a study of the temporal variability of atrazine in private well water. part i: study design, implementation, and database development

In 1988, the Iowa Department of Natural Resources, along withthe University of Iowa conducted the Statewide Rural WellWater Survey, commonly known as SWRL. A total of 686private rural drinking water wells was selected by use of aprobability sample and tested for pesticides and nitrates. Sixty-eight of these wells, the 10% repeat wells, were additionallysampled in October, 1990 and June, 1991. Starting inNovember, 1991, the University of Iowa, with sponsorshipfrom the United States Environmental Protection Agency,revisited these wells to begin a study of the temporalvariability of atrazine and nitrates in wells. Other wells, whichhad originally tested positive for atrazine in SWRL but werenot in the 10% repeat population, were added to the studypopulation. Temporal sampling for a year-long period beganin February of 1992 and concluded in January of 1993. Allwells were sampled monthly, one subset was sampled weekly,and a second subset was sampled for 14-day consecutiveperiods. Two unique aspects of this study were the use of animmunoassay technique to screen for triazines before gaschromatography/mass spectrometry (GC/MS) analysis andquantification of atrazine, and the use of well owners to samplethe wells. A total of 1771 samples from 83 wells are in thefinal data base for this study. This paper reviews the studydesign, the analytical methodologies, and development of thedata base. A companion paper (Pinsky et al., 1997) discussesthe analysis of the data from this survey.     

Environmental impact assessment: National approaches and international needs

This paper examines the spread and development of ‘environmental impact assessment’ (EIA) since the enactment of the U.S. Environmental Policy Act on January 1, 1970, which established for the first time under any jurisdiction the formal requirement that an EIA be made and that an ‘environmental impact statement’ (EIS) be filed prior to implementation of certain major development projects. The paper is divided into three parts. In the first part, we briefly review the forms of EIA introduced in the western industrial countries and contrast these with developments in the socialist countries of Eastern Europe, and in the Third World. The approaches to EIA adopted by five countries — the United States, Australia, Canada, the Federal Republic of Germany, and the Soviet Union — are used to illustrate the types of national approaches that have been followed. In the second part of the paper, we use some questions raised by impact assessments as codified in legislation or regulations at the national level to highlight some of the limitations of impact assessment. Finally, we turn to international impact assessments and describe the modest progress made to date. Key impediments to the development of appropriate conceptual and institutional frameworks and methodologies for international EIAs are noted. In conclusion, we offer some suggestions about needed actions at both the national and international levels.     

Seasonal and annual dynamics of harmful algae and algal toxins revealed through weekly monitoring at two coastal ocean sites off southern California, USA

Reports of toxic harmful algal blooms (HABs) attributed to the diatom Pseudo-nitzschia spp. have been increasing in California during the last several decades. Whether this increase can be attributed to enhanced awareness and monitoring or to a dramatic upswing in the development of HAB events remains unresolved. Given these uncertainties, the ability to accurately and rapidly identify an emerging HAB event is of high importance. Monitoring of HAB species and other pertinent chemical/physical parameters at two piers in southern California, Newport and Redondo Beach, was used to investigate the development of a site-specific bloom definition for identifying emerging domoic acid (DA) events. Emphasis was given to abundances of the Pseudo-nitzschia seriata size category of Pseudo-nitzschia due to the prevalence of this size class in the region. P. seriata bloom thresholds were established for each location based on deviations from their respective long-term mean abundances, allowing the identification of major and minor blooms. Sixty-five percent of blooms identified at Newport Beach coincided with measurable DA concentrations, while 36 % of blooms at Redondo Beach coincided with measurable DA. Bloom definitions allowed for increased specificity in multiple regression analysis of environmental forcing factors significant to the presence of DA and P. seriata. The strongest relationship identified was between P. seriata abundances 2 weeks following upwelling events at Newport Beach.     

