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This study highlights how Chinese economic development detrimentally impacted water quality in recent decades and how this has been improved by enormous investment in environmental remediation funded by the Chinese government. To our knowledge, this study is the first to describe the variability of surface water quality in inland waters in China, the affecting drivers behind the changes, and how the government-financed conservation actions have impacted water quality. Water quality was found to be poorest in the North and the Northeast China Plain where there is greater coverage of developed land (cities + cropland), a higher gross domestic product (GDP), and higher population density. There are significant positive relationships between the concentration of the annual mean chemical oxygen demand (COD) and the percentage of developed land use (cities + cropland), GDP, and population density in the individual watersheds (p < 0.001). During the past decade, following Chinese government-financed investments in environmental restoration and reforestation, the water quality of Chinese inland waters has improved markedly, which is particularly evident from the significant and exponentially decreasing GDP-normalized COD and ammonium (NH4+-N) concentrations. It is evident that the increasing GDP in China over the past decade did not occur at the continued expense of its inland water ecosystems. This offers hope for the future, also for other industrializing countries, that with appropriate environmental investments a high GDP can be reached and maintained, while simultaneously preserving inland aquatic ecosystems, particularly through management of sewage discharge.

This study highlights how Chinese economic development detrimentally impacted water quality in recent decades and how this has been improved by enormous investment in environmental remediation funded by the Chinese government. To our knowledge, this study is the first to describe the variability of surface water quality in inland waters in China, the affecting drivers behind the changes, and how the government-financed conservation actions have impacted water quality. Water quality was found to be poorest in the North and the Northeast China Plain where there is greater coverage of developed land (cities + cropland), a higher gross domestic product (GDP), and higher population density. There are significant positive relationships between the concentration of the annual mean chemical oxygen demand (COD) and the percentage of developed land use (cities + cropland), GDP, and population density in the individual watersheds (p < 0.001). During the past decade, following Chinese government-financed investments in environmental restoration and reforestation, the water quality of Chinese inland waters has improved markedly, which is particularly evident from the significant and exponentially decreasing GDP-normalized COD and ammonium (NH4+-N) concentrations. It is evident that the increasing GDP in China over the past decade did not occur at the continued expense of its inland water ecosystems. This offers hope for the future, also for other industrializing countries, that with appropriate environmental investments a high GDP can be reached and maintained, while simultaneously preserving inland aquatic ecosystems, particularly through management of sewage discharge.

As the largest renewable electricity source, hydropower represents an alternative to fossil fuels to achieve a low-carbon future. However, increasing evidence suggests that hydropower reservoirs are an important source of biogenic greenhouse gases (GHGs), albeit with large uncertainties. Combining spatially resolved assessments of GHG fluxes and hydroelectric capacity databases, we assessed that global GHG emissions from reservoirs is 0.38 Pg CO2 eq.yr−1, accounting for 1.0% of global anthropogenic emissions. The median carbon intensity for hydropower is ∼63.0 kg CO2eq. MWh−1, which is lower than that for fossil fuels, but higher than that for other renewable energy sources. High carbon intensity is mostly linked to shallow (water storage depth <20 m) and eutrophic reservoirs. Furthermore, we found that the reservoir carbon intensity (CI) value would be markedly increased to 131.5 kg CO2eq. MWh−1 when considering the dams under construction and planning. A low-carbon future will benefit from optimal dam planning and management measures, i.e., applying sludge removal treatments, thereby reducing the proportion of shallow reservoirs and anthropogenic pollution.

As the largest renewable electricity source, hydropower represents an alternative to fossil fuels to achieve a low-carbon future. However, increasing evidence suggests that hydropower reservoirs are an important source of biogenic greenhouse gases (GHGs), albeit with large uncertainties. Combining spatially resolved assessments of GHG fluxes and hydroelectric capacity databases, we assessed that global GHG emissions from reservoirs is 0.38 Pg CO2 eq.yr−1, accounting for 1.0% of global anthropogenic emissions. The median carbon intensity for hydropower is ∼63.0 kg CO2eq. MWh−1, which is lower than that for fossil fuels, but higher than that for other renewable energy sources. High carbon intensity is mostly linked to shallow (water storage depth <20 m) and eutrophic reservoirs. Furthermore, we found that the reservoir carbon intensity (CI) value would be markedly increased to 131.5 kg CO2eq. MWh−1 when considering the dams under construction and planning. A low-carbon future will benefit from optimal dam planning and management measures, i.e., applying sludge removal treatments, thereby reducing the proportion of shallow reservoirs and anthropogenic pollution.

