Ecological Risk, Mass Loading, and Occurrence of Nonylphenol (NP), NP Mono-, and Diethoxylate in Kaoping River and its Tributaries, Taiwan

Biochemically, nonylphenol ethoxylates (NPnEOs) and its breakdown products nonylphenol (NP), NP monoethoxylate (NP₁EO), and NP diethoxylate (NP₂EO) are considered endocrine disrupting compounds. These NPnEOs have been detected in aquatic environments and are of concern. NP, NP₁EO, and NP₂EO were detected in water samples collected from the main watercourse and polluted tributaries of Kaoping River, Taiwan. Concentrations were below the detection limit (<LOD) to 310 μg/l for NP, from <LOD to 27.2 μg/l for NP₁EO, and from <LOD to 27.5 μg/l for NP₂EO. It was found that concentrations of the three compounds in a low flow period were significantly greater than in the high flow period due to the low dilution effect. The risk to aquatic organisms by NP, NP₁EO, and NP₂EO was expressed as hazard quotient and hazard index and simulated with the Monte Carlo method. Results from this study suggested an inadequately treated domestic wastewater caused high concentrations of NP, NP₁EO, and NP₂EO and a high risk to aquatic organisms.     

Mercury transport,transformation, and bioaccumulation in the ecosystem of mercury — stibium geochemical province

A simple analytic technique — isotope dilution — was used for determination of the contents of total and methilated Hg in water, sediments, soils and biological objects collected in the basin of the river Katun. The inspected region is located on a territory of two mercury-stibium geochemical provinces. Evaluation of the Hg transport, transformation and bioaccumulation in aquatic and terrestrial ecosystems of the region showed that the main Hg transport occurs on suspended solids after Hg has been washed out from soil and bedrock by water of the river Katun and its tributaries and also by underground waters. Bottom sediments of some rivers of the basin content increased Hg concentrations. This effect is also noted in the sediments of a small reservoir formed on one of the tributaries. The investigations showed that Hg originating from natural sources differs considerably in its biochemical characteristics from Hg compounds coming from anthropogenic sources. So, natural Hg compounds have lower bioavailability for the water and terrestrial organisms of the region.     

多样生物污水净化系统研究及其应用

传统的污水生物处理方法经过近100年的应用和技术改进，其工艺和设备日臻完善，但仍存在投资大、能耗高、管理复杂等特点。多样生物污水净化系统是按照食物链代谢规律，设置微生物-植物-水生动物3个处理单元，污水中的有机物作为微生物的食料在第1单元被厌氧微生物消化降解成CO2、H2O、NH^ 4、CH4和PO^3-4等，除CH4作为生物能源可回收利用外，其他物质都是植物的营养物质，在第2单元被藻类等多种植物吸收，通过光合作用合成植物细胞，并释放O2。在第1、第2单元增殖的过量细胞和藻类成为水生动物的食料，在第3单元被浮游动物和鱼类捕食并转化成动物蛋白。污水中有机物在3个单元组成的生态净化系统中被多样生物逐级利用，最终转化成植物细胞和动物蛋白，使污水得到净化三级处理水平，不产生二次污染，是对环境安全的污水处理新技术之一，成为21世纪的新科技。该污水净化系统通过达到自我调控生态平衡，具有工艺流程简单、投资省、运行费用低、管理简便等优点，适合我国国情且应用前景前景广阔，尤其适用于小城镇污水处理。     

