Survey of toxicants and nutrients in composted waste materials

Currently, there is much activity in composting yard wastes (leaves, twigs, grass), sewage sludge and portions of municipal solid wastes (MSW) in the United States. The resultant compost is typically applied to agricultural or recreational land. A nationwide analytical survey was therefore conducted of 21 toxic and nutrient elements, polychlorinated biphenyls (PCBs) and gamma emission in 26 composts sampled nationwide in 1991. Those composts produced solely from sludge or MSW tended to be higher in metals such as Cd, Cu, Hg, and Zn as compared to totally yard waste compost. Molybdenum, P and Se were higher in composted sewage sludge and Na and Pb in composted MSW than in yard waste compost. PCBs and gamma emission were low or not detectable in most compost samples. Shards of metal and glass found particularly in MSW-containing composts would detract from its application especially in recreational areas. References dealing with the reactions of metals in composts and environmental effects of compost application to land are cited.     

Rhizotoxicity of cadmium and copper in soil extracts

Dissolved organic matter (DOM) influences metal speciation in soil solutions and, hence, metal toxicity. Root-elongation experiments were conducted to examine the effect of soil solution components, such as Ca, H, and DOM, on metal rhizotoxicity. A biotic ligand model (BLM) was tested for its ability to predict the rhizotoxicity of Cd and Cu in soil extracts. It was hypothesized that the concentration of Cd and Cu bound to functional groups at the root surface estimated using a BLM would be a better predictor of rhizotoxicity than the free-metal ion activity in solution. Both metals became less toxic at higher DOM, Ca, and H concentrations. Solution speciation and the effect on root growth explained most of the variability observed in the DOM experiments, but not in the cation experiments. It was concluded that Ca and H inhibited the rhizotoxicity of both metals tested. Rhizotoxicity data correlated better with estimates of metal-root complexes that have been estimated with a BLM than with free-metal ion activity or with total metal concentrations. The BLM seems to be a promising approach for predicting metal availability in soils and for assessing the associated risk.     

Trace metals in sediments and potential availability to Anadara granosa

Trace metals in the sediments non-residual fraction and their relative abundance in various sedimentary components from the culture bed of Anadara granosa were investigated. High levels of Cd (40%), Ni (40%), and Pb (43%) were associated with the sediment exchangeable phase (EP). The sediment moderately reducible phase (MRP) was more predominant than the easily reducible phase (ERP) and the organic sulphide phase (OSP) in the sorption of available trace metals. However, this area was not considered to be heavily impacted by trace metal pollution. Since there was no significant concentration gradients observed in sediments and bivalves collected from all stations, trace metal enrichment factors were determined. A. granosa collected from this area was enriched by Zn, Cu, Pb, Ni, Cd, and Ni.     

Causes of Sediment Toxicity to <Emphasis Type="Italic">Mytilus galloprovincialis</Emphasis> in San Francisco Bay,California

Since the San Francisco Regional Monitoring Program (RMP) sampling began, elutriate samples prepared with sediment from the Grizzly Bay monitoring station have been consistently toxic to bivalve larvae (Mytilus galloprovincialis). An investigation into the cause of toxicity was initiated with a Phase I Toxicity Identification Evaluation (TIE) using bivalve embryos. TIE results and chemical analyses of elutriate samples suggested that divalent metals were responsible for the observed toxicity. Following the initial characterization of trace metals as toxicants, additional TIEs were performed on elutriates prepared from three additional Grizzly Bay samples collected between 1997 and 2001. Additional TIEs included ethylenediamine tetraacetic acid (EDTA) treatments in a sediment-water interface (SWI) exposure system, and the use of a cation exchange column with serial elution of sample fractions with hydrochloric acid of increasing normality. EDTA significantly reduced toxicity in overlying water in the SWI system. The cation exchange column reduced both toxicity and concentrations of trace metals, and serial elution of the column added back both toxicity and specific metals contained in individual acid fractions. Chemical analyses of three elutriate samples demonstrated copper concentrations were within the range toxic to bivalves. Results of Phase I TIEs, additional Phase II treatments, SWI exposures, and metals analyses indicate the potential for metal toxicity in sediments from this estuarine site. When combined with the results of standard TIE methods, a solid-phase cation extraction and elution approach identified copper as the most probable cause of toxicity.     