Impact of microphytobenthos on the sediment biogeochemical cycles: A modeling approach

In marine biogeochemical modeling, the sediment is usually represented by diagenetic models, but in shallow ecosystems these models are incomplete, because they do not take into account the benthic primary production. While microphytobenthos (MPB) is known to strongly impact mineralization pathways and nutrient fluxes, MPB is rarely integrated as an explicit variable. To investigate the impact of microphytobenthos on early diagenesis in sediment, we built a fine-scale dynamic model, based on the diagenetic model OMEXDIA and including MPB and associated processes. The model outputs were similar to a data set of MPB-colonized sediment sampled in Florida Bay, suggesting that the model can recreate a realistic situation. The model showed that MPB activities induced a strong diurnal rhythm on concentration profiles, fluxes, and mineralization processes. When MPB was present at the sediment surface, the total mineralization was strongly enhanced thanks to the supply of labile organic matter. In contrast, coupled nitrification–denitrification was inhibited by a factor of 3.8. This inhibition can be explained by the competition for nitrate and ammonium between MPB and bacteria. Nitrogen uptake of MPB represented 96% of the daily supply of dissolved inorganic nitrogen. This was more than 50 times greater than N consumption by denitrification. With MPB, sediment nitrogen flux to the water column was reduced by a factor of 70, suggesting that sediment colonized by MPB represents a minor source of nutrients for phytoplankton and bacterioplankton. Results showed that current diagenetic models are not well-suited for shallow ecosystems with significant MPB primary production.     

Modeling China's semiconductor industry fluorinated compound emissions and drafting a roadmap for climate protection

Fluorinated compounds (FC) are high-global warming potential (GWP) greenhouse gases used and emitted during the manufacture of silicon semiconductor devices. Following the U.S. EPA's PFC Emissions Vintage Model (PEVM), uncontrolled FC emissions are modeled as proportional to total manufactured layer area (TMLA) of silicon. FC emissions of World Semiconductor Council (WSC) charter member countries (Europe, Japan, Korea, Taiwan and the United States), which voluntarily committed in 1999 to lower FC emissions by 2010 to 10% of baseline year emissions, are modeled for the period 1995–2020. For this same period, emissions from Chinese manufacturers under alternative emission reduction scenarios are modeled. If Chinese manufacturers were to adopt a baseline year of 2005 and a reduction target of 10% below baseline year emissions to be achieved by 2020, emissions would be 3.4 MMTCO₂eq, comparable to the similarly projected controlled emissions of an average WSC charter member country (=16.3/5 MMTCO₂eq) in 2020. The relative stringency of the alternative reduction scenarios considered for China vary between 50 and 95% reduction compared to business as usual (BAU). This is comparable to the stringency of the WSC charter members’ goals for which FC emission reduction technologies are currently available.     

Acute O 3 damage on first year coppice sprouts of aspen and maple sprouts in an open-air experiment

We studied the effect of high ozone (O(3)) concentration (110-490 nmol mol(-1)) on regenerating aspen (Populus tremuloides) and maple (Acer saccharum) trees at an open-air O(3) pollution experiment near Rhinelander WI USA. This study is the first of its kind to examine the effects of acute O(3) exposure on aspen and maple sprouts after the parent trees, which were grown under elevated O(3) and/or CO(2) for 12 years, were harvested. Acute O(3) damage was not uniform within the crowns of aspen suckers; it was most severe in the mature, fully expanded photosynthesizing leaves. Young expanding leaves showed no visible signs of acute O(3) damage contrary to expectations. Stomatal conductance played a primary role in the severity of acute O(3) damage as it directly controlled O(3) uptake. Maple sprouts, which had lower stomatal conductance, smaller stomatal aperture, higher stomatal density and larger leaf surface area, were tolerant of acute O(3) exposure. Moreover, elevated CO(2) did not ameliorate the adverse effects of acute O(3) dose on aspen and maple sprouts, in contrast to its ability to counteract the effects of long-term chronic exposure to lower O(3) levels.     

Evaluation of high volume particle sampling and sample handling protocols for ambient urban air mutagenicity determinations.

An investigation of high volume particle sampling and sample handling procedures was undertaken to evaluate variations of protocols being used by the U.S. Environmental Protection Agency. These protocols are used in urban ambient air studies which collect ambient and source samples for subsequent mutagenicity analysis of the organic extracts of the aerosol fraction. Specific protocol issues investigated include: (a) duration of sampling period, (b) type of filter media used to collect air particles, (c) necessity for cryogenic field site storage and dry ice shipping of filter samples, and (d) sample handling at the receiving laboratory. Six PM10 Hi-Vol samplers were collocated at an urban site in downtown Durham, North Carolina and operated simultaneously to evaluate 12 h versus 24 h collection periods and filter media choices of glass fiber, Teflon impregnated glass fiber (TIGF), and quartz fiber. Filters from the samplers plus field blanks were collected during each of 25 sampling periods. TIGF filters from two samplers were immediately placed on dry ice in the field and transported directly to cryogenic storage. TIGF, quartz, and glass fiber filters from three samplers were transported at ambient and maintained at room temperature for three to six days prior to cryogenic storage. One TIGF sample, which was collected on a previously tared filter, was subjected to controlled environment equilibration (40 percent relative humidity, 22 degrees C) for 8 to 24 h and weighed prior to cryogenic storage. All filters were subsequently stored at -70 degrees C to -80 degrees C prior to a one-time extraction and Salmonella (Ames) mutagenicity bioassay of the entire sample set.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dimethylsulfide and the algaPhaeocystis pouchetii in antarctic coastal waters

