Dissipation of Contaminants of Emerging Concern in Biosolids Applied to Nonirrigated Farmland in Eastern Colorado

In 2007, a 1.5‐year field‐scale study was initiated by the U.S. Geological Survey to evaluate the dissipation of contaminants of emerging concern (CECs) following a first agronomic biosolids application to nonirrigated farmland. CECs with the greatest decrease in concentration in the surface biosolids at 180 days post‐application included indole, d‐limonene, p‐cresol, phenol, and skatol. CECs that were present in the largest concentration in 180‐day‐weathered biosolids included stanols, nonylphenols, bisphenol A, bis(2‐ethylhexyl) phthalate, hexahydrohexamethyl cyclopenta‐benzopyran (HHCB), and triclosan. CECs that were detected in pre‐application soil were 3‐beta coprostanol, skatol, acetophenone, beta‐sitosterol, beta‐stigmastanol, cholesterol, indole, p‐cresol, and phenol, most of which are biogenic sterols or fragrances that have natural plant sources in addition to anthropogenic sources, yet their concentrations increased (in some cases, substantially) following biosolids application. Preliminary data indicate the nonylphenols (including NPEO1, NPEO2), OPEO1, benzo[a]pyrene, diethyl phthalate, d‐limonene, HHCB, triclosan, and possibly 3‐beta coprostanol, skatol, beta‐sitosterol, cholesterol, indole, and p‐cresol, migrated downward through the soil by 468 days post‐application, but indicated little uptake by mature wheat plants. This study indicates that some CECs are sufficiently persistent and mobile to be vertically transported into the soil column following biosolids applications to the land surface, even in semiarid regions.     

Large Biases in Regression‐Based Constituent Flux Estimates: Causes and Diagnostic Tools

It has been documented in the literature that, in some cases, widely used regression‐based models can produce severely biased estimates of long‐term mean river fluxes of various constituents. These models, estimated using sample values of concentration, discharge, and date, are used to compute estimated fluxes for a multiyear period at a daily time step. This study compares results of the LOADEST seven‐parameter model, LOADEST five‐parameter model, and the Weighted Regressions on Time, Discharge, and Season (WRTDS) model using subsampling of six very large datasets to better understand this bias problem. This analysis considers sample datasets for dissolved nitrate and total phosphorus. The results show that LOADEST‐7 and LOADEST‐5, although they often produce very nearly unbiased results, can produce highly biased results. This study identifies three conditions that can give rise to these severe biases: (1) lack of fit of the log of concentration vs. log discharge relationship, (2) substantial differences in the shape of this relationship across seasons, and (3) severely heteroscedastic residuals. The WRTDS model is more resistant to the bias problem than the LOADEST models but is not immune to them. Understanding the causes of the bias problem is crucial to selecting an appropriate method for flux computations. Diagnostic tools for identifying the potential for bias problems are introduced, and strategies for resolving bias problems are described.     

Enzymatic and microbial transformation assays for the evaluation of the environmental fate of diclofenac and its metabolites

Diclofenac has been of environmental concern due to the potential harmful effects on non-target organisms at environmentally relevant concentrations. In this study, we evaluated the transformation kinetics of diclofenac and its two major metabolites in two laboratory-scale experiments: the transformation of diclofenac in the presence of rat liver S9 fraction with co-factors, and the transformation of diclofenac, 4′-hydroxy-diclofenac and diclofenac β-O-acyl glucuronide in the inoculum used for the OECD 301C ready-biodegradability test. 4′-Hydroxy-diclofenac was identified as the major phase I metabolite and diclofenac β-O-acyl glucuronide was identified as the major phase II metabolite in the S9 assay. Transformation of diclofenac in the microbial degradation test did not occur significantly for 28 d, whereas 4′-hydroxy-diclofenac degraded slowly, indicating that the biological removal of diclofenac is not likely to occur in conventional STPs unless sorptive removal is significant. However, diclofenac β-O-acyl glucuronide deconjugated to form equimolar diclofenac within 7 d, in the microbial degradation test. The mixture of diclofenac and its two metabolites, formed after incubating diclofenac in S9 medium for 2 h, was spiked in the inoculum to link both assays. The concentrations of diclofenac and its metabolites, measured over time, agreed well with predicted values, using rate parameters obtained from independent experiments. The results show that phase II metabolites generated in mammals may deconjugate easily in conventional STPs to form a parent compound and that these processes should be considered during the environmental monitoring and risk assessment of diclofenac.     