Effect of dissolved organic matter of various origins and biodegradabilities on the bioaccumulation of polycyclic aromatic hydrocarbons in Daphnia magna

As a preliminary study of the influence of urban organic matter on the bioavailability of polycyclic aromatic hydrocarbons (PAHs), the effect of different types of dissolved organic matter (DOM) on the bioaccumulation of fluoranthene, pyrene, or benzo[a]pyrene in Daphnia magna was studied. Commercial humic substances, DOM from the aeration basin of a wastewater treatment plant, and highly biodegradable DOM (algae or animal extracts) were tested. The bioaccumulation of benzo[a]pyrene was reduced by each DOM (up to 80% reduction with humic substances). Pyrene bioaccumulation was also decreased by each DOM to a lesser extent. Fluoranthene bioaccumulation was affected by the presence of humic acids only. In each experiment, the solution containing humic DOM led to the lowest bioaccumulation. Supposing that only dissolved PAHs were bioavailable, the reduction of bioaccumulation allowed a biological estimate of the partition coefficients of DOM and PAH, K(DOC). The estimated coefficients were positively related to the aromaticity of DOM and negatively related to its biodegradability.     

Dissolved fraction of standard laboratory cladoceran food alters toxicity of waterborne silver to Ceriodaphnia dubia

The biotic ligand model (BLM) for the acute toxicity of cationic metals to aquatic organisms incorporates the toxicity-modifying effects of dissolved organic matter (DOM), but the default parameterization (i.e., assuming 10% of DOM is humic acid) does not differentiate DOM from different sources. We exposed a cladoceran (Ceriodaphnia dubia) to Ag in the presence of DOM from filtered YCT (standard yeast-Cerophyll(R)-trout chow food recommended by the U.S. Environmental Protection Agency [EPA] for cladocerans), from the Suwannee River (GA, USA; relatively little anthropogenic input), and from the Desjardins Canal in Hamilton (ON, Canada; receives treated municipal wastewater effluent). In all three treatments, the dissolved organic carbon (DOC) concentration was 2 mg/L (the concentration following addition of YCT slurry at the U.S. EPA-recommended volume ratio). The average 48-h median effects concentration (EC50) ratios for dissolved Ag in the presence and absence of DOM [i.e., (EC50 with DOM)/(EC50 without DOM)] were as follows: Suwannee River, 1.6; Desjardins Canal, 2.2; and YCT filtrate, 26.8. Therefore, YCT filtrate provided much more protection against Ag toxicity than that provided by DOM from the surface waters. The major spectral characteristic that differentiated YCT filtrate from the other two types of DOM was a strong tryptophan peak in the excitation- emission matrix for YCT. These results have important implications for interpreting Ag toxicity tests in which organisms are fed YCT, and they suggest BLM-calculated toxicity predictions might be improved by incorporating specific chemical constituents or surrogate indices of DOM. Another component of the protective effect against Ag toxicity, however, might be that the dissolved fraction of YCT served as an energy and/or nutrient source for C. dubia.     

Prevalence of asbestos in composted waste from 26 communities in the United States

Composting of yard waste, sewage sludge and municipal solid waste (MSW) for subsequent application to soils in agricultural, horticultural and recreational areas is being promoted nationwide. Since asbestos is a common contaminant in sewage sludge, an analytical survey was conducted for the presence of asbestos in composts collected from 26 communities nationwide resulting from sludge as well as yard waste and municipal solid waste. Asbestos was detected in 12 of the 26 composts or 46%. Asbestos was most consistently present in compost resulting from source material containing MSW and to a lesser extent sewage sludge rather than yard waste. The possible origins of asbestos in the compost source material, the mechanisms by which humans may be exposed, and the health significance are discussed.     

北京市生活垃圾堆肥现状及存在问题分析

在综合分析北京市目前垃圾堆肥现状的基础上,深入系统地总结了限制堆肥发展的制约因素以及存在的问题,并提出了促进垃圾堆肥发展调控的技术对策和建议。表明限制垃圾堆肥发展的关键因素不仅是堆肥技术本身的不完善,更重要的是堆肥质量和市场问题。     

堆肥化技术应用于生活垃圾预处理方案的费用-效益分析

在有关实验分析的基础上,从工程应用角度探讨垃圾综合处理中采用堆肥化技术作为预处理的可行性。采用费用-效益分析方法,通过对3组有无堆肥预处理工艺的垃圾处理方案的比较,以定量和定性的指标综合评价各组方案的技术经济效果。结果表明,根据我国城市垃圾成分特点,在卫生填埋和焚烧或综合处理中增加堆肥化技术作为预处理在工程上是可行的,经济指标优于传统垃圾处理方案。     

Trace metal availability and effects on benthic community structure in floodplain lakes

Effects of contaminants on communities are difficult to assess and poorly understood. We analyzed in situ effects of trace metals and common environmental variables on benthic macroinvertebrate communities in floodplain lakes. Alternative measures of trace metal availability were evaluated, including total metals, metals normalized on organic carbon (OC) or clay, simultaneously extracted metals (SEM), combinations of SEM and acid-volatile sulfide (AVS), and metals accumulated by detritivore invertebrates (Oligochaeta). Accumulated metal concentrations correlated positively with sediment trace metals and negatively with surface water dissolved OC. Sixty-eight percent of the variation in benthic community composition was explained by a combination of 11 environmental variables, including sediment, water, and morphological characteristics with trace metals. Metals explained 2 to 6% of the community composition when SEM-AVS or individual SEM concentrations were regarded. In contrast, total, normalized, and accumulated metals were not significantly linked to community composition. We conclude that examination of SEM or SEM - AVS concentrations is useful for risk assessment of trace metals on the community level.     

