Bight 98 Sediment Chemistry Harmonized

Sediment samples from 361 sites on the continental shelf between Point Conception, California, and Ensenada, Mexico were collected between July 13 and September 16, 1998. The sites were selected using a stratified random design, and of these 290 sites were in the U.S., and 71 sites were in Mexico off the coast of Baja California. For the 290 U.S. stations, five of the strata were located offshore (river mouths, large publicly owned treatment works [POTW] discharge areas, small POTW discharge areas, remaining shallow areas [5-30 m], and remaining mid-depth areas [30-120 m]). Three additional strata were located within bays and harbors, which included marinas, ports/industrial areas, and other bay and harbor areas. Another strata was chosen for temporal comparisons. A set of thirteen historical stations were chosen because of their coincidence with previous surveys, and the availability of data going back to 1977. The Subsets of the 290 U.S. sediment samples were analyzed for grain size, mineralogy, total nitrogen, TOC, 15 metals, and 5 classes of organic contaminants. In addition, sediments were analyzed for acid volatile sulfide (AVS), simultaneously extracted metals (SEM), and metals in the sediment interstitial water. Nine different laboratories participated in various portions of the chemical and physical analyses for this study. The target metal analytes for the 290 U.S. stations were aluminum, antimony, arsenic, beryllium, cadmium, chromium, copper, iron, lead, mercury, nickel, selenium, silver, zinc. The target organic analytes were chlordanes (a + g), Total DDT's (6 isomers - o,p-DDT,DDD, DDE and p,p-DDT,DDD,DDE), 42 polychlorinated biphenyl (PCB) congeners, 24 polynuclear aromatic hydrocarbons (PAHs), and C10 - C14 linear alkylbenzenes (LABs). In addition to sediment samples, 275 composite demersal fish tissue samples representing 226 sites were analyzed for chlordanes, DDTs and PCBs. There are corresponding sediment chemistry data for 147 composite samples representing 132 sites. The sediment samples from Mexico were analyzed for a smaller suite of contaminants, excluding TOC, TN, antimony, arsenic, barium, mercury, selenium. Sediments were evaluated by using area weighted means, medians, and confidence intervals on a strata basis. Stations and bight area above background were determined using an iron normalization approach. Relationships in the types and concentration of contaminants among the stations was studied using principle component analysis (PCA). The concentration of organic pollutants in the sediments was compared to the response from a P450 human reporter gene system (P450 HRGS) bioassay, new EPA Method 4425, to evaluate its effectiveness as a screening tool for contaminated sediments. An assessment of the percent of the Southern California Bight (SCB) impacted by anthropogenic pollution was made using a combination of the ERM quotient and the equilibrium partitioning approaches.1998年7月13日至9月16日期间，科研人员采集了美国加利福尼亚州康塞普西翁角（Point Conception）至墨西哥恩塞纳达（Ensenada）之间大陆架361个点位的沉积物样品。本次采样采用分层随机抽样设计选取点位，其中290个点位位于美国管辖海域，71个点位位于墨西哥下加利福尼亚州沿岸外海海域。针对这290个美国海域站位，设置了5个近海分层，包括河口、大型公共污水处理厂（Publicly Owned Treatment Works, POTW）排放区、小型POTW排放区、剩余浅海区域（水深5~30米）以及剩余中深海区域（水深30~120米）；另有3个分层设置于海湾与港口内部，涵盖游艇码头、港口/工业区以及其他海湾和港区；还设置了1个分层用于时间序列对比。另有13个历史站位被纳入本次研究，这些站位与此前的调查点位重合，且可获取追溯至1977年的历史数据。针对290份美国海域沉积物样品的子集，科研人员开展了粒度组成、矿物学特征、总氮（Total Nitrogen, TN）、总有机碳（Total Organic Carbon, TOC）、15种金属元素以及5类有机污染物的分析。此外，研究人员还对沉积物中的酸挥发性硫化物（Acid Volatile Sulfide, AVS）、同步提取金属（Simultaneously Extracted Metals, SEM）以及沉积物间隙水中的金属含量进行了检测。共有9家不同实验室参与了本研究各项化学与物理分析测试工作。针对290个美国海域站位的目标金属检测物包括：铝、锑、砷、铍、镉、铬、铜、铁、铅、汞、镍、硒、银、锌。目标有机检测物则包括：氯丹（α+γ型）、总滴滴涕类（6种异构体——o,p'-DDT、o,p'-DDD、o,p'-DDE以及p,p'-DDT、p,p'-DDD、p,p'-DDE）、42种多氯联苯（Polychlorinated Biphenyl, PCB）同系物、24种多环芳烃（Polynuclear Aromatic Hydrocarbons, PAHs）以及C10~C14直链烷基苯（Linear Alkylbenzenes, LABs）。除沉积物样品外，科研人员还对代表132个点位的275份复合底层鱼类组织样品开展了氯丹、滴滴涕类以及多氯联苯的分析，另有对应147份复合样品（覆盖132个点位）的沉积物化学数据可用于比对分析。墨西哥海域的沉积物样品仅开展了更少种类的污染物检测，未涵盖总有机碳（TOC）、总氮（TN）、锑、砷、钡、汞及硒。科研人员基于分层尺度，采用面积加权均值、中位数及置信区间对沉积物数据开展评估；通过铁归一化法甄别出高于背景值的站位及海湾区域。科研人员采用主成分分析（Principal Component Analysis, PCA），探究了不同站位间污染物类型与浓度的关联特征。将沉积物中有机污染物的浓度与人类P450报告基因系统（P450 Human Reporter Gene System, P450 HRGS）生物检测法、美国环境保护署新版方法4425（EPA Method 4425）的响应结果进行对比分析，以评估其作为污染沉积物筛查工具的应用效能。本研究结合效应中值商（ERM Quotient）与平衡分配法，评估了受人为污染影响的南加利福尼亚湾（Southern California Bight, SCB）受影响占比。