Temporal and spatial differences in nitrogen and phosphorus biogeochemistry and ecosystem functioning of a hypertrophic lagoon (Curonian Lagoon, SE Baltic Sea) revealed via Ecological Network Analysis.

In coastal lagoons, eutrophication and hydrology are interacting factors that produce distortions in biogeochemical nitrogen (N) and phosphorus (P) cycles. Such distortions affect nutrient relative availability and produce cascade consequences on primary producer's community and ecosystem functioning. In this study, the seasonal functioning of a coastal lagoon was investigated with a multielement approach, via the construction and analysis of network models. Spring and summer networks, both for N and P flows, have been simultaneously compiled for the northern transitional and southern confined area of the hypertrophic Curonian Lagoon (SE Baltic Sea). Ecological Network Analysis was applied to address the combined effect of hydrology and seasonality on biogeochemical processes. Results suggest that the ecosystem is more active and presents higher N and P fluxes in summer compared to spring, regardless of the area. Furthermore, larger internal recycling characterizes the confined compared to the transitional area, regardless of the season. The two areas differed in the fate of available nutrients. The transitional area received large riverine inputs that were mainly transferred to the sea without the conversion into primary producers' biomass. The confined area had fewer inputs but proportionally larger conversion into phytoplankton biomass. In summer, particularly in the confined area, primary production was inefficiently consumed by herbivores. Most phytoplanktonic N and P, in the confined area more than in the transitional area, were conveyed to the detritus pathway where P, more than N, was recycled, contributing to the unbalance in N:P stoichiometry and favouring N-fixing cyanobacteria over other phytoplankton groups. The findings of this study provide a comprehensive understanding of N and P circulation patterns in lagoon areas characterized by different hydrology. They also support the importance of a stoichiometric approach to trace relative differences in N and P recycling and abundance, that promote blooms, drive algal communities and whole ecosystem functioning.

Accumulation and Release of Cadmium Ions in the Lichen Evernia prunastri (L.) Ach. and Wood-Derived Biochar: Implication for the Use of Biochar for Environmental Biomonitoring.

Biochar (BC) boasts diverse environmental applications. However, its potential for environmental biomonitoring has, surprisingly, remained largely unexplored. This study presents a preliminary analysis of BC's potential as a biomonitor for the environmental availability of ionic Cd, utilizing the lichen Evernia prunastri (L.) Ach. as a reference organism. For this purpose, the lichen E. prunastri and two types of wood-derived biochar, biochar 1 (BC1) and biochar 2 (BC2), obtained from two anonymous producers, were investigated for their ability to accumulate, or sequester and subsequently release, Cd when exposed to Cd-depleted conditions. Samples of lichen and biochar (fractions between 2 and 4 mm) were soaked for 1 h in a solution containing deionized water (control), 10 µM, and 100 µM Cd2+ (accumulation phase). Then, 50% of the treated samples were soaked for 24 h in deionized water (depuration phase). The lichen showed a very good ability to adsorb ionic Cd, higher than the two biochar samples (more than 46.5%), and a weak ability to release the metal (ca. 6%). As compared to the lichen, BC2 showed a lower capacity for Cd accumulation (-48%) and release (ca. 3%). BC1, on the other hand, showed a slightly higher Cd accumulation capacity than BC2 (+3.6%), but a release capacity similar to that of the lichen (ca. 5%). The surface area and the cation exchange capacity of the organism and the tested materials seem to play a key role in their ability to accumulate and sequester Cd, respectively. This study suggests the potential use of BC as a (bio)monitor for the presence of PTEs in atmospheric depositions and, perhaps, water bodies.

Securing wider EU commitment to the elimination of hepatitis C virus.

