Chumbao River Case Report: Caffeine, Surfactants, and Organic Matter Analysis

Case Report Overview

Introduction

  • Context of the study: Discharge of domestic, industrial, and commercial wastewater exposes populations to emerging contaminants such as caffeine and surfactants, impacting water physicochemical parameters.

  • Objective: Evaluate the levels of caffeine, organic matter, and anionic surfactants in the Chumbao River's water micro-basin, Andahuaylas, Apurimac, Peru.

Environmental Concerns

  • Emerging contaminants: Chemical substances posing risks to health and environment found in concentrations of μg/L to ng/L in untreated wastewater effluents.

  • Sources of contamination:

    • Household products (drugs, cosmetics, processed foods) contributing residues through wastewater discharge.

    • Caffeine, highly soluble and persistent, is a marker for human contamination in water bodies due to its high correlation with coliform levels.

    • Anionic surfactants such as linear alkylbenzenesulfonate are common in cleaning products, indicating wastewater presence.

Study Area and Methodology

1. Study Area

  • Chumbao River Micro-basin: Located in districts of San Jeronimo, Andahuaylas, province of Andahuaylas, with an area of 766.46 km². The river spans 61.92 km, altitudes range from 4800 to 2000 m, and the average slope is 5.14%.

  • Hydrological data: Rainfall ranges between 500 mm and 800 mm annually.

2. Sampling Strategy

  • Sampling seasons: Carried out during low water (November 2021) and flooding periods (March 2022).

  • Sampling points: Seven points selected based on anthropogenic activity along an altitudinal gradient.

3. Analysis Parameters

  • Physicochemical indicators measured in-field (pH, temperature, electrical conductivity, dissolved oxygen (DO), total dissolved solids (TDS), turbidity).

  • Laboratory analyses of samples were conducted per APHA methods, including BOD5, COD, nutrient levels (phosphates, nitrates, nitrites), anionic surfactants, and heavy metals.

  • Caffeine Analysis: Quantified using HPLC with specified chromatographic conditions (Zorbax column, mobile phase of water and acetonitrile).

Results and Discussion

1. Physicochemical Parameters

  • pH: ranged from slightly alkaline to neutral, with seasonal variations specific to anthropogenic influences.

  • Turbidity: higher values observed in urbanized sampling points, indicative of sediment mobilization.

  • Conductivity: increased due to anthropogenic activities; maximum values reached 709.57 µS/cm.

  • Hardness and Color: affected by organic waste decomposition, with values exceeding ECA standards in urban areas.

  • Total Dissolved Solids (TDS): significant downstream trend, affected by flow conditions, with no values exceeding Peruvian ECA limits.

2. Nutrient Levels

  • Phosphate: Significant presence indicated potential contamination from urban waste

  • Nitrate: Below detection in both waters; nitrite levels indicated through operational water quality and exceeding limits per ECA due to organic pollution.

  • Sulfate: Varied significantly, showing signs of organic matter linked to wastewater.

3. Metals Analysis

  • Heavy Metals: Chromium levels exceeded ECA standards mainly due to mining activities. Iron and aluminum found within permissible limits; copper concentrations indicated urban contamination impacts.

4. Organic Matter Content

  • COD and BOD5: High values (COD: max 52 mg/L) indicated oxidizable organic waste in the river, exceeding ECA limits.

    • Total Phosphorus: values showed significant excess attributed to wastewater discharges, particularly in agricultural contexts.

5. Biodegradability Assessment

  • The waters showed high biodegradability due to organic compound presence, with varying biodegradability indices reflecting the types of wastewater involved.

6. Anionic Surfactants

  • Maximum concentrations exceeded the permissible limits in both study seasons, indicating urban wastewater as a significant contributor.

7. Caffeine Concentrations

  • Found at a maximum of 52.22 μg/L in urban sampling sites. Un- detectable levels during the rainy season suggest runoff effects.

8. Statistical Analysis

  • Correlation Matrix: Evaluated relationships among physicochemical parameters, highlighting impacts of anthropogenic activities and seasonal variations on water quality.

  • Principal Component Analysis (PCA): Identified characteristics separating headwaters from urbanized areas, showing greater organic pollution and contaminants in urban zones.

Conclusion

  • The Chumbao River serves multiple anthropogenic functions but is heavily affected by urban wastewater, leading to significant organic matter and emerging contaminant levels that exceed Peruvian ECA standards. Monitoring these contaminants remains essential for environmental protection, highlighting urgent needs for better wastewater management in the area.

Author Contributions

  • Detailed roles of each author in conceptualization, methodology, validation, and writing attributed, underscoring collaborative efforts in research.

Funding

  • Partial funding from Universidad Nacional José María Arguedas for the execution of research.

Data Availability

  • Data available upon request for further review.

References

  • Comprehensive list of citations for studies relevant to practices and findings presented in this report.