Sediment pollution and dynamic in the Mar Piccolo of Taranto (southern Italy): insights from bottom sediment traps and surficial sediments

Major and trace element, PAH, and PCB concentrations were measured in surface sediments and particles from sediment traps collected in the First and Second Basin of the Mar Piccolo (Gulf of Taranto) in two periods (June–July and August–September, 2013). The aim of the study was to evaluate pollution degree, sediment transport and particle redistribution dynamic within the area. Results confirm the higher contamination of sediments from the First Basin observed by previous researches, particularly for Cu, Hg, Pb, total PAHs, and total PCBs. Advective transport from the First to the Second Basin appears to be the leading transfer mechanism of particles and adsorbed contaminants, as evidenced by measured fluxes and statistical analyses of contaminant concentrations in surficial sediments and particles from sediment traps. Long-range selective transports of PAHs and microbial anaerobic degradation processes for PCBs have been also observed. These results are limited to a restricted time window but are consistent with the presence of transport fluxes at the bottom of the water column. This mechanism deserves further investigation and monitoring activities, potentially being the main responsible of pollutant delivering to the less contaminated sectors of the Mar Piccolo.     

Impact of land use changes on water quality in headwaters of the Three Gorges Reservoir

The assessment of spatial and temporal variation of water quality influenced by land use is necessary to manage the environment sustainably in basin scales. Understanding the correlations between land use and different formats of nonpoint source nutrients pollutants is a priority in order to assess pollutants loading and predicting the impact on surface water quality. Forest, upland, paddy field, and pasture are the dominant land use in the study area, and their land use pattern status has direct connection with nonpoint source (NPS) pollutant loading. In this study, two land use scenarios (1995 and 2010) were used to evaluate the impact of land use changes on NPS pollutants loading in basins upstream of Three Gorges Reservoir (TGR), using a calibrated and validated version of the soil and water assessment tool (SWAT) model. The Pengxi River is one of the largest tributaries of the Yangtze River upstream of the TGR, and the study area included the basins of the Dong and Puli Rivers, two major tributaries of the Pengxi River. The results indicated that the calibrated SWAT model could successfully reproduce the loading of NPS pollutants in the basins of the Dong and Puli Rivers. During the 16-year study period, the land use changed markedly with obvious increase of water body and construction. Average distance was used to measure relative distribution patterns of land use types to basin outlets. Forest was mainly distributed in upstream areas whereas other land use types, in particular, water bodies and construction areas were mainly distributed in downstream areas. The precipitation showed a non-significant influence on NPS pollutants loading; to the contrary, interaction between precipitation and land use were significant sources of variation. The different types of land use change were sensitive to NPS pollutants as well as land use pattern. The influence of background value of soil nutrient on NPS pollutants loading was evaluated in upland and paddy field. It was found that total nitrogen (TN) and total phosphorous (TP) in upland were more sensitive to NPS pollutants loading than in paddy fields. The results of this study have implications for management of the TGR to reduce the loading of NPS pollutants into downstream water bodies.     

Biodegradability of algal-derived organic matter in a large artificial lake by using stable isotope tracers

In order to understand the biodegradability of algal-derived organic matter, biodegradation experiments were conducted with ¹³C and ¹⁵N-labeled natural phytoplankton and periphytic algal populations in experimental conditions for 60 days. Qualitative changes in the dissolved organic matter were also determined using parallel factor analysis and the stable carbon isotopic composition of the hydrophobic dissolved organic matter through the experimental period. Although algal-derived organic matter is considered to be easily biodegradable, the initial amounts of total organic carbon newly produced by phytoplankton and periphytic algae remained approximately 16 and 44 % after 60 days, respectively, and about 22 and 43 % of newly produced particulate nitrogen remained. Further, the dissolved organic carbon derived from both algal populations increased significantly after 60 days. Although the dissolved organic matter gradually became refractory, the contributions of the algal-derived organic matter to the dissolved organic matter and hydrophobic dissolved organic matter increased. Our laboratory experimental results suggest that algal-derived organic matter produced by phytoplankton and periphytic algae could contribute significantly to the non-biodegradable organic matter through microbial transformations.     