Impact of the Combined Application of Biochar and Compost on Mine Soil Quality and Growth of Lady’s Finger (Abelmoschus esculentus)

Amelioration of mine soil is challenging because of the lack of biologically active organic matter. The study was aimed to recycle yard waste into compost and biochar and to use them to reclaim mine soil. Biochar prepared at 350 °C showed the highest stable organic matter yield index and was used for the experiments. Lady’s finger was grown on mine soil amended with biochar (1%–5%), compost (2%–10%), and biochar-compost mixtures (2%–10%). Mine soil pH increased in all treatments. Mine soil dehydrogenase activity (42%–224%), microbial biomass carbon (4%–257%), and hydrolase activity (3%–230%) increased by combined application of biochar and compost. Lady’s finger plant height, biomass, and fruit yield were superior in biochar–compost mixtures compared to biochar and compost alone treatment. Thus the use of compost along with biochar could be recommended for reclamation of mine soil.

     

Mercury Complexation with Dissolved Organic Matter Released from Thirty-Six Types of Biochar

Previous studies show mercury (Hg) can be effectively removed from solution by biochar, but limited attention was paid on the complexation between Hg and components released from biochars, e.g. dissolved organic matter (DOM). Here, aqueous data from batch-style experiments were modeled using PHREEQC, incorporating thermodynamic constants between Hg and DOM, which was assumed to be composed of thiol, carboxylic, and phenolic functional groups. Modelling results suggest that > 99% Hg complexed with thiol groups in DOM. The modelled concentrations of Hg–DOM complexes from low-T (low-temperature, 300°C) biochars were greater than from high-T (600°C) biochars. The concentrations of Hg–DOM complexes were lower in wood-based than in agricultural residue- and manure-based biochars. Hg–DOM complexes may affect Hg speciation, bioavailability, transport, and methylation processes. This research describes a method to evaluate Hg–DOM interactions, and the results indicate extra caution regarding Hg–DOM complex formation is required in the selection of biochar for Hg remediation.

     

城市生活垃圾可降解有机碳估算方法的研究

依据政府间气象变化委员会(IPCC)推荐的城市生活垃圾可降解有机碳公式,研究了我国城市生活垃圾可降解有机碳的估算公式。确定了我国城市生活垃圾中可降解有机碳的成分,即厨余、纸类、织物、竹木和灰渣,并以沈阳和武汉作为采样点,进行测定可降解有机碳,并给出中国城市生活垃圾中可降解有机碳推荐值。     

Effect of dissolved organic matter on the growth of algae, Pseudokirchneriella subcapitata, in Korean lakes: the importance of complexation reactions

The objective of this study was to investigate the effect of dissolved organic ligands, such as EDTA, humic acids, hydrophobic and hydrophilic fractions of dissolved organic matter (DOM), on the growth of Pseudokirchneriella subcapitata in cultured media and natural lake waters. The growth of algae was gradually increased on the addition of dissolved organic ligands, but markedly declined at high concentrations, due to reduced bioavailable iron concentrations (e.g., Fe3+ and Fe'--inorganic ferric iron). The results demonstrated that the high growth rates of P. subcapitata were correlated with the hydrophobic, but not hydrophilic, DOM from five lakes, spiked under the nutrients-controlled conditions. This was attributed to the role of DOM in controlling the bioavailable iron due to complexation of Fe(III) with -COOH and -OH functional groups on the hydrophobic DOM. Therefore, the hydrophobic DOM, as chelating agent, is a biologically important component in the lake waters, which affects the algal growth by interacting with bioavailable iron in the lake water and can change the results of bioassay experiments.     

我国城市生活垃圾处理技术方式的选择

介绍了我国城市生活垃圾常用的处理方式填埋、堆肥和焚烧以及厌氧发酵和热分解2种前沿技术,重点进行了优缺点的比较,进而提出了城市生活垃圾处理技术方式选择的定性化依据--因地制宜、因时制宜、因技术制宜和因财力状况制宜.     

