Gaetano Viviano

Organic persistent toxic substances in soils, waters and sediments along an altitudinal gradient at Mt. Sagarmatha, Himalayas, Nepal.

Persistent Organic Pollutants (POPs) and Polycyclic Aromatic Hydrocarbons (PAHs) are important classes of compounds of serious environmental concern. These compounds were measured in waters, sediments and soils from several high altitude sites in the Sagarmatha National Park (Nepal) and included in the Himalayan ridge. In water samples, low-level substituted PCBs and PBDEs, along with more volatile PAHs, were the most common contaminants. In sediment and soil samples, the PCB profile was mainly composed of medium-level chlorinated congeners and significantly correlated with altitude. The PAH profile for water and soil samples showed the main contribution of pyrogenic PAHs due to emissions of solid combustion, whereas the profile for sediments indicated the main contribution of pyrogenic PAHs from gasoline emissions. The PAH levels measured in Himalayan samples must be considered as low to medium contaminated, whereas the regarded Himalayan stations can be considered undisturbed remote areas concerning PCB, PBDE and OC compounds.

Multiple Carrying Capacities from a management-oriented perspective to operationalize sustainable tourism in protected areas

This article describes how the concept of Tourism Carrying Capacity (TCC) has shifted from a uni-dimensional approach to incorporating environmental, social and political aspects. This shift is demonstrated by a study of a large, internationally popular protected area used by trekkers, the Mt. Everest Region, where qualitative data collected from visitors was combined with environmental modeling using a participatory framework. Tourist satisfaction showed positive margins for further tourist industry expansion, but current environmental conditions limit growth and further development. Space and time dimensions were also considered. We observed that the limits on growth and further development can be manipulated, with a certain degree of flexibility, through investments and regulatory measures. We hypothesized that TCC can play an important role in the management of protected areas only if it is viewed as a systematic, strategic policy tool within a planning process rather than as a unique, intrinsic number that is not modifiable. We conclude that to translate the strategy into action using standard measures, further investigation is needed to balance the various TCC components as a part of a decision-making framework that includes the integration of different cultural approaches and policy needs.

Occurrence and sources of perfluoroalkyl acids in Italian river basins

This paper presents a survey on the occurrence and sources of 11 perfluoroalkyl acids (PFAA) in the main river basins in Italy, covering about 40% of the Italian surface area and 45% of the Italian population. Total concentrations of PFAA ranged from<LOD to 8μgL(-1), the highest concentrations being measured in the rivers impacted by industrial discharges. Among the rivers directly flowing into the sea, Brenta, Po and Arno present significant concentrations, while concentrations in Tevere and Adige, which are not impacted by relevant industrial activities, are almost all below the detection limits. The total estimated PFAA load of the five rivers was 7.5ty(-1) with the following percentage distribution: 39% PFBS, 32% PFOA, 22% short chain perfluorocarboxylic acids (PFCA), 6% PFOS and 1% long chain PFCA. PFOA and PFOS loads, evaluated in the present work, represent 10% and 2% of the estimated European loads, respectively. In Italy the most important sources of PFAA are two chemical plants which produce fluorinated polymers and intermediates, sited in the basin of rivers Po and Brenta, respectively, whose overall emission represents 57% of the total estimated PFAA load. Both rivers flow into the Adriatic Sea, raising concern for the marine ecosystem also because a significant PFOS load (0.3ty(-1)) is still present. Among the remaining activities, tanneries and textile industries are relevant sources of respectively PFBS and PFOA, together with short chain PFCA. As an example, the total PFAA load (0.12ty(-1)) from the textile district of Prato is equivalent to the estimated domestic emission of the whole population in all the studied basins.