Fluoride in weathered rock aquifers of southern India: Managed Aquifer Recharge for mitigation

Climatic condition, geology, and geochemical processes in an area play a major role on groundwater quality. Impact of these on the fluoride content of groundwater was studied in three regions—part of Nalgonda district in Telangana, Pambar River basin, and Vaniyar River basin in Tamil Nadu, southern India, which experience semi-arid climate and are predominantly made of Precambrian rocks. High concentration of fluoride in groundwater above 4 mg/l was recorded. Human exposure dose for fluoride through groundwater was higher in Nalgonda than the other areas. With evaporation and rainfall being one of the major contributors for high fluoride apart from the weathering of fluoride rich minerals from rocks, the effect of increase in groundwater level on fluoride concentration was studied. This study reveals that groundwater in shallow environment of all three regions shows dilution effect due to rainfall recharge. Suitable managed aquifer recharge (MAR) methods can be adopted to dilute the fluoride rich groundwater in such regions which is explained with two case studies. However, in deep groundwater, increase in fluoride concentration with increase in groundwater level due to leaching of fluoride rich salts from the unsaturated zone was observed. Occurrence of fluoride above 1.5 mg/l was more in areas with deeper groundwater environment. Hence, practicing MAR in these regions will increase the fluoride content in groundwater and so physical or chemical treatment has to be adopted. This study brought out the fact that MAR cannot be practiced in all regions for dilution of ions in groundwater and that it is essential to analyze the fluctuation in groundwater level and the fluoride content before suggesting it as a suitable solution. Also, this study emphasizes that long-term monitoring of these factors is an important criterion for choosing the recharge areas.     

Dry reforming of methane to syngas: a potential alternative process for value added chemicals—a techno-economic perspective

During the past decade, there has been increasing global concern over the rise of anthropogenic CO₂ emission into the Earth’s atmosphere (J Air Waste Manage Assoc 53:645–715, 2003). The utilization of CO₂ to produce any valuable product is need of the hour. The production of syngas from CO₂ and CH₄ seems to be one of the promising alternatives in terms of industrial utilization, as it offers several advantages: (a) mitigation of CO₂, (b) transformation of natural gas and CO₂ into valuable syngas, and (c) producing syngas with H₂/CO ratio 1 which may further be used for the production of valuable petrochemicals (J Air Waste Manage Assoc 53:645–715, 2003). A conceptual design for the production of synthesis gas by dry reforming of methane is presented here. An economic assessment of this process with an integrated methanol production section as a case was conceptualized and compared with the conventional steam methane reforming route to produce methanol. The economic study indicated that dry reforming of natural gas/methane is a competitive process with lower operating and capital costs in comparison with steam reforming assuming negligible cost of CO₂ import.     

Review of receptor modeling methods for source apportionment

Efforts have been made to relate measured concentrations of airborne constituents to their origins for more than 50 years. During this time interval, there have been developments in the measurement technology to gather highly time-resolved, detailed chemical compositional data. Similarly, the improvements in computers have permitted a parallel development of data analysis tools that permit the extraction of information from these data. There is now a substantial capability to provide useful insights into the sources of pollutants and their atmospheric processing that can help inform air quality management options. Efforts have been made to combine receptor and chemical transport models to provide improved apportionments. Tools are available to utilize limited numbers of known profiles with the ambient data to obtain more accurate apportionments for targeted sources. In addition, tools are in place to allow more advanced models to be fitted to the data based on conceptual models of the nature of the sources and the sampling/analytical approach. Each of the approaches has its strengths and weaknesses. However, the field as a whole suffers from a lack of measurements of source emission compositions. There has not been an active effort to develop source profiles for stationary sources for a long time, and with many significant sources built in developing countries, the lack of local profiles is a serious problem in effective source apportionment. The field is now relatively mature in terms of its methods and its ability to adapt to new measurement technologies, so that we can be assured of a high likelihood of extracting the maximal information from the collected data.

