Results from single‐species toxicity tests form the basis for guidance about concentrations of chemicals that are likely to be environmentally hazardous. Microcosm bioassays have been proposed as better tools for this purpose under some circumstances. Rarely have comparisons been made among the responses in the various test systems and those seen in natural communities. We compared the responses among single‐species algal assays, a synthetic microcosm (the Taub microcosm) and experimental ponds exposed to similar concentrations of atrazine by comparing concentrations of atrazine that reduced algal activity or biomass to 50% of control values (EC50). Eight algal species were examined; mean species EC50 values for 14C uptake ranged from 37 to 308 μg/L. For the Taub microcosm, EC50 values were 103 to 159 μg/L for 14C uptake, 126 to 165 μg/L for dissolved oxygen production and 106 to 164 μg/L for dissolved oxygen consumption. Values were dependent on the time intervals selected for calculations. In the ponds, EC50 values for 14C uptake were 100 μg/L and for chlorophyll a, 82 μg/L. The basic similarity among EC50 values across test systems suggests that results from a combination of single‐species assays, or the Taub microcosm, provided a reasonable estimate of the concentration of atrazine that produced similar direct effects on more natural communities.

We developed a rapid-test to screen for effects of biochar on seed germination and soils. Crop seeds were placed in containers and covered with 15 g of soil with 1% biochar by weight. Two agricultural soils from South Carolina USA were used. Eighteen biochars were produced from six primary feedstocks [pine chips (PC), poultry litter (PL), swine solids (SS), switchgrass (SG); and two blends of PC and PL, 50% PC/50% PL (55), and 80% PC/20% PL (82)]. Each feedstock was pyrolyzed at 350, 500 and 700°C. There were few biochar effects on seed germination. Shoot dry weight was increased for carrot, cucumber, lettuce, oat, and tomato; primarily with biochars containing PL. Soil pH, electrical conductivity and extractable phosphorus primarily increased with PL, SS, 55, and 82 treatments for both soil types and across species. This method can be an early indicator of biochar effects on seed germination and soil health.

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Essential nutrient concentrations in crops can affect human health. While biochar has the potential as a soil amendment to improve crop yields, it may also affect the concentrations of nutrients such as Ca, Fe, K, Mg, Mn, and Zn in edible portions of crops. To better characterize effects of biochar on important human nutrients in food crops, we evaluated the effects of biochar on lettuce (Lactuca sativa L. cv. Black-Seeded Simpson) leaf and carrot [Daucus carota subsp. sativus (Hoffm.) Schübl. cv. Tendersweet] developing taproot nutrients. Plants were grown in pots in a greenhouse using sandy loam (Coxville, fine, kaolinitic, thermic Typic Paleaquults) and loamy sand (Norfolk, fine-loamy, kaolinitic, thermic Typic Kandiudults,) series soils, amended with biochar produced from four feedstocks: pine chips (PC), poultry litter (PL), swine solids (SS), and switchgrass (SG); and two blends of PC plus PL [PC/PL, 50%/50% (55) and 80%/20% (82) by weight]. Biochar was produced at 350, 500, and 700 °C from each feedstock. Lettuce leaf and carrot taproot total nutrient concentrations were determined by inductively coupled plasma analysis. Biochar (especially at least in part manure-based, i.e., PL, SS, 55, and 82 at nearly all temperatures) primarily decreased nutrient concentrations in lettuce leaves, with Ca, Mg, and Zn affected most. Carrot taproot nutrient concentrations also deceased, but to a lesser extent. Some biochars increased leaf or taproot nutrient concentrations, especially K. This study indicated that biochar can both decrease and increase leaf and taproot nutrient concentrations important for human health. Thus, potential effects on nutrients in plants should be carefully considered when biochar is used as a soil amendment with vegetable crops.

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Two northern bobwhite (Colinus virginianus) reproduction tests were conducted concurrently to evaluate how the duration and time of initiation of methyl parathion exposure affected dose‐response relationships of reproductive parameters. In the long‐term exposure test, pairs of adult bobwhite were fed methyl parathion‐amended diets (0, 7, 10, 14, 20 or 28 ppm) for 25 weeks: 10 weeks prior to the onset of laying, 6 weeks as they came into laying condition and 9 weeks during egg laying. In the short‐term exposure test, quail received amended diets (0, 10, 14, 20, 28 or 40 ppm) for only three weeks during the egg laying period, followed by a three‐week posttreatment period. Fourteen birds died in the long‐term test, compared to two in the short‐term test. Significant dose‐related reductions in daily food consumption, egg production and the number of 14‐d‐old chicks were observed in both tests during the treatment periods. No dose‐related effects on fertility, hatch‐ability or chick weights were detected. In the long‐term test, there were dose‐related decreases in adult body weight, brain and serum cholinesterase activity and female serum calcium concentrations. Cholinesterase and calcium were not measured in the short‐term test. Eggshell weights were significantly decreased in both tests, but a dose‐related decrease in eggshell strength and thickness was detected only in the short‐term test. During the posttreatment period of the short‐term test, no dose‐related effects on reproductive parameters were observed, except that egg production did not recover until the third week after treatment. Except for the number of adult mortalities, all dose‐related effects observed in the long‐term exposure test also were observed in the short‐term test. The short‐term test design had two advantages that reduced variability unrelated to the chemical treatments: infertile and incompatible pairs could be removed from the experiment and pretreatment values could be obtained to serve as controls for each pair.