A statistical analysis of visibility-impairing particles in federal Class I areas

It is widely agreed that visibility conditions in many Class I areas are impaired to some extent. This paper provides an estimate of the degree of impairment in many of the Class I areas with respect to each of the six haze-forming aerosol classes as described in the supporting documents to the U.S. Environmental Protection Agency Regional Haze Rule. Analyses are performed comparing data from the Interagency Monitoring of Protected Visual Environments network to a modified version of the default natural conditions estimates from the Regional Haze Rule. Uncertainties in the measured annual mean concentrations and biases in the default natural condition estimates because of the effects of geography and meteorology are discussed. It is determined that all of the Class I areas in the contiguous 48 United States are significantly impaired with respect to sulfate aerosols, most of the Class I areas are significantly impaired with respect to nitrate and elemental carbon aerosols, and impairment with respect to organic mass, soil mass, and coarse mass is generally less discernable. No attempt is made to determine adverse impacts with respect to any specific source or group of sources.     

A synoptic survey of select wastewater-tracer compounds and the pesticide imidacloprid in Florida’s ambient freshwaters

Current wastewater treatment technologies do not remove many unregulated hydrophilic compounds, and there is growing interest that low levels of these compounds, referred to as emerging contaminants, may impact human health and the environment. A probabilistic-designed monitoring network was employed to infer the extent of Florida’s ambient freshwaters containing the wastewater (Includes reuse water, septic systems leachate, and wastewater treatment effluent.) indicators sucralose, acetaminophen, carbamazepine, and primidone and those containing the widely used pesticide imidacloprid. Extent estimates with 95% confidence bounds are provided for canals, rivers, streams, small and large lakes, and unconfined aquifers containing ultra-trace concentrations of these compounds as based on analyses of 2015 sample surveys utilizing 528 sites. Sucralose is estimated to occur in greater than 50% of the canal, river, stream, and large lake resource extents. The pharmaceuticals acetaminophen, carbamazepine, and primidone are most prevalent in rivers, with approximately 30% of river kilometers estimated to contain at least one of these compounds. Imidacloprid is estimated to occur in 50% or greater of the canal and river resource extents, and it is the only compound found to exceed published toxicity or environmental effects standards. Geospatial analyses show sucralose detection frequencies within Florida’s drainage basins to be significantly related to the percentage of urban land use (R²?=?0.36, p?<?0.001), and imidacloprid detection frequencies to be significantly related to the percentage of urban and agricultural land use (R²?=?0.47, p?<?0.001). The extent of the presence of these compounds highlights the need for additional emerging contaminant studies especially those examining effects on aquatic biota.     

Desorption of arsenic from drinking water distribution system solids

Previous work has shown that arsenic can accumulate in drinking water distribution system (DWDS) solids (Lytle et~al., 2004) when arsenic is present in the water. The release of arsenic back into the water through particulate transport and/or chemical release (e.g. desorption, dissolution) could result in elevated arsenic levels at the consumers' tap. The primary objective of this work was to examine the impact of pH and orthophosphate on the chemical release (i.e. desorption) of arsenic from nine DWDS solids collected from utilities located in the Midwest. Arsenic release comparisons were based on the examination of arsenic and other water quality parameters in leach water after contact with the solids over the course of 168~hours. Results showed that arsenic was released from solids and suggested that arsenic release was a result of desorption rather than dissolution. Arsenic release generally increased with increasing initial arsenic concentration in the solid and increasing pH levels (in the test range of 7 to 9). Finally, orthophosphate (3 and 5 mg PO₄/L) increased arsenic release at all pH values examined. Based on the study results, utilities with measurable levels of arsenic present in their water should be aware that some water quality changes can cause arsenic release in the DWDS potentially resulting in elevated levels at the consumer's tap.     

Evidence of enhanced atmospheric ammoniacal nitrogen in Hells Canyon national recreation area: implications for natural and cultural resources

Agriculture releases copious fertilizing pollutants to air sheds and waterways of the northwestern United States. To evaluate threats to natural resources and historic rock paintings in remote Hells Canyon, Oregon and Idaho, deposition of ammonia (NH3), nitrogen oxides (NOx), sulfur dioxide (SO2), and hydrogen sulfide (H2S) at five stations along 60 km of the Snake River valley floor were passively sampled from July 2002 through June 2003, and ozone data and particulate chemistry were obtained from the Interagency Monitoring of Protected Visual Environments (IMPROVE) station at Hells Canyon. NH3 concentrations were high; biweekly averages peaked at 5-19 ppb in spring and summer and the nutrient-laden Snake River is a likely source. Fine particulate ammonium nitrate (NH4NO3) averaged 2.6 microg/m3 during the 20% of worst visibility days with winter drainage of air masses from the Snake River Basin and possibly long distance transport from southern California. Other pollutants were within background ranges. NH3 is corrosive to clay-based pictographs; nitrogen deposition can alter natural biotic communities and terrestrial ecosystem processes at levels reported here.     

