The application of chemical and biological multi-metric models to a small urban stream for ecological health assessments

Nutrient or/and organic pollutions have been used as one of the key factors influencing the stream health, so research approaches were frequently focused on chemical analysis rather and biological analysis. Our objective of the present study was to diagnose the chemical and biological stream health using chemical multi-metric model of nutrient pollution index (NPI) and biological multi-metric fish model of the index of biotic integrity (IBI), respectively in an urban stream. Seven years dataset from 2008 to 2014 were used for the health assessments. The nutrients regime (TN, TP), sestonic chlorophyll, total suspended solids (TSS), electrical conductivity, BOD, and COD showed a typical polluted stream with large temporal and spatial fluctuations due to variations of Asian monsoon rain. The analysis of fish trophic guilds and fish tolerance guilds showed that omnivore fish species and tolerant species were dominated the community and the proportions were directly determined by water chemistry (nutrient and organic matters). Chemical model of NPI showed “poor-very poor health condition” by the criteria of the model and showed same results with the biological model of fish IBI. The degradation of the stream health was mainly due to massive effluents from the wastewater treatment plants. Overall, our data suggest that the multi-metric chemical and biological models may be used as a key tool diagnosing the stream health condition in an urban stream.     

Aligning indicators of community composition and biogeochemical function in stream monitoring and ecological assessments

Reliable and inexpensive indicators of ecosystem function are essential for accurately monitoring and describing ecosystem integrity. Currently, most state and federal assessments of aquatic ecological integrity rely on structural indicators and assume tight coupling of structure and function. We used fluorescent composition of dissolved organic matter as a metric for certain ecosystem functions and compared the resulting index of autochthonous microbial dissolved organic matter (DOM) to macroinvertebrate indicators and classifications of water quality attainment reported by the Maine Department of Environmental Protection (Maine DEP) at 142 stream sites. We observed that metrics of sensitive insect orders such as relative Plecoptera generic richness, relative Ephemeroptera abundance, and generic richness of EPT (Ephemeroptera, Plecoptera, and Trichoptera) were negatively correlated with higher values of metrics based on autochthonous microbial DOM sources. At the same time we observed an increase in the Hilsenhoff Biotic Index with increasing microbial DOM. We compared the abundance of this microbial DOM component to Maine DEP measured attainment classes and found that microbial DOM generally separated sites with high biological integrity from sites where the biotic community was highly degraded. This highlights that measures of biogeochemical ecosystem function complement measures of structure in biological assessments.     

Reference diatom assemblage response to restoration of an acid mine drainage stream

A prevalent legacy of coal mining within Appalachia and elsewhere is acid mine drainage (AMD), which drastically alters both the chemical and biological components of the receiving waters. Hewett Fork is one such affected stream. Although AMD treatment has reduced acidity considerably downstream, the ability of this stream to sustain a biological community compared to those found in reference conditions remains unclear. To assess this, tiles colonized with diatom assemblages from a reference stream were transplanted into Hewett Fork in 5 locations along a 6.9 km stream length and sampled after one, three, and six weeks. Diatom assemblage structure metrics, including species evenness (J’), species richness (S), relative abundance of dominant taxon, and Shannon diversity (H′), as well as chlorophyll a concentrations, Bray–Curtis dissimilarities, and Acid Mine Drainage Diatom Index of Biotic Integrity (AMD-DIBI) scores were calculated for each site and sampling time. One-way ANOVAs of structural metrics showed significant differences (P ≤ 0.001) between the reference site and the 2nd and 3rd most upstream sites within the study reach for the duration of the study, with the exception of the relative abundance of dominant taxa at an intermediate site during the third week. Conversely, the most downstream Hewett Fork assemblage, located 11.6 km from the primary AMD input, did not differ significantly (P > 0.05) from that of the reference assemblage for any structural metrics after the initial sampling period. Throughout the study, only three sites obtained “good” AMD-DIBI narrative class:the reference site (weeks 1, 3, and 6), the most downstream site (weeks 1, 3, and 6; 11.6 km downstream of primary AMD input) and the uppermost site (weeks 1 and 6; 4.7 km downstream of primary AMD input). Results suggested that after an initial one-week acclimation period, assemblages at the uppermost and most downstream sites along the reach were relatively similar to those found in reference conditions, while sites within the middle region continued to show signs of impairment, although the factor(s) causing this impairment remain unknown. These findings suggest that while treatment has been effective on a site-specific basis, the expected linear-response to treatment was not achieved due to underlying factors that are inhibiting reference-like biological communities from reestablishing within the affected stream reach.     

