Untersuchungen zur Renaturierung von Feuchtgebieten im Tijuana Ästuar unter besonderer Berücksichtigung von brackwasserhaltigen und salinen Teichen

This study represents the first comprehensive biological and hydrochemical investigation of small coastal ponds in the saltmarsh dominated Tijuana Estuary, southern California (U.S.). Special attention is given to the brackish water biotopes. Different salinities and considerable fluctuations in water level characterized these shallow ponds and restrict the biological settlement. Fluctuations of salinities ranged from brackish water to hyperhaline water conditions. Due to different salinity levels, the ponds vary in hydrochemistry, macroinvertebrate species composition and plant communities. The macroinvertebrate community of the brackish waters were dominated by Gastropoda, Odonata, and Coleoptera containing a mixture of freshwater/brackish water species and marine macroinvertebrates. Typical plants of the brackish habitat were Typha domingensis (Southern cattail), and Scirpus californicus (California bulrush) associated with Juncus acutus (Siny rush). These brackish habitats with a wide range of salinity fluctuations are sparsely colonized but represent a niche for typical highly adaptable species. Especially, it is a biotope for species with a wide range of salt tolerance. Therefore, endangered species occurred besides introduced or invasive species in the ponds of the Tijuana Estuary. This fact has to be taken into account in case of wetland restoration. Due to the freshwater influence, the restoration of brackish habitats focuses on the problem of invasive species.Die vorliegende Arbeit befasst sich mit der Situation des Tijuana-River-Ästuars im Südwesten Kaliforniens und untersucht insbesondere Flachgewässer mit Brackwassercharakter. Verschiedene Salzgehalte und erhebliche Schwankungen der Wasserstände sind für diese Gewässer charakteristisch und limitieren die biologische Besiedelung. Die Unterschiede in der Salinität reichen dabei von Brackwasserbedingungen bis hin zur Hypersalinität. Aufgrund der verschiedenen Salzgehalte variieren die Gewässer in der hydrochemischen Zusammensetzung, der Makroinvertebratenzusammensetzung und der Pflanzengesellschaften. Die Gruppe der Makroinvertebraten in den Brackwasserbiotopen wird von Schnecken, Libellen und Käfern dominiert, wobei Süß- und Brackwasserarten zusammen mit marinen Invertebraten auftreten. Typische Pflanzen der Brackwasserlebensräume sind Typha domingensis und Scirpus californicus, verbunden mit Juncus acutus-Pflanzen. Solche Brackwasserbiotope mit ihren stark schwankenden Salzgehalten sind zwar artenarm, aber sie stellen zugleich Nischen für Organismen mit speziellem hohem Adaptationsvermögen insbesondere hinsichtlich der Salztoleranz dar. So wurden bei den Untersuchungen gefährdete, aber auch invasive Arten gefunden. Diese Besonderheit ist bei allen Sanierungs- und Renaturierungsaktivitäten zu berücksichtigen

Biological Assessment of Tecate Creek (U.S.–Mexico) with Special Regard to Self-Purification

Macroinvertebrate organisms were sampled at four sites on Tecate Creek (U.S.–Mexico) and quantitatively evaluated using the SIGNAL-w (Stream Invertebrate Grade Number—Average Level-weighted) index. A morphological assessment of the stream structure was also carried out. Bioindication by SIGNAL reflected a very low water quality in the upper three sampled stream reaches, but with a significant improvement by the last site on the Rio Alamar, but only to a grade of critical to high pollution over a flowing distance of 29 km. Levels of BOD and ammonium-N at the Rio Alamar (Toll Bridge) site remained quite high, 56 mg/L and 48 mg/L, respectively. Metal levels also generally decreased as the water flowed downstream to the the Rio Alamar. Despite the fact that Tecate Creek has a quite natural morphological structure, solid inorganic surfaces and aquatic macrophytes (as settlement area) are mostly absent in Tecate Creek. This lack of stable habitats prevents the development of an effective biofilm which would significantly enhance self-purificatio