In 2016, the Hepatitis B and C Public Policy Association (HepBCPPA), gathered all the main stakeholders in the field of hepatitis C virus (HCV) to launch the now landmark HCV Elimination Manifesto, calling for the elimination of HCV in the EU by 2030. Since then, many European countries have made progress towards HCV elimination. Multiple programmes-from the municipality level to the EU level-were launched, resulting in an overall decrease in viremic HCV infections and liver-related mortality. However, as of 2021, most countries are not on track to reach the 2030 HCV elimination targets set by the WHO. Moreover, the COVID-19 pandemic has resulted in a decrease in HCV diagnoses and fewer direct-acting antiviral treatment initiations in 2020. Diagnostic and therapeutic tools to easily diagnose and treat chronic HCV infection are now well established. Treating all patients with chronic HCV infection is more cost-saving than treating and caring for patients with liver-related complications, decompensated cirrhosis or hepatocellular carcinoma. It is more important than ever to reinforce and scale-up action towards HCV elimination. Yet, efforts urgently need the dedicated commitment of policymakers at all governmental and policy levels. Therefore, the third EU Policy Summit, held in March 2021, featured EU parliamentarians and other key decision makers to promote dialogue and take strides towards securing wider EU commitment to advance and achieve HCV elimination by 2030. We have summarized the key action points and reported the 'Call-to-Action' statement supported by all the major relevant European associations in the field.

Surgical management of hip prosthetic failure in metallosis: A case series and literature review.

Local and remote complications can be observed in hip prosthesis failures associated with metallosis. Structural changes in the periprosthetic bone and soft tissues may not always be precisely assessed preoperatively due to metal artifacts. The unpredictability of the damage extension, potentially leading to complex and insidious surgeries, requires the availability of alternative surgical plan(s) for the reconstruction of the joint. The aim of the study is to present and analyze, with the literature data support, practical tips for the revision of the prosthetic components, the management of ARMD and of intraoperative complications in the unusual scenario of metallosis.

Biogeochemical modelling of a tropical coastal area undergoing seasonal upwelling and impacted by untreated submarine outfall.

A coupled 3D hydrodynamic-ecological model was applied to the Santa Marta Coastal Area (SMCA, Colombian Caribbean) to provide insights into the role of external stressors (e.g. wastewater outfall and upwelling) on the water quality and benthic - pelagic coupling. The model was calibrated and validated based on benthic metabolic measurements, satellite-derived chlorophyll-a (Chl-a) and sea surface temperature (SST) maps, field and literature water quality data. The model was able to reproduce the complex dynamics and fast transitions of temperature, nutrients, and phytoplankton, including the stratification and mixing periods during the non-upwelling (NUPW) and upwelling (UPW) seasons. Wide and fast changes in the temperatures and the highly flushed environment prevented excess phytoplankton growth and nutrient accumulation in the benthic and pelagic compartments. The model proved to be a reliable research tool to analyze the interactive effects of upwelling and untreated wastewater on the functioning of a tropical bay.

Hot moments and hotspots of cyanobacteria hyperblooms in the Curonian Lagoon (SE Baltic Sea) revealed via remote sensing-based retrospective analysis.

A temporally and spatially detailed historical (1985-2018) analysis of cyanobacteria blooms was performed in the Curonian Lagoon (Lithuania, Russia), the largest coastal lagoon in the Baltic Sea. Satellite data allowed the mapping of cyanobacteria surface accumulations, so-called "scums", and of chlorophyll-a concentration. The 34-year time series shows a tendency towards later occurrence (October-November) of the cyanobacteria scum presence, whereas the period of its onset (June-July) remains relatively constant. The periods when scums are present, "hot moments", have been consistently increasing in duration since 2008. The differences in the starting, ending and annual duration of cyanobacteria blooms have been significantly altered by hydro-meteorological conditions (river discharge, water temperature, and wind conditions) and their year-round patterns. The most important environmental factors that determined the temporal changes of the scum presence and area were the standing stock of cyanobacteria and the ambient wind conditions. The "hotspots", the areas where the blooms most likely occur, were distributed in the south-southwestern and central parts of the lagoon. The least affected areas were the northern part, which is connected to the coastal waters of the Baltic Sea, and the Nemunas River delta region. The longstanding, well-established spatial patterns of cyanobacteria blooms were linked to hydrodynamic features, namely water renewal time and current patterns, and to potential nutrient sources that included muddy sediments and the locations of colonies of piscivorous birds. Our findings confirmed that the annual and seasonal variations of cyanobacteria blooms and their regulation are a complex issue due to interactions between multiple factors over spatially and temporally broad scales. Despite great progress in the prevention and control of eutrophication and cyanobacteria blooms, the lagoon is still considered to be in a poor ecological status. This work provides a new and missing understanding on the spatial and temporal extent of cyanobacteria blooms and the factors that govern them. Such an understanding can help in planning management strategies, forecasting the magnitude and severity of blooms under changing nutrient loads and potential climate scenarios.

