Copper, zinc, and cadmium body concentrations in Hexaplex trunculus collected from the Tunisian coast

Copper, Zn, and Cd were analyzed in the soft tissues of the edible gastropod Hexaplex trunculus collected from seven localities along the Tunisian coast. The body concentration of these metals was significantly different depending on the gender and site. Copper and Zn varied, respectively, from 47.70 to 343.64 μg/g dry weight (dw) and 149.46 to 530.44 μg/g dw, being higher in males. Cadmium varied from 0.22 to 18.95 μg/g dw and was always higher in females. Overall, the highest concentrations of the three metals were all recorded in Gabès fishing harbor. Comparison of metal concentrations with the European standards compiled by the Food and Agriculture Organization showed that values exceeded standards in several localities. Imposex had been previously recorded in H. trunculus along the Tunisian coast; however, it does not seem to be related with Cu, Zn, and Cd pollution because the body concentration of these metals is not correlated with imposex degree. Nevertheless, interactive effects resulting from the combination of different pollutants and other stressors cannot be disregarded.     

DRAINMOD-FOREST: Integrated Modeling of Hydrology, Soil Carbon and Nitrogen Dynamics, and Plant Growth for Drained Forests

We present a hybrid and stand-level forest ecosystem model, DRAINMOD-FOREST, for simulating the hydrology, carbon (C) and nitrogen (N) dynamics, and tree growth for drained forest lands under common silvicultural practices. The model was developed by linking DRAINMOD, the hydrological model, and DRAINMOD-N II, the soil C and N dynamics model, to a forest growth model, which was adapted mainly from the 3-PG model. The forest growth model estimates net primary production, C allocation, and litterfall using physiology-based methods regulated by air temperature, water deficit, stand age, and soil N conditions. The performance of the newly developed DRAINMOD-FOREST model was evaluated using a long-term (21-yr) data set collected from an artificially drained loblolly pine ( L.) plantation in eastern North Carolina, USA. Results indicated that the DRAINMOD-FOREST accurately predicted annual, monthly, and daily drainage, as indicated by Nash-Sutcliffe coefficients of 0.93, 0.87, and 0.75, respectively. The model also predicted annual net primary productivity and dynamics of leaf area index reasonably well. Predicted temporal changes in the organic matter pool on the forest floor and in forest soil were reasonable compared to published literature. Both predicted annual and monthly nitrate export were in good agreement with field measurements, as indicated by Nash-Sutcliffe coefficients above 0.89 and 0.79 for annual and monthly predictions, respectively. This application of DRAINMOD-FOREST demonstrated its capability for predicting hydrology and C and N dynamics in drained forests under limited silvicultural practices.     

Antibiotic uptake by plants from manure-amended soils

Antibiotics are extensively given to livestock to promote growth and reduce diseases. Therefore, animal manure often contains antibiotics. Once manure is applied to agricultural land to improve soil productivity, crops would be exposed to antibiotics which may persist in soils from a few to several hundred days. The objective of this study was to evaluate the uptake of gentamicin and streptomycin by carrot (Daucus carota), lettuce (Lactuca sativa) and radish (Rhaphanus sativus) from manure-amended soil. The treatments were 0, 0.5 and 1 mg of antibiotic kg^?1 of soil. Two pot experiments were carried out in the greenhouse. The first was conducted on the three crops and the second exclusively on radish. In radish, the increase in the concentrations of gentamicin was significant between the 0 and both of 0.5 and 1.0 mg kg^?1 treatments, but not significant between the 0.5 and 1.0 mg kg^?1. The average values were 35.5, 60.0 and 57.4 μg kg^?1 for the 0, 0.5 and 1 mg kg^?1 rates, respectively. However, the increase in streptomycin concentration in radish was not significant between the three treatments, and the average values were, 12.1, 15.2 and 17.4 μg kg^?1 for the 0, 0.5 and 1 mg kg^?1 rates, respectively. In carrot roots and lettuce leaves no significant increase in the concentrations of gentamicin or streptomycin was observed between the treatments. The three crops absorbed relatively higher amounts of gentamicin (small molecule) than streptomycin (large molecule). Generally the levels of antibiotics in plant tissue increased with increasing the antibiotic concentration in the manure (1 mg kg^?1 > 0.5 mg kg^?1).     