Coupling high-resolution measurements to a three-dimensional lake model to assess the spatial and temporal dynamics of the cyanobacterium Planktothrix rubescens in a medium-sized lake

In a medium-sized pre-alpine lake (North Italy) the cyanobacterium Planktothrix rubescens has strongly dominated the phytoplankton assemblage since 2000, similar to many pre-alpine lakes, despite improvements in water quality. The objective of this study was to determine the factors governing the spatial distribution of P. rubescens, including the major hydrodynamic processes and the influence of long-term reduction in nutrient concentrations during a period of climate warming. We used an intensive field campaign conducted from February 2010 to January 2011, to evaluate distributions of phytoplankton phyla, as well as P. rubescens, using spectrally resolved fluorescence measurements. These data provided highly spatially and temporally resolved phytoplankton population data suitable to calibrate and validate a coupled three-dimensional hydrodynamic (ELCOM) and ecological model (CAEDYM) of the lake ecosystem. The simulations revealed the fundamental role of physiological features of P. rubescens that led to observed vertical patterns of distribution, notably a deep chlorophyll maximum, and a strong influence of lake hydrodynamic processes, particularly during high-discharge inflows in summer stratification. The simulations are used to examine growth-limiting factors that help to explain the increased prevalence of P. rubescens during re-oligotrophication.

Solid Waste and Water Quality Management Models for Sagarmatha National Park and Buffer Zone, Nepal Implementation of a Participatory Modeling Framework

Abstract The problem of supporting decision- and policy-makers in managing issues related to solid waste and water quality was addressed within the context of a participatory modeling framework in the Sagarmatha National Park and Buffer Zone in Nepal. We present the main findings of management-oriented research projects conducted within this framework, thus providing an overview of the current situation in the park regarding solid waste and water quality issues. We found that most of the solid waste generated in the park is composed of organic matter, paper, and minor reused waste that is mainly reused for cattle feeding and manure, while disposal of other nondegradable categories of collected waste (glass, metal, and plastic) is not properly managed. Particularly, burning or disposal in open dumps poses a great hazard to environmental, human, and animal health, as most dump sites situated close to water courses are prone to regular flooding during the rainy season, thereby directly contaminating river water. Pollutants and microbiological contamination in water bodies were found and anthropogenic activities and hazardous practices such as solid waste dump sites, open defecation, and poor conditions of existing septic tanks are suggested as possibly affecting water quality. Collection of these data on solid waste and water quality and compilation of management information on the targeted social-ecological system allowed us to develop consensus-building models to be used as management supporting tools. By implementing such models, we were able to simulate scenarios identifying and evaluating possible management solutions and interventions in the park. This work reveals insights into general dynamics that can support the quest for solutions to waste and water quality management problems in other protected areas and mountain landscapes where traditional livelihood and land use patterns are changing under the influence of a growing population, changing consumption patterns, and international tourism.

Impact of Global and Local Pressures on the Ecology of a Medium-Sized Pre-Alpine Lake

Abstract Both global and local anthropogenic pressures influence the process of lake eutrophication. The evaluation of their relative contribution requires long-term observation and articulated methodologies. An integrated lake and catchment modeling was performed on a medium-sized phosphorus-limited lake (Lake Pusiano, North Italy). Pristine conditions were simulated coupling model outcomes to paleolimnological analysis, while a specific statistical technique (Spectral Singular Analysis) was used to flatten the air temperature increasing trend between 1960 and 2010. Four different scenarios were simulated to characterize different degrees of local and global pressures on the lake ecological responses.

Mechanisms linking active rock glaciers and impounded surface water formation in high-mountain areas

Rock glaciers are slowly flowing mixtures of debris and ice occurring in mountains. They can represent a reservoir of water, and melting ice inside them can affect surface water hydrochemistry. Investigating the interactions between rock glaciers and water bodies is therefore necessary to better understand these mechanisms. With this goal, we elucidate the hydrology and structural setting of a rock glacier-marginal pond system, providing new insights into the mechanisms linking active rock glaciers and impounded surface waters. This was achieved through the integration of waterborne geophysical techniques (ground penetrating radar, electrical resistivity tomography and self-potentials) and heat tracing. Results of these surveys showed that rock glacier advance has progressively filled the valley depression where the pond is located, creating a dam that could have modified the level of impounded water. A sub-surface hydrological window connecting the rock glacier to the pond was also detected, where an inflow of cold and mineralised underground waters from the rock glacier was observed. Here, greater water contribution from the rock glacier occurred following intense precipitation events during the ice-free season, with concomitant increasing electrical conductivity values. The outflowing dynamic of the pond is dominated by a sub-surface seepage where a minor fault zone in bedrock was found, characterised by altered and highly-fractured rocks. The applied approach is evaluated here as a suitable technique for investigating logistically-complex hydrological settings which could be possibly transferred to wider scales of investigation.

