Eutrophication Factor Analysis Using Carlson Trophic State Index (CTSI) Towards Non-Algal Impact Reservoirs in Taiwan

Carlson trophic state index (CTSI) has been commonly adopted to assess the eutrophication potential of reservoirs or lakes in water quality management. This study aims to analyze the influencing factors of CTSI-based eutrophication by using Pearson correlation analysis and principal component analysis (PCA) with long-term data from 2008 to 2019 on 21 drinking water reservoirs in Taiwan. The trophic state index (TSI) deviation indicates that most drinking water reservoirs in Taiwan, around 45.5% of statistical data fall into non-algal turbidity with surplus phosphorus, especially in the spring and winter season. Besides, there are about 78 % of total collected data show that TSI (Chl-a) is less than TSI (SD) due to the small particulate predominance. On the other hand, three TSI variables (Secchi depth (SD), total phosphorus (TP) and chlorophyll-a (Chl-a)) of CTSI exhibits insignificant correlation to each other in most cases. At such a condition, the probability of eutrophication (TSI>50) based on TSI (SD) is 63%, while it is only as low as 20% based on TSI (TP) and TSI (Chl-a). The influencing factors of eutrophication variables by suspended solids (SS) composition and turbidity have shown that the SD is strongly influenced by non-algal SS. The deviations of three TSI have shown that the highest algae-induced eutrophication potential occurs in the summer season. In addition, the TP is the most significant loading factor of algae-induced eutrophication for drinking water reservoirs. It is concluded that the CTSI has limited applicability to identify the trophic status of drinking water reservoirs in Taiwan in the presence of sustainable non-algal turbidity comparative Chl-a that completely represents algal growth potential (AGP).

Globally consistent assessment of coastal eutrophication

Eutrophication is an emerging global issue associated with increasing anthropogenic nutrient loading. The impacts and extent of eutrophication are often limited to regions with dedicated monitoring programmes. Here we introduce the first global and Google Earth Engine-based interactive assessment tool of coastal eutrophication potential (CEP). The tool evaluates trends in satellite-derived chlorophyll-a (CHL) to devise a global map of CEP. Our analyses suggest that, globally, coastal waters (depth ≤200 m) covering ∼1.15 million km2 are eutrophic potential. Also, waters associated with CHL increasing trends—eutrophication potential—are twofold higher than those showing signs of recovery. The tool effectively identified areas of known eutrophication with severe symptoms, like dead zones, as well as those with limited to no information of the eutrophication. Our tool introduces the prospect for a consistent global assessment of eutrophication trends with major implications for monitoring Sustainable Development Goals (SDGs) and the application of Earth Observations in support of SDGs.

Nutrient transport and transformation in macrotidal estuaries of the French Atlantic coast: a modelling approach using C-GEM

Estuaries are key reactive ecosystems along the land–ocean aquatic continuum, with significant ecological and economic value. However, they have been facing strong morphological management changes as well as increased nutrient and contaminant inputs, possibly leading to ecological problems such as coastal eutrophication. Therefore, it is necessary to quantify the ingoing and outgoing fluxes of the estuaries, their retention capacity, and estuarine eutrophication potential. A 1-D Carbon–Generic Estuary Model (C-GEM) was used to simulate the transient hydrodynamics, transport, and biogeochemistry for estuaries with different sizes and morphologies along the French Atlantic coast during the period 2014–2016 using readily available geometric, hydraulic, and biogeochemical data. These simulations allowed us to evaluate the budgets of the main nutrients (phosphorus [P], nitrogen [N], silica [Si]) and total organic carbon (TOC), and their imbalance with respect to estuarine eutrophication potential. Cumulated average annual fluxes to the Atlantic coast from the seven estuaries studied were 9.6 kt P yr−1, 259 kt N yr−1, 304 kt Si yr−1, and 145 kt C yr−1. Retention rates varied depending on the estuarine residence times, ranging from 0–27 %, 0–34 %, 2–39 %, and 8–96 % for TP, TN, DSi, and TOC, respectively. Large-scale estuaries had higher retention rates than medium and small estuaries, which we interpreted in terms of estuarine residence times. As shown by the indicator of eutrophication potential (ICEP), there might be a risk of coastal eutrophication, i.e., the development of nonsiliceous algae that is potentially harmful to the systems studied due to the excess TN over DSi.

Changing Dietary Behavior for Better Biodiversity Preservation: A Preliminary Study

Broadly consumed dietary patterns, such as the European and Western ones, are exerting pressures on biodiversity both in Europe and globally, and shifting toward a sustainable dietary pattern has thus become a must. This paper constitutes a preliminary communication of the results of a research project on the issue. In this study, the pressures of three dietary patterns (European, Western, and Mediterranean) on biodiversity are addressed in terms of land use, water use, greenhouse gas emissions, and eutrophication impact indicators. The environmental impacts are calculated based on a compositional analysis of each dietary pattern and the environmental footprints of the corresponding food groups. Food balance sheets published by the FAO are used as a basis for the compositional analysis, while the environmental footprints of each of the representative food products are retrieved from related life cycle assessment (LCA) studies. The results show that a shift from the European to the Mediterranean dietary pattern would lead to 10 m2/capita/day land savings, 240 L/capita/day water savings, 3 kg CO2/capita/day reduction in greenhouse gas emissions, and 20 gPO4eq/capita/day reductions in eutrophication potential. Likewise, a shift from the Western to the Mediterranean dietary pattern would lead to 18 m2/capita/day land savings, 100 L/capita/day water savings, 4 kg CO2/capita/day reduction in greenhouse gas emissions, and 16 gPO4eq/capita/day reduction in eutrophication potential. Based on these findings, it is clear that this shift is urgently needed as a step toward environmentally sustainable dietary patterns, such as the Mediterranean one, to preserve biodiversity for future generations.

