Organochlorine Insecticides and PCB in Surficial Sediments (1968) and Sediment Cores (1976) from Lake Ontario

Surficial sediments were collected in 1968 and core sediments in 1976 from Lake Ontario. These were analysed for organochlorine insecticides and PCB. Residues of organochlorine compounds were higher in the three Ontario depositional basins than in sediment in the non-depositional zones. PCB was present at the highest concentration, with mean levels of 57 ppb for the whole lake. Residues of PCB in the three basins exhibited only minimal differences.ΣDDT was the second most frequently found contaminant. Both parent DDT and its two metabolites were present in sediment, giving a mean residue of 42.8 ppb for the whole lake. Differences in residues for the three basins were again minimal. DDT was present in sediments estimated to be deposited between 1958 and 1976. HEOD was present in only 40% of sediments and the mean residue for the whole lake was 0.6 ppb. The Niagara basin contained mean residues (1.4 ppm) of HEOD much above the other basins.Chlordane was virtually absent from the lake in the sediments collected in 1968 but appeared in cores between 1964-1976. Endosulfan appeared in lake sediments as a spill of deck cargo at a location in the Niagara basin. This spill dispersed with the current down the south shore to deposit in the Rochester basin.     

Organochlorine Insecticides and PCB in Surficial Sediments of Lake Michigan (1975)

Analyses of 286 surficial sediments (0-3 cm), collected in August 1975, were found to contain residues of DDT and its metabolites (∑DDT), heptachlor epoxide (HE), HEOD (dieldrin), chlordane, and polychlorinated biphenyls (PCB), but no detectable residues of endrin, endosulfan, or methoxychlor. Sixty-two samples were checked for mirex but no residues were detected to a limit of 0.2 ng/g. ∑DDT residues were measurable in 93.4% of bottom sediments, HEOD in 48.3%, HE in 53.9%, chlordane in 21.6%, and PCB in 79.6% above detection limits for each compound. The mean residuesfor the whole lake were calculated to be 11.9 ng/g ∑DDT, 0.25 ng/g HEOD, 0.67 ng/g HE, 0.37 ng/g chlordane, and 9.7 ng/g PCB. Depositional zones were two to four times higher in the concentrations of these organochlorine compounds than the non-depositional zones. Basins varied in the levels of contamination for the different compounds. ∑DDT was highest in the Milwaukee basin (40.8 ng/g), HEOD was highest in the Waukegan basin (0.77 ng/g), chlordane was highest in the Grand Haven basin (1.47 ng/g), and HE and PCB were highest in the Fox basin (2.70 and 73.5 ng/g). The distribution of ∑DDT conformed well with the depositional basins of the lake as related to the redistribution of sediment following restrictions on DDT use. For HEOD, HE, and PCB the sediment distributions indicated active usage in 1975 and the probable location of loading sources.     

Organochlorine Insecticides and PCB in the Surficial Sediments of Lake Superior (1973)

Analysis of 405 Lake Superior surficial sediments (0-3 cm depth) collected in 1973 were found to contain low levels of DDE, HEOD, and PCB, but no detectable mirex, heptachlor expoxide, endrin, endosulfan, or chlordane. p,p’-DDE was detected in 50%, HEOD in 9%, and PCB in 44% of the sediment samples at trace or low measurable levels. Mean residues for the whole lake were p,p’-DDE 0.71 ± 1.65 ng/g, HEOD below the detection level of 0.25 ng/g, and PCB 3.3 ± 5.7 ng/g. p,p’-DDE was more concentrated in depositional basins than in non-depositional zones while PCB levels were similar for the two zones.     

Support Vector Machines and Multilayer Perceptron Networks Used to Evaluate the Cyanotoxins Presence from Experimental Cyanobacteria Concentrations in the Trasona Reservoir (Northern Spain)

Cyanobacteria also known as blue-green algae can be found in almost every conceivable environment. Cyanobacteria blooms occur frequently and globally in water bodies and they are a major concern in terms of their effects on other species such as plants, fish and other microorganisms, but especially by the possible acute and chronic effects on human health due to the potential danger from cyanobacterial toxins produced by some of them in recreational or drinking waters. Consequently, anticipation of cyanotoxins presence is a matter of importance to prevent risks. The aim of this study is to build a cyanotoxin diagnostic model by using support vector machines and multilayer perceptron networks from cyanobacterial concentrations determined experimentally in the Trasona reservoir (recreational reservoir used as a high performance training centre of canoeing in the Northern Spain). The results of the present study are two-fold. In the first place, the significance of each biological and physical-chemical variables on the cyanotoxins presence in the reservoir is presented through the model. Secondly, a predictive model able to forecast the possible presence of cyanotoxins is obtained. The agreement of the model with experimental data confirmed its good performance. Finally, conclusions of this innovative research work are exposed.     

