Agricultural nitrate monitoring in a lake basin in Central Italy: a further step ahead towards an integrated nutrient management aimed at controlling water pollution

Water pollution from point sources has been considerably reduced over the last few decades. Nevertheless, some water quality problems remain, which can be attributed to non-point pollution sources, and in particular to agriculture. In this paper the results of a study intended to assess the consequences, in terms of NO₃ water pollution, of growing a crop, whose impact in terms of P pollution is already well known, are presented. The potential consequences, in terms of water pollution from nitrates of a BMP expressly applied to reduce P pollution are also discussed. The study site is the Lake Vico basin, Central Italy, which has suffered a shift in trophic state since the mid 1990s, caused by P compounds used for intensive cultivation of hazelnut trees. The results of the monitoring campaign described in this paper allow to assert that hazelnut tree cropping has probably caused a considerable increase in nitrate concentration in the groundwater, although not in the lake water, because of the specific hydrogeological characteristics of the basin. The main conclusion is that monitoring is essential to single out environmental characteristics peculiar of a specific area, which even the most sophisticated model would not have been able to highlight. This is why monitoring and model simulations should be integrated.     

TG, FT-IR and NMR characterization of n-C16H34 contaminated alumina and silica after mechanochemical treatment

This paper deals with the application of mechanochemistry to model systems composed of alumina or silica artificially contaminated with n-C16H34. The mechanochemical treatment was carried out by means of a ring mill for times ranging from 10 to 40h. Thermogravimetry and infrared and nuclear magnetic resonance spectroscopies were used for the characterization of the mechanochemical products. The results have indicated that, in the case of alumina, almost all the contaminant n-C16H34 undergoes a complex oxidative reaction path whose end products are strongly held on the surface. These end products are most likely made of crosslinked, partially oxidized hydrocarbon chains bond to the solid surface via COO(-) groups. In the case of silica, the hydrocarbon undergoes a different, equally complex reaction path, but to a lower extent. In this case the end products are most probably carbonylic compounds and graphitic carbon. Then, for both solid matrices, the mechanochemical treatment promotes significant modification of the chemical nature of the polluting hydrocarbon with end products much more difficult to remove from the surface. As the systems studied are models of sites contaminated by aliphatic hydrocarbon, the results are worthy of consideration in relation to the mobility of the contaminants in the environment.     

Effects of ranitidine and its photoderivatives in the aquatic environment

This study was designed to assess the overall ecotoxicity of ranitidine, a histamine H₂-receptor antagonist that inhibits stomach acid production. Hence, in addition to ranitidine, its main two photoderivatives, obtained by solar simulator irradiation in water, were investigated. The photoproducts were identified by their physical features. Bioassays were performed on rotifers and microcrustaceans to assess acute and chronic toxicity, while SOS Chromotest and Ames test were utilized to detect the genotoxic potential of the investigated compounds. The results showed that ranitidine did not show any acute toxicity at the highest concentration tested (100 mg/L) for all the organisms utilized in the bioassays. Chronic exposure to these compounds caused inhibition of growth population on rotifers and crustaceans. Genotoxic and mutagenic effects were especially found for one photoproduct suggesting that transformation products, as frequently demonstrated, may show effects higher than the respective parental compound.     

The effect of export to the deep sea on the long-range transport potential of persistent organic pollutants

Background

Export to the deep sea has been found to be a relevant pathway for highly hydrophobic chemicals. The objective of this study is to investigate the influence of this process on the potential for long-range transport (LRT) of such chemicals.

Methods

The spatial range as a measure of potential for LRT is calculated for seven PCB congeners with the multimedia fate and transport model ChemRange. Spatial ranges for cases with and without deep sea export are compared.

Results and Discussion

Export to the deep sea leads to increased transfer from the air to the surface ocean and, thereby, to lower spatial ranges for PCB congeners whose net deposition rate constant is similar to or greater than the atmospheric degradation rate constant. This is fulfilled for the PCB congeners 101, 153, 180, and 194. The spatial ranges of the congeners 8, 28, and 52, in contrast, are not affected by deep sea export. With export to the deep sea included in the model, the spatial ranges of the heavier congener are similar to those of the lighter ones, while the intermediate congeners 101 and 153 have the highest potential for long-range transport.

Conclusions

Transfer to the deep ocean affects the mass balance and the potential for LRT of highly hydrophobic chemicals and should be included in multimedia fate models containing a compartment for ocean water.     

World-Wide Species Richness Patterns of Tiger Beetles (Coleoptera: Cicindelidae): Indicator Taxon for Biodiversity and Conservation Studies

The family of tiger beetles (Cicindelidae) is an appropriate indicator taxon for determining regional patterns of biodiversity because (1) its taxonomy is stabilized; (2) its biology and general life history are well understood, (3) individuals are readily observed and manipulated in the field, (4) the family occurs world-wide and in a broad range of habitat types; (5) each species tends to be specialized within a narrow habitat; (6) patterns of species richness are highly correlated with those of other vertebrate and invertebrate taxa; and (7) the taxon includes species of potential economic importance. Logistical advantages provide some of the strongest arguments for selecting tiger beetles as an appropriate indicator taxon. Species numbers of tiger beetles are relatively well known for 129 countries. Eight countries alone account for more than half the world total of 2028 known species. Species numbers are also indicated for eleven biogeographical zones of the world. For gridded squares across North America, the Indian subcontinent, and Australia, species richness of tiger beetles, birds, and butterflies shows significant positive correlations. However, tiger beetle species numbers can be reliably determined within fifty hours on a single site, compared to months or years for birds or butterflies, and the advantage of using tiger beetles in conservation biology is evident     

Testing kernel density reconstruction for Lagrangian photochemical modelling

In recent years, a number of pioneering works have shown as Lagrangian models can be of great interest when dealing with photochemistry, provided that special care is given in the reconstruction of chemicals concentration in the atmosphere. Density reconstruction can be performed through the so-called “box counting” method: an Eulerian grid for chemistry is introduced and density is computed counting particles in each box. In this way one of the main advantages of the Lagrangian approach, the grid independence, is lost. In this paper, a new approach to Lagrangian photochemical modelling is investigated and the chemical module of the Photochemical Lagrangian Particle Model (PLPM) is described and fully tested for stability, reliability and computational weight. Photochemical reactions are treated in PLPM by means of the complex chemical mechanism SAPRC90 and four density reconstruction methods have been developed, based on the kernel density estimator approach, in order to obtain grid-free accurate concentrations.