Accumulation of Cd,Cu and Zn in shoots of maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) exposed to 0.8 or 20 nM Cd during vegetative growth and the relation with xylem sap composition

This work focuses on the exposure of maize plants to nanomolar concentrations of Cd, which is relevant for agricultural soils cropped with food and feed plants. Maize plants were cultivated in nutrient solution at 0.8 or 20 nM Cd during the vegetative growth stages. No significant hormesis or toxic effects of Cd were observed on maize growth, but a decrease in the allocation of Cd to shoots between the 0.8 and 20 nM Cd exposures revealed that the plants already responded to these low concentrations of Cd according to a shoot Cd excluder strategy. The Cd, Cu and Zn concentrations in shoots decreased with time as the result of an early decrease in the root/shoot ratio and of a decrease in the coefficient of allocation to aboveground for Zn and Cd at 20 nM. As a consequence, shoots of young plants were richer in micronutrients Cu and Zn but also in toxic Cd. The rate of delivery of Cd, Cu and Zn from xylem sap was successfully used to predict the time course of concentrations of Cd, Cu and Zn in the shoot. However, it overestimated the actual concentrations of Cd in the shoot, presumably because the reallocation of this trace element from shoots back to roots was not taken into account.     

University of Benin water supply system: Microbiological and physico-chemical assessments

The microbiological and physico-chemical characteristics of the drinking water supplied by the Central Borehole at the University of Benin, Ugbowo Campus were investigated. The investigation entailed assessment of the pH, turbidity, total suspended solids, total dissolved solids, dissolved oxygen, temperature, salinity, conductivity, nitrate, nitrite, phosphate, sulphate, chloride, N-nitroso compounds, cadmium, chromium, nickel, lead, zinc, manganese, iron, coliform count, BOD₅ and COD of the water at the Central Borehole and at ten residential quarters. The assessment indicated that the water was fit for drinking and other domestic applications. Results were also compared with WHO, EU and Nigeria FEPA standards. The results showed that the pH values of the water (5.01–5.86) and total coliform count (1–2/100 ml) expressed as MPN were outside the limits set by the WHO, EU and FEPA. The data also showed that the other water quality parameters assessed were within WHO, EU and FEPA permissible limits. The results of ANOVA showed that significant changes occurred during distribution.     

Stream buffer effectiveness in an agriculturally influenced area, southwestern Georgia: responses of water quality, macroinvertebrates, and amphibians

To determine useful metrics for assessing stream water quality in the Southeastern Coastal Plain, we examined differences among two buffered and three unbuffered streams in an agricultural landscape in southwestern Georgia. Potential indicators included amphibian diversity and abundance, aquatic macroinvertebrate populations, riparian vegetative structure, water quality, and stream physical parameters. Variability among sites and treatments (buffered vs. unbuffered) existed, with sites in the same treatment as most similar, and disturbances from a nearby eroding gully strongly affecting one unbuffered site. Of the invertebrate metrics examined, percentages of clingers, Ephemeroptera-Plecoptera-Trichoptera (EPT), Elmidae (Coleoptera), Crustacea (Decapoda and Amphipoda), and dipterans were found to be possible indicators of stream health for perennial streams within this region. Overall, buffered sites showed higher percentages of sensitive invertebrate groups and showed lower and more stable concentrations of nitrate N, suspended solids, and fecal coliforms (FCs). Percent canopy cover was similar among sites; however, riparian vegetative coverage and percent leaf litter were greatest at buffered sites. No differences in amphibian abundance, presence, and absence within the riparian area were apparent between sites; however, instream larval salamanders were more abundant at buffered streams. In this study, stream buffers appeared to decrease nutrient and sediment loads to adjacent streams, enhancing overall water quality. Selected benthic macroinvertebrate metrics and amphibian abundance also appeared sensitive to agricultural influences. Amphibians show potential as indicator candidates, however further information is needed on their responses and tolerances to disturbances from the microhabitat to landscape levels.     

Reproduction in short-beaked common dolphins (<Emphasis Type="Italic">Delphinus delphis</Emphasis>) from the western North Atlantic

A single population of short-beaked common dolphins (Delphinus delphis Linnaeus) occurs in the western North Atlantic from Florida to Newfoundland. Dolphins killed in a swordfish driftnet fishery between 1989 and 1998 provided samples for the present study. These were combined with additional observations from carcasses collected from stranding programs. Samples were examined from 74 female and 161 male short-beaked common dolphins. A highly significant male bias in the sex ratio of both the bycatch and stranding samples suggests that sex-based habitat partitioning or school segregation occurs in this population. Age was estimated from decalcified thin sections of teeth and testis and ovarian samples were examined both macro- and microscopically. Analyses showed that reproduction was both seasonal and synchronized. Females reached sexual maturation at approximately age eight; males matured at 9.5 years. Conception occurred during July and August (mean day 24 July). Gestation was estimated to last just under a year, so most females gave birth during July and August (mean day 15 July). Annual pregnancy rate was estimated to be between 25 and 33%. Males undergo a fivefold seasonal increase in testes mass and a twofold increase in seminiferous tubule diameter. Peak sperm production potential was observed in July. At the end of the breeding season testis size and activity decreased after August. Male dolphins in this population are hypothesized to engage in some form of sperm competition.     

Determination of protective effect of carob (Ceratonia siliqua L.) extract against cobalt(II) nitrate-induced toxicity

Environmental Science and Pollution Research - Cobalt (Co) is widely used in many industrial fields such as batteries and paints. Cobalt, a dangerous heavy metal, can be found in high...     

Transfer factors of (134)Cs to crops from Typic Haplustept under tropical region as influenced by potassium application

Under greenhouse condition a pot culture investigation was carried out using Inceptisol soil (Typic Haplustept) contaminating with (134)Cs @ 1muCikg(-1) soil to study the transfer factor to Mustard, Gram, Spinach and Wheat crops as influenced by potassium application (0, 27.3, 54.6 and 81.9mgKkg(-1) soil). Potassium application in general improved the biomass, grain yield and also the potassium concentration in all the crops. Irrespective of the crops, (134)Cs transfer factor to straw and grain was highest in control treatment (no K addition) and found to decrease significantly with increase in K application levels. The (134)Cs uptake was highest in Spinach followed by Mustard, Gram and Wheat crops. The weighted transfer factor values (straw plus grain) to Spinach, Mustard, and Gram were observed to be 5.54, 4.38 and 2.20 times higher as compared to Wheat crop.