Bias in the development of health and ecological assessments and potential solutions

The effectiveness and credibility of environmental decisions depend on the information provided by scientific assessments. However, the conflicting assessments provided by government agencies, industries, and environmental advocacy groups suggest that biases occur during assessment processes. Sources of bias include personal bias, regulatory capture, advocacy, reliance on volunteer assessors, biased stakeholder and peer review processes, literature searches, standardization of data, inappropriate standards of proof, misinterpretation, and ambiguity. Assessors can adopt practices to increase objectivity, transparency, and clarity. Decision-makers, managers of assessors, and institutions that commission assessments can adopt other practices that reduce pressures on assessors and reduce opportunities for expression of the personal biases of assessors. Environmental assessment should be recognized as a discipline with its own technical and ethical best practices.     

Organic matter breakdown as a measure of stream health in New Zealand streams affected by acid mine drainage

Functional indicators of stream health have the potential to provide insights into stream condition that cannot be gained by traditional structural indices. We examined breakdown of leaves, wood, and cotton cloth strips at 18 sites along a gradient of effects of drainage from coal mines in New Zealand to determine the usefulness of these methods as functional indicators of stream health. The pH varied from 2.7 to neutral across the streams, and the more acidic streams typically had higher concentrations of aluminum, iron, zinc, and other metal ions. Precipitates of metal (mainly iron) hydroxides were present in most streams affected by mine drainage, especially in those with a pH of 4–5. Breakdown rates of all organic matter types were highest in several reference streams with neutral pH and lowest in sites with high rates of metal hydroxide deposition. Breakdown was relatively fast in the most acidic streams (pH < 3), in some cases as fast as at reference sites; these sites also had elevated nutrient concentrations. Shredding invertebrates were absent in litterbags from acidic streams and common at only 2 reference sites; their presence contributed to fast breakdown of leaves in the field and in lab microcosms. Microbial respiration was closely related to breakdown rates of leaves and wood; it was high at neutral and highly acidic streams, but lower at sites with pH 4–5, where metal hydroxides were precipitating onto solid surfaces. In these metal hydroxide-stressed streams, leaf and wood breakdown was slower, and associated biota, including microbes, were more affected than by water chemistry stressors (pH, dissolved metals) associated with mine drainage. Litter breakdown and microbial respiration provide insight into the functioning of streams, yielding different responses than traditional structural measures based on macroinvertebrates, which did not accurately distinguish impacts from acid mine drainage.     

Evaluation of denitrification in an urban stream receiving wastewater effluent

Urban streams often contain elevated concentrations of nitrogen (N) which can be amplified in systems receiving effluent from wastewater treatment plants (WWTP). In this study, we evaluated the importance of denitrification in a stream draining urban Greensboro, NC, USA, using two approaches: (1) natural abundance of ¹⁵N–NO₃⁻ in conjunction with background NO₃⁻–N concentrations along a 7 km transect downstream of a WWTP; and (2) C₂H₂ block experiments at three sites and at three habitat types within each site. Overall lack of a longitudinal pattern of δ¹⁵N–NO₃⁻ and NO₃⁻–N, combined with high concentrations of NO₃⁻–N suggested that other factors were controlling NO₃⁻–N flux in the study transect. However, denitrification did appear to be significant along one portion of the transect. C₂H₂ block experiments showed that denitrification rates were much higher downstream of the WWTP compared to upstream, and showed that denitrification rates were highest in erosional and depositional areas downstream of the WWTP and in erosional areas upstream of the plant. Thus, the combination of the two methods for evaluating denitrification provided more insight into the spatial dynamics of denitrification activity than either approach alone. Denitrification appeared to be a significant sink for NO₃⁻–N upstream of the WWTP, but not downstream. Approximately 46% of the total NO₃⁻–N load was removed via denitrification in the upstream, urban section of the stream, while only 2.3% of NO₃⁻–N was lost downstream of the plant. This result suggests that controlling NO₃⁻–N loading from the plant could result in considerable improvement of downstream water quality.     