Permanganate oxidation of methylated and non-methylated aquatic humus in Norway

The chemical composition of aquatic humus was investigated by permanganate oxidation. Both methylated and non-methylated samples were investigated and the results compared with those of different soil humic fractions investigated earlier.The total amount of oxidation products identified from the methylated sample was 2%, and from the non-methylated sample 0.9%. The composition of the oxidation products from methylated aquatic humus was 42% benzenecarboxylic acid methyl esters (8 different compounds), 43% methoxy-benzenecarboxylic acid methyl esters (12 compounds), 10% dimethoxy-benzenecarboxylic acid methyl esters (4 compounds), and 5% of 1, 2, 3-propanetricarboxylic acid trimethyl ester. The unmethylated aquatic humus yielded 84% benzenecarboxylic acid methyl ester (7 compounds), 7% methoxy-benzenecarboxylic acid methyl esters (2 compounds), and 9% of 1, 2, 3-propanetricarboxylic acid trimethyl ester. Three diazines isolated from methylated material were believed to be artefacts from diazomethane treatment. Two of the diazines have earlier been found by oxidation of methylated soil samples, the third, C₁₀H₁₂N₂O₆, is an oxidation product of methylated aquatic humus only.Oxidation of aquatic humus yielded more benzenecarboxylic acids and methoxy-benzenecarboxylic acids than soil humic fractions, and less dimethoxy-benzenecarboxylic acids. No aliphatic dicarboxylic acids were detected among the oxidation products of the aquatic humus.The compounds identified are mainly the same as those found by oxidation of different soil humic fractions, although their yields clearly demonstrated that the aquatic humus differed in composition from the soil fractions.     

Fundamental roles of biological barriers in mercury accumulation and transfer in freshwater ecosystems (analysis at organism,organ, cell and molecular levels)

In the framework of an ecotoxicological approach to the processes of bioaccumulation and transfer of Hg in freshwater systems, we present a synthesis of our experimental studies concerning the interactions between inorganic Hg and MeHg and biological barriers

- at organism and organ levels : three biological models are selected: fish (Salmo gairdneri), burrowing mayfly nymphs (Hexagenia rigida) and rooted macrophytes (Elodea densa, Ludwigia natans). Results show strong specificities of the biological barriers (gills, intestine, roots, ...) towards metal fixation and absorption, closely related to the chemical form of the metal, the contamination sources (water, sediments or food) and the physico-chemical characteristics of the medium ;

- at cell and molecular levels : biophysical study of Hg fixation on membrane reveals a new binding site on the phospholipids, the primary amine group on serine and ethanolamine polar heads, jointly with the SH groups of proteins ; Hg(II) induces a strong rigidification of the phospholipidic bilayers. Inorganic Hg and MeHg transports through model membranes (BLM) are essentially due to diffusion of neutral chloride species. These interactions between Hg compounds and membranes are strongly dependent on Hg chemical speciation (pH and pCl effects).

     

Methyl Mercury Production and Distribution in River Water-Sediment Systems Investigated Through Radiochemical Techniques

The toxicological consequences of Hg releases to the environment are largely governed by the conversion ofinorganic Hg to the most toxic methylmercury (MeHg), that is biomagnified through aquatic food chains. To gain further insight on the biological and physico-chemical factors controlling MeHg production and distribution among freshwater sediments and water, we used a sensitive and specific radiochemical procedure, developed at the National Institute for Minamata Disease. Systems containing ²⁰³Hg²⁺-spiked sediment cores (0.7 μg total Hg g^-1 d.w.) and overlying water, both from a pristine mountain stream in Southern Japan, were incubated for 21–38 days in different conditions. Inorganic Hg and MeHg in sediment and water were extracted in dithizone-benzene and measured after separation by thin-layer chromatography. The conversion of added Hg to MeHg was 3.0 to 13.7% in sediments, with a tendency for higher proportions in the top layers. Surprisingly, more MeHg was found in the sediment (11.3%) and water (66.5%) of a system bubbled with air than in one bubbled with nitrogen (4.2 and 44.1%). Artificially increased levels ofbioturbation reduced by half the MeHg concentrationsand % of added total Hg in sediment and water. In allsystems, 55–68% of total Hg and MeHg in water wereassociated to suspended particles >1μm. MeHgbioaccumulation factors (BFs) from water ranged270–8100 and from sediment, 0.2–5.7 (wet weight basis). BFs in relation to water where 3 times higher for MeHg than for total Hg.     

