淡水藻类在监测水质和净化污水中的应用

淡水藻类作为水体中的初级生产者,分布广泛,适应性强,在水生生态系统食物链中占据着十分重要的地位,在水质监测中起着关键的作用。通过对藻类生长与水环境之间的相互关系进行简要的概述,探讨了pH值和氮磷对淡水藻类的生长的影响,以及淡水藻类的生长对外界环境的影响。藻类不但应用于水质监测,而且还能去除水体中的氮、磷等营养物质和其它有机物,对自然水域中的污水有良好的净化作用。重点论述淡水藻类在水质监测和污水净化中的作用以及利用淡水藻类来处理污水的方法。并提出了保护水资源的相关建议,为综合监测和治理水环境提供一定的理论依据和支持。     

Synergistic impacts of sediment contamination and dam presence on river functioning

1. Dam presence is commonly associated with strong accumulation of polluted sediments. In spite of this context of multiple stressors, physical effects are often solely considered in the ecological assessment of the dam impacts. 2. We studied four ‘reservoir/downstream reach’ systems differing in levels of sediment contamination in reservoirs. Using assemblages and biotrait (i.e. ecological or biological attribute) responses of macroinvertebrate communities and leaf litter breakdown, we examined the individual effects and potential interactions between sediment contamination and dam presence along the gradient of ecotoxic pressure. 3. Leaf breakdown rates ranged from 0.0044° per day in the most contaminated reservoir to 0.0120° per day in the reference reservoir. Comparisons of community trait profiles among reservoirs highlighted a gradient of trait responses to sediment contamination. 4. In the absence of toxic contamination, the dam‐induced modifications in biotraits of invertebrate assemblages were not related to a reduction of leaf litter breakdown. Conversely, contaminated sediment in reservoir induced strong functional disturbances (i.e. bioecological shifts and reduction of leaf litter breakdown) downstream of dams. 5. Key biotrait categories positively related to leaf litter breakdown rate have been identified. They corresponded mainly to shredders and/or small‐sized (<0.5 cm) insects, using aquatic (e.g. crawlers) or aerial (e.g. fliers) active dispersal strategies. In addition, trait categories positively correlated to contamination level have been considered as ‘response’ traits. They corresponded to large‐sized (>4 cm) species, having several generations per year (polyvoltin), using asexual reproduction and/or disseminating by drift (aquatic, passive). 6. In the current context of ecological continuity restoration, this study has identified the risks associated with the presence of historical contamination in the run‐of‐river reservoirs for downstream ecosystem health.     

Stream macroinvertebrate response to catchment urbanisation (Georgia, U.S.A.)

SUMMARY 1. The effects of catchment urbanisation on water quality were examined for 30 streams (stratified into 15, 50 and 100 km² ± 25% catchments) in the Etowah River basin, Georgia, U.S.A. We examined relationships between land cover (implying cover and use) in these catchments (e.g. urban, forest and agriculture) and macroinvertebrate assemblage attributes using several previously published indices to summarise macroinvertebrate response. Based on a priori predictions as to mechanisms of biotic impairment under changing land cover, additional measurements were made to assess geomorphology, hydrology and chemistry in each stream. 2. We found strong relationships between catchment land cover and stream biota. Taxon richness and other biotic indices that reflected good water quality were negatively related to urban land cover and positively related to forest land cover. Urban land cover alone explained 29–38% of the variation in some macroinvertebrate indices. Reduced water quality was detectable at c. >15% urban land cover. 3. Urban land cover correlated with a number of geomorphic variables such as stream bed sediment size (–) and total suspended solids (+) as well as a number of water chemistry variables including nitrogen and phosphorus concentrations (+), specific conductance (+) and turbidity (+). Biotic indices were better predicted by these reach scale variables than single, catchment scale land cover variables. Multiple regression models explained 69% of variation in total taxon richness and 78% of the variation in the Invertebrate Community Index (ICI) using phi variability, specific conductance and depth, and riffle phi, specific conductance and phi variability, respectively. 4. Indirect ordination analysis was used to describe assemblage and functional group changes among sites and corroborate which environmental variables were most important in driving differences in macroinvertebrate assemblages. The first axis in a non‐metric multidimensional scaling ordination was highly related to environmental variables (slope, specific conductance, phi variability; adj. R²=0.83) that were also important in our multiple regression models. 5. Catchment urbanisation resulted in less diverse and more tolerant stream macroinvertebrate assemblages via increased sediment transport, reduced stream bed sediment size and increased solutes. The biotic indices that were most sensitive to environmental variation were taxon richness, EPT richness and the ICI. Our results were largely consistent over the range in basin size we tested.     