In situ toxicity tests of fishes in acid waters

Toxicity of waters within the North Branch of the Moose River to various life stages of lake trout (Salvelinus namaycush), brook trout (Salvelinus fontinalis), creek chub (Semotilus atromaculatus), and blacknose dace (Rhinichthys atratulus) were examined in situ. Study sites were selected that were expected to range from toxic to favourable water quality. For example, pH varied from 4.25 to 7.17, inorganic monomeric Al ranged from ND (< 0.01 mg/l) to 0.40 mg/l, and Ca, from 0.41 to 4.27 mg/l.Toxicity tests were conducted at times when the life stages would naturally occur in these waters and were continued until a range of mortality was observed at the various sites. These experiments suggested that the extent of the drainage system that is toxic to fish increases during snowmelt and major runoff events. Summer base flow water quality was generally the least toxic.Critical life stages were upon hatching and as early feeding fry. In general, young of the year fish were the most tolerant life stage tested. Yearling and adult fish, however, were very sensitive. Blacknose dace were the most sensitive fish of the four species tested, and brook trout were the most tolerant.Hydrogen ion (H⁺) concentration was the most toxic variable in the majority of tests. Inorganic monomeric Al was the most toxic in several, and the combination of H⁺ and Al seemed to cause increased toxicity in many instances. A three-variable model employing hours of exposure, H⁺ concentration, and inorganic monomeric Al predicted mortality quite well. A simple two-variable model using H⁺ and color was nearly as good (R² from 0.49 to 0.94).Documented differences in toxicity among sites and species agreed with observed patterns of fish distribution. These in situ results indicated that laboratory estimates of safe levels of pH and concentrations of Al can result in mortality of fishes in surface waters subject to acidification.     

Value of laboratory tests in employer-sponsored health risk assessments for newly identifying health conditions: analysis of 52,270 participants

Background

Employer-sponsored health risk assessments (HRA) may include laboratory tests to provide evidence of disease and disease risks for common medical conditions. We evaluated the ability of HRA-laboratory testing to provide new disease-risk information to participants.

Methodology/Principal Findings

We performed a cross-sectional analysis of HRA-laboratory results for participating adult employees and their eligible spouses or their domestic partners, focusing on three common health conditions: hyperlipidemia, diabetes mellitus, and chronic kidney disease. HRA with laboratory results of 52,270 first-time participants were analyzed. Nearly all participants had access to health insurance coverage. Twenty-four percent (12,392) self-reported one or more of these medical conditions: 21.1% (11,017) self-identified as having hyperlipidemia, 4.7% (2,479) self-identified as having diabetes, and 0.7% (352) self-identified as having chronic kidney disease. Overall, 36% (n = 18,540) of participants had laboratory evidence of at least one medical condition newly identified: 30.7% (16,032) had laboratory evidence of hyperlipidemia identified, 1.9% (984) had laboratory evidence of diabetes identified, and 5.5% (2,866) had laboratory evidence of chronic kidney disease identified. Of all participants with evidence of hyperlipidemia 59% (16,030 of 27,047), were newly identified through the HRA. Among those with evidence of diabetes 28% (984 of 3,463) were newly identified. The highest rate of newly identified disease risk was for chronic kidney disease: 89% (2,866 of 3,218) of participants with evidence of this condition had not self-reported it. Men (39%) were more likely than women (33%) to have at least one newly identified condition (p<0.0001). Among men, lower levels of educational achievement were associated with modestly higher rates of newly identified disease risk (p<0.0001); the association with educational achievement among women was unclear. Even among the youngest age range (20 to 29 year olds), nearly 1 in 4 participants (24%) had a newly identified risk for disease.

Conclusions/Significance

These results support the important role of employer-sponsored laboratory testing as an integral element of HRA for identifying evidence of previously undiagnosed common medical conditions in individuals of all working age ranges, regardless of educational level and gender.     