The effects of hydrological extremes on denitrification, dissimilatory nitrate reduction to ammonium (DNRA) and mineralization in a coastal lagoon.

Hydrological extremes of unusually high or low river discharge may deeply affect the biogeochemistry of coastal lagoons, but the effects are poorly explored. In this study, microbial nitrogen processes were analyzed through intact core incubations and 15N-isotope addition at three sites in the eutrophic Sacca di Goro lagoon (Northern Adriatic Sea) both under high discharge (spring) and after prolonged low discharge (late-summer) of the main freshwater inputs. Under high discharge/nitrate load, denitrification was the leading process and there was no internal recycling. The site located at the mouth of the main freshwater input and characterized by low salinity exhibited the highest denitrification rate (up to 1150 ± 81 µmol N m-2 h-1), mostly sustained by nitrification stimulated by burrowing macrofauna. In contrast, we recorded high internal recycling under low discharge, when denitrification dropped at all sites due to low nitrate concentrations, reduced bioturbation and nitrification. The highest recycling was measured at the sites close to the sea entrance and characterized by high salinity and particularly at the clams cultivated area (up to 1003 ± 70 µmol N m-2 h-1). At this site, internal recycling was sustained by ammonification of biodeposits, bivalve excretion and dissimilatory nitrate reduction to ammonium (DNRA), which represented 30% of nitrate reduction. Flash floods and high nitrate loads may overwhelm the denitrification capacity of the lagoon due to the reduced residence time and to the saturation of microbial enzymatic activity, resulting in high transport of nitrate to the sea. Prolonged dry periods favor large internal recycling, due to a combination of high temperatures, low oxygen solubility and low bioturbation, which may prolong the extent of algal blooms with negative effects on lagoon biogeochemical services. We conclude that hydrological extremes, which are expected to become more frequent under climate change scenarios, strongly alter N cycling in coastal sediments.

N2 fixation dominates nitrogen cycling in a mangrove fiddler crab holobiont.

Mangrove forests are among the most productive and diverse ecosystems on the planet, despite limited nitrogen (N) availability. Under such conditions, animal-microbe associations (holobionts) are often key to ecosystem functioning. Here, we investigated the role of fiddler crabs and their carapace-associated microbial biofilm as hotspots of microbial N transformations and sources of N within the mangrove ecosystem. 16S rRNA gene and metagenomic sequencing provided evidence of a microbial biofilm dominated by Cyanobacteria, Alphaproteobacteria, Actinobacteria, and Bacteroidota with a community encoding both aerobic and anaerobic pathways of the N cycle. Dinitrogen (N2) fixation was among the most commonly predicted process. Net N fluxes between the biofilm-covered crabs and the water and microbial N transformation rates in suspended biofilm slurries portray these holobionts as a net N2 sink, with N2 fixation exceeding N losses, and as a significant source of ammonium and dissolved organic N to the surrounding environment. N stable isotope natural abundances of fiddler crab carapace-associated biofilms were within the range expected for fixed N, further suggesting active microbial N2 fixation. These results extend our knowledge on the diversity of invertebrate-microbe associations, and provide a clear example of how animal microbiota can mediate a plethora of essential biogeochemical processes in mangrove ecosystems.

Zebra Mussel Holobionts Fix and Recycle Nitrogen in Lagoon Sediments.

