pp´DDT and pp´DDE Accumulation in a Food Chain of Lake Maggiore (Northern Italy): Testing Steady-State Condition

- DOI: http://dx.doi.org/10.1065/espr2006.01.010 Background, Aims and Scope Although pp'DDT usage was strongly limited or banned in most parts of the world during the last three or four decades, the parent compound, its homologues and their metabolites still occur at levels which might pose a risk for many ecosystem components. A case of DDT pollution of industrial origin was discovered in 1996 in Lake Maggiore, the second largest (212 km2) and deepest (370 m) lake in Italy, causing concern for wildlife and human health. The extensive monitoring of many biotic and abiotic compartments which followed from 1998 in order to assess the pollution level and its trend in time, provided a great availability of data referring to DDT contamination of the different fish species of the lake. In this study, the recent contamination levels in selected fish species were compared to those measured in 1998 to evaluate the temporal pollution trend of the lake and its natural recovery, given that no remediation measures were carried out on the contaminated soils and sediments in this time span. Moreover, a modelling approach to test the equilibrium condition between water and pelagic fish species was used. Analytical results of pp'DDT and pp'DDE concentrations in lake water were used as input data in the bioenergetic model by Connolly & Pedersen (1988) to calculate concentrations in two fish species and to compare the predicted and the measured contamination. Methods Sampling and analytical determination of DDT homologues in lake water: Five water sampling campaigns were carried out from May 2002 to February 2004 in three sampling sites of Lake Maggiore. Suspended and dissolved pollutants were determined separately. Quantitative DDT homologue analyses were performed by HRGC coupled with ECD detection by the external standard method. Single water extracts were put together in correspondence with the stratification zones of the water column inferred on the basis of the temperature profile to improve analytical sensitivity. Selection of fish data: Concentrations of DDT and DDE in fishes were selected from recent literature (CIPAIS 2003, 2004). Bioaccumulation model: The bioenergetic model proposed by Connolly & Pedersen (1988) was used to assess the bioaccumulation of pp'DDT and pp'DDE of Alosa fallax (landlocked shad) and Coregonus spp. (whitefish), selected among the different species as representative of a secondary consumer level. Results and Discussion The average concentrations of pp'DDT and pp'DDE in water to be used as input data in the bioenergetic model were obtained considering all the concentrations measured at the three sampling stations in the epylimnion where the fish species considered in this study spend most of their life. The resulting values were 0.05 and 0.16 ng/L for pp'DDT and pp'DDE, respectively. Average measured pp'DDT and pp'DDE concentrations in landlocked shad were 0.81 +/- 0.39 and 1.69 +/- 0.71 mg/kg lipids, respectively, and were 0.29 +/- 0.12 and 1.06 +/- 0.41 mg/kg lipids for the whitefish. Calculated and measured values turned out to be in quite good agreement for pp'DDT, while measured pp'DDE concentrations were higher than expected on the basis of the bioenergetic model in both species. Probably metabolic transformations of pp'DDT accumulated in fish tissues in the past are responsible for the observed differences between calculated and expected pp'DDE concentrations in fish. Conclusions Pelagic fishes of Lake Maggiore seem to maintain the DDT accumulated during their life time and the most efficient mechanism responsible for the fish population recoveries is probably their generation changes; for this reason, equilibrium models cannot be used until negligible pp'DDT concentrations are reached in fish tissues. Recommendations and Outlook The limit proposed for pp'DDT in water by the EU Directive 2000/60, which will come in force in 2008, is 0.2 ng/L, four times higher than the average concentration measured in Lake Maggiore waters. Nevertheless, concentrations measured in Lake Maggiore fish were very close and sometimes exceeded the Maximum residue limits (MRLs) settled by the Italian legislation for foods (0.1 mg/kg w.w. for fish containing 5–20% lipid). It seems, therefore, that the 'environmental quality standard' of 0.2 ng/L cannot guarantee the suitability of fish for human consumption.     

A sustainable sulfate process to produce TiO2 pigments

Titanium dioxide (TiO₂) is a widely used white pigment. TiO₂ production in 2006 was about 1,400,000 metric tons in the USA. The two major processes to manufacture TiO₂ are the chloride process and the sulfate process. Currently, the TiO₂ industry finds the waste generated in the chloride process less than the waste generated in the sulfate process in its present design, despite generating large quantities of process-related carbon dioxide and carbon monoxide. As a consequence, the sulfate process appears less economical, notably due to the production of green vitriol, FeSO₄·7H₂O, as a major waste. Here, we describe a more sustainable sulfate process based on an earlier study on thermal decomposition of iron(II) sulfates. In the sustainable sulfate process, FeSO₄·7H₂O waste is used for greener production of sulfuric acid, H₂SO₄, used in turn for the digestion of ilmenite. Theoretical and actual yields of waste byproducts per metric ton of TiO₂ produced are used to show the environmental and economic advantages of the sustainable sulfate process.     

The use of clays to sequestrate organic pollutants. Leaching experiments

Leaching experiments are performed from clay-pollutant systems in order to evaluate the capability of clays to sequestrate organic pollutants from wastewaters. Reference kaolinite KGa-1b, montmorrillonite SWy-2 and reference soil BCR^®-700 are the sorbent materials. 2,4,6-trichloroaniline (2,4,6-TCA) and 4-chlorophenol (4-CP) are the typical pollutants, sorbed at amounts of 10.0 mg g⁻¹ and 5.8 mg g⁻¹ on SWy-2 and 7.3 mg g⁻¹ and 2.2 mg g⁻¹ on KGa-1b, respectively.The leaching agents are ultrapure water and model solutions of acid rain and surface waters that simulate meteoric leaching. 1.0 mM HNO₃, 1.0 mM H₂SO₄ solutions and a methanol/water 50/50 (v/v) mixture simulate leaching agents of industrial source.The results are compared and the preferential capability of the clays to sequestrate the more lipophilic 2,4,6-TCA is evidenced.The bond interactions are discussed and explained through preferential adsorption reactions. For montmorrillonite also a simultaneous intercalation in the phyllosilicate interlayer is proposed.     

