Uptake and accumulation of antimicrobials,triclocarban and triclosan,by food crops in a hydroponic system

Commonly used in personal care products, triclocarban (TCC) and triclosan (TCS) are two chemicals with antimicrobial properties that have recently been recognized as environmental contaminants with the potential to adversely affect human health. The objective of the study described herein was to evaluate the potential of food crops to uptake TCC and TCS. Eleven food crops, grown in hydroponic nutrient media, were exposed to a mixture of 500 μg L^?1 TCC and TCS. After 4 weeks of exposure, roots accumulated 86–1,350 mg kg^?1 of antimicrobials and shoots had accumulated 0.33–5.35 mg kg^?1 of antimicrobials. Translocation from roots to shoots was less than 1.9 % for TCC and 3.7 % for TCS, with the greatest translocation for TCC observed for pepper, celery, and asparagus and for TCS observed for cabbage, broccoli, and asparagus. For edible tuber- or bulb-producing crops, the concentrations of both TCC and TCS were lower in the tubers than in the roots. Exposure calculations using national consumption data indicated that the average exposure to TCC and TCS from eating contaminated crops was substantially less than the exposure expected to cause adverse effects, but exceeded the predicted exposure from drinking water. Exposure to antimicrobials through food crops would be substantially reduced through limiting consumption of beets and onions.     

连续流动分析法测定地表水中总氮

采用50 mm流动检测池,建立了连续流动分析法测定地表水中总氮。方法检出限为0.02 mg/L,水样加标回收率为100%~101%,平行样品相对偏差为0.10%~0.27%,精密度(RSD,n=6)为0.72%~1.10%。实验结果表明,该方法准确可靠、灵敏度高、重现性好、分析速度快、操作简便,适用于地表水中总氮的分析。     

Evaluation of the SO2 and NOX offset ratio method to account for secondary PM2.5 formation

The U.S. Environmental Protection Agency (EPA), state and local agencies have focused their efforts in assessing secondary fine particulate matter (aerodynamic diameter ≤2.5 µm; PM_2.5) formation in prevention of significant deterioration (PSD) air dispersion modeling. The National Association of Clean Air Agencies (NACAA) developed a method to account for secondary PM_2.5 formation by using sulfur dioxide (SO₂) and nitrogen oxides (NO_x) offset ratios. These ratios are used to estimate the secondary formation of sulfate and nitrate PM_2.5. These ratios were first introduced by the EPA for nonattainment areas in the Implementation of the New Source Review (NSR) Program for Particulate Matter Less than 2.5 Micrometers (PM_2.5), 73 FR 28321, to offset emission increases of direct PM_2.5 emissions with reductions of PM_2.5 precursors and vice versa. Some regulatory agencies such as the Minnesota Pollution Control Agency (MPCA) have developed area-specific offset ratios for SO₂ and NO_x based on Comprehensive Air Quality Model with Extensions (CAMx) evaluations for air dispersion modeling analyses. The current study evaluates the effect on American Meteorological Society/Environmental Protection Agency Regulatory Model (AERMOD) predicted concentrations from the use of EPA and MPCA developed ratios. The study assesses the effect of these ratios on an electric generating utility (EGU), taconite mine, food processing plant, and a pulp and paper mill. The inputs used for these four scenarios are based on common stack parameters and emissions based on available data. The effect of background concentrations also evaluates these scenarios by presenting results based on uniform annual PM_2.5 background values. This evaluation study helps assess the viability of the offset ratio method developed by NACAA in estimating primary and secondary PM_2.5 concentrations. An alternative Tier 2 approach to combine modeled and monitored concentrations is also presented.

Implications:

On January 4, 2012, the EPA committed to engage in rulemaking to evaluate updates to the Guideline on Air Quality Models (Appendix W of 40 CFR 51) and, as appropriate, incorporate new analytical techniques or models for secondary PM_2.5. As a result, the National Association of Clean Air Agencies (NACAA) developed a screening method involving offset ratios to account for secondary PM_2.5 formation. The use of this method is promising to evaluate total (direct and indirect) PM_2.5 impacts for permitting purposes. Therefore, the evaluation of this method is important to determine its viability for widespread use.     

The deadly effects of "nonlethal" predators

Nonconsumptive predator effects are widespread and include plasticity as well as general stress responses. Caged predators are often used to estimate nonconsumptive effects, and numerous studies have focused on the larval stages of animals with complex life cycles. However, few of these studies test whether nonconsumptive predator effects, including stress responses, are exclusively sublethal. Nor have they assessed whether these effects extend beyond the larval stage, affecting success during stressful life-history transitions such as metamorphosis. We conducted experiments with larvae of a dragonfly (Leucorrhinia intacta) that exhibits predator-induced plasticity to assess whether the mere presence of predators affects larval survivorship, metamorphosis, and adult body size. Larvae exposed to caged predators with no ability to attack them had higher levels of mortality. In the second experiment, larvae reared with caged predators had higher rates of metamorphic failure, but there was no effect on adult body size. Our results suggest that stress responses induced by exposure to predator cues increase the vulnerability of prey to other mortality factors, and that mere exposure to predators can result in significant increases in mortality.     