Short-term effects of aerially-applied fire-suppressant foams on water chemistry and macroinvertebrates in streams after natural wild-fire on Kangaroo Island, South Australia

In remote areas, wild-fires often must be controlled by applying fire-retardants and suppressants dropped from small aircraft. However, impacts of these chemicals on natural stream ecosystems are poorly known. Unintentional aerial application of fire-fighting chemicals (Phos-Chek WD-881 and ForExspan S) onto two small streams during a natural wildfire on Kangaroo Island, South Australia, provided an opportunity to study the short-term effects on water chemistry and aquatic invertebrates. Within 2 weeks of application, samples of water and macroinvertebrates were collected from sites upstream of the application point, within the zone of application, and downstream where burning had been controlled on two streams. Three sites on a reference stream in the same sub-catchment that had been burned by the same fire but without application of fire-suppressants were also sampled. All sites were resampled three months later (within two weeks of the first flushing rains). There were no marked differences in water quality among the sites on the reference stream but in one of the impacted streams where flow had ceased before the fire, dissolved and total phosphorus concentrations were elevated at the site where the fire-suppressants were applied. Phosphorus concentrations were reduced 2–3-fold at this site after brief flushing by rain. Conversely, dissolved and total N and P concentrations at the other impacted stream that flowed permanently did not differ among the sites and there was no evidence for persistent changes to water quality from the applied fire-suppressant foams. Taxon richness was higher at the application and downstream sites than at upstream sites in the two impacted streams. There were also no discernible effects of the fire-suppressants on macroinvertebrate assemblage composition or taxon richness within the two streams two weeks after the chemical application or soon after flushing rains. Assemblage composition in the temporary stream was significantly different from that in the reference and the other impacted stream but also appeared unaffected by the fire-suppressants. The lack of impact on resident stream macroinvertebrates may result partly from their inherent high tolerance to the harsh physical and chemical conditions of these streams, many of which typically cease flow in summer.     

The ecological integrity of the lower Olifants River,Limpopo province,South Africa: 2009–2015 – Part B: Tributaries of the Olifants River

Monitoring on the Lowveld reaches of the Olifants River, Limpopo River System, and its Steelpoort, Blyde, Klaserie and Selati tributaries was initiated in 2009. Analysis of the 2009–2015 data from four Olifants River sites showed deterioration in the river’s ecological condition between where it enters the Lowveld and where it enters the Kruger National Park, with a slight recovery within the Kruger National Park. Physico-chemical, aquatic macroinvertebrate and fish data collected in 2009–2015 at six sites on the Steelpoort, Blyde, Klaserie and Selati tributaries of the Olifants River corroborated the ecological condition of these tributaries. The Selati was the most polluted and was in a critically modified condition, whereas the Klaserie and Steelpoort were in fair condition and the Blyde was in good condition. The Selati appeared to have a significant negative impact on the water quality, macroinvertebrates and fish of the Olifants River within the Kruger National Park.     

The ecological integrity of the Lower Olifants River,Limpopo province,South Africa: 2009–2015 – Part A: Olifants River main stem

The major rivers of the South African ‘Lowveld’ (low-latitude savanna) suffer numerous impacts from upstream economic activities. Whereas monitoring these rivers is required to detect biodiversity losses, record pollution events and devise mitigation strategies, current monitoring programmes are inadequate. In 2009, the South African Earth Observation Network initiated an intensive long-term research programme on the Lowveld reaches of the Olifants River. Physico-chemical parameters, aquatic macroinvertebrates and fish abundances were recorded at four Lowveld sites in the Olifants River. We review six years of this programme. The results suggest deterioration in the ecological condition of the Olifants River with no discernible improvement through protected areas. Trends could not be detected. The parameters measured, sampling methods and/or sampling frequency might be responsible for the limited trends observed, or alternatively the results simply reflect stable conditions despite on-going pollution. Real time monitoring and an expansion in the parameters monitored would add value to the monitoring programme.     

