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Abstract Polygeneration is a sustainable energy concept, which could deliver multiple energy vectors (power, heat and cooling) and other useful products (desalinated water, hydrogen, etc.) by possible integration of suitable technologies. In this study, a polygeneration system for coastal area applications is driven by a hybrid solar/bio-oil boiler to produce the energy intensive products of cooling, power, desalinated water and hot air for drying. Solar thermal is the primary energy source to drive the polygeneration system, whereas the bio-oil boiler is the auxiliary source to drive it at non-sunshine hours. The performance characteristics of the hybrid system is investigated to identify the effects of various key parameters such as temperatures of heat source, sink and evaporator along with expander Built in Volume ratio. The obtained results at a typical operating condition show that the parabolic trough collector aperture area is 130 m2, the system produces net power output of 47 kW, desalinated water of 1.205 m3/h, 92 kW of hot air for drying and 141 kW of cooling. The overall energy and exergy efficiencies of the proposed system are found to be 22% and 87%, respectively.

The Cretaceous-Palaeogene (K-Pg) boundary mass extinction event is related to major global environmental changes resulting from a large extraterrestrial impact. Organic-walled cyst-producing marine dinoflagellates (dinocysts) survived the K-Pg mass-extinction relatively unscathed, making them ideally suited for reconstructing these environmental changes. So far, one of the best dinocyst records available is from the K-Pg boundary Global Stratotype Section and Point (GSSP) at El Kef (NW Tunisia). There, the dinocyst record shows major fluctuations across the boundary, likely reflecting strong responses to environmental changes. These fluctuations have so far not been confirmed by other studies. Therefore, in this study we performed a high-resolution marine palynological study on a closely spaced sample set from the Elles section, some 75km south of El Kef, in order to generate a palaeoenvironmental and palaeoclimatic record across the K-Pg boundary to allow verification and refinement of earlier reported environmental changes. To better constrain the reconstructions based on qualitative biotic proxies we employed the quantitative sea surface temperature proxy TEX86. Unfortunately, the TEX86 proxy record of the studied section is compromised because of post-depositional oxidation. However, the diverse dinocyst assemblages at Elles show strong fluctuations similar to the El Kef record, therefore confirming the earlier recorded signals, showing rapid, regionally consistent changes. These records imply that the latest Cretaceous was characterized by a gradual cooling trend and the onset of relative sea level fall. Within the immediate post-extinction interval, in the first thousands of years after the impact, dinocyst assemblages reveal multiple incursions of higher-latitude dinocyst species implying repeated pulses of cooling. These results signify that the earliest Danian climatic and environmental conditions were relatively unstable across the Tunisian shelf.

The growth cycle in nutrient-rich, aquatic environments starts with a diatom bloom that ends in mass sinking of ungrazed cells and phytodetritus. The low grazing pressure on these blooms has been attributed to the inability of overwintering copepod populations to track them temporally. We tested an alternative explanation: that dominant diatom species impair the reproductive success of their grazers. We compared larval development of a common overwintering copepod fed on a ubiquitous, early-blooming diatom species with its development when fed on a typical post-bloom dinoflagellate. Development was arrested in all larvae in which both mothers and their larvae were fed the diatom diet. Mortality remained high even if larvae were switched to the dinoflagellate diet. Aldehydes, cleaved from a fatty acid precursor by enzymes activated within seconds after crushing of the cell, elicit the teratogenic effect. This insidious mechanism, which does not deter the herbivore from feeding but impairs its recruitment, will restrain the cohort size of the next generation of early-rising overwinterers. Such a transgenerational plant-herbivore interaction could explain the recurringly inefficient use of a predictable, potentially valuable food resource--the spring diatom bloom--by marine zooplankton.

Abstract In the last three decades, scholars and operators have paid increasing attention to the environmental sustainability and energy efficiency of seaports. To achieve high competitiveness in seaports in response to environmental and energy regulation, port authorities (PAs), policymakers, port users and local communities have to invest considerable resources. This paper investigates the role of the managerial instruments in the decision-making processes of PAs for reducing and preventing negative environmental and energy effects from ports. This research consists of a two-step study. First, we conduct a literature review to analyse the academic views by systematically reading the reports to investigate practitioners’ views on the performance indicators for environmental sustainability and energy efficiency in the port industry. Second, we provide, through a qualitative method, a portrait of the Italian seaports and a multiple case study to confirm the developed conceptual managerial key performance indicators (KPIs). Specifically, applying the Balanced Scorecard model, this paper provides managerial KPIs to support PAs in their decision-making processes within the inter-organizational relationships with shipping lines for developing environmentally sustainable and energy efficient ports.