Levels of the Organophosphorus Pesticide Diazinon in the Chollas Creek Watershed, San Diego CA, since Its Phase-Out in 2004

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Nutrient removal in tropical subsurface flow constructed wetlands under batch and continuous flow conditions

The aim of this investigation was to evaluate the influence of batch versus continuous flow on the removal efficiencies of chemical oxygen demand (COD), nitrogen (N) and total phosphorus (TP) in tropical subsurface flow constructed wetlands (SSF CW). The quantitative role of the higher aquatic plants in nutrient removal in these two operational modes was also investigated. Results indicated no significant difference (p > 0.05) in COD removal between batch and continuous flow modes for either the planted or unplanted treatments. Furthermore, the batch-loaded planted wetlands showed significantly (p < 0.05) higher ammonium removal efficiencies (95.2%) compared with the continuously fed systems (80.4%), most probably because the drain and fill batch mode presented systematically more oxidized environmental conditions. With respect to TP removal, for both planted and unplanted beds, there was significant enhancement (p < 0.05) in batch flow operation (69.6% for planted beds; 39.1% for unplanted beds) as compared to continuous flow operation (46.8% for planted beds; 25.5% for unplanted beds). In addition, at a 4-day hydraulic retention time (HRT), the presence of plants significantly enhanced both ammonia oxidation and TP removal in both batch and continuous modes of operation as compared to that for unplanted beds. An estimation of the quantitative role of aeration from drain and fill operation at a 4-day HRT, as compared to rhizosphere aeration by the higher aquatic plant, indicated that drain and fill operation might account for only less than half of the higher aquatic plant’s quantitative contribution of oxygen (1.55 g O2 per m2 per day for batch flow versus 1.13 g O2 per m2 per day for continuous flow)

Fate of diclofenac in wetland mesocosms planted with Scirpus validus

Uptake and accumulation of the pharmaceutical compound, diclofenac by the macrophyte Scirpus validus was measured in hydroponic solutions with 0.5–2.0 mg L−1 of diclofenac added for a maximum exposure period of 21 d. Findings showed that diclofenac can be reduced significantly (80%) by photodegradation, but diclofenac is also taken up by the plant to levels ranging from 0.17 to 1.49 μg g−1 (fresh weight) in the roots and 0.13–0.49 μg g−1 (fresh weight) in the shoots. Bioaccumulation factors (BAFs) for diclofenac in the shoots (0.17–0.51) were lower than the values calculated in the roots (0.40–1.36). The fact that diclofenac was detected in the shoots demonstrated that diclofenac can be subsequently translocated within the plant after root uptake, although this passive translocation was relatively slow mainly due to diclofenac's high hydrophobicity. This study demonstrates that aquatic plants may contribute directly to the aqueous depletion of emerging organic pollutants in wetlands systems and phytoremediation may be an option for the removal of certain pharmaceutical compounds

Application of constructed wetlands for wastewater treatment in tropical and subtropical regions (2000–2013)

Constructed wetlands (CWs) have been successfully used for treating various wastewaters for decades and have been identified as a sustainable wastewater management option for developing countries. With the goal of promoting sustainable engineered systems that support human well-being but are also compatible with sustaining natural (environmental) systems, the application of CWs has become more relevant. Such application is especially significant for developing countries with tropical climates, which are very conducive to higher biological activity and productivity, resulting in higher treatment efficiencies compared to those in temperate climates. This paper therefore highlights the practice, applications, and research of treatment wetlands under tropical and subtropical conditions since 2000. In the present review, removal of biochemical oxygen demand (BOD) and total suspended solid (TSS) was shown to be very efficient and consistent across all types of treatment wetlands. Hybrid systems appeared more efficient in the removal of total suspended solid (TSS) (91.3%), chemical oxygen demand (COD) (84.3%), and nitrogen (i.e., 80.7% for ammonium (NH)4-N, 80.8% for nitrate (NO)3-N, and 75.4% for total nitrogen (TN)) as compared to other wetland systems. Vertical subsurface flow (VSSF) CWs removed TSS (84.9%), BOD (87.6%), and nitrogen (i.e., 66.2% for NH4-N, 73.3% for NO3-N, and 53.3% for TN) more efficiently than horizontal subsurface flow (HSSF) CWs, while HSSF CWs (69.8%) showed better total phosphorus (TP) removal compared to VSSF CWs (60.1%). Floating treatment wetlands (FTWs) showed comparable removal efficiencies for BOD (70.7%), NH4-N (63.6%), and TP (44.8%) to free water surface (FWS) CW systems.Published versio