Changes in Nutrient Loading in an Agricultural Watershed and Its Effects on Water Quality and Stream Biota

Non-point-sources of nitrogen (N) and phosphorus (P) are recognized as major causes of eutrophication of surface waters. Adoption of policies to reduce pollution in the former German Democratic Republic following re-unification of Germany in 1990 provided an opportunity to examine how taking agricultural land out of production affected nutrient loads and aquatic biota in a small rural watershed. Between 1994 and 1996, soluble reactive phosphorus (SRP) and dissolved inorganic nitrogen (DIN) loads in a first-order agricultural stream decreased by >90% while instream concentrations decreased by 89% for DIN and 40% for SRP. This reduction in nutrients coincided with a decrease in precipitation (from 760 to 440 mm between 1994 and 1996) and an increase in the area of land set aside from agricultural production (from 0.3% in 1990 to a maximum of 8% in 1994). The biomass of primary producers (episammic algae) showed no clear response to this decrease in nutrient concentrations. However, benthic invertebrate composition shifted from a chironomid–amphipod to an oligochaete–gastropod dominated community in response to the decrease in DIN and changes in episammic algal abundance and sediment organic carbon concentrations. Results from our 4-year study showed reductions in soil nutrient losses combined with less precipitation resulted in less P and N in a rural stream and a change in benthic invertebrate community composition and abundance.     

Rapid assessment of rivers using macroinvertebrates: Case studies in the Nepean River and Blue Mountains,NSW

Abstract Two sets of data were used to evaluate the procedure for rapid assessment of rivers described by Chessman (1995): (i) 72 samples from four habitats at 27 sites on the Nepean River and tributaries; and (ii) 41 riffle samples from the Blue Mountains. In the Nepean system all the sites had moderate anthropogenic disturbance but none had gross organic pollution. There were, however, conductivity differences related to mixed sandstone and shale lithology. The sites differed widely in natural physical attributes such as stream order (2–6) and altitude (40–600 m). The Blue Mountains data included sites with little or no anthropogenic disturbance and sites greatly affected by organic pollution. There was again a wide range of altitudes (15–1000 m) but stream orders were more restricted (1–4). The occurrence of macroinvertebrate families was analysed using cluster analysis (TWINSPAN) and ordination (semi-strong hybrid multidimensional scaling). Relationships between the patterns observed, the SIGNAL biotic index, and physical and chemical data were investigated. The Nepean data showed that the sample size of 100 animals used in the rapid procedure was sufficient to reveal natural distribution patterns in the communities, and that SIGNAL was essentially independent of these patterns. In the Blue Mountains, water pollution had a greater effect on macroinvertebrate communities than the physical habitat, and SIGNAL distinguished sites with differing levels of pollution.     

Is realised connectivity among populations of aquatic fauna predictable from potential connectivity?

1. Effective management of aquatic fauna requires knowledge of the ways in which populations in different catchments and sub‐catchments are connected. A powerful way to estimate this is using genetic markers, which provide information on the average amount of genetic connectivity among populations over generations. Although many studies of genetic connectivity have appeared in the literature, there are innumerable species that have not been studied. 2. This study explores whether it is possible to make broad generalisations about population connectivity, based on readily available information in the form of species life history and architecture of the aquatic habitat. 3. A number of models have been proposed to explain the pattern of connectivity shown by aquatic species with different life‐history characteristics, for example, the stream hierarchy model, Isolation by Distance, the Death Valley Model, the headwater model and panmixia. 4. In this study, we propose a dichotomous key to assign species to different models of potential connectivity. The key is based on a few very simple questions about the life history of the species and the geographical arrangement of study sites. We then assessed the performance of the key with 109 data sets of Australian fish and macroinvertebrates, using genetic data to provide an estimate of realised connectivity. 5. The realised connectivity fitted the proposed potential connectivity model in over 70% of cases, and we suggest this might be a useful initial approach for managers where empirical data are lacking.     

Use of diatom indices to categorise impacts on and recovery of a floodplain system in South Africa

The trophic status of the Ramsar-accredited Nyl River floodplain, which is stressed by sewage treatment effluents, and its ability to restore normal conditions, were assessed in 2014–2015 using diatoms as biological indicators. The Trophic Diatom Index, Specific Pollution Sensitivity Index and the Generic Diatom Index were used to characterise water quality under high and low flow conditions in 2014. An additional survey was conducted in May 2015, following an accidental sulphuric acid spill above the Sewage Treatment Works (STW). Significant linear correlations were identified between physico-chemical parameters and the indices, as well as between the three indices themselves, validating their use to infer water quality. Water quality deteriorated from the source of the Klein Nyl River, especially at the STW, but improved within the Nylsvley Nature Reserve wetland sampling site (NYL).