Impact of river flow modification on wetland hydrological and morphological characters

A good number of researchers investigated the impact of flow modification on hydrological, ecological, and geomorphological conditions in a river. A few works also focused on hydrological modification on wetland with some parameters but as far the knowledge is concerned, linking river flow modification to wetland hydrological and morphological transformation following an integrated modeling approach is often lacking. The current study aimed to explore the degree of hydrological alteration in the river and its effect on downstream riparian wetlands by adopting advanced modeling approaches. After damming, maximally 67 to 95% hydrological alteration was recorded for maximum, minimum, and average discharges. Wavelet transformation analysis figured out a strong power spectrum after 2012 (damming year). Due to attenuation of flow, the active inundation area was reduced by 66.2%. After damming, 524.03 km² (48.9% of total pre-dam wetland) was completely obliterated. Hydrological strength (HS) modeling also reported areas under high HS declined by 14% after post-dam condition. Wetland hydrological security state (WSS) and HS matrix, a new approach, are used to explore wetland characteristics of inundation connectivity and hydrological security state. WSS was defined based on lateral hydrological connectivity. HS under critical and stress WWS zones deteriorated in the post-dam period. The morphological transformation was also well recognized showing an increase in area under the patch, edge, and a decrease in the area under the large core area. All these findings established a clear linkage between river flow modification and wetland transformation, and they provided a good clue for managing wetlands.

     

Linking ecological and ecotoxicological techniques to support river rehabilitation

Human activities in river catchments interfere with natural fluxes of water and materials. Diffuse inputs and point-sources of toxicants have modified the ecological state of riverine communities considerably, and sanitation schemes are now under development for various rivers. To improve analysis, monitoring and prospecting the role of toxicants in river ecosystems a review of the available methods is undertaken. Ecotoxicological techniques are discussed in relation to basic ecological principles that are thought to regulate the functioning of communities. The response to toxicants among species is highly diverse and therefore the choice of test species (e.g. of typical riverine insects as caddisflies or mayflies) is critical, as it is the use of test-batteries. Long-term exposure may lead to developmental disturbances that may be assessed through morphometric techniques like analysis of asymmetry. Multi-generation exposure, although rarely studied, provides a useful insight into the genetic consequences of pollution. Selection for tolerant species or varieties has been experimentally assessed for smaller organisms such as insects, micro-algae, and bacteria. There is also perspective for multivariate analysis of species distribution in relation to pollutant exposure. Furthermore, a system approach to benthic ecology and sediment testing is needed. Such an approach reflects the strong linkage of ecological and ecotoxicological processes. Toxicants are transformed by biological activity; in some cases this alleviates toxicant stress, but in other cases degradation products are toxic as well. The risk of transformation to mutagenic products in the environment is indicated. The re-assessment of some of the classical ecotoxicological techniques is needed to adequately fulfil the needs of ecological recovery programs. To this purpose integration of ecotoxicological and ecological tools is needed.     

曝气耦合表面流湿地技术净化河道水体的工艺优化及该技术对药物类污染物的去除效果

采用曝气耦合表面流湿地工艺处理劣Ⅴ类河水,通过单因素实验和响应面分析优化工艺条件并探讨耦合技术对药物类污染物的去除效果。工艺优化后的曝气条件为：曝气量0.45 L·(min·L)⁻¹,水力停留时间1 d,曝气间歇时间2 h(每曝气1 h),曝气位置(曝气深度/水深)0.5处。此条件下耦合技术去除TN、${\rm{NH}}_4^{+}{\text{-}}{\rm{N }}$、TP和COD的效率为55.6%、78.7%、68.1%和53.4%。应用耦合技术处理了2个不同浓度级别(150 ng·L⁻¹和1 000 ng·L⁻¹)的含药物类污染物的河水。结果表明,耦合技术对酮洛芬、普萘洛尔、甲氧苄啶、罗红霉素、布洛芬和缬沙坦的去除效果皆优于对照实验,对罗红霉素和布洛芬的去除具有协同效应,同时,耦合技术对常规污染物TN、${\rm{NH}}_4^{+}{\text{-}}{\rm{N}}$和TP 的去除也具有协同效应。本研究可为河道治理中表面流湿地技术的改进及河道水体中药物类污染物的去除提供参考。     