It is premature to sell carbon offsets from ocean iron fertilization unless research provides the scientific foundation to evaluate risks and benefits.

Biodiversity indicators provide a vital window on the state of the planet, guiding policy development and management. The most widely adopted marine indicator is mean trophic level (MTL) from catches, intended to detect shifts from high-trophic-level predators to low-trophic-level invertebrates and plankton-feeders. This indicator underpins reported trends in human impacts, declining when predators collapse ("fishing down marine food webs") and when low-trophic-level fisheries expand ("fishing through marine food webs"). The assumption is that catch MTL measures changes in ecosystem MTL and biodiversity. Here we combine model predictions with global assessments of MTL from catches, trawl surveys and fisheries stock assessments and find that catch MTL does not reliably predict changes in marine ecosystems. Instead, catch MTL trends often diverge from ecosystem MTL trends obtained from surveys and assessments. In contrast to previous findings of rapid declines in catch MTL, we observe recent increases in catch, survey and assessment MTL. However, catches from most trophic levels are rising, which can intensify fishery collapses even when MTL trends are stable or increasing. To detect fishing impacts on marine biodiversity, we recommend greater efforts to measure true abundance trends for marine species, especially those most vulnerable to fishing.

Purpose– This is a benchmarking study and the purpose of this paper is to investigate if there is any association between operational efficiency in the integrated water management industry in Italy and the typology of service providers, and as a consequence, the nature of concession contract.Design/methodology/approach– The study is focussed on 38 optimal territorial areas (ATOs), e.g. a circumscribed geographical area where the provision of integrated water services is considered efficient. It uses Data Envelopment Analysis (DEA) to calculate ATO efficiency and a stepwise regression procedure performed to investigate the effect of contract type on the operational efficiency rate of the ATO.Findings– This study shows that there are some inefficiencies in the water service supply industry in Italy. The estimated average pure technical and scale efficiency of ATOs are 92.62 and 93.91 percent, respectively, while the average technical efficiency is 87.61 percent and the lowest is slightly higher than 13 percent. Operational inefficiencies might not be determined by size only. In fact, results show that the water service provider and contract agreement typologies are associated with efficiency. In particular, operational efficiency is higher in those ATOs where the water service supply concession contracts that fit the schemes of the new legislative framework prevail or where the service is mostly provided by a private equity owned or by mixed public-private companies.Research limitations/implications– It was assumed that any incremental level of water quality beyond the minimum acceptable threshold as required by law is not important to increase the operation efficiency score; henceforth, no variables measuring the water quality were introduced in the DEA model. The result of the study may be not fully representative of the Italian water service sector, because the unavailability of accurate and consistent public databank in Italy did not allowed to have a larger sample.Practical implications– This paper is one of the first in Italy to investigate the association between the operational efficiency of the ATOs and the nature of water service providers and contract agreements used.Originality/value– This paper is one of the first in Italy to investigate the association between the operational efficiency of the ATOs and the nature of water service providers and contract agreements used.

In many aquatic ecosystems, most microbes live in matrix-enclosed biofilms and contribute substantially to energy flow and nutrient cycling. Little is known, however, about the coupling of structure and dynamics of these biofilms to ecosystem function. Here we show that microbial biofilms changed the physical and chemical microhabitat and contributed to ecosystem processes in 30-m-long stream mesocosms. Biofilm growth increased hydrodynamic transient storage-streamwater detained in quiescent zones, which is a major physical template for ecological processes in streams-by 300% and the retention of suspended particles by 120%. In addition, by enhancing the relative uptake of organic molecules of lower bioavailability, the interplay of biofilm microarchitecture and mass transfer changed their downstream linkage. As living zones of transient storage, biofilms bring hydrodynamic retention and biochemical processing into close spatial proximity and influence biogeochemical processes and patterns in streams. Thus, biofilms are highly efficient and successful ecological communities that may also contribute to the influence that headwater streams have on rivers, estuaries and even oceans through longitudinal linkages of local biogeochemical and hydrodynamic processes.