Restoring lakes through external phosphorus load reduction: the case of Lake Pusiano (Southern Alps)

Abstract We estimated the external phosphorus load (EPL) between 1960 and 2015 in Lake Pusiano, a mid-sized subalpine lake that reached its maximum trophic state in the mid-1980s. Using historical data we also estimated the internal phosphorus load (IPL) between 1972 and 2015. EPL reached its maximum in the mid-1980s with phosphorus (P) values ~21 t yr−1 compared to the current value close to 6 t yr−1. IPL was one order of magnitude less and ranged between 0.25 t yr−1 (2015) and 3.6 (1985) t yr−1. The strong reduction of the P load determined a marked decrease of both P (from 200 to 23 μg L−1) and chlorophyll a (from 18 to 8 μg L−1) in-lake concentrations. The process of eutrophication and subsequent recovery, however, showed hysteresis between P load and in-lake P concentrations. In recent years, in particular, the P concentrations at winter overturn seem to be independent from the P load, related to modifications in the hydrological management of the lake that favored P flush-out in October–November, when the EPL is maximal. This process led to a marked decrease of the total P concentrations at winter overturn (23 μg L−1), which recently resulted in lower-than-target concentrations (30 μg L−1) established by the Lombardy Region. The lake, nevertheless, suffers from the presence of the toxic cyanobacterium Planktothrix rubescens, and eradicating this species and further improving water quality will likely require an additional abatement of the EPL.

Phosphorus content in a deep river sediment core as a tracer of long-term (1962–2011) anthropogenic impacts: A lesson from the Milan metropolitan area

Reconstructions of past fluvial contamination through the analysis of deep sediment cores are rarely reported in literature. We examined the phosphorus fractions in a deep (2.6 m) sediment core of the Lambro River downstream of the highly anthropized Milan metropolitan area and upstream of the Po river the main Italian watercourse. The core covered the period 1962-2011. Total phosphorus concentrations resulted typical of a strongly impacted environment (4788 mg P kg DW-1 on average) with the highest concentrations related to the 1960s (7639 mg P kg DW-1) reflecting the period of maximum demographic growth. Afterwards, phosphorus concentrations decreased thanks to the infrastructural and legislative initiatives carried out in the 1980s and the 1990s to reduce the impact of urban point sources. Subsequently, total phosphorus concentrations stabilized on values around 3000 mg P kg DW-1 and did not diminish further, even after the second phase of infrastructural interventions carried out in the second half of the 2000s. This was related to the increasing relative impact of the combined sewer overflows in the sewage system and to the strong phosphorus enrichment of the basin. Most of the phosphorus was in inorganic forms (86% of the total) that have been identified as the final target of the domestic effluent inputs. The contribution of organic phosphorus was lower but constant over the period 1962-2011. It likely originated from the agricultural areas located south of the city of Milan. In conclusion, this study underlines how past interventions have been effective in reducing urban point sources but it also highlights the current difficulties related to the growing importance of other sources influenced by the surface runoff (i.e., combined sewer overflows and agriculture). The study also emphasizes a general phosphorus enrichment of the Lambro River basin and its impact on the Po River and the Adriatic Sea.

Chemical characterization of biomass fuel particulate deposits and ashes in households of Mt. Everest region (NEPAL)

During a sampling campaign, carried out during June 2012, inside some traditional households located in four villages (Phakding, Namche, Pangboche and Tukla) of Mt. Everest region in southern part of the central Himalaya (Nepal), particulate matter (PM) depositions and ashes have been collected. Moreover, outdoor PM depositions have also been analyzed. Chemical characterization of PM depositions and ashes for major ions, organic carbon, elemental carbon (EC), metal content and PAHs (Polycyclic Aromatic Hydrocarbons) allowed identifying, as major contributes to indoor PM, the following sources: biomass burning, cooking and chimney ashes. These sources significantly affect outdoor PM depositions: in-house biomass burning is the major source for outdoor EC and K+ as well as biomass burning and cooking activities are the major sources for Polycyclic Aromatic Hydrocarbons.