This overview summarises the present knowledge on major sources of pollution, which are of concern for the Mediterranean Sea. Eutrophication, red tides, organic loads, hydrocarbon spills, heavy metal contamination and their biological effects are described on the light of the ecological characteristics of the Mediterranean. In particular special attention is paid to the "new pollution" processes; i.e. , the introduction of novel substances with biological activity that might have synergetic effects with "classical pollutants". Different compartments and marine ecosystems are considered and compared. The degree of anthropogenic impact and its apparent trends are discussed. Possible monitoring plans and remedial actions for a sustainable management of coastal zones subjected to increasing pollution are also suggested. 相似文献
Models for the formation of biogenic iodine in marine aerosols have been proposed in the literature. Here, we analyse the possible species and reactions that could occur in the proposed models. We calculate the enthalpies of formation for the species and the enthalpies of corresponding reactions. We propose a modified model using iodous acid (HOIO) and reactions that are particularly suited to humid conditions.Selected article from the Regional Symposium on Chemistry and Environment, Krusevac, Serbia, June 2003, organised by Dr. Branimir Jovancicevic 相似文献
Environmental appearance of Q1, a natural heptachloro compound with the molecular formula C9H3Cl7N2, was studied in samples from different sites all over the world. Q1 was expected to have a bipyrrole backbone, similar to other compounds ascribed to natural sources. A method for isolation of Q1 was developed by combination of adsorption chromatography on silica and normal phase HPLC with an amino phase. UV-detection of Q1 supports the aromatic character of the compound.
The high levels detected in samples of marine mammals and birds suggested that Q1 is both a persistent and a bioaccumulative contaminant. This was underscored by calculated log KOW in the range of other lipophilic organohalogens. In accordance with earlier studies, highest Q1 concentrations were found in the Southern Hemisphere, but with a highly selective GC/ECNI-MS-SIM method, detection of Q1 was also achieved in many samples from the Northern Hemisphere. In addition to marine mammals and birds, Q1 was also detected in fish from the Mediterranean Sea and the Antarctic. Traces were also detected in SRM 1588 certified cod liver oil, but Q1 was not detected in fish from Hong Kong and Lake Baikal. 相似文献
Gaseous emissions from agriculture contribute to a number of environmental effects. Carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) are greenhouse gases taking part to the global problem of climate change. Ammonia (NH3) emissions are responsible of soil acidification and eutrophication and contribute also to indirect emissions of N2O. This work evaluated the influence of the type of floor on the emissions of these gases in the raising of weaned pigs. Two trials were carried out. In the first trial, the animals were kept either on fully slatted floor or on straw-based deep litter and, in the second one, either on fully slatted floor or on sawdust-based deep litter. For each trial and on each type of floor, 2 successive batches of weaned pigs were raised without changing the litter or emptying the slurry pit between the 2 batches. The rooms were automatically ventilated to maintain a constant ambient temperature.The performance of the animals was not significantly different according to the floor type. In trial 1, the nitrogen contents of the straw deep litter (including the substrate) and slurry were respectively 276 and 389 g pig−1. In trial 2, the sawdust deep litter and slurry nitrogen contents were respectively 122 and 318 g pig−1.Raising pigs on straw deep litter produced proportionately around 100% more NH3 than raising pigs on slatted floor (0.61 g NH3-N d−1 pig−1 vs. 0.31 g NH3-N d−1 pig−1; P < 0.05). Differences in CO2, H2O and CH4 emissions were not significant between systems. Raising pigs on sawdust deep litter produced also proportionately more NH3 (+52%; 0.55 g NH3-N d−1 pig−1 vs. 0.36 g NH3-N d−1 pig−1; P < 0.01) but also more CO2 (+25%; 427 g d−1 pig−1 vs. 341 g d−1 pig−1; P < 0.001) and H2O (+65%; 981 g d−1 pig−1 vs. 593 g d−1 pig−1; P < 0.001) and less CH4 (−40%; 0.52 g d−1 pig−1 vs. 0.86 g d−1 pig−1; P < 0.001) than raising pigs on slatted floor. Practically no N2O emission was observed from rooms with slatted floor while the N2O emissions were 0.03 and 0.32 g N2O-N d−1 pig−1 for the straw and sawdust deep litter respectively. The warming potential of the greenhouse gases (N2O + CH4), were about 22, 34 and 168 g CO2 equivalents per day and per pig on fully slatted floor, straw or sawdust deep litter respectively.In conclusion, pollutant gas emissions from rearing of weaned pig seem lower with fully slatted plastic floor system than with deep litter systems. 相似文献
The Minicontainer-test, first described by Eisenbeis (1993), was designed to study the kinetics of organic residue decomposition
at a microsite level. It is derived from the litterbag technique and consists of polyethylene minicontainers (volume about
1.5 cm3) filled with a test substrate (litter, straw, cellulose, etc.). The minicontainers (MCs) are closed at either end with plastic
gauze discs of variable mesh size (e.g. 20 μm, 250 μm, 500 μm or 2 mm). A definite number of such units are inserted into
PVC-bars, which can be implanted into the soil horizontally or vertically, or be exposed on the soil surface horizontally.
The bars are very stable and can be exposed in different environments for months to years. If required, the bars can be removed
temporarily and stored, e.g. during soil cultivation. Should fresh litter be used, two phases of decomposition can be distinguished:
a fast initial phase, which can be mainly related to the effect of leaching, and a second slow phase depending mainly on the
activity of soil organisms and litter quality. Several questions can be addressed to investigations using MCs, e.g. 1) parts
of the soil fauna which are involved in decomposition (nematodes, microarthropods, and smaller specimens of the macrofauna,
e.g. enchytraeidae, diplopods and dipteran larvae) can be extracted from the litter substrate using a miniscale high gradient
extractor, 2) the organic mass loss of litter can be determined, 3) microbial biomass (Cmic, Nmic) can be assessed by fumigation extraction and 4) microbial activity (respiration) in the test substrate can also be assessed
by use of standardised methods. Compared to litterbag studies, the larger number of small replicate units improves the statistical
evaluation. Until today the Minicontainer-test has been applied in forestry and agriculture, e.g. studying the effects of
liming, soil restoration and the application of insecticides, e.g. Diflubenzuron (Dimilin) and Btk (Bacillus thuringiensis var.kurstaki). 相似文献