Implications: Efforts have been made over the past 50 years to use air quality data to estimate the influence of air pollution sources. These methods are now relatively mature and many are readily accessible through publically available software. This review examines the development of receptor models and the current state of the art in extracting source identification and apportionments from ambient air quality data.     

Impact of Massanjore Dam on hydro-geomorphological modification of Mayurakshi River,Eastern India

Massanjore reservoir (area ~67 km²) located 84 km downstream from the most distant upstream source capacitates 620,000,000 m³ of water, and regulated flow characters are highly responsible for dam downstream alteration of hydrological, sedimentological and geomorphological characteristics of Mayurakshi River. In dam after condition, monsoon water level (mean water level during monsoon months) and pre-monsoon water level (mean water level during pre-monsoon months, i.e., March–May) have attenuated about 0.56 and 0.32 m, respectively. Maximum duration of high flow period during monsoon has reduced up to 16.5 %; coefficient of variation of diurnal fluctuation of water level during monsoon has increased from 31 to 47 %. Suspended sediment load in Mayurakshi River is reduced to 34 % in dam after period as recorded at Narayanpur gauge station. Average suspended sediment load has decreased even after Tilpara barrage construction from 4.960 to 4.350 mg/L. Average suspended sediment load is 7.875 mg/L in the sites of dam upstream course, and this average is only 4.46 mg/L in different sites of dam downstream course. Volume of discharge has decreased up to 11.3 % during monsoon time in dam after condition. Such reduction in discharge volume in turn has reduced about 24.6 % bed load-carrying capacity. As a result, huge deposition within channel invigorated channel bed aggradations (average 73.6 cm up to Saspara, site 14 at Fig. 1) in dam after condition. Narrowing of active channel, coarsening of channel bed materials, lowering of lateral stability, accelerating rise of braiding index, mixed response of the channel adjustment of the tributaries to local scale positive or negative base level change due to river bed aggradations and degradation, etc. signify the morphological alteration of dam downstream course.

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Fig. 1 Mayurakshi River basin indicating Massanjore Dam, Tilpara barrage and sample working sites

     

Assessing agricultural land-use change in the Midlands region of KwaZulu-Natal,South Africa: application of mixed multinomial logit

On-farm tree cultivation is considered an important strategy to mitigate detrimental environmental impacts of agricultural land-use change (ALUC). In South Africa, however, little is known about farm-level incentives and constraints that govern ALUC decisions among small-scale farmers. To address this knowledge gap, this study employs a mixed multinomial logit model by using a combination of revealed and stated preference data. After correcting for endogeneity, the estimated results show that decisions about ALUC are rationally derived and driven by clear but heterogeneous preferences and trade-offs between crop productivity, food security and labour saving. The results further show that the decision to plant sugarcane is constrained by landholding, whilst farmland afforestation is negatively influenced by household size. Decisions to convert land use are also driven by the behaviour of peer groups and agro-ecological conditions. Based on these findings, important policy implications for sustainable land use are outlined.     

Household preferences and willingness to pay (WTP) for freshwater quality improvement in Pakistan’s Swat River Valley

This two-part study investigates household preferences and willingness to pay (WTP) for water quality improvement of the Swat River in Pakistan. First, a four-point Likert scale was used to rank preferences for water quality benefits without using any financial metric. Results show that households have comparatively strong preferences for non-use benefits. Second, a contingent valuation question was designed to determine WTP for adopting a management plan developed exclusively for water quality improvement in the Swat River. The estimated annual mean WTP per household for water quality improvement is $2.40 when donating to an NGO. Generalizing this value to households living in Swat Valley would generate up to $544,000 per year. The present value aggregate benefit for 15 years would be sufficient to cover the present value of aggregate costs to adopt the management plan. A mandatory program that would require paying for the management plan generates half the WTP compared to the voluntary plan, but is still sufficient to cover costs and may be more feasible than a voluntary program because payment is assured.