Mercury pollution caused by a chlor-alkali plant

Since the beginning of the last decade, a chlor-alkali plant operates in Sagua la Grande, in the central part of Cuba. The factor is equipped with a treatment system for trapping Hg in the waste water, which did not always function efficiently. During 1985–1988, a first evaluatian of the environmental impact by Hg was made. Analyses of a terrestrial plant (Mimosa pudica), soils, sediments and aquatic organisms, taken from a dam upstream, that atmospheric pollution by Hg is only restricted to the factory and its surrounding. Nevertheless, the liquid wastes discharged to Sagua la Grande River, have affected aquatic systems downstream up to the estuarine zone of the river mouth. This is confirmed by the examination of core and surface sediment samples, suspended matter, awnaquatic plant (water hyacinth, Eichhornia crassipes) and a sea urchin (Lytechinus variegatus). Different control measures have now limited the Hg discharges and should bring a progressive recuperation of the affected area.     

Microbially-mediated gross N transfer rates in field soils in relation to physico-chemical transfer processes

Abstract

Measurements of gross N transfer in soils have as yet not distinguished between biological or physico-chemical processes. Here, we present a new approach that allows microbially-mediated gross N transfer rates to be estimated in undisturbed soils without adding ¹⁵N. It is based on the assumption that in undisturbed soil, the soil microbial growth rate is equal to its death rate. To assess the contribution of biological versus physico-chemical N transfer processes, we combined the new approach with the ¹⁵N-pool dilution technique. The relationship between both processes varied with soil C and fine particle contents. Nearly equal rates were observed within the carbon-poor soil (0.35% C_org, low fine particle content), whereas up to 2.5 times higher physico-chemical than biological N transfer rates were measured within the carbon-enriched soil (0.86% C_org, higher fine particle content). Furthermore, microbially-mediated gross N transfer rates increased three-fold after N fertilization compared to the unfertilized control.     

Distribution of mercury in the aquatic food web of Onondaga Lake,New York

Historical discharges of mercury (Hg) to Onondaga Lake, New York, have resulted in elevated Hg concentrations in lake fishes. In 1990, a remedial investigation and feasibility study (RI/FS) was initiated to evaluate problems related to Hg and other hazardous substances in the lake. As part of the RI/FS, the distribution of Hg in the aquatic food web was determined to provide input to a site-specific model of Hg cycling and to evaluate potential ecological risks of Hg in the lake. Mercury concentrations were measured in surficial sediments, sediment interstitial water, lake water, phytoplankton, Zooplankton, benthic macroinvertebrates, and fishes (including planktivores, benthivores, and piscivores). The percentage of total Hg accounted for by methyl-Hg (CH₃Hg) generally increased with higher trophic levels, confirming that CH₃Hg is more efficiently transferred to higher trophic levels than is inorganic Hg. Concentrations of total Hg in amphipods and chironomids were closely related to concentrations of total Hg in sediments, suggesting that sediments are a likely source of Hg for benthic macroinvertebrates. Mercury concentrations in edible muscle tissue (fillets) of lake fishes have declined substantially from values found in the early 1970s, reflecting the large reductions in Hg discharges to the lake that have occurred since that time. The CH₃Hg concentrations in fillets and whole bodies of fishes generally were similar, indicating that concentrations in fillets often can provide estimates of concentrations in whole bodies. Methyl-Hg concentrations and bioaccumulation factors increased with higher trophic levels in both the pelagic and benthic components of the lake food web.     

水源涵养和生态保育清洁小流域河流沉积物重金属的特征及潜在风险——以董铺—大房郢水库为例

[目的]为了解安徽省合肥市饮用水源地水源涵养和生态保育清洁小流域(董铺水库和大房郢水库)汇水河流表层沉积物中重金属对下游水库的影响。[方法]在该区域3条主要汇水河流采集了23个沉积物样品,分别测定了沉积物中7种重金属(Zn,Cu,Cr,As,Cd,Pb和Hg)的含量,并采用潜在生态风险指数法(I_R)和地累积指数法(I_(geo))评估其潜在生态风险,主成分分析法解析其可能来源。[结果]研究区域重金属分布存在差异,As和Cd在泗水河上的C_1和C2两点含量超过了维护人体健康的土壤环境质量二级标准限值,且Cd在此两点的易利用态占比为34.97%和37.67%,具有较强的生物有效性;Cd生态风险指数普遍偏高,达强度等级,其中泗水河上的C_1和C2两点达极强等级;同时S_8点Hg生态风险达到强度等级,其余6种重金属生态风险水平较低。该区域重金属主要来自于人与自然混合源和人为源,贡献率分别为51.11%和27.70%。[结论]在泗水河下游流域Cd污染较为突出,为减小其对下游水库的影响,应加强Cd的污染治理。     

