Irrigating Onions and Potatoes with Chromium and Nickel: Its Effects on Catalase and Peroxidase Activities and the Cross-Contamination of Plants

Tropospheric ozone (O₃) has long been documented to cause an injury to plants, but a plants’ protectant, widely applicable in agronomical practice, does not exist. We evaluated the potential antiozonate efficacy of the antitranspirant di-1-p-menthene (Vapor Gard) compared with ethylenediurea (EDU) on Bel-W3 tobacco plants. Plants were treated either with water, or by EDU (10, 100, and 500 mg dm^?3), or by vapor (1, 5, 10, and 50 ml dm^?3) and were exposed either to O₃-enriched (90 ppb) or O₃-free air, for 12 days and 8 h day^?1. EDU when applied at 10 mg dm^?3 did not protect the plants against O₃, but when applied at 100 and 500 mg dm^?3 offered a significant protection to the plants. Vapor, when applied at 1 ml dm^?3 did not protect the plants against O₃, neither by terms of foliar visible injury nor by terms of aboveground biomass. In addition, when applied at 10 and 50 ml dm^?3 caused phytotoxicity to all the plants, which it was expressed as necrotic spots on the leaves’ surface, misshaping of the leaves, or short plants' height_. It is obvious that vapor does not protect Bel-W3 tobacco plants against O₃. The antiozonate role of di-1-p-menthene is species-specific and probably occurs only under short-term exposures.     

Occurrence of Organotin Compounds in the Aquatic Environment of Greece

The presence of organotin (OT) compounds was investigated in coastal areas (10 stations), wastewater treatment systems (six stations), rivers (19 stations) and lakes (12 stations) throughout Greece, in three sampling campaigns organized between October 1998 and September 1999. A screening method for the determination of toluene extractable organotins (TEOTs) by Electrothermal Atomic Absorption Spectrometry (ETAAS) was used during the first two sampling campaigns. TEOTs (sum of tributyltin, TBT, dibutyltin, DBT and triphenyltin, TPhT) were detected in most seawater and wastewater samples at concentrations up to 19.4 and 89.9 ng l^?1, respectively, while they were detected occasionally in surface water. During the third sampling campaign, OT compounds were extracted in selected stations using direct derivatization with NaBEt₄ in acidic medium and analysed by Gas Chromatography–Mass Spectrometry (GC–MS). In seawater, the levels of TBT, DBT and monobutyltin (MBT) were varied between < 2 and 70, 159 and 19 ng l^?1, respectively and tend to decrease with increasing distance from the coastline. TPhT was not detected in any of the samples. Significant concentrations of OT species were detected in influent wastewater, up to 384, 76.2 and 67.8 ng l^?1 for TBT, DBT and MBT, respectively. OTs were mainly associated with the suspended solids and were totally removed during wastewater treatment.     

Foliar status and factors affecting foliar and soil chemistry in a natural aleppo pine forest

The foliar status and the factors affecting the foliar chemistry in a natural Aleppo pine forest grown on calcareous soils in Greece were examined. It was found that the Aleppo pine needles had significantly higher calcium (Ca) concentrations, but significantly lower concentrations of magnesium (Mg), potassium (K), phosphorus (P), iron (Fe) and manganese (Mn) than the respective average concentrations of natural Aleppo pine forests in Spain. It was also found that only foliar Ca and Mn had a significant correlation with the exchangeable Ca and available Mn in soils, respectively. Principal component analysis showed that the nature of the calcareous parent material, (colluvial rocks and hard limestones) were the main factors affecting both foliar and soil chemistry. This finding is important as colluvial soils always coexist with other soil types in hilly and mountainous regions containing calcareous material.