Effect of Manufacturing Process and Xanthan Gum Addition on the Properties of Cassava Starch Films

The objective of this work was to manufacture biodegradable films by two different processes (casting and extrusion), from different combinations of cassava starch and xanthan gum. These films were produced by casting and by extrusion from six different starch-xanthan gum combinations (0, 2, 4, 6, 8 and 10% w/w), containing glycerol as plasticizer (20% w/w) and were also characterized according to their microstructure, optical, mechanical, and barrier properties. Scanning electron microscopy of the starch-xanthan gum extruded films showed reticulated surface and smooth interior, suggesting that xanthan was driven to the surface and gelatinized starch to the interior of the films during extrusion. Films manufactured by casting were entirely homogeneous. In general, casted films presented lower opacity and water vapor permeability and higher stress at break than films manufactured by extrusion. Xanthan gum addition affected mechanical properties of starch films, improving their stress and strain at break, especially for extruded samples, but these properties did not show stability at different RH conditions.     

Effects of workplace thermal conditions on safe work behavior

The effect of workplace thermal conditions on worker safety has not previously been adequately investigated, due in part to the difficulty of defining a suitable safety performance measure. This report describes a study conducted in two industrial plants to determine if a correlation exists between the safety-related behavior of workers and workplace thermal conditions. Both heat exposure measurements and behavioral observations were taken over a 14-month period, for a total of over 17,000 observations. The results indicate that temperatures below and above those typically preferred by most people have a significantly detrimental effect on the safety-related behavior of workers. This is demonstrated by an index based on the ratio of observed unsafe behaviors to the total number of observed behaviors. The relationship between this index of unsafe behavior and the ambient temperature formed a U-shaped curve. The minimum unsafe behavior index occurred within the zone of preferred temperature (approximately 17°C to 23°C, WBGT). Other factors such as metabolic workload and time during the shift also had significant effects on worker safety-related behavior.     

Selenium and nano-selenium in plant nutrition

Selenium (Se) is a naturally occurring metalloid element which occurs nearly in all environments. Se is considered as a finite and non-renewable resource on the Earth. The common sources of Se in earth’s crust occur in association with sulfide minerals such as metal selenide, whereas it is rarely found in elemental form (Se⁰). While there is no evidence of Se need for higher plants, several reports show that when Se added at low concentrations, Se exerts beneficial effects on plant growth. Se may act as quasi-essential micronutrient through altering different physiological and biochemical traits. Thus, plants vary considerably in their physiological and biochemical response to Se. This review focusses on the physiological importance of Se forms as well as different Se fertilizers for higher plants, especially plant growth, uptake, transport, and metabolism.     

Physiological responses of Avicennia marina seedlings to the phytotoxic effects of the water-soluble fraction of light Arabian crude oil

Stomatal behavior, growth performance and the accumulation of polynuclear aromatic hydrocarbons (PAHs) were evaluated in seedlings of the mangrove Avicennia marina (Forssk.) Vierh., treated with a water-soluble fraction (WSF) of Abu-Dhabi light Arabian crude oil through foliar spraying or soil application.Irregular stomatal behavior and weak stomatal control over transpiration were observed during the first 24 hours, where stomatal resistances of plants sprayed with 150 and 300 g PAHs plant^–1 were significantly lower than that of the control plants. After six weeks, all treated plants showed no significant difference in their relative growth rate (RGR) or in the net assimilation rate (NAR) compared with the control plants.Tri-aromatic hydrocarbons were the most accumulated in tissues of the treated plants. Penta- and hexa-aromatics, on the other hand, were undetectable in the WSF and consequently in the treated plants. A linear relationship was observed between the dose applied to plants and the amounts of tissue accumulated PAHs (r ²=0.515 for soil application and r ²=0.984 for foliar spray). In plants sprayed with 300 g PAHs plant^–1, the total PAHs accumulated were more than that accumulated in plants treated through soil application.These findings suggest that: aqueous extraction of crude oil tends to signify the percentage of the low molecular weight PAHs, e.g. naphthalene, to the total PAHs; disturbed stomatal behavior in the first day of the treatment may be due to the venting of the volatile low molecular weight aromatic hydrocarbons (e.g. benzene, toluene, and xylenes) through the stomata; and uptake of water-soluble hydrocarbons by plants is equally possible through both of the root system and the foliage. The ecological implications of these finding are discussed in relation to oil pollution of mangrove stands under field conditions.     

COVID-19 pandemic: impacts on bees,beekeeping, and potential role of bee products as antiviral agents and immune enhancers

Environmental Science and Pollution Research - COVID-19 pandemic has passed to the front all the contradictions of the beekeeping sector: the valuable role of bee products as immune enhancers and...     

Correction to: Reducing ammonia emission by aluminum sulfate addition in litter and its influence on productive,reproductive, and physiological parameters of dual-purpose breeding hens

Environmental Science and Pollution Research -