Environmental Impacts of Beef as Corrected for the Provision of Ecosystem Services

We aimed to assess whether the environmental impacts in terms of global warming potential (GWP), acidification potential (AP), eutrophication potential (EP), and land occupation (LO) of beef can be decreased when ecosystem and cultural/provisioning services are included in the evaluation. We used four Italian production systems: Fat, with beef imported calves kept in confinement; CoCaI, with beef cows and calves kept in confinement; SpEx, with beef cows and calves kept on pasture and finishing conducted in confinement; and Pod, with Podolian cows and calves kept on pasture and finishing conducted in confinement. After the economic allocation, the GWP of system Pod decreased considerably and showed values lower than those computed for systems CoCaI and SpEx (P < 0.05 and P < 0.001, respectively). System Pod showed the lowest AP and EP as compared with all the other systems (P < 0.01). Systems Fat and CoCaI showed the smallest LO, with values lower than systems Pod (P < 0.05) and SpEx (P < 0.001). We conclude that the environmental impacts of extensive and local beef production systems in terms of GWP, AP, and EP was markedly reduced when the provision of accessory services was included in the calculation. Conversely, LO did not markedly change due to the high absolute values needed to allow pasture-based feeding. The estimation of additional positive aspects linked to the use of natural pastures, such as removal of carbon dioxide, increased biodiversity, and exploitation of feeds nonedible by humans, may allow a further reduction of LO.

Analysis of eutrophication potential of municipal wastewater

One of the main factors of the increased eutrophication level of surface waters is the high anthropogenic loads of biogenic substances discharged into water bodies. Municipal wastewaters, containing large amounts of nitrogen and phosphorus play one of the key roles in the acceleration of eutrophication intensity. The main direction in the prevention of eutrophication caused by wastewater discharge has become the reduction of nutrient loads introduced to wastewater receivers in accordance with strict legal requirements achievable only in advanced technologies. The treated wastewater quality standards are actually developed for total nitrogen and total phosphorus content, disregarding the fact that eutrophication potential of treated wastewater is determined by the content of non-organic nutrient forms directly bioavailable for water vegetation. That is why the currently used energy-consuming and expensive technologies do not always guarantee effective protection against eutrophication and its consequences. The goal of the study was to analyze the most widely used wastewater treatment technologies for enhanced biological nutrients removal in treated wastewater eutrophication potential. For this purpose, an analysis of the operation of 18 wastewater treatment plants based on different technologies in Finland, Canada, Poland, Russia and the United States was realized. The analysis concluded that the eutrophication potential of treated wastewater to a large extent is conditioned by the applied technology. The results of the research concluded that the eutrophication potential can serve an important criterion for decision-making regarding the proper selection of wastewater treatment technologies aimed at eutrophication mitigation.

Mapping the Environmental Cost of a Typical Citrus-Producing County in China: Hotspot and Optimization

The environmental sustainability of the largest citrus plantation globally is facing a great challenge in China. Further, there is a lack of quantitative, regional hotspot studies. In this study, the life cycle assessment (LCA) was used to quantify the environmental cost of citrus production based on 155 farmers’ surveys from typical citrus orchards in Danling County, southwest China, which produced 0.65% of the country’s total citrus production. The results showed that the average values of environmental risk indicated by global warming potential (GWP), acidification potential (AP), and eutrophication potential (EP) were 11,665 kg CO2-eq ha−1, 184 kg SO2-eq ha−1, and 110 kg PO4-eq ha−1, respectively. The production and utilization of fertilizer ranked the first contribution to the environmental impacts among all the environmental impacts, which contributed 92.4–95.1%, 89.4–89.8%, and 97.8–97.9% to global warming potential, acidification potential, and eutrophication potential, respectively. Specific to the contribution of fertilizers to environmental costs, the production and utilization of nitrogen (N) fertilizer accounted for more than 95% of the total environmental costs. Thus, the spatial distribution of environmental costs in this county was well matched with that of N input. Compared with the average values of investigated 155 orchards, the high yield and high N use efficiency (HH) orchard group with younger and better educated owners achieved a higher citrus yield and N use efficiency with less fertilizer input and lower environmental costs. Five field experiments conducted by local government and Danling Science and Technology Backyard were used to further certify the reduction potential of environment costs. These field results showed that the local recommendation (LR) treatment increased citrus yield and N use efficiency by 1.9–49.5% and 38.0–116%, respectively, whereas decreased environmental costs by 21.2–35.2% when compared with the local farmer practice in the HH orchard group. These results demonstrated that an optimum nutrient management based on the local field recommendation in citrus-producing areas is crucial for achieving a win-win target of productivity and environmental sustainability in China and other, similar countries.