ABSTRACT

Agricultural activity enhances topsoil erosion and facilitates the transport of pesticides that alter watershed sediment quality. Agricultural stream (bayou) sediment quality in Mississippi, USA, was evaluated across three bayous, habitats (upstream, midstream, downstream), and seasonally from 2011 to 2014 for pesticide contamination, effects, and bioavailability to Hyalella azteca. Four-week (28-day) H. azteca sediment bioassays were conducted to assess survival and growth and tissue residues. Fourteen pesticides were detected in at least one sediment sample and nine pesticides were detected in H. azteca tissues. Sediment pesticides p,p’-DDT and p,p’-DDE were greatest in Cow Oak Bayou and heptachlor and bifenthrin were greatest in Howden Lake Bayou. Seasonally, λ-cyhalothrin and p,p’-DDT were greatest in winter while trifluralin, atrazine, and clomazone were greatest in the fall. H. azteca survival and growth ranged from 0 to 100% and 0.8–4.1 mg, respectively, with Cow Oak, downstream habitats, and spring samples having the greatest survival and growth. Greatest tissue pesticide residues were atrazine (1271 µg/kg), p,p’-DDT (1,093 µg/kg), and β-cyfluthrin (1003 µg/kg). Tissue pesticide residues were influenced primarily by p,p’-DDT with Cow Oak and fall tissue samples having the lowest residues. H. azteca tissue p,p’-DDT residues contributed to biological impairment. Although banned in the USA for 40 years, p,p’-DDT continues to impact sediment quality.

摘要

农业活动加剧了表土侵蚀，并促进了农药的运输，从而改变了流域的沉积物质量。对美国密西西比州的三个河流生境（上游，中游，下游）以及2011年至2014年的季节性农业农药（bayou）沉积物质量进行了评估，以评估农药污染，影响和对透明质酸的生物利用度。进行了为期四周（28天）的阿兹台克血沉生物测定，以评估存活和生长以及组织残留。在至少一个沉积物样品中检测到14种农药，在双歧杆菌组织中检测到9种农药。沉积物农药p，p'- DDT和p，p'-DDE在Cow Oak Bayou中最大，而七氯和联苯菊酯在Howden Lake Bayou中最大。在冬季，λ-氟氯氰菊酯和p，p'- DDT最高，而在秋季，三氟拉林，阿特拉津和广灭灵最大。阿兹台克人的存活和生长范围分别为0至100％和0.8-4.1 mg，其中牛橡树，下游生境和春季样品的存活和生长最大。组织农药残留量最大的是阿特拉津（1271 µg / kg），p，p'- DDT（1,093 µg / kg）和β-氟氰菊酯（1003 µg / kg）。组织农药残留主要受考橡树的p，p'- DDT影响，而秋天组织残留量最低。H.azteca组织p，p'-滴滴涕残留会造成生物损伤。尽管在美国已被禁止使用40年，但p，p'- DDT继续影响沉积物质量。