Bivalves are ubiquitous filter-feeders able to alter ecosystems functions. Their impact on nitrogen (N) cycling is commonly related to their filter-feeding activity, biodeposition, and excretion. A so far understudied impact is linked to the metabolism of the associated microbiome that together with the host constitute the mussel's holobiont. Here we investigated how colonies of the invasive zebra mussel (Dreissena polymorpha) alter benthic N cycling in the shallow water sediment of the largest European lagoon (the Curonian Lagoon). A set of incubations was conducted to quantify the holobiont's impact and to quantitatively compare it with the indirect influence of the mussel on sedimentary N transformations. Zebra mussels primarily enhanced the recycling of N to the water column by releasing mineralized algal biomass in the form of ammonium and by stimulating dissimilatory nitrate reduction to ammonium (DNRA). Notably, however, not only denitrification and DNRA, but also dinitrogen (N2) fixation was measured in association with the holobiont. The diazotrophic community of the holobiont diverged substantially from that of the water column, suggesting a unique niche for N2 fixation associated with the mussels. At the densities reported in the lagoon, mussel-associated N2 fixation may account for a substantial (and so far, overlooked) source of bioavailable N. Our findings contribute to improve our understanding on the ecosystem-level impact of zebra mussel, and potentially, of its ability to adapt to and colonize oligotrophic environments.

Denitrification, Nitrogen Uptake, and Organic Matter Quality Undergo Different Seasonality in Sandy and Muddy Sediments of a Turbid Estuary.

The interaction between microbial communities and benthic algae as nitrogen (N) regulators in poorly illuminated sediments is scarcely investigated in the literature. The role of sediments as sources or sinks of N was analyzed in spring and summer in sandy and muddy sediments in a turbid freshwater estuary, the Curonian Lagoon, Lithuania. Seasonality in this ecosystem is strongly marked by phytoplankton community succession with diatoms dominating in spring and cyanobacteria dominating in summer. Fluxes of dissolved gas and inorganic N and rates of denitrification of water column nitrate (Dw) and of nitrate produced by nitrification (Dn) and sedimentary features, including the macromolecular quality of organic matter (OM), were measured. Shallow/sandy sites had benthic diatoms, while at deep/muddy sites, settled pelagic microalgae were found. The OM in surface sediments was always higher at muddy than at sandy sites, and biochemical analyses revealed that at muddy sites the OM nutritional value changed seasonally. In spring, sandy sediments were net autotrophic and retained N, while muddy sediments were net heterotrophic and displayed higher rates of denitrification, mostly sustained by Dw. In summer, benthic oxygen demand increased dramatically, whereas denitrification, mostly sustained by Dn, decreased in muddy and remained unchanged in sandy sediments. The ratio between denitrification and oxygen demand was significantly lower in sandy compared with muddy sediments and in summer compared with spring. Muddy sediments displayed seasonally distinct biochemical composition with a larger fraction of lipids coinciding with cyanobacteria blooms and a seasonal switch from inorganic N sink to source. Sandy sediments had similar composition in both seasons and retained inorganic N also in summer. Nitrogen uptake by microphytobenthos at sandy sites always exceeded the amount loss via denitrification, and benthic diatoms appeared to inhibit denitrification, even in the dark and under conditions of elevated N availability. In spring, denitrification attenuated N delivery from the estuary to the coastal area by nearly 35%. In summer, denitrification was comparable (~100%) with the much lower N export from the watershed, but N loss was probably offset by large rates of N-fixation.

Estimation of the number of HCV-positive patients in Italy.

BACKGROUND: HCV is one of the main causes of cirrhosis, hepatocellular carcinoma (HCC) and liver transplantation. AIM: The aim of this study was to estimate the number of living individuals diagnosed with hepatitis C in Italy. This study also aimed to stratify these subjects as diagnosed and cured, diagnosed awaiting a cure, and undiagnosed (individuals who were not diagnosed, living or lived with hepatitis C). METHODS: To quantify the number of ill patients in Italy, an inquiry was conducted based on questionnaires submitted to three nationally representative regions, namely, Campania, Lazio and Piemonte, as representatives of the three main areas of Italy (North, Centre and South regions). The data were collected through a questionnaire to acquire demographic and clinical information on patients in the participating hospitals. The questionnaires contained 6 questions on sex, age, region of residence, disease condition, type of exemption and category. The questionnaires were administered individually to consecutive patients through face-to-face interviews conducted by specialised personnel in each centre. Data were collected between September 2017 and January 2018. RESULTS: In total, 2,860 questionnaires were analysed. They were completed by the patients (55% male), who had an average age of 61 years (64 years for women and 59 years for men). In total, 54% of the sample declared that they were still infected with HCV (1,548 patients out of 2,860 respondents), while the remaining subjects declared that they had been cured. The inquiry showed that 46.6% of the sample had at least a 016 exemption (chronic hepatitis), while more than 51% (1,469 interviewed patients out of 2,860 respondents) had a different type of exemption. Only 2% of the respondents declared that they had no exemption. Assuming that the analysed sample is representative of the actual HCV-positive population in Italy and considering the number of 016 exempt patients in the regional data, the model estimates that there are 443,491 cured and HCV-positive living patients and 240,043 ill patients who have yet to be treated. CONCLUSIONS: Although this study has limitations, it represents a considerable improvement over the previously available studies. This study can help decision-makers implement more effective strategic planning to eliminate hepatitis C.

