CALORIC CONTENT AND IRON, MANGANESE, AND ZINC CONCENTRATIONS OF SEDIMENT, CHAOBORIDS, AND CHIRONOMIDS OF HAM'S AND ARBUCKLE LAKES

Scope of Study. Caloric content and concentrations of iron, manganese, and zinc of the sediments, chaoborids, and chironomids were studied in Ham's and Arbuckle lakes from March 1978 to November 1979. Attempts were made to break up summer stratification by mechanical pumping of surface water to the bottom. Laboratory experiments were conducted to examine iron uptake and caloric content under controlled conditions.; Findings and Conclusions. In Ham's and Arbuckle lakes, respectively, temperature ranged from 7-28 and 5-27(DEGREES)C, dissolved oxygen from 0.2-16.4 and 0-12.0 mg ('-1), alkalinity from 116-176 and 127-165 mg ('-1), conductivity from 220-482 and 290-456 (mu)mhos cm('-1), and Secchi disc transparency from 43-150 and 120-252 cm. Percent loss on ignition of the sediment was similar in the two lakes and ranged from 5.7-14.7%. During pumping in Ham's Lake, values of loss on ignition were less at the destratified station than in the stratified arm. Estimates of percent organic matter, as measured by an oxidation procedure, were considerably lower than gravimetric estimates.; Eighteen taxa were identified in each lake. In Ham's Lake 17 taxa were taken from the destratified stations in the central pool, while only 12 were taken from the stratified station. The caloric content of Chaoborus punctipennis (Say) ranged from 5832-6850 cal g('-1) in Ham's Lake. Caloric content was greater at the stratified station than in the central pool during summer. Values for this species and for chironomids were significantly less in Arbuckle Lake. Maximum concentration in sediments of the two lakes was 3230 cal g('-1).; Sorbed iron of the sediments and total iron of the water ranged from nondetectable to 17.9 (mu)g g('-1) and 15-1571 (mu)g ('-1), respectively, in the two lakes. During pumping in summer, values of total iron were larger in the central pool than in the stratified arm in Ham's Lake, while little variation existed in sorbed iron of the sediments. Iron concentration in Chironomus riparius (Walker) ranged from 1060-6697 (mu)g g('-1). The range for Chaoborus punctipennis was less. In the sediment manganese was considerably higher than sorbed iron; however, the reverse was observed in organisms. In the water values of manganese and iron were similar except for extremely high values of manganese during summer anoxia. Values of sorbed zinc in the sediment and total zinc in the water were low in both lakes with maxima of 2.8 (mu)g g('-1) and 32.9 (mu)g ('-1), respectively. Concentrations of zinc in organisms were less than values of iron and similar to manganese. Soluble zinc represented 74% of total zinc in the water; whereas, soluble iron and manganese generally averaged less than 20%.; In laboratory experiments the concentrations of iron were comparable to those measured in the field. Iron values were consistently lower in organisms in oxygenated jars than in anoxic jars. No significant difference existed among organisms subjected to different levels of iron.