Paschke Mark W, Redente Edward F
Colorado State University, Department of Rangeland Ecosystem Science, Fort Collins, Colorado 80523-1478, USA.
Environ Toxicol Chem. 2002 Dec;21(12):2692-7.
Copper toxicity thresholds for plant species that are used in restoration activities in western North America have not been established. As a result, ecological risk assessments must rely on toxicity thresholds established for agronomic species, which usually differ from those of species used in restoration. Thus, risk assessors have the potential for classifying sites as phytotoxic to perennial, nonagronomic species and calling for intensive remediation activities that may not be necessary. The objective of this study was to provide a better estimate of Cu toxicity thresholds for five grass species that are commonly used in restoration efforts in the western United States. We used a greenhouse screening study where seedlings of introduced redtop (Agrostis gigantea Roth.), the native species slender wheatgrass (Elymus trachycaulus [Link] Gould ex Shinners var. Pryor), tufted hairgrass (Deschampsia caespitosa [L.] Beauvois), big bluegrass (Poa secunda J. Presl var. Sherman), and basin wildrye (Leymus cinereus [Scribner & Merrill] A. Love var. Magnar) and the agricultural species common wheat (Triticum aestivum L.) were grown in sand culture and exposed to supplemental concentrations of soluble Cu of 0 (control), 50, 100, 150, 200, 250, and 300 mg/L. We determined six measures of toxicity: the 60-d mean lethal concentration (LC50), 60-d mean effective concentration (EC50)-plant, 60-d EC50-shoot, 60-d EC50-root, phytotoxicity threshold (PT50)-shoot, and the PT50-root. Results suggest that these restoration grass species generally have higher Cu tolerance than agronomic species reported in the past. Of the species tested, redtop appeared to be especially tolerant of high levels of substrate and tissue Cu. Values of EC50-plant for restoration grasses were between 283 and 710 mg Cu/L compared to 120 mg Cu/L for common wheat. Measured PT50-shoot values were between 737 and 10,792 mg Cu/L. These reported thresholds should be more useful for risk assessors than those currently used, which are based largely on agronomic crops.
北美西部用于恢复活动的植物物种的铜毒性阈值尚未确定。因此，生态风险评估必须依赖于为农艺物种确定的毒性阈值，而这些阈值通常与用于恢复的物种不同。因此，风险评估者有可能将某些场地归类为对多年生非农艺物种具有植物毒性，并要求开展可能并非必要的强化修复活动。本研究的目的是更准确地估计美国西部恢复工作中常用的五种草种的铜毒性阈值。我们进行了一项温室筛选研究，将引进的匍匐翦股颖（Agrostis gigantea Roth.）、本地物种细茎冰草（Elymus trachycaulus [Link] Gould ex Shinners var. Pryor）、丛生发草（Deschampsia caespitosa [L.] Beauvois）、大蓝草（Poa secunda J. Presl var. Sherman）和盆地野麦草（Leymus cinereus [Scribner & Merrill] A. Love var. Magnar）以及农作物普通小麦（Triticum aestivum L.）的幼苗种植在砂培中，并使其暴露于浓度为0（对照）、50、100、150、200、250和300 mg/L的可溶性铜补充浓度下。我们测定了六项毒性指标：60天平均致死浓度（LC50）、60天平均有效浓度（EC50）-植株、60天EC50-地上部分、60天EC50-根部、植物毒性阈值（PT50）-地上部分和PT50-根部。结果表明，这些用于恢复的草种通常比过去报道的农艺物种具有更高的耐铜性。在测试的物种中，匍匐翦股颖似乎对高水平的基质和组织铜特别耐受。恢复草种的EC50-植株值在283至710 mg Cu/L之间，而普通小麦为120 mg Cu/L。测得的PT50-地上部分值在737至10792 mg Cu/L之间。这些报告的阈值对风险评估者来说应该比目前主要基于农作物的阈值更有用。