Chemosymbiotic bivalves contribute to the nitrogen budget of seagrass ecosystems.

In many seagrass sediments, lucinid bivalves and their sulfur-oxidizing symbionts are thought to underpin key ecosystem functions, but little is known about their role in nutrient cycles, particularly nitrogen. We used natural stable isotopes, elemental analyses, and stable isotope probing to study the ecological stoichiometry of a lucinid symbiosis in spring and fall. Chemoautotrophy appeared to dominate in fall, when chemoautotrophic carbon fixation rates were up to one order of magnitude higher as compared with the spring, suggesting a flexible nutritional mutualism. In fall, an isotope pool dilution experiment revealed carbon limitation of the symbiosis and ammonium excretion rates up to tenfold higher compared with fluxes reported for nonsymbiotic marine bivalves. These results provide evidence that lucinid bivalves can contribute substantial amounts of ammonium to the ecosystem. Given the preference of seagrasses for this nitrogen source, lucinid bivalves' contribution may boost productivity of these important blue carbon ecosystems.

An ounce of prevention is worth a pound of cure: Managing macrophytes for nitrate mitigation in irrigated agricultural watersheds.

Although ubiquitous elements of agricultural landscapes, the interest on ditches and canals as effective filters to buffer nitrate pollution has been raised only recently. The aim of the present study was to investigate the importance of in-ditch denitrification supported by emergent aquatic vegetation in the context of N budget in agricultural lands of a worldwide hotspot of nitrate contamination and eutrophication, i.e. the lowlands of the Po River basin (Northern Italy). The effectiveness of N abatement in the ditch network (>18,500 km) was evaluated by extrapolating up to the watershed reach-scale denitrification rates measured in a wide range of environmental conditions. Scenarios of variable extents of vegetation maintenance were simulated (25%, 50% and 90%), and compared to the current situation when the natural development occurs in only 5% of the ditch network length, subjected to mechanical mowing in summer. Along the typical range of nitrate availability in the Po River lowlands waterways (0.5-8 mg N L-1), the current N removal performed by the ditch network was estimated in 3300-4900 t N yr-1, accounting for at most 11% of the N excess from agriculture. The predicted nitrate mitigation potential would increase up to 4000-33,600 t N yr-1 in case of vegetation maintenance in 90% of the total ditch length. Moreover, a further significant enhancement (57% on average) of this key ecosystem function would be achieved by postponing the mowing of vegetation at the end of the growing season. The simulated outcomes suggest that vegetated ditches may offer new agricultural landscape management opportunities for effectively decreasing nitrate loads in surface waters, with potential improved water quality at the watershed level and in the coastal zones. In conclusion, ditches and canals may act as metabolic regulators and providers of ecosystem services if conservative management practices of in-stream vegetation are properly implemented and coupled to hydraulic needs.

Pleomorphic clinical spectrum of metallosis in total hip arthroplasty.