Progress in remediation and revegetation of the barren Jales gold mine spoil after in situ treatments

A series of single extractions and short-term plant tests were performed in order to test a variety of inexpensive mineral amendments for the in situ inactivation of trace elements on the fine-grained spoil of the former gold mine of Jales, Portugal. Based on the results of these tests, mesocosms (lysimeters) were constructed and a small-scale semi-field trial was carried out since 1998. The long-term effect of steelshots (SS, iron grit), beringite (B), and municipal compost (C) as spoil amendments was investigated. Vegetation establishment on the treated spoils was successful with Holcus lanatus L. in year 1 and Pinus pinaster Ait. in year 2. Therefore, a detailed monitoring program was implemented for determining the sustainability of trace elements in situ inactivation by C (5%), CB (5% compost combined with 5% beringite), CSS (5% compost combined with 1% steelshots), and CBSS (5% compost combined with 5% beringite and 1% steelshots) treatments (all amendments are expressed by soil dry weight) and of the revegetation. After 3 years, revegetation was excellent in the CSS treatment, and successful for the CBSS. Volunteer plant species became established in treated spoils during year 2. In contrast, the trees planted on the C treated spoil declined from year 2 and some died. In year 3, the trees on the CB treatment started to decline. Arsenic and zinc exposure are suggested to explain the negative effects on pine growth. In agreement with results of single extractions, compost addition in the spoil increased long-term arsenic percolation. Lead leaching was also enhanced. The CBSS and CSS treatments were the most effective for limiting water-soluble As and decreasing long-term metal leaching.     

A comparison of bacterial,ciliate and macroinvertebrate indicators of stream ecological health

We evaluate the reliability of communities of bacteria and ciliated protozoa as indicators of freshwater ecological health. Samples of epilithic biofilm were taken from 18 freshwater streams, impacted by varying types and degrees of catchment modification. Communities of bacteria and ciliates were characterised using DNA fingerprinting techniques (automated ribosomal intergenic spacer analysis and terminal restriction fragment length polymorphism, respectively) and macroinvertebrate data also obtained, for comparison. Similar to the macroinvertebrates, the taxa richness of ciliate communities was reduced in more developed stream catchments; significant differences in the evenness of ciliate communities were also detected. We could identify no significant relationship between the richness of bacterial taxa and the percentage catchment development. However, a significant trend was detected between bacterial community structure and the predominant catchment land use (rural vs. urban) using a Bray–Curtis measure of similarity, a relationship not detected for the ciliate and macroinvertebrate communities. These findings indicate that stream bacterial, ciliate and macroinvertebrate communities each respond differently to various catchment conditions and highlight the potential of microbial communities to provide novel, alternative indicators of stream ecosystem health.     

树叶凋落物在受酸性矿山废水污染溪流中的分解

为了解华南地区酸性矿山废水对溪流中树叶分解的影响,在广东省大宝山矿区附近的1条受酸性矿山废水污染（pH值为2．7—3．4且富含多种重金属元素）的3级溪流中,利用2种孔径（5ram的网袋和0．1ram的布袋）的分解网袋对2种树叶（人面子和蒲桃）进行了为期101d的树叶分解研究。结果表明,人面子树叶网袋和布袋中的树叶干重剩余率分别为39％和48％,而蒲桃树叶网袋和布袋中的干重剩余率仍保持较高的水平,分别为61％和70％。根据指数衰减模型计算出树叶分解的半衰期,人面子树叶在网袋和布袋中的分解半衰期分别为57d和69d,而蒲桃树叶则分别为14-4d和217d。蒲桃树叶的分解速率明显比人面子树叶慢。在网袋中定殖的底栖动物主要是集食者,其中优势类群为摇蚊幼虫,占底栖动物个体总数的99％。摇蚊种群在网袋中的数量波动对2种树叶分解速率的影响并不明显。结果表明,受酸性矿山废水的影响,底栖动物群落的多样性大为减少。同时由于各种金属氧化物在树叶表面的不断沉淀,使树叶处于缺氧状态,抑制了微生物的活动,导致树叶分解速率大为降低。     

