Suppliment2

Description

This dataset contains the environmental chemistry, water‑quality, and derived risk‑assessment variables used to develop and evaluate a multi‑stressor ecological‑risk framework for a coastal watershed in Maine. It includes measurements of sediment‑associated metals, total phosphorus, total nitrogen, chlorophyll‑a, dissolved oxygen, and supporting physicochemical parameters collected across multiple sites. These data were used to calculate metal Risk Quotients (RQ), the Nutrient‑Conditioned Metal Risk Index (NCMRI), and the Comprehensive Multi‑Stressor Risk Index (CMRI). The dataset supports analyses of nutrient enrichment, hypoxia, and metal contamination interactions, including univariate, bivariate, and multivariate assessments. It enables replication of all risk‑index calculations, environmental‑gradient analyses, and site‑level vulnerability classifications presented in the associated manuscript. This dataset is intended for researchers studying watershed processes, ecological risk assessment, nutrient–metal interactions, and multi‑stressor dynamics in aquatic systems.

Steps to reproduce

1. Import raw data Load the original field and laboratory data containing, for each site and date: Sediment metals: 𝐶 𝑖 (e.g., Cu, Zn, Pb, etc.; mg/kg dry weight) Total phosphorus (TP): 𝜇 𝑔 / 𝐿 Dissolved oxygen (DO): mg/L Any additional water‑quality and physicochemical variables. 2. Standardize units and clean data Convert all metals to mg/kg dry weight and TP to 𝜇 𝑔 / 𝐿 . Ensure DO is in mg/L. Standardize site IDs and dates, remove duplicates, and handle non‑detects (e.g., replace <DL with DL/2, as specified in the manuscript). 3. Calculate metal Risk Quotients (RQ) For each metal 𝑖 : 𝑅 𝑄 𝑖 = 𝐶 𝑖 𝑃 𝑁 𝐸 𝐶 𝑖 where 𝑃 𝑁 𝐸 𝐶 𝑖 is the selected sediment guideline (e.g., TEC/PEC or equivalent). Add one column per metal (e.g., RQ_Cu, RQ_Zn, etc.). 4. Compute worst‑case metal risk ( 𝑅 𝑄 max ) 𝑅 𝑄 max = max ⁡ ( 𝑅 𝑄 1 , 𝑅 𝑄 2 , . . . , 𝑅 𝑄 𝑛 ) Store as RQ_max. 5. Compute the nutrient conditioning factor and NCMRI Use TP (in 𝜇 𝑔 / 𝐿 ) and a mesotrophic reference threshold 𝑇 𝑃 ref = 25   𝜇 𝑔 / 𝐿 . Nutrient conditioning factor: 𝑁 𝐶 𝐹 𝑇 𝑃 = 1 + 𝑇 𝑃 𝑇 𝑃 ref Nutrient‑Conditioned Metal Risk Index: 𝑁 𝐶 𝑀 𝑅 𝐼 = 𝑅 𝑄 max × 𝑁 𝐶 𝐹 𝑇 𝑃 Store as NCF_TP and NCMRI. 6. Compute the dissolved oxygen conditioning factor With 𝐷 𝑂 ref = 5  mg/L : 𝑁 𝐶 𝐹 𝐷 𝑂 = 1 + 𝐷 𝑂 ref − 𝐷 𝑂 𝐷 𝑂 ref Values of 𝑁 𝐶 𝐹 𝐷 𝑂 increase as DO declines below 5 mg/L. Store as NCF_DO. 7. Compute the Comprehensive Multi‑Stressor Risk Index (CMRI) 𝐶 𝑀 𝑅 𝐼 = 𝑅 𝑄 max × 𝑁 𝐶 𝐹 𝑇 𝑃 × 𝑁 𝐶 𝐹 𝐷 𝑂 Store as CMRI. 8. (Optional) Derive risk classes If used, classify CMRI into categorical risk levels (e.g., Low, Moderate, High) using the thresholds defined in the manuscript, and store as Risk_Class.

Institutions

• Unity College

  Maine, Unity

Categories

Licence