The concentrations of dimethylsulfide (DMS), dimethylsulfoniopropionate (DMSP) and dimethylsulfoxide (DMSO) were measured in water collected from the Southern Ocean 10 km offshore from Davis Station, Antarctica, during the period May 1987 to January 1988, inclusive. During winter and spring, when the sea-ice was up to 1.9 m thick, DMS, DMSP and DMSO concentrations were low (0.2 to 1.5 nM), as were phytoplankton numbers. The maximum concentration of the sulfur compounds generally occurred in the top 10 m of the water column. DMS levels rose dramatically from early December onwards, reaching a peak of 290 nM at a depth of 15 m in January. This concentration is higher than reported elsewhere in the ocean. These high concentrations occurred at the same time as a bloom of the algaPhaeocystis pouchetii. A significant correlation occurred between DMS concentration and cell numbers of the alga. The ratio of DMS concentration to the number of cells of the alga was considerably higher than reported for blooms of this species elsewhere in the ocean. Up to 10% of the total global flux of DMS to the atmosphere may emanate from antarctic seas.     

添加玉米秸秆对绿花菜尾菜堆肥植物毒性的影响

为揭示不同比例作物秸秆和蔬菜尾菜堆肥过程中种子毒性变化及其影响机理,开展了为期55 d的以玉米（Zea mays L.）秸秆为辅料,绿花菜（Brassica oleracea L.var.botrytis L.）尾菜为主料的工厂化条垛堆肥,分别设置加入高（湿重比4∶12）和低（湿重比1∶12）比例秸秆与尾菜的堆肥处理.测定了不同时期堆肥p H、电导率（EC）、可溶性有机碳（DOC）、硝氮（NO₃^--N）、氨氮（NH₄⁺-N）、碳氮比（C/N）、大白菜种子（Brassica rapa L.）的发芽指数（Germination Index,GI）、相对生长指数（Relative Growth Index,RGI）和α-淀粉酶、蛋白酶、脂肪酶的变化.结果表明,高比例秸秆堆肥处理的高温（>55℃）持续期显著高于低比例处理.堆肥结束时两个处理的堆肥均呈碱性,且EC、DOC、NH₄⁺-N和NO₃^--N含量均降低,C/N...     

The importance of considering multiple interacting species for conservation of species at risk

Conservation of species at risk of extinction is complex and multifaceted. However, mitigation strategies are typically narrow in scope, an artifact of conservation research that is often limited to a single species or stressor. Knowledge of an entire community of strongly interacting species would greatly enhance the comprehensiveness and effectiveness of conservation decisions. We investigated how camera trapping and spatial count models, an extension of spatial-recapture models for unmarked populations, can accomplish this through a case study of threatened boreal woodland caribou (Rangifer tarandus caribou). Population declines in caribou are precipitous and well documented, but recovery strategies focus heavily on control of wolves (Canis lupus) and pay less attention to other known predators and apparent competitors. Obtaining necessary data on multispecies densities has been difficult. We used spatial count models to concurrently estimate densities of caribou, their predators (wolf, black bear [Ursus americanus], and coyote [Canis latrans]), and alternative prey (moose [Alces alces] and white-tailed deer [Odocoileus virginianus]) from a camera-trap array in a highly disturbed landscape within northern Alberta's Oil Sands Region. Median densities were 0.22 caribous (95% Bayesian credible interval [BCI] = 0.08–0.65), 0.77 wolves (95% BCI = 0.26–2.67), 2.39 moose (95% BCI = 0.56–7.00), 2.64 coyotes (95% BCI = 0.45–6.68), and 3.63 black bears (95% BCI = 1.25–8.52) per 100 km². (The white-tailed deer model did not converge.) Although wolf densities were higher than densities recommended for caribou conservation, we suggest the markedly higher black bear and coyote densities may be of greater concern, especially if government wolf control further releases these species. Caribou conservation with a singular focus on wolf control may leave caribou vulnerable to other predators. We recommend a broader focus on the interacting species within a community when conserving species.