Effects of water hardness and dissolved organic material on bioavailability of selected organic chemicals

The influence of water hardness and dissolved organic matter (DOM) on bioavailability of organic chemicals to Daphnia magna was studied by using benzo[a]pyrene (BaP), pyrene, atrazine, and 3,3',4,4'-tetrachlorobiphenyl (TCB) as model compounds. Two types of DOM were used, namely Lake Kontiolampi, Joensuu, Finland water (KL) and Nordic reference fulvic acid (NoFA) dissolved in artificial freshwater. Binding of the four contaminants by KL DOM decreased with increasing water hardness. Furthermore, increasing hardness reduced the binding of BaP and pyrene to NoFA. The binding of atrazine and TCB by NoFA was low and was not significantly affected by water hardness. In the DOM-free samples, the bioconcentration of the four contaminants in D. magna usually was not affected by water hardness. In the presence of DOM, the bioconcentration factors (BCFs) were lower (except for atrazine) than in the DOM-free controls. In the presence of both types of DOM, increasing water hardness resulted in higher BCFs for BaP. The bioconcentration of pyrene and TCB increased with increasing water hardness in the presence of KL DOM. In conclusion, the effects of DOM and water hardness on bioavailability of hydrophobic chemicals depend on the type of chemical and on the properties of DOM.     

Characterization,DBPs formation,and mutagenicity of different organic matter fractions in two source waters

Dissolved organic matters (DOM) are critical in the formation of the mutagenic disinfection byproducts (DBPs). In this study, five DOM fractions were isolated and investigated from a contaminated river and a clean reservoir source waters using resin adsorption. The DOM fractions were characterized with excitation–emission matrix, and several typical DBPs formation potentials and the mutagenicity of each DOM fraction were measured. Among these fractions, hydrophobic neutrals (HON), hydrophilic acids (HIA) and hydrophilic bases (HIB) generated the highest carbon-containing DBPs in the river source water, as did HIB and hydrophobic bases (HOB) in reservoir water. Hydrophobic acids (HOA), HON, and HIA were the three most important fractions forming nitrogen-containing DBPs. Following chlorination, the mutagenicity of HON, HIA, HOA and HIB was 1503, 626, 422 and 116 ng 4-NQO/mg DOC in river water, respectively. Only HIA and HOA were mutagenic with 85 and 10 ng 4-NQO/mg DOC in reservoir water, respectively. The soluble microbial products like substances and aromatic proteins contributed significantly to the mutagenicity of river water; whereas the humic acid-like and fulvic acid-like substances were the primary contributors to the mutagenicity of reservoir water.     

Integrated assessment of mangrove sediments in the Camamu Bay (Bahia, Brazil)

Camamu Bay, an Environmentally Protected Area, may be affected by the pressures of tourism and oil exploration in the adjacent continental platform. The current quality of the mangrove sediments was evaluated by porewater bioassays using embryos of Crassostrea rhizophorae and by an analysis of benthic macrofauna and its relationships with organic compounds, trace metals and bioavailability. Porewater toxicity varied from low to moderate in the majority of the samples, and polychaetes dominated the benthos. The Grande Island sampling station (Station 1) presented more sandy sediments, differentiated macrobenthic assemblages and the highest metal concentrations in relation to other stations and guideline values, and it was the only station that indicated a possible bioavailability of metals. The origin of the metals (mainly barium) is most likely associated with the barite ore deposits located in the Grande and Pequena islands. These results may be useful for future assessment of the impact of oil exploration in the coastal region.     

Effect of dissolved organic matter source on acute copper toxicity to Daphnia magna

The protective effect of dissolved organic matter (DOM) on metal toxicity to aquatic organisms has been reported by numerous authors. Bioavailability models such as the biotic ligand model (BLM) thus account for this factor to predict metal toxicity to aquatic organisms. Until now, however, few attempts have been made to assess the effect of the DOM source on metal speciation and toxicity and, accordingly, on BLM predictions. The aims of this study were to investigate to what extent DOMs differ in their ability to decrease acute copper toxicity to the cladoceran Daphnia magna and to evaluate if ultraviolet (UV) absorbance measurements may be a simple and effective method to incorporate DOM variability into the acute Cu-BLM for D. magna. Acute toxicity tests were carried out in artificial test water enriched with DOMs isolated from six locations in Europe and North America and in seven natural European surface waters. The acute Cu-BLM for D. magna was then used to estimate the copper complexing capacity of each DOM (expressed as % active fulvic acid, %AFA). A factor of 6 difference was observed between the lowest and the highest copper complexing capacity. A significant linear relationship was observed between the UV-absorbance coefficient at 350 nm (epsilon350) and the %AFA. Linking this relationship to the acute Cu-BLM resulted in a significant improvement of the predictive capacity of this BLM. Without accounting for this relationship, 90% of the predicted 48-h 50% effective concentrations (EC50) were within a factor of 2 of the observed EC50s; taking this relationship into account, 90% of the EC50s were predicted with an error of less than factor 1.3. The present study and other studies seem to indicate that UV absorbance may be a good measure of biologically and toxicologically relevant differences in copper binding behavior of DOM.