Effects of Land Use and Sample Location on Nitrate‐Stream Flow Hysteresis Descriptors during Storm Events

The U.S. Geological Survey's New Jersey and Iowa Water Science Centers deployed ultraviolet‐visible spectrophotometric sensors at water‐quality monitoring sites on the Passaic and Pompton Rivers at Two Bridges, New Jersey, on Toms River at Toms River, New Jersey, and on the North Raccoon River near Jefferson, Iowa to continuously measure in‐stream nitrate plus nitrite as nitrogen (NO₃ + NO₂) concentrations in conjunction with continuous stream flow measurements. Statistical analysis of NO₃ + NO₂ vs. stream discharge during storm events found statistically significant links between land use types and sampling site with the normalized area and rotational direction of NO₃ + NO₂‐stream discharge (N‐Q) hysteresis patterns. Statistically significant relations were also found between the normalized area of a hysteresis pattern and several flow parameters as well as the normalized area adjusted for rotational direction and minimum NO₃ + NO₂ concentrations. The mean normalized hysteresis area for forested land use was smaller than that of urban and agricultural land uses. The hysteresis rotational direction of the agricultural land use was opposite of that of the urban and undeveloped land uses. An r² of 0.81 for the relation between the minimum normalized NO₃ + NO₂ concentration during a storm vs. the normalized NO₃ + NO₂ concentration at peak flow suggested that dilution was the dominant process controlling NO₃ + NO₂ concentrations over the course of most storm events.     

Modeling the Highly Dynamic Loading of Mercury Species in the Carson River and Lahontan Reservoir System,Nevada

The semiarid Carson River — Lahontan Reservoir system in Nevada, United States is highly contaminated with mercury (Hg) from historic mining with contamination dispersed throughout channel and floodplain deposits. Work builds on previous research using a fully dynamic numerical model to outline a complete conceptualization of the system that includes transport and fate of both sorbed and dissolved constituents. Flow regimes are defined to capture significant mechanisms of Hg loading that include diffusion, channel pore water advective flux, bank erosion, and overbank deposition. Advective flux of pore water is required to reduce dilution and likely represents colloidal‐mediated transport. Fluvial concentrations span several orders of magnitude with spatial and temporal trends simulated within 10‐24% error for all modeled species. Over the simulation period, 1991‐2008, simulated loads are 582 kg/yr (THg²⁺), 4.72 kg/yr (DHg²⁺), 0.54 kg/yr (TMeHg), and 0.07 kg/yr (DMeHg) with bank erosion processes the principal mechanism of loading for both total and dissolved species. Prediction error in the reservoir is within one‐order of magnitude and considered qualitative; however, simulated results indicate internal cycling within the receiving reservoir accounts for only 1% of the reservoir's water column contamination, with river channel sediment sources more influential in the upper reservoir and bank erosion processes having greater influence in the lower reservoir.     

上海城区多环芳烃的多介质归趋模拟研究

利用城市多介质逸度模型模拟了稳态假设下上海城区16种PAHs在大气、水体、沉积物和植物等中的浓度分布,与实测值进行对比,并根据模拟结果计算了相间迁移通量.结果表明,大气直接排放输入是PAHs进入环境的主要途径,迁移过程包括扩散、沉降和侵蚀等,平流输出是其在系统中损失的主要途径;土壤和沉积物是PAHs主要的汇(占94.4%),其在不透水层上覆盖的膜中浓度达到最大(156g/m3),PAHs在沉积物和土壤中停留时间最长;随着环数的增加, PAHs在水体、植被和土壤中的降解损失所占比例从2.3%逐渐增加至48.9%,而在大气中的降解损失则从91.5%减少至4.0%.模型计算浓度与实测浓度吻合较好,验证了模型的可靠性,并通过灵敏度分析,确定了模型的关键参数.     

