Marcello Di Bonito

Dynamic characteristics of sulfur, iron and phosphorus in coastal polluted sediments, north China

The cycling of sulfur (S), iron (Fe) and phosphorus (P) in sediments and pore water can impact the water quality of overlying water. In a heavily polluted river estuary (Yantai, China), vertical profiles of fluxes of dissolved sulfide, Fe2+ and dissolved reactive phosphorus (DRP) in sediment pore water were investigated by the Diffusive Gradients in Thin films technique (DGT). Vertical fluxes of S, Fe, P in intertidal sediment showed the availability of DRP increased while the sulfide decreased with depth in surface sediment, indicating that sulfide accumulation could enhance P release in anoxic sediment. In sites with contrasting salinity, the relative dominance of iron and sulfate reduction was different, with iron reduction dominant over sulfate reduction in the upper sediment at an intertidal site but the reverse true in a freshwater site, with the other process dominating at depth in each case. Phosphate release was largely controlled by iron reduction.

Models of Geochemical Speciation : Structure and Applications

Being able to predict the behavior of trace elements in the environment is crucial for environmental risk assessment studies. For this reason, modeling, in addition to experimental methods, has become an indispensable tool to better understand the (bio)-geochemistry of trace elements and the processes involved in their availability, transport and ecotoxicity. In this chapter we briefly outline the development of geochemical modeling over time and its basic principles. A comprehensive description of the state-of-the-art ion-binding and surface complexation models presently available for dissolved and particulate organic matter, metal (hydr)oxides of aluminum, iron, manganese and silica and clay minerals is given. A significant part of this chapter is dedicated to the application of these models for studying surface waters and soils. The most common model platforms used for this purpose together with the available (thermodynamic) databases of model parameters are summarized. In two separate sections we highlight the application of an assemblage model (with submodels for the various adsorbents) to describe trace element solid-solution partitioning and speciation in surface waters and soils; here particular attention is given to the derivation of site-specific inputs concerning the geochemical reactive metal content and the contents of adsorbents metal (hydr)oxides, clay and organic matter). Consideration is therefore given to the most recent developments in bio-geochemical modeling to link metal speciation to bioavailability, biotic accumulation and toxicity. Finally, future prospects of geochemical modeling are discussed, giving an overview of the potential directions for development.

SEWAGE SLUDGE IN EUROPE AND IN THE UK: ENVIRONMENTAL IMPACT AND IMPROVED STANDARDS FOR RECYCLING AND RECOVERY TO LAND

Abstract Sewage treatment and sewage sludge (also called biosolids) represent a serious environmental issue that has affected modern society for the past century. In response to this, an increasing number of controls and resulting regulations have been introduced to avoid polluting our rivers and seas with pathogens, oxygen-demanding organic debris, potentially toxic elements (PTEs) and eutrophying nutrients. Over the past few decades, improved technology and more stringent regulations, driven in Europe by the increasingly precautionary European Community (EC) legislation, have worked together to achieve a net decrease of the amount of some of the pollutants, both through treatment of the wastewater and by cutting or forbidding the intake of contaminants at source. The growing importance of cleaning up wastewater before returning it to natural waters has led to (1) a vast increase of the quantity and the quality of the sludge resulting from the treatment of wastewater, with a greater amount of pollutants removed during the treatment process; (2) a greater effort towards the reuse and recycling of the sludge as opposed to disposal (e.g. landfilling, incineration). One of the consequences of this situation is a rising interest in using soils (agricultural or not) to address the latter through various applications. In fact, as the sludge has to be disposed off safely, soils can be used as a system of assimilating, recycling or disposing off the sewage sludge. Science and legislation are trying to provide the safest possible route to accomplish these targets, but the subject is not free from controversy, often causing hot debates between the interested parties. This chapter aims to review the improved standards achieved with sewage sludge, touching in particular the British experience in the field of regulating the disposal and reuse of these materials.

Status, sources and contamination levels of organochlorine pesticide residues in urban and agricultural areas: a preliminary review in central–southern Italian soils

