Issue 4

3,4-dichloroaniline (3,4-DCA) is a hardly biodegradable and hydrolysable compound, characterized as a persistent pollutant for water, soil and sediment and highly toxic for living organisms. In this work, the impact of different micrometeorological conditions on uptake of 3,4-DCA was investigated in maize (Zea mays L.) plants grown hydroponically. For this purpose, seedlings of a uniform vigor were developed in appropriate nutrient solution supplied with an initial amount of 3,4-DCA (growth solution) under controlled high light (HL) and low light intensity (LL) conditions and under high (HH) and low relative humidity (LH) conditions in the combinations of HL/HH, LL/HH and HL/LH. Plants grown under HL/LH were replenished with the initial amount of 3,4-DCA after 48 h from the application of the growth solution (AGS). The measurements which took place were related to the uptake of 3,4-DCA and of growth solution by plants. Also, the fresh weight of plants was measured. Results showed that maize was capable of removing noticeably high amounts of 3,4-DCA (up to three quarters of the initial amount) from the growth solution after completion of the first 24 h period from AGS, irrespective of micrometeorological conditions. It was also demonstrated that almost the whole available amount of 3,4-DCA was removed from the growth solution after a 48 h period from AGS under HL/LH. Plants under these conditions removed a significantly higher volume of growth solution compared to the HH conditions, irrespective of measurement time. The significant increase of the 3,4-DCA uptake (almost the whole available amount) by maize plants which were replenished with this compound under LH compared to HH, indicated a considerable capability of these plants to remove high concentrations of 3,4-DCA from the growth solution after 72 h from AGS. The fresh weight of maize plants under the examined micrometeorological conditions did not change significantly in the majority of the cases, as regards to different micrometeorological conditions. On the contrary, this plant parameter was significantly higher in 3rd compared to 1st measurement day in all examined conditions. The increase of 3,4-DCA uptake rates by maize plants grown under low relative humidity conditions, 72 hrs from AGS, could be associated with the expected acceleration of the plants transpiration rates and with the plant growth rate, as expressed by the fresh weight, as in these conditions plants remove considerably high volume of growth solution. The information obtained from the aforementioned results on plant uptake of 3,4-DCA in maize plants could be a first step in designing suitable management practices such as phytoremediation strategies which might reduce environmental pollution.

The aim of this study was to compare particulate matter (PM) pollutants performed at three different enclosed parking garages (A, B and C) and two streets (1 and 2) in Belgium. Particle mass concentrations, number concentrations and their size distributions were measured in real time using an Electrical Low Pressure Impactor Plus (ELPI+) instrument. PM1, PM2.5 and PM10 particle ranges were characterized under this study and these concentrations were compared with the reference values recommended by the World Health Organization (WHO), United States Environmental Protection Agency (USEPA) and the European Union (EU). The results showed that the average mass concentrations in the garages ranged from 28-50 µg Nm-3 for PM1, 43-60 µg Nm-3 for PM2.5 and 58-90 µg Nm-3 for PM10, while in the streets they varied from 14-18 µg Nm-3 for PM1, 23-27 µg Nm-3 for PM2.5 and 54-59 µg Nm-3 for PM10 respectively. The number concentrations were obtained in the range of 28x103 to 47x103 particles cm-3 for the garages while 17x103 to 22x103 particlescm-3 for the streets. In all garages, it has been observed that PM2.5 concentrations exceeded the 24h reference values recommended by WHO and USEPA while and PM10 concentrations exceeded WHO and EU guidelines. Particle number size distributions showed dominant quantities of fine particles in all measurements, while two distinct particle sizes of coarse and fine modes were observed in the mass size distributions.

The unintended release of hydrocarbons into the environment can negatively impact human and animal health, and could further change the characteristics of soils. The aim of the present work was to investigate the rate of biodegradation at 10 and 20% diesel fuel in contaminated soil amended with 10% of three different organic wastes (tea leaf, soy cake, and potato skin) for a period of 126-days. 82 and 25% oil loss was recorded in soil amended with soy cake at 10% and 20 % oil pollution, respectively. Diesel fuel utilizing bacteria counts were high in all organic wastes amended treatments, ranging from 150×106 to 176 ×106 CFU g-1 of soil, compared with the unamended control soil which gave 23 ×106 CFU g-1. Dehydrogenase activity in soil was markedly enhanced by the application of organic wastes. Diesel oil composition monitored by GC/MS indicated complete degradation of n-C9 – C12. First-order kinetic model showed that among the three organic wastes used, soy cake had the highest biodegradation rate constant of 0.153 day−1 at 10% oil pollution, while biodegradation rate was 0.033 day−1 at 20% oil pollution. The results showed there is potential for soy cake, potato skin and tea leaf to enhance biodegradation of diesel in contaminated soil.

The performance of a laboratory scale electrocoagulation system for the removal of Cr and Ni from model wastewater was studied systematically using iron and aluminum electrodes with an effective surface area of 13.8 cm2 and a distance of 4 cm. The influence of several parameters, such as initial concentration, electrode combination, current supply and initial pH was investigated during electrocoagulation process. The increase in initial concentration favored removal rate, did not affect nickel removal, but restricted chromium removal, thus indicating its required mechanism of reducing hexavalent ion to trivalent. The best removal efficiency, when metals existed separately in treated solutions, was accomplished with the use of iron electrodes for Cr (50%) and with aluminum electrodes for Ni (90%). When metals co-existed, iron electrodes achieved the best result, which was 76% for Cr and 82% for Ni, leaving 30 mg l-1 and 17 mg l-1 of residual concentrations, respectively, after 180 min of treatment. Solutions’ nominal pH appeared to be optimal, since increasing or decreasing their initial value did not benefit the electrocoagulation process. Chromium and nickel simultaneous removal was best achieved for conditions of 100 mg l-1 initial concentration, pH 5 and a current of 0.8 A.