生物炭与土壤调理剂对滨海荒芜重盐碱地的改良效应

以土壤改良剂对荒芜重盐碱地生物改良和开发利用为研究目标,在华北低平原区滨海荒芜重盐碱地开展了施用生物炭（B）和调理剂（C）种植先锋作物油葵的大田试验.生物炭用量设2个水平（0和1.25 kg ·m^-2）调理剂施用量设3个水平,分别为0、0.83和1.66 kg ·m^-2,共6个处理.油葵收获后按照每30 cm一层采至90 cm搜集土样.结果表明,施用生物炭提高0~30 cm和60~90 cm土层含盐量,而土壤调理剂则显著降低0~30 cm土壤含盐量.没有发现生物炭或调理剂对土壤pH有显著影响.生物炭处理显著抑制土壤硝化作用,导致0~90 cm土层NO₃^--N含量显著下降,NH₄⁺-N含量提高,对有机质（SOM）含量没有显著影响.施用土壤调理剂提高0~30 cm土壤SOM含量,调理剂施用量为1.66 kg ·m^-2时0~90 cm土层的NO₃^--N含量显著增加.单施生物炭与调理剂或者二者组合均显著增加0~90 cm土壤NH₄⁺-N含量、有效磷（Olsen-P）含量和有效钾（K_ex）含量,但生物炭对这3种养分含量的提升效果更显著,土壤调理剂则在增加0~30 cm土壤有机质和降盐方面更有效.施用高量调理剂促进土壤硝化作用,而施用生物炭恰恰起到硝化抑制剂的作用,因此,将生物炭与土壤调理剂结合施用,是滨海荒芜重盐碱地防止NO₃^--N淋失、减少环境污染、增肥降盐并保障耐盐先锋作物高肥低盐生长环境的有效措施.     

Marine habitat mapping in support of Marine Protected Area management in a subarctic fjord: Gilbert Bay, Labrador, Canada

This paper presents an approach that allows production of benthic substrate and habitat maps in fjord environments. This approach is used to support the management of the Gilbert Bay Marine Protected Area (MPA) in southeastern Labrador, Atlantic Canada. Multibeam sonar-derived bathymetry, seabed slope, and acoustic reflectance (backscatter) were combined using supervised classification methods and GIS with ground-truthed benthic sampling in order to derive maps of the substrates and main benthic habitats. Six acoustically distinct substrate types were identified in the fjord, and three additional substrate types without a unique acoustic signature were recognized. Ordination by multidimensional scaling and analysis of similarity generalized these to four acoustically distinct habitat types. Greatest within-habitat (alpha) diversity was found in the coralline-algae encrusted gravel habitat. Greatest between-habitat (beta) diversity was found in the management Zones 1 and 2, which have the highest level of protection. The study confirmed that the zoning plan for the MPA, which was designed to protect spawning and juvenile fish habitat for a local genetically distinct population of Atlantic cod, afforded highest levels of protection to areas with highest habitat diversity.     

黄河包头段不同粒径沉积物分形校正下重金属的吸附研究

推导了分粒级的表面分形维数计算公式,根据推导公式计算了分粒级沉积物的分维值.应用已有的表面分形分维计算公式分别计算了黄河包头段沉积物整体的表面分形分维(1.91)及＜63 μm粒级的分维值(1.36),揭示出黄河水环境的磨蚀和分选2个原因引起黄河包头段沉积物低的分维值.用分形校正吸附模型、Freundlich和Langmuir吸附模型对黄河包头段重金属分粒级沉积物吸附进行了拟合,表明分形校正吸附模型具有较好的适用性,同时揭示分形校正吸附模型与MEA理论结合能更好的对热力学吸附结果进行描述;由吸附结果分析得出4种重金属因粒径引起的吸附量变化程度序列为Cu＞Pb＞Zn≈Cd,初始浓度高的吸附量曲线变化较初始浓度低的曲线变化明显,同时指出Cu、Pb的吸附主要与矿物组成有关,而Zn、Cd的吸附则与吸附剂沉积物空间几何性质(或沉积物表面物理特征)有关.     

宁夏生态移民社区生活空间融合与重构的影响因素及机理——以宁夏闽宁镇为例

生态移民的空间位移引致了迁入区多因素的相互作用及长期演化,成为多学科深入探究的重要问题之一。以闽宁镇生态移民社区为例,采用主成分分析法和地理探测器分析法,对生态移民社区生活空间融合的影响因素和机理进行了研究,结果发现：（1）生态移民社区生活空间融合与重构受多种因素影响,生活基础设施、经济收入增长、移民社区环境、邻里关系、政府政策、民族生活六个主成分对生态移民社区生活空间融合的影响可以起到解释作用。（2）影响生态移民社区生活空间的因子解释力由强到弱依次排序为：X₁生活基础设施>X₂经济收入增长>X₃邻里关系>X₄政府政策>X₅民族生活>X₆移民社区环境;交互探测结果表明社区各要素因子交互后因子解释力呈双线性增强,即任意两个因子交互作用对于生态移民社区生活空间融合的影响强度都大于单个因子的独自作用强度。（3）各影响因素之间的互动影响,共同促进生态移民社区固有的生活方式、文化习惯、社会交往关系的演化,进而形成了生活空间的融合与重构。     

Using risk assessment to achieve cost-effective property transfers and site closures for former UST sites

Risk assessment has been increasingly applied as a tool in making risk management decisions that affect cleanup of contaminated sites, property transactions, and liability issues. As a site-specific evaluation, risk assessment takes into account the unique characteristics and intended future uses for site property in evaluating chemical concentrations which may remain in place without risk to public health and the environment. The results of a risk assessment can be used to determine reuse options for a property, facilitate site closure, and reduce liabilities (Copeland and Robles, 1994; Copeland et al., 1993a). This article describes the risk assessment process, the role of risk assessment in determining the need for remedial action and identifying site-specific cleanup goals, and the cost effectiveness of applying risk assessment in remedial decisions. Because of the prevalence of former UST sites throughout the United States, this article focuses on risk assessment and remediation of UST sites. However, the process can be applied at sites where other chemicals have been released. Three case studies are presented to illustrate the application of risk assessment in achieving cost-effective site closure at sites containing leaking underground storage tanks.