Abstract
The elemental composition of freshwater and saltwater samples around the South Pacific island of Upolu, Samoa has been investigated together with other indicators of water quality. Up to 69 elements from Li (3) to U (92) are measured in each sample, analyzed by Mattauch–Herzog-inductively coupled plasma-mass spectrometry (MH-ICP-MS). One hundred and seventy-six samples were collected from surface freshwater sources (24 rivers, two volcanic lakes, one dam) and from seawater sources from the surface to 30 m depth (45 inner reef, reef, and outer reef locations) around Upolu Island, including river mouths and estuaries. Principal component and hierarchical clustering correlation analyses were performed on quantile normalized log transformed elemental composition data to identify groups of samples with similar characteristics and to improve the visualization of the full spectrum of elements. Human activities, such as the use of herbicides and pesticides, may relate to observed elevated concentrations of some elements contained in chemicals known to have deleterious obesogenic effects on humans that may also cause coral reef decline. Furthermore, the salinity of some saltwater samples tested were very high, possibly due to climate variability, which may additionally harm the health and biodiversity of coral reefs.
Highlights
The quality of freshwater and saltwater resources in relation to their elemental composition, salinity, and many other water quality parameters, such as microbial diversity and microplastics content, is a serious contemporary environmental concern for aquatic life and for humans that dependMolecules 2020, 25, 4871; doi:10.3390/molecules25214871 www.mdpi.com/journal/moleculesMolecules 2020, 25, 4871 on these waters
Coral reefs are distributed around most of the perimeter of Upolu Island, along which three areas have been assigned to marine protected areas (MPA), as detailed in a recent hydrographic risk assessment [35]
A “Boat” team consisting of two divers and a drone operator circumnavigated the island, docking locally at the end of each day, being picked up to return home, and driving to the last destination each morning to begin sampling along the coastal segment. 50 mL sampling tubes were used to acquire all water samples from the surface of each of a river’s headwater and its mouth and location(s) in between, from lakes, and from the inner reef, reef, and outer reef locations that included depths to 30 m that capture water in contact with shallow water coral reefs
Summary
The quality of freshwater and saltwater resources in relation to their elemental composition, salinity, and many other water quality parameters, such as microbial diversity and microplastics content, is a serious contemporary environmental concern for aquatic life and for humans that dependMolecules 2020, 25, 4871; doi:10.3390/molecules25214871 www.mdpi.com/journal/moleculesMolecules 2020, 25, 4871 on these waters. For the determination of the complete inorganic spectrum of elements in aqueous samples, there are several analytical techniques currently in use, such as electrothermal atomic absorption spectroscopy (ETAAS), inductively coupled plasma optical emission spectrometry (ICP-OES), and various types of inductively coupled plasma-mass spectrometry (ICP-MS) [8,9,10,11]. These techniques are typically limited in the practical number of elements that can be analyzed from a single sample. We have developed a method for simultaneous multi-element detection across the breadth of the chemical periodic table in various aqueous samples using a Mattauch–Herzog geometry-inductively coupled plasma-mass spectrometry (MH-ICP-MS) [12]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