Effects of O<Subscript>3</Subscript> stress on physico-chemical and biochemical properties and composition of main microbial groups of a soil cropped to soybean

Tropospheric O₃ (ozone) stress can negatively affect forest productivity and crop yields. Yet, relatively little attention has been paid to the effects of O₃ stress on belowground system. Here, a pot experiment was conducted in open top chambers to monitor the response of physico-chemical properties, main microbial groups, and potential enzyme activities of a soil cropped to soybean (Glycine max; a highly sensitive species to O₃) and exposed to background O₃ concentration (45?±?5 ppb, control) and O₃ stress (80?±?10 ppb, O₃+ and 110?±?10 ppb, O₃++) with sampling at branching, flowering, and podding stages. The growth of soybean was significantly inhibited by O₃ stress, which showed significant effects on soil microbial biomass C and pH during the whole growth of soybean at the highest concentration. The O₃++ stress significantly decreased soil pH at flowering stage, and increased soil pH at podding stage; the O₃+ stress and growth stage?×?O₃+ stress showed significant influences on the potential activities of acid phosphomonoesterase, invertase, and amylase. The O₃ stress significantly reduced the abundances of total PLFAs (phospholipid fatty acid), bacterial PLFAs, and AMF (arbuscular mycorrhizal) PLFAs at branching and podding stages. Our results suggest that the main soil microbial groups might be indirectly affected by the O₃ stress through the alteration of soil physico-chemical properties with changes in the potential enzyme activities of soil.     

Multicompartment ecotoxicological models to study mercury bioaccumulation and transfer in freshwater systems

We have developed a methodology based on interactive ecotoxicological models —experimental ecosystems —, to quantify actions and interactions of abiotic and contamination factors, on bioaccumulation and transfer of Hg compounds (HgCl₂ and CH3HgCl) in freshwater systems. The first stage in the research program is based on a three compartment system : water, natural sediment and rooted macrophytes. Several abiotic factors are considered (temperature, pH, photoperiod, light intensity), in relation to two contamination sources-water column and sediment. Among the many results obtained, Hg accumulation in aquatic plants from the water source reveals small differences between the two chemical forms of the metal, the ratios between Hg concentrations in the whole plants being close to 1.5, in favor of MeHg ; after contamination by the sediment source, these ratios are higher than 20, always in favor of MeHg. Comparative study of a very large number of ecotoxicological conditions, resulting from the crossing of two or three levels for the different abiotic and contamination factors taken into account, shows important interactions, especially between pH and temperature, with reference to Hg bioaccumulation.     

Effects of effluents from a sewage treatment plant on the aquatic organisms

The effects of sewage pollution on the distribution and abundance of some orgnanisms over a period of 4 mo at the Ahmadu Bello University Main Campus sewage treatment plant and Kubanni river were studied. Physico-chemical parameters such as dissolved oxygen; temperature; hydrogen ion concentration (pH); electrical conductivity and chemical oxygen demand influenced by pollution were measured with respect to the population of aquatic organisms. The organisms were used as biological indices to monitor the ecological imbalance caused by the effluent. The variations in concentrations of some heavy metals were also measured. The studies revealed that at the source of pollution there were no organisms except for some insect larva such as Eristalis, Psychoda, and some microscopic algae like Oscillatoria, Anaebaena, and Polysystis. A location (site 5) on Kubanni river just before the confluence of the sewage effluent and the river was taken as the control. There was a wide variety of organisms (crustaceans, rotifers, and fish) at the control point.     

The sulphur-mercury(II) system in natural waters

Sulphur is an essential element for aquatic biosystems, the life processes of which lead to the formation of low molecular weight S compounds in the water. The results of our calculations indicate a pronounced tendency for Hg(II) to form HgS (or HgOHSH) and Hg(SR)₂ complexes in the presence of H₂S and thiols. Likewise, McHg will form CH₃HgSH and CH₃HgSR complexes, but in this case the chloride complex will dominate at low concentrations of H₂S and thiols. In acidic low salinity water, CH₃HgCl is the dominant McHg species at the lowest concentration of sulphide/thiols (0.1 nM), whereas a hundredfold increase of the sulphide/thiol concentration, or an increase of the pH to neutral or slightly alkaline conditions, will result in a total dominance for CH₃HgSH and CH₃HgSR.     