化学物质水体归趋与影响数据库(CAFE)，一种用于评估水环境中化学物质溢出水平的工具

化学物质水体归趋与影响 (简称CAFE)数据库是一个允许快速并无限制访问数据的集中式数据库。CAFE将现有的32 377种化学物质的归趋数据和4 498种化学物质的毒性效果数据整合至用户友好的工具中,以物种敏感度分布(SSD)的形式总结毒性数据,并提供了相关的1%和5%危害浓度(HC₁和HC₅)。为探究CAFE数据与报道的化学事故之间的联系,一项数据可用性评估显示,2000年至2014年间在美国国家应急中心呈报的55种化学物质中,32种物质的归趋和20种物质的毒性在CAFE中均有记录;2003年至2014年间由美国海洋及大气管理局呈报的205种化学物质中,86种物质的归趋和103种物质的毒性在CAFE中也均有记录。我们假设2种化学物质在环境中溢出(丙烯腈,溢出量为625桶 ;变性乙醇,溢出量为857桶),根据模型对其环境浓度进行模拟,进而说明CAFE在实际中的应用。在24 h时程的SSD中,大多数物种很可能分别在溢出后最初的35 min内和15 h内受到丙烯腈和变性酒精的影响。丙烯腈浓度在溢出后45 min已低于HC₅(17 mg?L^L-1),变性酒精浓度在溢出后60 h已低于HC₅(2 676 mg?L^L-1)。将100种化学物质以CAFE数据为基础得出的HC₅与发表的HC₅进行对比,我们发现超过一半的数值都在2倍差异以内,较少的一部分数值则超过了10倍差异。CAFE的发展提高了获取相关环境信息的能力,并可能应用于水体环境污染物溢出分析之外的更多领域。
精选自Adriana C. Bejarano, James K. Farr, Polly Jenne, Valerie Chu, Al Hielscher. The chemical aquatic fate and effects database (CAFE), a tool that supports assessments of chemical spills in aquatic environments. Environmental Toxicology and Chemistry: Volume 35, Issue 7, pages 1576–1586, July 2016. DOI: 10.1002/etc.3289
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3289/full
     

巢湖生态系统中微量有机污染物的研究进展

本文综述了目前巢湖生态系统中微量有机污染物研究的主要进展。巢湖微量有机污染物研究起步较晚,但发展较快。目前已研究的微量有机污染物包括有机氯农药、多氯联苯、多环芳烃、多溴联苯醚、邻苯二甲酸酯、全氟烷基酸类物质、四溴双酚A、抗生素和有机磷农药。研究内容主要包括水、大气、降尘、沉积物、悬浮物、水生生物等多介质分布、来源解析、跨界面迁移、归趋模拟与风险评估等方面。期望本文的综述,可以为巢湖微量有机污染物风险管理和水质改善提供重要决策支撑,对于在其他湖泊开展此类研究有所裨益。     

A fate constant data program

A program for compiling equilibrium and kinetic constants for predicting chemical transport and transformation in the environment is described. The fate constant data are obtained by searching the literature for reported measurements, by convening a panel of experts to postulate transformation pathways and products, by using computational techniques to estimate values, and by performing laboratory studies when measurements cannot be found or computed. Emphasis is placed throughout the program on quality control features to assure the reliability of the data.     

Multi‐phase non‐steady state equilibrium model for evaluation of environmental fate of organic chemicals

A simple mathematical fate model, Multi‐Phase Non‐Steady State Equilibrium Model (MNSEM) is proposed to evaluate distribution, persistence, and concentrations of chemicals in a model environment consisting of air, water, soil and sediment phases. The model is applied to evaluation of environmental fate and concentration of trichloroethylene and 1,4‐dichlorobenzene under generic conditions representative of Japan.

Evaluated chemical concentrations in air are within a factor of 3 of average values in Japanese atmosphere, and evaluated concentrations in water, sediment, or fish are greater than an order of magnitude below detection limits in real environments, so that evaluated concentrations are in reasonable agreement with environmental measurement data in Japan.

Although MNSEM is not a model for site‐specific evaluation of environmental fate, results suggested that this model is an adequate method to aid in evaluation of fate of chemicals under generic environment conditions. Evaluated concentration‐profiles may be used to estimate average chemical exposure concentrations for humans and the environment.