# Tracing Crustal and Anthropogenic Sources of Metal(loid)s in Hurricane Harvey Floodwater Remnants in Houston, Texas

## TL;DR

This study identifies the sources of metal contamination in floodwaters from Hurricane Harvey in Houston, showing that vehicle emissions and building materials contributed significantly beyond natural sources.

## Contribution

The study introduces a novel approach using multivariate analysis and rare earth elements to trace metal sources in floodwaters.

## Key findings

- Three main sources of metal(loid) contamination were identified: crustal materials, vehicular emissions, and the built environment.
- Vehicular residues and building materials contributed significantly to floodwater contamination beyond natural crustal dissolution.

## Abstract

Probable sources of metal­(loid) contamination in Hurricane
Harvey
floodwater remnants from diverse land use settings in Houston, Texas,
were investigated. The primary novelties of this work are that we
(i) analyzed a wide suite of 51 elements, including rare earths and
(ii) implemented two independent multivariate statistical techniques
to obtain clues to metal­(loid) sources. This approach differs from
many previous studies that simply reported the concentrations of a
limited number of metals in hurricane floodwaters. Hierarchical cluster
analysis and principal component analysis both resolved three major
and statistically distinct source categories: crustal materials, vehicular
emissions, and the built environment. The crustal source was confirmed
using light rare earth ternary diagrams, yttrium/holmium ratios, cerium
and europium anomalies, and Oddo-Harkins patterns. The influence of
motor vehicles and traffic was identified using enrichment factors
and simultaneous barium–cadmium–antimony and gallium–cadmium–antimony
three-component variations. Efflux from the built environment was
validated via signature elemental ratios and zinc–tin–lead
ternary variations. Overall, the deluge appears to have mobilized
metal­(loid)­s with vehicular residues and building materials contributing
substantially to floodwater contamination beyond natural crustal dissolution.
The source attribution framework developed herein provides a generalized
approach to identify metal­(loid) sources in any flood-prone urban
environment.