Linking biosensor responses to Cd, Cu and Zn partitioning in soils

Soils bind heavy metals according to fundamental physico-chemical parameters. Bioassays, using bacterial biosensors, were performed in pore waters extracted from 19 contrasting soils individually amended with Cd, Cu and Zn concentrations related to the EU Sewage Sludge Directive. The biosensors were responsive to pore waters extracted from Zn amended soils but less so to those of Cu and showed no toxicity to pore water Cd at these environmentally relevant amended concentrations. Across the range of soils, the solid-solution heavy metal partitioning coefficient (K(d)) decreased (p<0.01) with increasing amendments of Cu and Zn; Cu exhibited the highest K(d) values. Gompertz functions of Cu and Zn, K(d) values against luminescence explained the relationship between heavy metals and biosensors. Consequently, biosensors provide a link between biologically defined hazard assessments of metals and standard soil-metal physico-chemical parameters for determining critical metal loadings in soils.     

Strong links between metal contamination, habitat modification and estuarine larval fish distributions

Changes to larval fish assemblages may have far reaching ecological impacts. Correlations between habitat modification, contamination and marine larval fish communities have rarely been assessed in situ. We investigated links between the large-scale distribution of stressors and larval fish assemblages in estuarine environments. Larval fish communities were sampled using a benthic sled within the inner and outer zones of three heavily modified and three relatively unmodified estuaries. Larval abundances were significantly greater in modified estuaries, and there were trends towards greater diversity in these systems. Differences in larval community composition were strongly related to sediment metal levels and reduced seagrass cover. The differences observed were driven by two abundant species, Paedogobius kimurai and Ambassis jacksoniensis, which occurred in large numbers almost exclusively in highly contaminated and pristine locations respectively. These findings suggest that contamination and habitat alteration manifest in substantial differences in the composition of estuarine larval fish assemblages.     

Identifying unknown antibiotics with persistent and bioaccumulative properties and ecological risk in river water in Beijing,China

Environmental Science and Pollution Research - The goal of this study was to identify antibiotics with potential risk in river water of the megacity Beijing, China. This was accomplished by using a...     

Perfluoroalkyl substances in the Lingang hybrid constructed wetland,Tianjin, China: occurrence,distribution characteristics,and ecological risks

Environmental Science and Pollution Research - In this study, the occurrence, spatial distribution, sources, and ecological risks of perfluoroalkyl substances (PFASs) in the surface waters of the...     

潜流人工湿地去除毒死蜱、双酚A、4-壬基酚

为研究潜流人工湿地对毒死蜱、BPA及4-NP的去除效果,选取宽叶香蒲、芦苇、花叶香蒲及小香蒲4种湿地植物,通过SPE-HPLC测定进出水中3种污染物的浓度,计算4种植物潜流人工湿地对3种污染物的去除效率。结果表明,水力停留时间3 d,4组植物对毒死蜱、BPA和4-NP去除率均高于60%,各植物组对毒死蜱和4-NP的去除效果之间无显著性差异,宽叶香蒲对BPA的去除率为82.66%,显著高于其余3种植物组62.96%~69.63%。在静态条件下,毒死蜱、BPA和4-NP在模拟系统内降解过程符合一级降解动力学方程,降解方程分别为：c=124.63exp（-t/25.393）+3.7618 ①,c=316.61exp（-t/34.955）+0.56475 ②,c=168.91exp（-t/17.061）+12.133 ③（c,剩余浓度,μg/L;t,停留时间,h）,半衰期分别为18、21和11 h。     

天津市典型河网区沉积物中重金属分布及生态风险评价

选择天津市典型河网区为研究对象,分析了沉积物中6种重金属(Cr、Cu、Mn、Ni、Pb和Zn)的分布特征,并采用富集系数法和潜在生态危害指数法分析了重金属的来源,进而评价了其生态风险。结果表明,表层沉积物中Cr、Cu、Mn、Ni、Pb和Zn的平均含量分别是58.18、23.52、524.60、22.93、25.24和49.51 mg/kg,其中Cr、Mn和Ni含量均低于天津市土壤背景值,而Cu、Pb和Zn含量在部分样点高于背景值;在垂直分布上,沉积物中Cr和Ni的含量相对稳定,而Cu、Mn、Pb和Zn的含量从底层到表层均先增加后降低。重金属富集系数(EF)分析显示,河网区表层沉积物中Cu和Zn在个别样点以及Pb在近一半样点存在人为输入过程(EF1.5),与接纳上游及区域的生活污水、农田退水有关,而Cr、Mn和Ni均来自自然源。重金属综合潜在生态危害指数(RI)评价表明,整个河网区表层沉积物为轻微生态危害水平,对区域的水环境质量不构成威胁。     