不同雨强对太湖河网区河道入湖营养盐负荷影响

为揭示太湖河网区不同雨强下入湖河道面源污染规律,以太湖入湖负荷最大的河道大浦河为例,通过一周年逐日高频监测水体各形态氮、磷及溶解性有机碳等营养盐情况,结合河道流量及降雨量的自动监测资料,分析了大雨、中雨、小雨及无雨等4种降雨强度下太湖河网区典型河道的流量和营养盐负荷特征.结果表明,作为太湖河网区的典型入湖河道,大浦河时常发生往复流现象,观测的365 d内,有60 d日均流量为负值,占16%;河道流量对雨强的响应较为迟缓,仅强降雨事件( 25 mm·d~(-1))下,降雨当日河道流量才显著增加;中雨期平均流量仅比无雨期高了29%,在统计上不显著.河道水体营养盐浓度在不同降雨强度下差异不显著,大雨、中雨、小雨及无雨事件下河道总氮浓度分别为(3. 00±0. 58)、(3. 34±0. 93)、(3. 55±1. 05)和(3. 37±1. 14) mg·L~(-1),小雨事件当天水体总氮浓度均值最高,而4种类型降雨事件下河道总磷含量分别为(0. 228±0. 068)、(0. 258±0. 121)、(0. 219±0. 083)和(0. 225±0. 121) mg·L~(-1),差异性也不显著,就平均值而言,中雨时河道总磷浓度最高.夏季典型降雨过程分析表明,不同雨强发生之后河道溶解性有机碳和各形态氮的浓度变化不大,但大雨之后次日河道各形态磷浓度有明显增高,持续时间为2 d,中雨后次日河道总磷和颗粒态磷有明显增高,持续时间仅为1 d,小雨后磷浓度基本无变化.大雨、中雨、小雨和无雨时总氮日负荷分别为7. 64、3. 19、3. 21和2. 62 t·d~(-1),总磷日负荷分别为0. 59、0. 26、0. 22和0. 20 t·d~(-1),受入湖流量影响,大雨期营养盐日负荷显著高于中雨及以下强度的降雨;然而,由于一年内大雨出现频次较少,大雨期氮和磷总入湖负荷占年负荷的比重不大,大雨期总氮和总磷分别入湖61. 11 t和4. 72 t,占观测周年的5. 6%和5. 8%,这与山区河道降雨负荷间的关系有着显著区别.本高频观测表明,太湖流域平原河网区河道面源污染汇集过程复杂,入湖负荷受降雨强度的影响相对较小,入湖水量是营养盐负荷的重要影响因素.本研究结果对太湖流域平原河网区湖泊的面源污染的估算及控制对策的制定具有参考价值.     

A Water Quality Monitoring Network Design Methodology for the Selection of Critical Sampling Points: Part I

The principal instrument to temporally and spatially manage water resources is a water quality monitoring network. However, to date in most cases, there is a clear absence of a concise strategy or methodology for designing monitoring networks, especially when deciding upon the placement of sampling stations. Since water quality monitoring networks can be quite costly, it is very important to properly design the monitoring network so that maximum information extraction can be accomplished, which in turn is vital when informing decision-makers. This paper presents the development of a methodology for identifying the critical sampling locations within a watershed. Hence, it embodies the spatial component in the design of a water quality monitoring network by designating the critical stream locations that should ideally be sampled. For illustration purposes, the methodology focuses on a single contaminant, namely total phosphorus, and is applicable to small, upland, predominantly agricultural-forested watersheds. It takes a number of hydrologic, topographic, soils, vegetative, and land use factors into account. In addition, it includes an economic as well as logistical component in order to approximate the number of sampling points required for a given budget and to only consider the logistically accessible stream reaches in the analysis, respectively. The methodology utilizes a geographic information system (GIS), hydrologic simulation model, and fuzzy logic.     

Spatial variability of sydney air quality by cumulative semivariogram

This paper establishes that an isotropic spatial correlation function in the form of a modified Bessel function of the second kind, first order, can be used to model the spatial variability of a pollution concentration field over a sufficiently long period of time in which the variability due to meteorological factors has been smoothed out. The corresponding cumulative semivariogram is derived and fitted by nonlinear least-squares to monthly averaged ozone data at 18 monitoring stations of the Sydney region. The good fit of the model indicates that the Sydney airshed has homogeneous and isotropic subregions whose radius of influence is about 17 km. The Bessel function form of the spatial correlation has a physical meaning as it is derived from the diffusion equation; hence, it is expected that the model can be used, in general, to represent the spatial variability of a smoothed homogeneous and isotropic concentration field.     

Safeguarding the Pantanal Wetlands: Threats and Conservation Initiatives

Abstract:  The Pantanal, one of the largest wetlands on the planet, comprises 140,000 km² of lowland floodplain of the upper Rio Paraguai basin that drains the Cerrado of central Brazil. The diverse mosaics of habitats resulting from the varied soil types and inundation regimes are responsible for an extraordinarily rich terrestrial and aquatic biota, exemplified by the bird richest wetland in the world—463 birds have been recorded there—and the largest known populations of several threatened mammals, such as Pampas deer ( Ozotoceros bezoarticus ), marsh deer ( Blastocerus dichotomus ), giant otter ( Pteronura brasiliensis ), and jaguar ( Panthera onca ). Until recently, deforestation of the adjoining Brazilian central plateau was considered the major threat to this area, but now deforestation is a critical problem within the floodplain itself. More than 40% of the forest and savanna habitats have been altered for cattle ranching through the introduction of exotic grasses. And there are other threats that lead to large-scale disruption of ecological processes, severely affecting biodiversity. Although the Pantanal wetland is a Biosphere Reserve and is considered a Wetland of International Importance, only 2.5% of the upper Paraguai River basin is formally protected. To date, protected areas have been created opportunistically and as such, although of undoubted value, protect only a fraction of the Pantanal's wildlife and habitats. Among the conservation initiatives in the area, the private sector is increasingly participating in the establishment of private reserves. The prospects are far from optimistic, however, and the major challenge is to find alternative socioeconomic models that allow for conservation and economic uses of the land in association with the development of specific environmental legislation that reflects the unique characteristics of the region.