Organochlorine pesticides (OCPs) are synthetic chemicals commonly used in agricultural activities to kill pests and are persistent organic pollutants (POPs). They can be detected in different environmental media, but soil is considered an important reservoir due to its retention capacity. Many different types of OCPs exist, which can have different origins and pathways in the environment. It is therefore important to study their distribution and behaviour in the environment, starting to build a picture of the potential human health risk in different contexts. This study aimed at investigating the regional distribution, possible sources and contamination levels of 24 OCP compounds in urban and rural soils from central and southern Italy. One hundred and forty-eight topsoil samples (0–20xa0cm top layer) from 78 urban and 70 rural areas in 11 administrative regions were collected and analysed by gas chromatography–electron capture detector (GC–ECD). Total OCP residues in soils ranged from nd (no detected) to 1043xa0ng/g with a mean of 29.91xa0ng/g and from nd to 1914xa0ng/g with a mean of 60.16xa0ng/g in urban and rural area, respectively. Endosulfan was the prevailing OCP in urban areas, followed by DDTs, Drins, Methoxychlor, HCHs, Chlordane-related compounds and HCB. In rural areas, the order of concentrations was Drinsu2009>u2009DDTsu2009>u2009Methoxychloru2009>u2009Endosulfansu2009>u2009HCHsu2009>u2009Chlordanesu2009>u2009HCB. Diagnostic ratios and robust multivariate analyses revealed that DDT in soils could be related to historical application, whilst (illegal) use of technical DDT or dicofol may still occur in some urban areas. HCH residues could be related to both historical use and recent application, whilst there was evidence that modest (yet significant) application of commercial technical HCH may still be happening in urban areas. Drins and Chlordane compounds appeared to be mostly related to historical application, whilst Endosulfan presented a complex mix of results, indicating mainly historical origin in rural areas as well as potential recent applications on urban areas. Contamination levels were quantified by Soil Quality Index (SoQI), identifying high levels in rural areas of Campania and Apulia, possibly due to the intensive nature of some agricultural practices in those regions (e.g., vineyards and olive plantations). The results from this study (which is in progress in the remaining regions of Italy) will provide an invaluable baseline for OCP distribution in Italy and a powerful argument for follow-up studies in contaminated areas. It is also hoped that similar studies will eventually constitute enough evidence to push towards an institutional response for more adequate regulation as well as a full ratification of the Stockholm Convention.

Source patterns and contamination level of polycyclic aromatic hydrocarbons (PAHs) in urban and rural areas of Southern Italian soils

Polycyclic aromatic hydrocarbons (PAHs) are a group of persistent organic pollutants. They have been identified as a type of carcinogenic substance and are relatively widespread in environment media such as air, water and soils, constituting a significant hazard for human health. In many parts of the world, PAHs are still found in high concentrations despite improved legislation and monitoring, and it is therefore vital defining their profiles, and assessing their potential sources. This study focused on a large region of the south of Italy, where concentration levels, profiles, possible sources and toxicity equivalent quantity (TEQ) level of sixteen PAHs were investigated. The survey included soils from five large regions of the south of Italy: 80 soil samples (0–20xa0cm top layer) from urban and rural locations were collected and analysed by gas chromatography–mass spectrometry. Total PAHs and individual molecular compounds from the US Environmental Protection Agency priority pollutants list were identified and measured. Results showed that 16 PAHs varied significantly in urban and rural areas, and different regions presented discordant characteristics. Urban areas presented concentrations ranging from 7.62 to 755xa0ngxa0g−1 (meanu2009=u200984.85xa0ngxa0g−1), whilst rural areas presented ranges from 1.87 to 11,353xa0ngxa0g−1 (meanu2009=u2009333xa0ngxa0g−1). Large urban areas, such as Rome, Naples and Palermo, exhibited high PAHs total concentration, but high values were also found in rural areas of Campania region. Different PAHs molecular ratios were used as diagnostic fingerprinting for source identification: LWMPAHs/HWMPAHs, Fluo/(Fluou2009+u2009Pyr), BaA/(BaAu2009+u2009Chr), Ant/(Antu2009+u2009u2009Phe) and IcdP/(IcdPu2009+u2009BghiP). These ratios indicated that PAHs sources in the study area were mainly of pyrogenic origin, i.e. mostly related to biomass combustion and vehicular emission. On the other hand, values in Sicilian soils seemed to indicate a petrogenic origin, possibly linked to emissions from crude oil combustion and refineries present in the region. Finally, results allowed to calculate the toxicity equivalent quantity (TEQBAP) levels for the various locations sampled, highlighting that the highest values were found in the Campania region, with 661 and 54.20xa0ngxa0g−1, in rural and urban areas, respectively. These findings, which could be linked to the presence of a large solid waste incinerator plant, but also to well-documented illegal waste disposal and burning, suggest that exposure to PAH may be posing an increased risk to human health in some of the studied areas.

Extraction and Characterization of Pore Water in Contaminated Soils

Abstract Chemical elements that are either present naturally in the soil or introduced by pollution are more usefully estimated in terms of “availability” of the element, since it is this property that can be related to mobility and uptake by plants. A good estimate of the immediately available fraction can be achieved by measuring the concentration, or activity, of chemical species in soil pore water. Current analytical techniques enable the application of this approach to trace elements, such as plant and animal micronutrients and those defined as potentially toxic elements (PTEs) in environmental studies. A complete chemical analysis of soil pore water represents a powerful diagnostic tool for the interpretation of many soil chemical phenomena relating to soil fertility, mineralogy, and environmental fate. This chapter describes some of the current methodologies used to extract soil pore water. In particular, five laboratory-based methods are described and discussed in detail: (i) high speed centrifugation-filtration, (ii) low (negative-) pressure Rhizon samplers and passive diffusion samplers, (iii) high pressure soil squeezing, (iv) equilibration of dilute soil suspensions, and (v) diffusive gradients in thin-films (DGT). A number of operational factors are presented: pressure applicable (i.e., pore size accessed), moisture prerequisites of the soil, pore water yield, efficiency, duration of extraction, materials and possible sources of contamination for micronutrient and PTE studies. There is also consideration of the advantages and disadvantages of the methods, including costs and material availability.