Evaluation of the Sub-lethal Toxicity of Bleached Kraft Pulp Mill Effluent to Carassius auratus and Dicentrarchus labrax

The effluents from bleached Kraft pulp mill (BKME) and paper industry are toxic to different aquatic organisms being an important source of contamination to aquatic environments due to the presence of several chemicals produced during the production of Kraft pulp. The main objective of the present study was to evaluate the exposure effects of a secondary-treated BKME in two different species of fish: Carassius auratus and Dicentrarchus labrax. Both species were exposed to different concentrations of secondary-treated effluent (1%, 10%, 25%, 50%, 100%) in semi-static tests under controlled laboratory conditions. At the end of the experimental period (21 days), samples of livers were collected for CYP1A determination and histopathological evaluation. The results show significant changes (p?<?0.05) of CYP1A induction in carp exposed to 50% and in sea bass exposed to 25% of the effluent. Histopathological alterations were also observed according to the different concentrations of the tested effluent suggesting that tested BKME cause damage to exposed organisms.     

Infiltration of inorganic compounds from the Glatt River,Switzerland, into a groundwater aquifer

The behavior of dissolved (<0.45 μm) inorganic compounds during infiltration of river water into the adjacent aquifer (unconsolidated glacio-fluvial sediments) was investigated at the Glatt River, Switzerland, field site. The water was sampled in the river and from wells at distances of 2.5, 5, 13, and 110 m along an estimated groundwater flow line. Sodium, K, Ca, Mg, Sr, Cr, Cu, Zn, Cd, Pb, Cl^?, NO₃ ^?, SO₄ ^2?, and PO₄ ^3? were measured using AAS, NAA, and ion chromatography. Groundwater concentrations of these species are mainly determined by the concentrations in the river. However, the concentrations of NO₃ ^?, (PO₄ ^3?), Cr, Cu, Zn, Cd, and Pb are also subject to seasonal variations in the near infiltration field (≤ 5 m). These variations are probably triggered by temperature dependent biological processes which influence parameters such as pH, redox potential and complexing agents. The redox potential controls the chemical behavior of Mn, which influences the solubility of heavy metal compounds. The extent of inorganic pollution in the investigated system is still much below drinking water standards, but for Cd, reaches the toxicity limit for aquatic organisms.     

Determination of methylmercury in fish by headspace-gas chromatography with microwave-induced-plasma detection

Some additional experiments checking out the extraction method recently developed for the determination of MeHg in biological samples by Headspace Gas Chromatography with Microwave Induced Plasma atomic emission spectroscopy detection were performed. In this method, the MeHg is cleaved from the biological tissue by H₂SO₄ and by addition of iodoacetic acid converted to the iodide form. These reaction steps take place in a closed headspace vial. The H₂SO₄ concentration and the sample matrix have an important influence on the recovery of the MeHg from the sample and these effects are discussed. The method was then applied to the determination of MeHg in cod fish caught in the North Sea. Levels found ranged from 0.13 to 0.63 μg g⁻¹ dw with a mean of 0.33 μg g⁻¹ on the 25 samples analyzed. The total Hg content of these samples was also determined by Cold Vapour Atomic Absorption Spectrometry, and all data pooled ranged from 0.19 to 0.90 μg g⁻¹ with a mean of 0.40 μg g⁻¹. A study of the ratio MeHg/total Hg revealed that MeHg always constituted more than 60 % of the total Hg level, with a mean of 83 % on the 25 samples. The percentage MeHg did not increase or decrease markedly when the total Hg content increased. It could be concluded that these North Sea samples are not much contaminated by Hg and are surely suitable for consumption.     