Resource dynamics and detritivore production in an acid stream

1. Life history patterns and production of eight shredder‐detritivore species were studied in relation to the detritus dynamics of a small acidic stream in England. Mean annual detritus inputs (direct and lateral sources combined) were approximately 400 g m^?2 year^?1 and showed significant seasonal and annual variation. 2. Detritus standing stock did not increase significantly during times of high input, reflecting low retention efficiency. However, the mean detritus standing stock was relatively large (108 g m^?2) reflecting a slow decomposition rate typical of acid streams. 3. Four species were univoltine with highly synchronous patterns of emergence and recruitment (Leuctra inermis, Leuctra hippopus, Capnia vidua and Amphinemura sulcicollis). Two species were univoltine with extended patterns of emergence and recruitment (Nemoura cinerea, Potamophylax cingulatus). Leuctra nigra was apparently semivoltine, while Protonemura meyeri showed two successive cohorts in the second year of the study, suggesting either bivoltinism or cohort splitting. 3. Secondary production of the dominant shredders was 1.67 g m^?2 year^?1 in 1997 and 1.99 g m^?2 year^?1 in 1998, which is low compared with other small European streams. This was probably because of an impoverished invertebrate community and poor food quality associated with acid conditions. Food availability probably did not account for the low production as the detritus standing stock far exceeded the estimated shredder ingestion of 42–50 g m^?2 year^?1. 4. Despite low overall shredder production, species‐specific production was high, possibly because of competitive release in this species‐poor acid stream. Periods of high production and growth showed no relationship with detritus availability but were closely related to life history.     

Using macroinvertebrates to assess ecological integrity of streams remediated for acid mine drainage

Studies assessing stream restoration of acid mine drainage (AMD) usually use community metrics that emphasize only a few attributes of ecological integrity. We used a variety of measures to examine recovery of macroinvertebrate communities in a watershed receiving passive treatment for AMD. We measured density, richness, functional diversity (FD), taxonomic diversity (Δ, a measure of taxonomic relatedness), and community taxonomic composition at 4 stream sites over an 11‐year period: 1 reference not affected by AMD, 2 downstream of treatment systems, and 1 AMD‐impacted site with no treatment. Our objectives were to determine if communities have responded to remediation, and examine whether FD and Δ provided additional insights into ecology integrity. Richness, FD, and Δ at the reference site were significantly higher than for other sites, but did not consistently differentiate treated and untreated sites. Additional information provided by FD and Δ on attributes related to functional redundancy and taxonomic relatedness was self‐evident given the simplicity of nonreference communities. Ordination of community composition incorporating knowledge of taxa autecologies indicated that treated sites were slightly less impacted than the untreated site, and trend analysis indicated slight improvement at 1 treated site. However, communities below treatment remained taxonomically distinct, with much lower densities than reference condition. Macroinvertebrate communities showed less recovery than was determined for benthic diatom communities at the same sites in a previous study. Several attributes of ecological integrity for different types of stream organisms should be incorporated into bioassessment of AMD restoration because they can vary in their response.     

Proteome changes in the initial bacterial colonist during ecological succession in an acid mine drainage biofilm community

Proteomes of acid mine drainage biofilms at different stages of ecological succession were examined to understand microbial responses to changing community membership. We evaluated the degree of reproducibility of the community proteomes between samples of the same growth stage and found stable and predictable protein abundance patterns across time and sampling space, allowing for a set of 50 classifier proteins to be identified for use in predicting growth stages of undefined communities. Additionally, physiological changes in the dominant species, Leptospirillum Group II, were analysed as biofilms mature. During early growth stages, this population responds to abiotic stresses related to growth on the acid mine drainage solution. Enzymes involved in protein synthesis, cell division and utilization of 1- and 2-carbon compounds were more abundant in early growth stages, suggesting rapid growth and a reorganization of metabolism during biofilm initiation. As biofilms thicken and diversify, external stresses arise from competition for dwindling resources, which may inhibit cell division of Leptospirillum Group II through the SOS response. This population also represses translation and synthesizes more complex carbohydrates and amino acids in mature biofilms. These findings provide unprecedented insight into the physiological changes that may result from competitive interactions within communities in natural environments.     