Species-specific responses to metals in organically enriched river water, with emphasis on effects of humic acids

Invertebrate communities in polluted rivers are often exposed to a wide variety of compounds. Due to complex interactions, 'pollution tolerant' species are not necessarily the most tolerant species to toxicants tested under standard laboratory conditions. It was hypothesized that the distribution of species in polluted rivers is not only dependent on the tolerance of species to toxicants, but also on species-specific capacities to modify or compensate for negative effects of toxicants. To test this hypothesis, species-specific responses to metals in organically enriched river water were studied under controlled conditions. The zebra mussel Dreissena polymorpha and the midge Chironomus riparius were exposed to metal-polluted water from the River Dommel. Additionally, the (interactive) effects of metals and humic acids (HA) on both species were evaluated. In spite of a lower tolerance of Chironomus riparius to metals in laboratory studies, the midge was the most tolerant of the two test species to metal-polluted site water. The results indicated that the sensitivities of the two test species determined in laboratory tests were inversely related to their sensitivities to polluted river water. In accordance with these results, midge larvae were protected from copper (Cu) toxicity by HA, while metal toxicity was not reduced (Cu) or even amplified (cadmium) by HA for the zebra mussel. Thus, the presence of (naturally occurring) HA in site water may partly account for discrepancies between responses of species to bioassays and toxicity tests. It is suggested that these differences in responses to metals in site water are strongly influenced by species-specific preferences for organic compounds (like HA). It is concluded that the response to organic compounds present in site water largely determines whether a species is classified as 'pollution tolerant' or 'pollution sensitive'.     

Linking contemporary river restoration to economics,technology, politics,and society: Perspectives from a historical case study of the Po River Basin,Italy

River restoration is a novel paradigm of ‘mirescape’ (land-and-water-scape) management that developed along with the emergence of aquatic ecology. River restoration can be seen as the application of an ecological perspective to return rivers to nature. However, the river restoration paradigm is also the contemporary iteration of historical phases of mirescape management. We review the long and varied recorded history of the Po River in northern Italy as a case study to illustrate the transformations and common themes of mirescape management. We find, first, that significant changes in mirescape management and river condition only occur in the context of larger social, political, technological and economic transformations. Second, we show how particular cultural understandings, economic interests, technological innovations and political powers have driven particular paradigms of mirescape management. These have tended towards increasing territorial separation of wet and dry. We find, third, that these separations lead not only to increasing economic precariousness for many, but also to increasingly severe disasters. We conclude that river restoration faces social and political challenges to becoming relevant at a mirescape scale, due to its lack of integration with land management, or with current social, political, technological and economic transformations. To act on this conclusion, we suggest philosophically aligned social movements that river restoration could work with to improve impact and uptake.     

Visible injury, crown condition, and growth responses of selected Italian forests in relation to ozone exposure

The impact of ozone on forest ecosystems in Italy is monitored within the CONECOFOR programme. Ozone levels are measured in 30 plots using passive samplers. Response parameters used are: crown condition (transparency), BAI (basal area increment), and visible symptoms on spontaneous vegetation. Levels of AOT40 are above the concentration-based critical level of 5 ppmh in all sites, but the evidence of impact on forest vegetation remains limited. Ozone is a predictor of crown transparency residuals in beech sites over two consecutive years, but the variance explained amounts to less than 10%. The relation between BAI reduction and ozone is even less certain. Transparency and BAI are more readily explainable in terms of ecological conditions of the site and climate fluctuations. The interpretation of visible symptoms is doubtful, and is conditioned by the prevailing ecological factors in the areas.     

Effects of metal pollution on earthworm communities in a contaminated floodplain area: Linking biomarker, community and functional responses

Effects on earthworms in the contaminated floodplain area the Biesbosch, the Netherlands, were determined at different levels of organization using a combination of field and laboratory tests. The species Lumbricus rubellus, collected from different polluted sites in the Biesbosch, showed reduced values for the biomarker neutral red retention time (NRRT), mainly explained by high metal concentrations in the soil and the resulting high internal copper concentrations in the earthworms. Organic pollutant levels in earthworms were low and did not explain reduced NRRTs. Earthworm abundance and biomass were not correlated with pollutant levels in the soil. Litterbag decomposition and bait-lamina feeding activity, measures of the functional role of earthworms, were not affected by metal pollution and did not show any correlation with metal concentrations in soil or earthworms nor with NRRT. Effects at the biochemical level therefore did not result in a reduced functioning of earthworm communities.     