Distribution of marine cladocerans in the Indian Ocean

Cladocera of the Indian Ocean have been studied, on the basis of samples collected during the International Indian Ocean Expedition (IIOE). Out of a total of 1927 samples, 552 contained Cladocera. Although the distribution of this group is mainly coastal, one species, Evadne tergestina, has been found in oceanic waters also, where it may establish seasonal populations. Evadne spinifera was recorded off the Australian and South African coasts in the southern hemisphere, and in the Northeastern part of the Arabian Sea coastal waters in the northern hemisphere. Podon polyphemoides was reported from a single station in South African waters. Penilia avirostris was found in coastal waters throughout the Indian Ocean. Short-term distribution patterns of E. tergestina and P. avirostris are discussed. The possible value of this group as food for pelagic fishes has been indicated. This work makes clear that adequate sampling in space and time is required along the Continental Shelf of the Indian Ocean in order to obtain more comprehensive information on this group.Visiting Scientist at Indian Ocean Biological Centre, Cochin, India under UNESCO contract SC/2077/70-20579.     

A Chemical Characterization of A Lagoon Ecosystem: The Sacca Di Goro (Po River Delta, Italy)

This work reports on the results of a preliminary estimate of the presence and distribution of common and rare elements in a typical estuarine environment of the Po River Delta. Different environmental compartments (sediment, water, macroalgae and benthic animals) were considered, and analysis conducted on samples taken at two different sites characterized by low and high hydrodynamic regime. Resulting evidence of differences between the matrices, especially in relation to their different nature and sampling site are given.     

Screening organic micropollutants in surface waters by SPE extraction and ecotoxicological testing

Complex mixtures of toxic substances occurring in surface waters are difficult to characterise by chemical analyses because each compound occurs at a very low concentration and requires a specific analytical method to be identified. Ecotoxicological tests on water extracts can be used as a screening tool to evaluate quickly and simply the overall quality of a water body with regard to micropollutant contamination. In this work, a pre-concentration procedure based on solid-phase extraction (SPE), suitable for both biological testing and analytical determination, is proposed. The extraction procedure is an improved version of a methodology used to evaluate the toxicity of organic micropollutants occurring in surface waters. It offers the advantage of using disposable commercial cartridges, which are easier to manage than the columns prepared with macromolecular resins. Water extracts from two representative Italian rivers, characterised by a different gradient of potential contamination and prepared according to the new concentration techniques, are used. The acute toxicity of the water extracts is tested on Daphnia magna and the bioluminescence inhibition in Vibrio fischeri. Criteria based on the concentration factor (CF) are proposed for assessing the hazard to aquatic life due to the exposure to toxic substances in surface waters. The aim of hazard ranking is to focus analytical efforts towards those samples that show the highest toxic potential.     

Community Experiments Using Benthic Chambers: Microbial Significance in Highly Organic Enriched Sediments

The structure of the benthic microbial loop was studied in order to understand heterotrophic pathways in the suboxic sediments of the Rapallo Harbour in autumn, 1996. Sediments were characterized by the large accumulation of organic detritus (17.2 - 21.4 μg chloroplastic pigment equivalents (CPE)g^-1; carbohydrates and proteins: 7.8-16.7 and 6.7-7.5 mg g^-1). Due to the high organic load, benthic bacteria and protozoa displayed extremely high densities (1.4 × 10⁹ cells g^-1 and 26.9 × 10⁵ cells g^-1). Meiofauna, protozoa and bacteria showed an approximate biomass ratio of 1:2:20. the presence of large amounts of organic matter appeared to determine a shift of the benthic size structure toward the increasing dominance of the smaller components of the benthic food webs. These data indicate that the sediments of the Rapallo Harbour were dominated by microbial biomasses to a larger extent than in non-food limited environments, characterized by a lower organic contamination. On the results presented in this study, the microbial dominance in highly organic enriched sediments can be explained with: (1) a reduction of the top-down control and grazing pressure of meio- and macrofauna on the microbial components; (2) the opportunistic composition and high metabolic activity of the microbial components.     

Biochemical composition and trophic strategies of the amphipod Eurythenes gryllus at hadal depths (Atacama Trench,South Pacific)

Amphipods Eurythenes gryllus were collected at 7800?m depth in the Atacama Trench (South Pacific) for studying their biochemical composition (in terms of proteins, lipids and carbohydrates and fatty acid content) and to gather information on bioenergetic strategies and trophic habits of organisms living in this extreme environment. The effect of long-term formalin storage on the biochemical determinations was also determined. Proteins were the dominant biochemical class of organic compounds (39–53%D.W.), whereas carbohydrates accounted for a very small fraction (1–2%D.W.). Lipid concentrations of E. gryllus accounted for 7–18%D.W. and were much lower than those reported for other deep-sea amphipods. These differences are likely to be more dependent upon food availability in the Atacama Trench rather than upon temperature. Lipid composition of E. gryllus revealed the dominance of monounsaturated fatty acids with polyunsaturated fatty acids accounting for a very small fraction, suggesting that hadal amphipods are higher dependent upon lipid reserves than amphipods inhabiting at shallow depths. The ratio of C18:1Δ⁹ to C18:1Δ¹¹ was >11 confirming the necrophagous trophic habits of this hadal amphipod.