Synthetic Detergents: Their Influence upon Iron-Binding Complexes of Natural Waters

Area of Science:

• Environmental Chemistry
• Limnology
• Algal Physiology

Background:

• Organic compounds in natural waters influence nutrient availability for aquatic life.
• Iron is an essential micronutrient for algal growth, but its bioavailability can be limited.

Purpose of the Study:

• To investigate the role of natural organic compounds in iron bioavailability for the green alga Chlamydomonas reinhardi.
• To determine the impact of detergents on the iron-binding capacity of these organic compounds.

Main Methods:

• Extraction of organic compounds from Michigan lakes and streams.
• Culturing Chlamydomonas reinhardi with extracted compounds and iron.
• Two-dimensional paper chromatography to identify iron-complexing fractions.
• Assessing iron-binding capacity in the presence and absence of alkyl benzene sulfonate.

Main Results:

• Organic compounds enhanced algal growth when iron was present, indicating iron complexation.
• Iron was complexed by organic fractions containing amine groups.
• Alkyl benzene sulfonate (a detergent) at concentrations over 0.3 ppm inhibited the iron-binding capacity of these organic compounds.
• Separating the sulfonate restored the iron-binding capability.

Conclusions:

• Detergents can interfere with the natural complexation of iron by organic matter in aquatic ecosystems.
• This interference may reduce iron availability, potentially impacting primary production in lakes and streams.
• Further research is needed to understand the ecological implications of detergent-induced changes in iron mobility.