Justin Custado

PhD Candidate | Earth systems geochemistry

Research & teaching


The overarching question that I seek to answer in my research is: what does the distribution, transport, and transformation of chemical species in natural systems tell us about hydrological and terrestrial processes that influence the water and carbon cycles?

Earth science is inherently interdisciplinary, and this is reflected in the wide range of methods that researchers use to address a variety of questions. In my research, I utilize an array of laboratory, computational, and field approaches to generate and analyze data.

Isotope geochemistry

I measure different chemical parameters (major ions,  isotopes, mineralogy) in water and rock samples that I acquire from the field using various analytical instruments (ICP-OES, ICP-MS, MC ICP-MS, CRDS, XRD) and methods. For my current projects, I am particularly interested in quantifying the stable isotopic composition of lakes and precipitation (δ¹⁸O, δ²H, Δ'¹⁷O) and the strontium isotopic signatures (⁸⁷Sr/⁸⁶Sr) of rivers and rocks.

Data analysis & visualization, numerical modeling

Python is my primary tool for data analysis and visualization, particularly for larger datasets that I generate or mine from public repositories. I enjoy exploring datasets across different temporal and spatial scales, applying time series analysis or GIS techniques to interpret regional climate data and produce maps. I also build numerical models, primarily to perform isotopic mass balance calculations. Currently, I am exploring basic chemical equilibrium calculations using PHREEQC software.

Checkout my GitHub repository for some of the scripts and datasets that I have published!

Fieldwork

Teaching

Teaching has been a consistent part of my career, from training factory plant workers to calibrate instruments in my first job to serving as the graduate teaching assistant for several undergraduate classes. Among these experiences, my favorite has been teaching summer courses in the field. I've been fortunate enough to serve as an instructor in the 2019 DOST-SEI Climate Science Youth Camp in Camiguin, Philippines and Brown Environment Leadership Lab in the Eastern Sierras, USA.