve management strategies. Tradescantia zebrina is a herbaceous species increasingly reported as invasive in the understory of disturbed forest ecosystems. In this study, we assess the effect of spatial and seasonal variation on biological attributes of this species in the Atlantic Forest. To this end, we measured attributes of T. zebrina associated with plant growth and stress in the four seasons at the forest edge and in the forest interior of invaded sites in the Iguaçu National Park, Southern Brazil. The invasive plant had higher growth at the forest edge than in the forest interior and lower leaf asymmetry and herbivory in the winter than in the summer. Our findings suggest that the forest edge environment favours the growth of T. zebrina. This invasive species is highly competitive in the understory of semi-deciduous seasonal forests all over the year. Our study contributes to the management of T. zebrina by showing that the summer is the best season for controlling this species.

Larvae of migratory Characiformes species in an archipelago in the Lower Amazon River

In the Amazon basin, most of the migratory Characiformes species represent an important fishing resource for local people. However, the lack of information about the main areas and periods of reproduction and the importance of certain environments for the maintenance of species may jeopardize the renewal of fish stocks. Thus, the aim was to examine the spatial and seasonal variation in the density of larvae of migratory Characiformes species in an archipelago in the Lower Amazon River and to assess the importance of this environment for the biological recruitment of the studied species. The capture of larvae was carried out in places close to restinga swamps, steep ruts, and inlet areas with a plankton net (300 µm) in monthly sampling from January to December 2013. An analysis of variance was used to verify differences in larval density between seasons and sampling months. A total of 30,997 larvae were captured and showed no significant differences in their distributions between habitats. However, a variation between the phases of the hydrological cycle was evident, in which the highest larval concentrations were observed during the flooding (17.72 larvae.10m-3) and the drought (1.33 larvae.10m-3). The study area has a great capacity to assist in the maintenance and renewal of regional fish stocks, as it is an important retention and nursery site for larvae of Characiformes that drift along the main channel of the Amazon River.

Spatial and Seasonal Variation of Polycyclic Aromatic Hydrocarbons (Pahs) Deposition Flux and Sources in Shanghai

Spatial and temporal variations of PAHs deposition flux and sources may significantly facilitate risk evaluations of super magacity in China. A study on polycyclic aromatic hydrocarbons of wet deposition and dry deposition in Shanghai was conducted from January to December, 2019. 17 sites were investigated located in four representative functional areas, covering iron and steel industry (BS), petrochemical industry (JS), central city (CC) and agricultural area (CM). The results showed that atmospheric PAHs level in shanghai was the lowest in autumn and the highest in winter. As industrial area, BS and JS demonstrated higher PAHs deposition fluxes than those in CC and CM sites. Triangle map indicated that the PAHs distribution in winter and spring samples were more homogeneous, suggesting possible common origins, whereas that of summer and autumn seemed to be more dispersed. Isomar ratio and positive matrix factorization model were employed to identify the potential sources of PAHs in specific functional areas. BS was dominated by a high percentage (46%) of coal combustion. In JS site, the petroleum volatilization source percentage was 47.6%. The highest biomass burning (55.3%) contributions were in CM. Vehicle emission (49.3%) was identified as the predominant source of PAHs in CC. This study highlighted that local emission sources have a greater influence on PAHs deposition to specific functional regions in Shanghai.

Spatial and seasonal variation of zooplankton assemblages in two tidal control structures in Northeastern Brazil

Zooplankton is a group of organisms that can help to understand the quality of aquatic ecosystems, as they are responsible for transforming energy matter, thus making it available to other links, making them important in aquatic trophodynamics. This study analyzed spatial and temporal variations in zooplankton communities found in two tidal control structures on Ilha do Maranhão, northeastern Brazil. Sampling took place from September 2017 to July 2018. Abiotic parameters (temperature, salinity, and transparency) and plankton samples were recorded monthly throughout the study period at each sampling site. The results found for the abiotic parameters showed a well-defined pattern, with a clear division between the dry and rainy periods. Forty taxa represented the zooplankton community of the São Luís tidal control structure, and from São José de Ribamar by 21 taxa, represented mainly by copepods, ichthyoplankton, foraminifera, polychaetes, and mollusks. The analysis of ecological indices of richness, evenness, and diversity showed a difference in the distribution of organisms among the study areas. We identified an important influence of the physicochemical parameters on the zooplankton communities of São Luís and São José de Ribamar, according to the statistical analyzes used in this study.

Spatial And Seasonal Variation For Water Quality Indices of Gomal Zam Dam And Its Tributaries In The South Waziristan District, Pakistan

This study investigated the quality of water in the Gomal Zam Dam and its tributaries, south Waziristan District, Pakistan. For this purpose, water samples were collected from the Gomal Zam Dam and its tributaries in the winter and summer seasons (n=24 in each season). Water samples were analyzed for the anions using a multi-parameter analyzer (CONSORT 6030, Belgium) and cations by the Atomic Absorption Spectrophotometer (AAS, AAnalyst 700, PerkinElmer). Water characteristics were compared and found within drinking water guidelines set by the world health organization (WHO), except turbidity. Water characteristics were evaluated for the water quality index (WQI) and sodium hazards such as sodium adsorption ratio (SAR) and sodium percentage (Na%). Based on WQI and sodium hazards, the water of Gomal Zam Dam and its tributaries were observed as good and in permissible levels for drinking and irrigation water, respectively. The winter season has slightly poor water quality compared to the summer season due to higher contamination. Gibbs’s and Piper's models showed that the water quality of Gomal Zam Dam and its tributaries was mainly characterized by the weathering of bedrocks. The studied water is classified as Na-Cl type and Mg-HCO3 types in the summer and winter seasons, respectively. Statistical analyses revealed that geogenic sources of rock weathering are the dominant factor for controlling the water quality of the area.

Comparative Study of Water Quality Parameters along NH, SH and Link Road of Shivalik Foothills in Himachal Pradesh

A study was conducted to evaluate the spatial and seasonal variation in the quality of the surface water sources along national highway, state highway and link road. Physicochemical properties of water were estimated using water samples collected during the pre-monsoon, monsoon, and post-monsoon seasons in the year 2018 and 2019. The water quality parameters (pH, EC, Turbidity, TDS, BOD, COD, Cl-, NO3- and heavy metals) were calculated. The investigation revealed that pH (6.91-7.35), EC (0.17-0.29 dS m-1), TDS (140.12-175.54 mg l-1), Turbidity (2.34-3.87 NTU), BOD (2.25-2.89 mg l-1), COD (13.49-20.19 mg l-1), Cl- (14.36-30.15 mg l-1), NO3- (3.12-4.89 mg l-1) and various heavy metals were within permissible limits and varied significantly (p<0.05) on spatial variations. Maximum effects of vehicular emissions along the roadside water bodies were observed at NH followed by SH and minimum was noticed at LR. Among the seasons, maximum values of water quality parameters were observed during pre-monsoon season followed by monsoon and then post-monsoon.