Development of a multimetric water quality Indicator for tracking progress towards the achievement of Chesapeake Bay water quality standards

Estimating the contribution of environmental variables to water quality in the postrestoration littoral zones of Taihu Lake using the APCS-MLR model

Water quality monitoring is one of the most important aspects of postrestoration assessments because it affects water pollution control and the development of sustainable management strategies. However, a comprehensive understanding of potential water pollution and source apportionment in restoration projects is still lacking. In this study, the water quality variables of three restored national wetland parks with different cofferdam systems (i.e., an eco-layered cofferdam, a fully enclosed cofferdam, and open water) in the littoral zone of Taihu Lake were monitored monthly for three years (2019-2021). Hydrochemical and meteorological variables were used as auxiliary parameters for multivariate statistics, including principal component analysis (PCA) and absolute principal component score-multiple linear regression (APCS-MLR), to accurately estimate the source apportionment of the potential factors influencing the water environment. PCA extracted three or four potential sources, accounting for 64.71 %, 65.40 %, and 63.85 % of the total variance. The APCS-MLR results showed that wind direction and volatile suspended solids were the primary sources affecting water quality in open water, with a sum of the mean source contributions of 40.7 %. In fully enclosed cofferdam systems, the dire state of endogenous pollution was the greatest potential source affecting water quality, with a mean contribution of 41.2 %. The eco-layered cofferdam alleviated the contributions of suspended solids (mean contribution of 23.7 %) and nutrients in the water column (mean contribution of 30.8 %); however, the contribution of organic matter in the cofferdam was relatively high (mean contribution of 13.4 %). Based on these results, eco-layered cofferdams play a positive role in eutrophication control and ecological restoration in the littoral zone of large shallow lakes. Meanwhile, adding meteorological variables to assist hydrochemical variables in multivariate statistics may improve the accuracy and certainty of pollution source apportionment and support decision-makers in developing water quality protection and management strategies for postrestoration projects in littoral zones.

A systematic approach for assessing water, energy and food security during the COVID-19 pandemic: case study of Mexico

Assessing the security of the water-energy-food nexus is a topic of great importance, which allows determining the situation of each resource to implement actions for sustainable management of these resources in today's society. For this reason, a systematic procedure is proposed to evaluate the synergies of the water-energy-food nexus in a large region that is divided into subregions that allow considering their interactions. The new procedure considers the availability, accessibility and regional interdependence of resources while annexing economic and social aspects. A composite index called the WEF Global Index is developed, which involves the WEF nexus index and has nine indicators that evaluate the availability, accessibility and regional interdependence of each resource in the water-energy-food nexus. This new index considers the Gross Domestic Product per capita and the involved population. As a case study, the 32 states of Mexico were considered to assess the effects of the COVID-19 pandemic on the economy and the security of the water-energy-food nexus at the state level. For this, the composite index was evaluated in the years 2019 and 2020. The results show that from 2019 to 2020, the value of the global index increased in 13 states, in 21 states the security index of the WEF nexus increased, and in 9 states the GDP per capita index increased. On the other hand, the results indicate that in 11 states there was no improvement in the nexus security index due to the increase in water demand, which considerably affected the water availability indicator.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10668-022-02671-2.

Spatial analysis of water quality parameters in Hilo Bay, Hawai'i, using a combination of interpolated surfaces and hot spot analysis

Hilo Bay estuary, located on the northeastern side of Hawai'i Island, experiences variability in water quality parameters due to its numerous water inputs. This estuary experiences influxes of water from three sources: groundwater to the east, marine water from the north, and surface water from the Wailuku River to the west. High rainfall and river flow impacts Hilo Bay's water quality including salinity, turbidity, and chlorophyll a concentration. Here, maps of Hilo Bay water quality were examined to assess spatial patterns of these important parameters. Exploring the patterns of these water quality parameters by creating inverse distance weighted (IDW) interpolation surfaces of survey points and clusters based on hot spot analyses during low- and high-flow conditions showed statistically significant differences in spatial water quality in Hilo Bay. Water quality maps after a storm show (1) an overall decrease in salinity, (2) a river plume from the Wailuku River associated with a turbidity hot spot, and (3) a chlorophyll a hot spot offset from the river plume in the center of the bay. Using spatial analysis to analyze water quality throughout the entirety of Hilo Bay before and after storm events can lead to a better understanding of how this ecosystem is affected during these types of events, and furthermore, adopting this method of sampling and analysis allows for a greater representation of water quality all over the bay and can improve the monitoring of water quality in this important ecosystem.