The Effect of Temperature Adjustment on Reference Evapotranspiration and Reconnaissance Drought Index (RDI) in Iran

The reference evapotranspiration (ET₀) is necessary to calculate Reconnaissance Drought Index (RDI). To estimate ET₀, FAO56 Penman-Monteith method which needs reference stations data is commonly used. Most of the meteorological stations in Iran are classified as non-reference satations and The use of their data in ET₀ calculation can affect the RDI. The objective of the present study is to evaluate the effect of temperature adjustment based on the reference condition on ET₀ and RDI values in non-reference stations of Iran. For this purpose, the meteorological data, recorded during 1960–2014 in 27 non-reference stations located in arid and semi-arid regions, were used. First, the values of ET₀ were determined using observed values of temperature. Using these values, RDI were computed by Log-Normal and Gamma distributions at annual and 6-month scales. Then the values of minimum, maximum and dew point temperatures were adjusted on the basis of the reference condition. The values of ET₀ and consequently RDI were calculated using adjusted data. On the basis of obtained results, at annual and 6-month scales, using observed values of temperature instead of adjusted values in non-reference stations cause to overestimate the value of ET₀. Also, using observed data with no adjustment can change the drought class which was determined on the basis of RDI. According to these results, temperature adjustment based on reference condition can change the values of ET₀ and RDI which was calculated by using Log-Normal or Gamma distributions at annual and 6-month scales.     

便携式生态水文实验与监测系统(Eco-monitors)的集成与应用

生态水文实验与监测装置的研制对生态水文过程模拟、参数获取与结果验证具有重要意义。在合理创新基础上,构建了便携式生态水文实验与监测系统(Eco-monitors)。Eco-monitors由植被覆盖度动态获取系统(VC-DAS)、便携式光合作用测量系统、便携式人工模拟降雨装置、土壤水运动监测装置及径流/土壤水采样装置等功能模块组成。Eco-monitors及其各功能模块的集成与设计重点突出便携性特点,既包括现有产品如便携式光合作用测量系统、土壤水运动监测装置及径流/土壤水采样装置;也包括自主创新部分如植被覆盖度动态获取系统(VC-DAS)采用摄像头方案代替传统的数码相机,便携式人工模拟降雨装置采用人工压力泵,克服了蓄电池或电力传动装置供电要求高且难以携带的限制。Eco-monitors在多项研究项目中得到了成功应用。     

Field and Laboratory Studies of the Toxicity to Phytoplankton of Polychlorinated Biphenyls (PCBs) Desorbed from Fine Clays and Natural Suspended Particulates

Polychlorinated biphenyls (PCBs; Aroclor 1254) were adsorbed to natural (Hudson River and New York Bight) and commercial (illite) particles in the laboratory, then allowed to desorb for several hours into the surrounding aqueous medium in the presence of either of two laboratory strains of diatom species or a complete natural phytoplankton assemblage. Cell density, photosynthesis, and chlorophyll a concentration in the cultures were followed for 2 to 3 days. In two experiments, PCB-carrying natural particles were removed after desorption and prior to the introduction of algae. All incubations were carried out in the laboratory or in dialysis membrane bags suspended in the tidal channel of an estuarine marsh.Cultures containing 90 μg of illite-bound Aroclor 1254/L of water were severely damaged within 4 hours, by which time 72% of the PCBs had desorbed from particles and become available to the diatoms. Similarly, a natural phytoplankton community, incubated under natural conditions in the presence of 50 μg of Hudson River sediment-associated PCB/L of water, registered significant reductions of photosynthesis and chlorophyll a content for at least 3 days. When PCB-bearing New York Bight particles were removed from the medium prior to the introduction of algae, sufficient desorbed PCBs remained to reduce growth rates and chlorophyll a content of the culture. The latter experiment clearly demonstrates particle to water to cell transfer of desorbed PCBs.     