PURPOSE: To summarize the biological effects of metal debris from hip arthroplasties which characterize a polymorphic clinical spectrum of local and remote manifestation. METHODS: Retrospective study. Patient, implant, and surgical characteristics were collected, including implant survival, clinical manifestations, cause of arthroplasty revision or implant failure, and peri- and intra-operative complications. The primary endpoint was implant survivorship. Hip revision arthroplasty was decided considering clinical signs and symptoms, abnormal imaging (XR, MR, TC, echotomography, scintigraphy), and blood metal ion level. An ad hoc electronic form was used to collect demographic, epidemiological, and clinical variables. In-between group comparisons of quantitative variables were performed with the Student t test and the Mann-Whitney for parametric and non-parametric variables, respectively. Logistic regression analyses were carried out to assess the relationship between clinical and radiographic characteristics and stem and cup revision. Radiographic measurements of implant positioning validity and reliability were assessed using Krippendorff's alpha reliability coefficient. The statistical software STATA version 15 (StatsCorp, TX) was used to perform statistical computations. RESULTS: In this MoM THA series, the most incident cause of implant failure was ARMD in 11 out of 14 (78.6%) patients. All clinical failure manifestations, revision surgery highlights, and intra-operative findings are reported. CONCLUSIONS: The local adverse reactions include lesions of different clinical relevance from small asymptomatic soft tissue lesions to dramatic osteolysis, necrosis, effusion, and growing masses which can cause secondary pathological effects. Symptoms of systemic toxicity are rarely described but may have been largely unreported in literature. Despite the extensive literature on the topic, the patient's management is still uncertain and challenging. Every metallic implant (e.g., screws, plates, spinal instrumentations) has a potential local or systemic adverse effect. Organizing a national registry of arthroplasty should be mandatory, in order to collect data about the patients, the surgery, the implanted device (with a careful post-marketing tracking), and the follow-up for all the procedures performed at a national level. The data collected in the registry will allow to analyze the implant survival and to better recognize the undesirable and sometimes unexpected effects of different biomaterials on the whole body.

Environmental Drivers Controlling Bacterial and Archaeal Abundance in the Sediments of a Mediterranean Lagoon Ecosystem.

The environmental factors controlling the abundance of Bacteria and Archaea in lagoon ecosystems are poorly understood. Here, an integrated physico-chemical, biogeochemical, and microbiological survey was applied in the Sacca di Goro lagoon (Po River Delta, Italy) to investigate the variation of bacterial and archaeal abundance, as assessed by Fluorescence In Situ Hybridization, along winter and summer environmental gradients. We hypothesised that bacterial and archaeal cells respond differentially to physico-chemical parameters of the sediment, which can be manifested in variations of total cells number. Our results suggest that Archaea are an important component of microbial communities (up to 20%) and they are also quite constant along the sediment depth investigated, while Bacteria tend to decrease in the subsurface sediments. The abiotic (i.e. temperature, ammonium, pH) and trophic parameters (i.e. chlorophyll a) explain differentially the variations of bacterial and archaeal distribution, and raise interesting questions about the ecological significance of the microbial composition in this area.

Variation in benthic metabolism and nitrogen cycling across clam aquaculture sites.

As bivalve aquaculture expands globally, an understanding of how it alters nitrogen is important to minimize impacts. This study investigated nitrogen cycling associated with clam aquaculture in the Sacca di Goro, Italy (Ruditapes philipinarum) and the Eastern Shore, USA (Mercenaria mercenaria). Ammonium and dissolved oxygen fluxes were positively correlated with clam biomass; R. philippinarum consumed ~6 times more oxygen and excreted ~5 times more NH4+ than M. mercenaria. There was no direct effect of clams on denitrification or dissimilatory nitrate reduction to ammonium (DNRA); rather, nitrate availability controlled the competition between these microbial pathways. Highest denitrification rates were measured at sites where both water column nitrate and nitrification were elevated due to high densities of a burrowing amphipod (Corophium sp.). DNRA exceeded denitrification where water column nitrate was low and nitrification was suppressed in highly reduced sediment, potentially due to low hydrologic flow and high clam densities.

Nitrogen budget in a lowland coastal area within the Po River basin (northern Italy): multiple evidences of equilibrium between sources and internal sinks.