Marine algae have emerged as an alternative feedstock for the production of a number of renewable fuels, including biogas. In addition to energy potential, other characteristics make them attractive as an energy source, including their ability to absorb carbon dioxide (CO2), higher productivity rates than land-based crops and the lack of water use or land competition. For Ireland, biofuels from marine algae can play an important role by reducing imports of fossil fuels as well as providing the necessary energy in rural communities. In this study, five potential seaweed species common in Irish waters, Saccorhiza polyschides, Ulva sp., Laminaria digitata, Fucus serratus and Saccharina latissima, were co-digested individually with bovine slurry. Batch reactors of 120ml and 1000ml were set up and incubated at 35 degrees C to investigate their suitability for production of biogas. Digesters fed with S. latissima produced the maximum methane yield (335 ml g volatile solids(-1) (g(VS)(-1) followed by S. polyschides with 255 ml g(VS)(-1). L. digitata produced 246ml g(VS)(-1) and the lowest yields were from the green seaweed Ulva sp. 191ml g(VS)(-1). The methane and CO2 percentages ranged between 50-72% and 10-45%, respectively. The results demonstrated that the seaweed species investigated are good feedstocks candidates for the production of biogas and methane as a source of energy. Their use on a large-scale process will require further investigation to increase yields and reduce production costs.

Marine algae have emerged as an alternative feedstock for the production of a number of renewable fuels, including biogas. In addition to energy potential, other characteristics make them attractive as an energy source, including their ability to absorb carbon dioxide (CO2), higher productivity rates than land-based crops and the lack of water use or land competition. For Ireland, biofuels from marine algae can play an important role by reducing imports of fossil fuels as well as providing the necessary energy in rural communities. In this study, five potential seaweed species common in Irish waters, Saccorhiza polyschides, Ulva sp., Laminaria digitata, Fucus serratus and Saccharina latissima, were co-digested individually with bovine slurry. Batch reactors of 120ml and 1000ml were set up and incubated at 35 degrees C to investigate their suitability for production of biogas. Digesters fed with S. latissima produced the maximum methane yield (335 ml g volatile solids(-1) (g(VS)(-1) followed by S. polyschides with 255 ml g(VS)(-1). L. digitata produced 246ml g(VS)(-1) and the lowest yields were from the green seaweed Ulva sp. 191ml g(VS)(-1). The methane and CO2 percentages ranged between 50-72% and 10-45%, respectively. The results demonstrated that the seaweed species investigated are good feedstocks candidates for the production of biogas and methane as a source of energy. Their use on a large-scale process will require further investigation to increase yields and reduce production costs.

European seas are experiencing rapid development. The anthropogenic demand for marine resources and space exerts the need for novel concepts for sustainable resource exploitation and smart space allocation. Multi-Use (MU) is an emerging concept to overcome spatial claims and support Blue Growth, however its actual potentials and current status of implementation in different sea basins is to a large extent unexplored. An analytical framework using a mixed method approach is proposed for the identification and analysis of MU potentialities in eight EU countries of the Euro-Mediterranean sea basin. The paper addresses opportunities and challenges of ten existing and potential MU combinations driven by three maritime sectors: tourism, renewable energy and Oil & Gas industry. Opportunities and challenges for MU development were presented in terms of drivers, added values, barriers and impacts. Results show that highest potential for MU development are related to tourism-driven MU combinations (e.g. pescatourism), but also emerging MU potentials exist related to Floating Offshore Wind energy and aquaculture (Gulf of Lion) and the re-use of Oil & Gas decommissioned platforms (Northern-Central Adriatic Sea). Findings were discussed for their geospatial distribution and their policy, socio-economic, technical and environmental boundary conditions. Recommendations on actions to foster MU development in the Euro-Mediterranean sea space are provided.

European seas are experiencing rapid development. The anthropogenic demand for marine resources and space exerts the need for novel concepts for sustainable resource exploitation and smart space allocation. Multi-Use (MU) is an emerging concept to overcome spatial claims and support Blue Growth, however its actual potentials and current status of implementation in different sea basins is to a large extent unexplored. An analytical framework using a mixed method approach is proposed for the identification and analysis of MU potentialities in eight EU countries of the Euro-Mediterranean sea basin. The paper addresses opportunities and challenges of ten existing and potential MU combinations driven by three maritime sectors: tourism, renewable energy and Oil & Gas industry. Opportunities and challenges for MU development were presented in terms of drivers, added values, barriers and impacts. Results show that highest potential for MU development are related to tourism-driven MU combinations (e.g. pescatourism), but also emerging MU potentials exist related to Floating Offshore Wind energy and aquaculture (Gulf of Lion) and the re-use of Oil & Gas decommissioned platforms (Northern-Central Adriatic Sea). Findings were discussed for their geospatial distribution and their policy, socio-economic, technical and environmental boundary conditions. Recommendations on actions to foster MU development in the Euro-Mediterranean sea space are provided.