在沿海地区使用的金属结构与钢丝网砼结构闸门的防腐蚀处理

水工金属结构与闸门涂装涂料工艺 ,建议仿上述造船舶行业的涂装工艺 ,在加工厂内先将进厂的原材料 (钢板 )表面抛丸除锈 ,趁钢材尚热时喷涂富锌 (或其他 )底漆 ,然后制造产品 ,这样会更好地保证与提高底漆的质量与简便工艺操作。待产品运抵工地现场后 ,再涂刷中间层与面漆 ,使所涂的防锈涂料能起到它应有的防护作用 ,延长使用防护周期。2 .2　防污涂料防污涂料是配合防锈涂料的使用 ,去阻止海洋生长的动植物体附着水工构筑物表面 ,而污损该构筑物的表面。海洋中约有 6 0 0多种附着植物和 130 0多种附着动物 ,这些附着生物的幼虫或胞子能漂浮…     

Removal of lead(II) and copper(II) from aqueous solution using foitite from Linshou mine in Hebei, China

Foitite from Linshou mine in China's Hebei province was investigated as an adsorbent to remove Pb(II) and Cu(II) from aqueous solution. The results showed that foitite can readily remove heavy metal ions from aqueous solution. The data shows that the metal uptake for Pb(II) increases rapidly, accounting for 74.47% when contact time was 2 min. In contrast to Pb(ll), there was a worse capability for adsorption of Cu(II). In the first 4 min, the metal uptake accounted for 34.7%. According to the analytical results obtained from X-ray diffraction, laser Raman spectrum, X-ray energy dispersive spectrometer, and Zeta potential, the removal mechanism of Pb(II) and Cu(II) by using foitite can be explained as following: firstly, the existence of an electrostatic field around foitite particles can attract heavy metal ions and consequently combine heavy metal ions with OH; secondly, heavy metal ions in the solution are exchanged with the Fe3+ and Al3+ in the foitite.     

Triazine Residues in Suspended Solids (1974–1976) and Water (1977) from the Mouths of Canadian Streams Flowing into the Great Lakes

Forty-five suspended solids collected during 1974 and 1976 from 12 streams on the Canadian side of the Great Lakes contained no detectable residues of triazines to a limit of 0.05 μg/g. Of ninety-two stream waters sampled in July, 1977, 77% contained atrazine, 52% desethylatrazine, and 28% simazine above a detectable level of 0.03 μg/L. Mean concentrations of these three triazines in the 92 streams were 1.6, 0.3, and 0.2 μg/L respectively. The highest mean triazine residue occurred in those stream waters entering Lake Erie (4.0 μg/L); there was little difference in the mean concentrations of waters entering Lakes Ontario (1.1 μg/L), St. Clair (1.3 (μg/L), and Huron (1.4 μg/L). While triazine herbicides were found entering the Great Lakes there was no threat to water quality as defined by the objectives of the International Joint Commission.     

Inactivation of enteric microbes in water by electro-chemical oxidant from brine (NaCl) and free chlorine.

Oxidant solutions of mostly free chlorine can be electrochemically produced on-site from brine (NaCl) solution and used to disinfect water at the household or community level. In this study electrochemical oxidant (ECO) from brine and free chlorine were evaluated under laboratory conditions for inactivation of test microbes. Purified suspensions of Escherichia coli, the rugose strain of Vibrio cholerae, Clostridium perfringens spores, MS2 coliphage and Cryptosporidium parvum oocysts were treated with 2 mg/L or 5 mg/L solutions of ECO or free chlorine at 5 degrees C and 25 degrees C and pH 6, 8, and 10 (pH 7 and 25 degrees C only for C. parvum oocysts) for contact times <60 min. Under nearly all conditions, inactivation kinetics were more rapid for E. coli, V. cholerae, C. perfringens spores and MS2 coliphage with ECO than with free chlorine. ECO reduced E. coli, V. cholerae and MS2 by >4 log10 within 30 min and C. perfringens spores by >2 log10 within 10 min at pH 8 and 25 degrees C. Contrary to previous results, however, C. parvum oocysts were not inactivated by ECO, and the reasons for this difference are uncertain. The on-site electrolytic generation of oxidants from brine provided a convenient and inexpensive disinfectant containing free chlorine that was effective against many enteric microbes, for the treatment of household and community drinking-water supplies worldwide. However, the effectiveness of such oxidants for inactivating C. parvum oocysts was variable and sometimes ineffective.     