Impact assessment of soils treated with refinery effluent

The effluent collected from the Panipat oil refinery was analysed for different physico-chemical properties. The systematic investigations were carried out to evaluate the effect of refinery effluent on soil fertility by assessing its impact on various soil physico-chemical and biological properties temporally using pot culture experiments. Different concentrations of effluent viz. control, 25%, 50%, 75%, 100% were used for the study. It was observed that application of effluent significantly increased pH, EC, TH, TDS, Ca²⁺, Mg²⁺, alkalinity, Cl^?, SO₄^2?, Fe, P, Na, K, heavy metals, soil dehydrogenase activity and organic content of soil during all intervals of time except bulk density and specific gravity. On the basis of the study it may be suggested that use of treated oil refinery effluent has no adverse effects on physico-chemical properties of soil and can also be used as an alternate source for irrigating crops as it increases the nutrient content of the soil which is essential for the proper growth and maintenance of crop plants.     

Catclaw (Mimosa buincifiera): a pest or a means to restore soil fertility in heavily eroded soil from the central highlands of Mexico?

 In the central highlands of Mexico, heavily eroded soils are often colonized by catclaw (Mimosa buincifiera): an N₂-fixing shrub. An experiment was carried out to investigate how this shrub affected characteristics of the soil and its biological functioning. Soil was sampled from outside and under the canopy of catclaw at three sites characterized by different degrees of erosion and an increase in plant density. The soil microbial biomass C, total amounts of bacteria, fungi, actinomycetes and free-living N₂-fixing micro-organisms were measured, while production of CO₂ and dynamics of nitrate (NO₃ ^–), nitrite (NO₂ ^–) and ammonium (NH₄ ⁺) were monitored in an aerobic incubation at 22±1  °C for 35 days. The C content was 1.6 times greater in the area with the largest density of plants and the least erosion (RECUP) compared with the site with the lowest density and greatest erosion (DEGR), while it was 1.2 times greater under the canopy of the catclaw than outside it (average of the three sites). The incorporation of N into the soil organic matter was greater under the canopy of the catclaw than outside it as the C:N ratio was on average 8.4 and 9. 1, respectively. The microbial biomass C, as a percentage of soil organic matter, was 1.5 times greater in the RECUP than in the DEGR site. Greatest total number of colony-forming bacteria and fungi (mean of organisms found under and outside the canopy) were found in the RECUP treatment and lowest in the DEGR treatment. Free-living N₂-fixing organisms and actinomycetes showed opposite trends. Greater total numbers of colony-forming bacteria, fungi, actinomycetes and free-living N₂-fixing organisms (mean of the three treatments) were found under the canopy of catclaw than outside of it, Production of CO₂ was 1.8 times greater in the RECUP than in the DEGR and 1.6 times greater under the canopy of catclaw than outside. Production of NO₃ ^– was 1.3 times greater in the RECUP than in the DEGR and 3.5 times greater under the canopy of catclaw than outside. There was no significant effect of location or canopy on NO₂ ^– and NH₄ ⁺ concentrations. It is concluded that the natural vegetation of catclaw increased microbial biomass and soil organic matter content under, but also outside its canopy, and preserved N better, releasing greater amounts of inorganic N upon mineralization. Catclaw can serve as a first colonizer of heavily eroded soil and be replaced by other vegetation, natural or crops, when fertility is restored. Received: 4 November 1999     

Facts and fallacies concerning mercury uptake by fish in acid stressed lakes

Concerns about Hg contamination of fish have changed in emphasis from Hg-contaminated systems to more remote and apparently unpolluted systems. For remote lakes, a negative relationship between lake pH and Hg in fish has been demonstrated, implying an effect on Hg uptake from lake acidification. Though this relationship was discussed, and hypotheses put forward concerning the possible mechanisms 8 yr ago, the factors regulating Hg uptake by aquatic biota are still poorly understood. Several recent studies have prompted workers to observe that frequently cited concepts about processes affecting Hg accumulation and cycling are in fact over-simplifications. This review attempts to synthesize and clarify the present state of knowledge. We critically evaluate evidence for a number of controlling factors in the context of the concentrations, the chemical species and the biological uptake processes for Hg. The factors include: trophic status and organic content of water, food chain transfer and biomagnification of Hg, organism age and size effects, feeding strategies, biological and chemical methylation, concentration of cations including H⁺ and Ca²⁺ and the immediate source of Hg.