Comparative life cycle assessments of incineration and non-incineration treatments for medical waste

Background, aim, and scope  Management of the medical waste produced in hospitals or health care facilities has raised concerns relating to public health, occupational safety, and the environment. Life cycle assessment (LCA) is a decision-supporting tool in waste management practice; but relatively little research has been done on the evaluation of medical waste treatment from a life cycle perspective. Our study compares the environmental performances of two dominant technologies, hazardous waste incineration (HWI) as a type of incineration technology and steam autoclave sterilization with sanitary landfill (AL) as a type of non-incineration technology, for specific medical waste of average composition. The results of this study could support the medical waste hierarchy. Materials and methods  This study implemented the ISO 14040 standard. Data on steam autoclave sterilization were obtained from an on-site operations report, while inventory models were used for HWI, sanitary landfill, and residues landfill. Background data were from the ecoinvent database. The comparative LCA was carried out for five alternatives: HWI with energy recovery efficiencies of 0%, 15%, and 30% and AL with energy recovery efficiencies of 0% and 10%. Results  The assumptions on the time frame for landfill markedly affect the impact category scores; however, the orders of preference for both time frames are almost the same. HWI with 30% energy recovery efficiency has the lowest environmental impacts for all impact categories, except freshwater ecotoxicity. Incineration and sanitary landfill processes dominate global warming, freshwater aquatic ecotoxicity, and eutrophication of incineration and non-incineration alternatives, respectively. Dioxin emissions contribute about 10% to human toxicity in HWI without energy recovery alternatives, and a perturbation analysis yielded identical results. As regards eutrophication, non-incineration treatments have an approximately sevenfold higher impact than incineration treatments. Discussion  The differences between short-term and long-term time frame assumptions mainly are decided by heavy metals dissolved in the future leachate. The high heat value of medical waste due to high contents of biomass, plastic, and rubber materials and a lower content of ash, results in a preference for incineration treatments. The large eutrophication difference between incineration and non-incineration treatments is caused by different N element transformations. Dioxin emission from HWI is not the most relevant to human toxicity; however, large uncertainties could exist. Conclusions  From a life cycle perspective, the conventional waste hierarchy, implying incineration with energy recovery is better than landfill, also applies to the case of medical waste. The sanitary landfill process is the key issue in non-incineration treatments, and HWI and the subsequent residues landfill processes are key issues in incineration treatments. Recommendations and perspectives  Integrating the medical waste hierarchy and constructing a medical waste framework require broader technologies to be investigated further, based on a life cycle approach. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Highly effective reduction of fecal indicator bacteria counts in an ecologically engineered municipal wastewater and acid mine drainage passive co-treatment system

Passive co-treatment of municipal wastewater and synthetic acid mine drainage in a laboratory-scale, four-stage continuous flow reactor system was examined for changes in fecal indicator bacteria (FIB) counts. Raw municipal wastewater (MWW) from the City of Norman, Oklahoma was mixed at a 2:1 ratio with high-strength synthetic acid mine drainage and introduced to the system. The MWW contained varying concentrations of total coliforms (TC), fecal coliforms (FC), Escherichia coli, and fecal streptococci (FS). Initial concentrations ranged from 6 to 13, 0.6 to 6, 3 to 5, and 0.1 to 0.7 million cfu/100 mL, for TC, FC, E. coli, and FS, respectively. During the 6.6-day system residence time, a 100% reduction of all FIB was observed. However, FIB exhibited evidence of sub-lethal injury with slower colony formation rates on standard growth media after 81 h of retention. Extending standard incubation periods resulted in higher concentrations of all FIB in each treatment stage, except the final stage where only E. coli and TC counts increased. Although this co-treatment regime reduced FIB concentrations more effectively than conventional active or passive MWW treatment systems, further work can be done to optimize the efficiency of treating these wastes simultaneously.     

The ecological effect of acid conditions and precipitation of hydrous metal oxides in a Rocky Mountain stream

Periphyton and benthic invertebrates assemblages were studied at the confluence of two Rocky Mountain streams, Deer Creek and the Snake River near Montezuma, Colorado. Upstream from the confluence the Snake River is acidic and enriched in dissolved trace metals, while Deer Creek is a typical Rocky Mountain stream. In the Snake River, downstream from the confluence, the pH increases and hydrous metal oxides precipitate and cover the streambed. The algal and benthic invertebrate communities in the upstream reaches of the Snake River and in Deer Creek were very different. A liverwort, Scapania undulata var. undulata, was abundant in the Snake River, and although periphyton were very sparse, there were as many benthic invertebrates as in Deer Creek. Downstream from the confleunce, the precipitation of hydrous metal oxides greatly decreased the abundance of periphyton and benthic invertebrates. This study shows that in streams metal precipitates covering the streambed may have a more deleterious effect on stream communities than high metal-ion activities.