Partition of metals in the Vistula River and in effluents from sewage treatment plants in the region of Cracow (Poland)

The Vistula River suffers from heavy pollution with multiple origins. In the upper reaches, metallic and chlorine pollution originates from the mining and industrial region of Upper Silesia. Downstream from Upper Silesia, urban and industrial sewage adds more metallic and organic contaminants from the large urban agglomeration of Cracow. Although the river status is monitored routinely, little is known about the partition of metals between particulate and dissolved forms. This study focuses on metal partitioning and on the impact of the two main wastewater treatment plants at Cracow on metal concentrations in the Vistula River. The Cd, Co, Cu, Mn, Pb and Zn content was measured in both dissolved and particulate fractions. High metal concentrations in the Vistula River persist, although current levels seem to be lower than those in the past. Metal concentrations in the Vistula River and effluents from the sewage treatment plants at Cracow are similar, indicating a relatively minor contribution from the treated sewage. However, untreated sewage may be a significant source of contaminants. Despite high anthropogenic metal concentrations, the metal partitioning coefficients (K_d) in the Vistula are similar to these found in unpolluted rivers. Within a narrow pH range, K_d values depend on the metal affinity to particles, but there is no evidence of dependence on particle or chloride concentrations. An important fraction of the toxic metals Pb and Cd is associated with particles, which may decrease their immediate availability to the biota of the river.     

Morphometric differentiation and gene flow in emerald shiners (Notropis atherinoides) from the lower Great Lakes and the Niagara River

Differences in habitat (e.g., water velocity, prey, and predator regimes) are a driving force causing adaptive divergence among fish populations. This study used geometric shape analysis to assess morphological differences among emerald shiner (Notropis atherinoides) populations inhabiting the Niagara River, Lake Erie, and Lake Ontario. It was expected that emerald shiners inhabiting the two lakes would have more robust bodies and smaller heads, while river emerald shiners were expected to display more fusiform bodies with larger heads. The results of this study indicate that emerald shiners from Lake Erie and the Niagara River had a more robust form on average than individuals from Lake Ontario. Specifically, emerald shiners collected from Lake Ontario displayed more streamlined bodies and larger heads than emerald shiners collected from Lake Erie and the Niagara River. In addition, this divergence in body shape has apparently occurred despite the lack of distinct genetic differentiation as measured with microsatellite variation. Our results suggest that differences in water velocity alone may not be responsible for phenotypic variation in body shape among these emerald shiner populations, and other factors such as differences in prey or predator regimes are likely involved.     

Assessment of Renibacterium salmoninarum infections in four lake whitefish (Coregonus clupeaformis) stocks from northern Lakes Huron and Michigan

Lake whitefish (Coregonus clupeaformis) from four stocks in northern Lakes Michigan and Huron were collected seasonally from fall 2003 through summer 2006 and examined for the presence of Renibacterium salmoninarum, the causative agent of bacterial kidney disease (BKD), using culture techniques on modified kidney disease medium (MKDM) and the quantitative enzyme-linked immunosorbent assay (Q-ELISA). R. salmoninarum was detected in 62.31% (according to Q-ELISA) of the 1284 examined lake whitefish, with some fish displaying the typical signs of BKD, such as renal congestion, swelling, and whitish nodules. Kidney cultures on MKDM yielded bacteria with morphological and biochemical characteristics identical to those of R. salmoninarum recovered from other Great Lakes fish species, as well as those from other parts of the world. Isolate identification was confirmed via nested polymerase chain reaction. Antibiograms demonstrated high sensitivity to enrofloxacin and ciprofloxacin, sensitivity to oxytetracycline, erythromycin, azithromycin, chloramphenicol, novobiocin, and carbenicillin, and resistance to polymyxin B, clindamycin, and kanamycin. Statistical analysis of R. salmoninarum prevalence and intensities revealed significant interactions among stocks, years and sampling seasons, with highest prevalence generally in fall and frequent wide variation in prevalence and intensity from one season to the next for a particular stock. It was surprising to find that the prevalence of R. salmoninarum exceeded 50% in the four stocks, much higher than originally thought. Moreover, a positive association between R. salmoninarum intensity and the abundance of the swimbladder nematode, Cystidicola farionis, was identified. Our findings suggest that Great Lakes lake whitefish are vulnerable to serious fish pathogens.     

Predation risk and prey fish vertical migration in Lake Superior: Insights from an individual based model of siscowet (Salvelinus namaycush)

Drivers of movement patterns in prey fishes are often multifactorial in nature, but difficult to discern in complex lake ecosystems. Our objectives were to examine interactions between predatory siscowet lake trout and kiyi and deepwater sculpin, under different modeling scenarios to address the ramifications of prey distribution strategies on foraging by siscowet. We built an individual based model (IBM) of free moving siscowet to examine changes in predation rate on prey species given four scenarios of prey distribution. The scenarios included: 1) the nominal scenario where kiyi perform diel vertical movements (DVM) as observed in western Lake Superior; 2) a random distribution scenario where siscowet move randomly; 3) a no DVM scenario where kiyi maintain position near the bottom 24 h a day; and 4) a no DVM scenario where kiyi maintain position near 35-m 24 h a day. In the nominal scenario, there was strong agreement between simulated distribution, growth and diet of siscowets relative to observations in Lake Superior. In scenarios 3 and 4, when kiyi maintained their distribution at 35-m or near the bottom, predation rates by siscowet were approximately 14 times and 2 times higher, respectively, compared to the normal strategy exhibited by kiyi (scenario 1). These findings indicate that the present kiyi DVM strategy significantly reduces predation compared to other evaluated strategies and helps stabilize predator-prey interactions over relatively long timescales. Future analyses examining the supply and demand in the Lake Superior food web may quantify the specific importance of DVM in stabilizing predator-prey interactions.     