Organochlorine pollutants in human blood and their relation with age, gender and habitat from North-east India

Organochlorine pesticides (OCPs) have been beneficial to man and environment but their inadvertent use has caused considerable harm to human health. Despite the proliferation of different types of pesticides, organochlorines such as HCH and DDT still account for two third of the total consumption in India because of their low cost and versatility in action again various pests. Since, Assam, a state in North-eastern part of India is an endemic area with perennial transmission where mosquito borne diseases are serious health problems; these pesticides are still being used in huge quantities in vector control as well as in agriculture. A total of 331 human blood samples were collected from district Nagaon and Dibrugarh of Assam to determine the residue levels of DDT and HCH in human blood. The concentrations of selected persistent organochlorine pollutants were measured with gas chromatography-electron capture detector. The results demonstrated that the mean levels of total DDT and HCH were 743 μg L(-1) and 627 μg L(-1) for district Nagaon while 417 μg L(-1) and 348 μg L(-1) for district Dibrugarh. The difference of total HCH and total DDT between these two districts was found to be highly significant (P<0.0001). Among DDT metabolites, the same trend was observed for both the districts as p,p-DDT was the principal component contributed 41% for Nagaon and 58% for Dibrugarh. In case of HCH residues, for Nagaon, β-HCH was the predominant contaminant comprised more than 34% while for Dibrugarh, it was α-HCH that was contributing 43% of total HCH concentration.     

Environmental concentrations of boron, LAS, EDTA, NTA and Triclosan simulated with GREAT-ER in the river Itter

A computer simulation of the environmental concentrations of some typical consumer-product ingredients was performed using the geo-referenced exposure model GREAT-ER (Geo-referenced Regional Environmental Assessment Tool for European Rivers) in the river Itter. Boron and LAS were chosen as typical detergent ingredients along with EDTA, NTA and Triclosan as examples of household and cosmetic product ingredients. The simulations were based on consumption figures of the respective chemical in consumer products in the year 2000. For EDTA, the consumption figure used for the calculation had to be extended to commercial products since the EDTA-use in domestic products could not account for the measured concentrations alone. The resulting PEC (Predicted Environmental Concentration) for all investigated compounds showed very good accordance to the measured concentrations in the Itter which were monitored in the same year. The concentrations did not deviate more than by a factor of 3. GREAT-ER's calculated 90th-percentile was never exceeded by the monitoring result thus reflecting a reasonable accuracy.     

Phytoplankton functional groups in a monomictic reservoir: seasonal succession,ecological preferences,and relationships with environmental variables

Environmental Science and Pollution Research - The seasonal succession of phytoplankton functional groups (PFGs), their ecological preferences, relationships between environmental variables and...     

Flocculation of dissolved Pb, Cu, Zn and Mn during estuarine mixing of river water with the Caspian Sea

This is the first study of the flocculation of dissolved Pb, Cu, Zn and Mn during mixing of river water with the largest lake in the world (the Caspian Sea). Flocculation of dissolved metals was investigated on a series of mixtures with salinities ranging from 3.2 to 7.4 per thousand. The flocculation rates {Cu (74%) > Pb (61%) > Mn (58%) > Zn (34%)} are indicative of the non-conservative behavior of metals during estuarine mixing. Statistical analysis indicates that the flocculation of Pb and Mn is governed by salinity. The flocculation rates reveal that the overall metal pollution loads may decline by about 57% during estuarine mixing.     

Biological responses of midge (Chironomus riparius) and lamprey (Lampetra fluviatilis) larvae in ecotoxicity assessment of PCDD/F-, PCB- and Hg-contaminated river sediments

Environmental Science and Pollution Research - We evaluated the utility of chironomid and lamprey larval responses in ecotoxicity assessment of polychlorinated dibenzo-p-dioxins, dibenzofurans...     

Trace elements accumulation and their variations with growth, sex and habitat: effects on Formosan squirrel (Callosciurus erythraeus)

Formosan squirrels are considered a useful bio-indicator because their habitat exists within that of humans. Therefore, concentrations of 19 trace elements were determined in tissues of this species for assessment of environmental pollution in urban Kamakura and rural Izuohshima. Results of analyses revealed high Cu concentrations in the livers of Formosan squirrels. Moreover, concentrations of some trace elements from automobile exhausts-V, Zn, Cu and As-in the specimens from Kamakura were higher than those from Izuohshima. These results reflect the presence of pollution caused by human activities in Kamakura.