Detailed studies on pollutants genesis, path and transformation are needed in agricultural catchments facing coastal areas. Here, loss of nutrients should be minimized in order to protect valuable aquatic ecosystems from eutrophication phenomena. A soil system N budget was calculated for a lowland coastal area, the Po di Volano basin (Po River Delta, Northern Italy), characterized by extremely flat topography and fine soil texture and bordering a network of lagoon ecosystems. Main features of this area are the scarce relevance of livestock farming, the intense agriculture, mainly sustained by chemical fertilizers, and the developed network of artificial canals with long water residence time. Average nitrogen input exceeds output terms by ~60 kg N ha(-1) year(-1), a relatively small amount if compared to sub-basins of the same hydrological system. Analysis of dissolved inorganic nitrogen in groundwater suggests limited vertical loss and no accumulation of this element, while a nitrogen mass balance in surface waters indicates a net and significant removal within the watershed. Our data provide multiple evidences of efficient control of the nitrogen excess in this geographical area and we speculate that denitrification in soil and in the secondary drainage system performs this ecosystemic function. Additionally, the significant difference between nitrogen input and nitrogen output loads associated to the irrigation system, which is fed by the N-rich Po River, suggests that this basin metabolizes part of the nitrogen excess produced upstream. The traditionally absent livestock farming practices and consequent low use of manure as fertilizer pose the risk of excess soil mineralization and progressive loss of denitrification capacity in this area.

Herbicide contamination and dispersion pattern in lowland springs.

Herbicides reduce the diversity of flora and fauna in freshwater ecosystems and also contaminate groundwater due to leaching. Herbicide contamination can be a serious threat for all groundwater-dependent ecosystems (GDE), altering their chemical and biological quality. Successful management to protect GDE is dependent on detailed knowledge of the hydrogeological and hydrochemical features of the surrounding environment. We consider the possible diffuse contamination by herbicides of groundwater and of GDE as lowland springs, semi-artificial ecosystems with elevated biodiversity. The main objectives of the present work were thus: (1) to map herbicide contamination in lowland springs, (2) to evaluate the potential risk for biota and (3) to quantify the extent of the area from which the herbicide use can affect the water quality of lowland springs. In June and August 2009, nearly 23 springs within the Po River Plain (Northern Italy) were sampled and analyzed for five herbicides used to control weeds in maize. Hydrogeological properties, half-lives of the herbicides and their concentrations in both groundwater and springs were used to quantify the area from which the contamination could originate. Such evaluation was performed by means of GIS techniques. Terbuthylazine were the only herbicide found, together with its metabolite desethylterbuthylazine. In 16 out of 84 measurements, their concentrations were above the threshold for drinking water; however, they were always below the ecotoxicological end-points of aquatic flora and fauna. Spatial analyses reveal that the theoretical area from which herbicides can contaminate spring water is within a distance varying between a few and 1800 m. Our findings indicate that conservation plans should focus on the fields adjacent to or surrounding the springs and should address the optimization of irrigation practices, restoration of buffer strips, crop rotation and in general more sustainable agricultural practices in the proximity of these fragile GDE.

Inorganic nitrogen control in wastewater treatment ponds from a fish farm (Orbetello, Italy): denitrification versus Ulva uptake.

The aim of this study was to quantify the N removal efficiency of an Ulva-based phytotreatment system receiving wastewaters from a land-based fish farm (Orbetello, Italy), to identify the main biogeochemical pathways involved and to provide basic guidelines for treatment implementation and management. Fluxes of O2 and nutrients in bare and in Ulva colonised sediments were assessed by light/dark core incubations; denitrification by the isotope pairing technique and Ulva growth by in situ incubation of macroalgal disks in cages. O2 and nutrient budgets were estimated as sum of individual processes and further verified by 24-h investigations of overall inlet and outlet loads. Ulva uptake (up to 7.8 mmol Nm(-2) h(-1)) represented a net sink for water column and regenerated NH4+ whilst N removal via denitrification (10-170 micromol Nm(-2) h(-1)) accounted for a small percentage of inorganic nitrogen load (<5%). Laboratory experiments demonstrated a high potential for denitrification (over 800 microM Nm(-2) h(-1)) indicating that N loss could be enhanced. The control of Ulva standing stocks by optimised harvesting of surplus biomass may represent an effective strategy to maximise DIN removal and could result in the assimilation of approximately 50% of produced inorganic nitrogen.