Use of otolith chemistry to discriminate juvenile Chinook salmon (Oncorhynchus tshawytscha) from different wild populations and hatcheries in Lake Huron

Chinook salmon (Oncorhynchus tshawytscha) in Lake Huron consist of wild and hatchery-reared fish distributed among several populations. This study tested whether otolith chemistry can be used to identify the natal origin of Chinook salmon in this system. Concentrations of nine elements (Mg, K, Mn, Fe, Zn, Rb, Sr, Ba, and Pb) in the otoliths of Chinook salmon juveniles from 24 collection sites (17 streams and 7 hatcheries) around Lake Huron were analyzed using laser-ablation inductively-coupled mass spectrometry. Differences in otolith chemistry were found between rearing environments (wild and hatchery), among geological regions (Precambrian, Ordovician, Silurian, Devonian, and Carboniferous), and among collection sites. Discriminant function analysis showed high classification accuracies of juveniles to their rearing environment (wild versus hatchery, 82%), geological region (84%), and collection site (87%) of origin. With these values, there is excellent potential for otolith chemistry to be used to predict the natal origin of adults, and thus inform research and management of Chinook salmon in Lake Huron.     

Hydrological alterations as the major driver on environmental change in a floodplain Lake Poyang (China): Evidence from monitoring and sediment records

Due to the lack of long-term records on shallow lake environmental change, knowledge of the processes and mechanisms behind the limnological response of many shallow floodplain lakes to hydrological alterations and nutrient loading is often limited. We examined seasonal monitoring data and a dated sediment core from Lake Poyang, a large floodplain lake located on the Yangtze floodplain in the SE China. Multivariate analysis based on contemporary data (diatoms and water quality) revealed that the seasonal changes in the diatom assemblage of the lake were correlated with water temperature and Secchi depth (SD), although the weak spatial effect was not negligible. During the dry winter season, low water temperature, low SD, and high nutrient levels, were accompanied by high abundances of planktonic Aulacoseira species along with Stephanodiscus hantzschii, a species well adapted to cold and eutrophic waters. During the summer wet season, however, when water temperature and SD were high and nutrient levels low, benthic and epiphytic diatoms, such as the genus Achnanthes, dominated. Sediment records of diatoms and geochemistry were used to estimate long-term variation in the ecological condition of the lake. During the past ~60 years, the lake has shifted from a natural hydrologically connected, oligotrophic lake dominated by benthic and epiphytic diatoms to a poorly hydrologically connected, eutrophic state driven by nutrient-tolerant planktonic and eutrophic diatoms. Furthermore, our results indicate that the proposed Poyang dam may severely affect the water quality and ecosystem of the lake by altering its seasonal hydrology.     

Water quality assessment and apportionment source of pollution from neighbouring rivers in the Tapeng Lagoon (Taiwan) using multivariate analysis: a case study.

Factor analysis was conducted to explain the characteristics and variation in the quality of water during the disassembly of oyster frames and fishery boxes. The result shows that the most important latent factors in the Tapeng Lagoon are the ocean factor, the primary productivity factor, and the fishery pollution factor. Canonical discriminant analysis is applied to identify the source of pollution in neighbouring rivers outside the Tapeng Lagoon. The two constructed discriminant functions (CDFs) showed a marked contribution to all the discriminant variables, and that total nitrogen, algae, dissolved oxygen, and total phosphate combined in the nutrient effect factor. The recognition capacities in these two CDFs were 95.6% and 4.4%, respectively. The water quality in the Kaoping river most strongly affected the water quality in the Tapeng Lagoon. Disassembling the oyster frames and fishery boxes improved the water quality markedly. However, environmental topographic conditions indicate that strengthening stream pollution prevention and constructing another entrance to the ocean are the best approaches for improving the quality of water in the Tapeng Lagoon by reducing eutrophication. These approaches and results yield useful information concerning habitat recovery and water resource management.