Assessment of plant-driven uptake and translocation of clofibric acid by Scirpus validus

Pharmaceutical compounds are now considered as emerging contaminants of environmental concern. The overall objective of this study was to evaluate the uptake and translocation of clofibric acid (CA) by the macrophyte Scirpus validus growing hydroponically. A set of the three replicates was established for each exposure time and for each CA concentration. Plants were grown in 4 L vessels (four plants per vessel corresponding to the three exposure period studies, i.e., 7, 14, 18, and 21 days) which contained an aerated modified Hoagland nutrient solution that was spiked with CA at concentrations of 0.5, 1.0, and 2.0 mg L−1. At each exposure period, CA concentration was measured in the nutrient solutions. A sea sand disruption method was employed for the extraction of CA from plant tissues. The determination of the pharmaceutical concentration was carried out using solid phase extraction (SPE) followed by chromatographic analysis. The quantification of CA concentrations in both nutrient solutions (after SPE) and plant tissues (after extraction) was conducted by chromatographic analysis. CA concentrations of 5.4–26.8 μg g−1 (fresh weight) were detected in the roots and 7.2–34.6 μg g−1 (fresh weight) in the shoots after 21 days. Mass balance calculations showed that S. validus uptake alone accounted for a significant contribution (6–13 % for the roots and 22–49 % for the shoots) of the total loss of CA. The bioaccumulation factors (BAFs) based on fresh weight for the roots ranged from 6.6 to 23.2, while values for the shoots ranged from 9.5 to 32.1. All the BAFs for the shoots were greater than those in the roots, implying that CA has greater tendency to be translocated to the shoots, rather than the roots of S. validus. All the shoot-to-root concentration ratios were more than 1, denoting that the shoots of S. validus do preferentially accumulate CA. We demonstrated that CA can be actively taken up, subsequently translocated and accumulated by aboveground tissues of S. validus. Since S. validus could account for the removal of 28–62 % of the total mass loss of CA from the system, such phytoremediation technology has great potential for the removal of pharmaceuticals such as CA from inflowing waters

Pharmaceutical removal in tropical subsurface flow constructed wetlands at varying hydraulic loading rates

Determining the fate of emerging organic contaminants in an aquatic ecosystem is important for developing constructed wetlands (CWs) treatment technology. Experiments were carried out in subsurface flow CWs in Singapore to evaluate the fate and transport of eight pharmaceutical compounds. The CW system included three parallel horizontal subsurface flow CWs and three parallel unplanted beds fed continuously with synthetic wastewater at different hydraulic retention times (HRTs). The findings of the tests at 2–6 d HRTs showed that the pharmaceuticals could be categorized as (i) efficiently removed compounds with removal higher than 85% (ketoprofen and salicylic acid); (ii) moderately removed compounds with removal efficiencies between 50% and 85% (naproxen, ibuprofen and caffeine); and (iii) poorly removed compounds with efficiency rate lower than 50% (carbamazepine, diclofenac, and clofibric acid). Except for carbamazepine and salicylic acid, removal efficiencies of the selected pharmaceuticals showed significant (p 0.05), implying that their removal is not well related to the compound’s hydrophobicity