Riverine Wetlands Research Articles

El rol de los bañados de desborde fluvial en la retención de nutrientes y su actividad metabólica

El objetivo de este trabajo fue analizar los efectos de los bañados de desborde fluvial sobre la calidad del agua y el metabolismo del curso de agua. Para ello se estudiaron cuatro cauces, dos que recorren la periferia de un casco urbano y que tienen zonas de bañados de desborde fluvial conservados, y que mantienen su conexión con el agua subterránea, y otros dos periurbanos y que sus bañados de desborde fluvial han sido degradados por el avance de la urbanización, desconectándolos de las capas freáticas. En cada uno, se muestrearon tres tramos de 50 metros de longitud. El primero, localizado aguas arriba de la zona de bañados (llamado “Arriba”), el segundo en el tramo medio del curso de agua que recorre el bañado (llamado “Medio”), y el último aguas abajo del bañado (llamado “Abajo”). Las variables estudiadas incluyeron, en cuatro períodos del año y en cada tramo, parámetros físico-químicos (temperatura, conductividad, pH, oxígeno disuelto, turbidez, sólidos disueltos y suspendidos, concentraciones de formas del nitrógeno y fósforo disuelto y total) y biológicos, vinculados a la actividad metabólica del biofilm y a la densidad de bacterias. Además, en dos momentos del año, se realizaron ensayos de retención de nutrientes y metabolismo fluvial en los tramos medios de los cursos fluviales. Los resultados muestran que los bañados de desborde fluvial mejor conservados a) disminuyen significativamente el oxígeno disuelto y aumentan la concentración de sólidos suspendidos en el cauce; b) incrementan significativamente los procesos metabólicos fluviales, tales como la respiración o la producción primaria; c) poseen tasas elevadas de asimilación de nutrientes por la biota; d) actúan como depuradores de bacterias coliformes en el cauce principal. Estos patrones generales pueden ser detectados aunque se observa mucha variabilidad en los cauces, y su intensidad varía a lo largo del año y en función de las condiciones físico-químicas del flujo.

Los microorganismos que habitan los bañados de desborde fluvial como indicadores de los efectos de la urbanización y la actividad agropecuaria

Los bañados de desborde fluvial (BDF) desempeñan un papel integral en la ecología de las cuencas fluviales y en su capacidad de autodepuración. La demanda antrópica de espacio y agua pone en riesgo su biota y los beneficios ecosistémicos que brindan. Los objetivos del trabajo fueron analizar los ensambles de microorganismos que habitan en BDF, relacionar sus variaciones al impacto antrópico y evaluar cómo la microbiota puede ser indicadora de estos cambios ambientales. Se estudiaron los ensambles de diatomeas bentónicas, fitoplancton, zooplancton, ostrácodos y hongos de cuatro BDF: dos de ubicación periurbana con uso del suelo agrícola y hortícola (Del Gato y Carnaval), y dos de ubicación rural y uso ganadero (Cajaravillas y Chubichaminí). En la mayoría de los grupos las diferencias vinculadas a la ubicación geográfica se expresaron claramente, resultando en una agrupación de ensambles en: BDF rurales (con un número de especies sensibles a la contaminación y a la eutrofización comparativamente mayor) y BDF periurbanos (donde fueron más importantes las especies muy tolerantes a la contaminación y a la eutrofización). En estos últimos, tanto la participación de los grandes grupos taxonómicos como los niveles tróficos estuvieron más restringidos y relacionados a la vía detritívora por sobre la fotosintética, y allí también se acentuaron las estrategias para afrontar el estrés hídrico. Los resultados evidencian los efectos de la presión humana, la importancia que adquieren los microorganismos y la necesidad de una planificación adecuada del uso del territorio para evitar la pérdida de funciones y beneficios en estos ambientes.

Los bañados de desborde fluvial: una mirada desde la geohidrología

Los bañados de desborde fluvial (BDF) abarcan tramos (cientos de metros a kilómetros) de los sistemas fluviales pampeanos, con características y funciones particulares. Estos humedales se originan por un afloramiento del nivel freático y una disminución local del gradiente hidráulico, lo que da lugar a un ensanchamiento del curso de agua principal y la aparición de una red de microdrenaje que acompaña a este último. Estas condiciones favorecen el desarrollo de humedales asociados al curso principal, con un importante desarrollo de la vegetación característica de suelos muy húmedos. El objetivo de este trabajo fue el de analizar las características hidrológicas y la calidad del agua de los BDF en zonas urbanizadas con actividad agrícola (localizados en losarroyos Carnaval y Del Gato) y en zonas rurales con ganadería extensiva (ubicados en los arroyos Cajaravillas y Chubichaminí), del NE de la provincia de Buenos Aires, con el fin de reconocer cómo los diferentes usos del suelo modifican las condiciones de conservación de los humedales. Los análisis geohidrológicos se realizaron a escala regional (cuenca), semi-detalle (subcuenca) y detallada (BDF). Los resultados mostraron que la sobreexplotación de las aguas subterráneas afecta a la permanencia del agua en los humedales, debido a la desconexión entre el nivel freático y el nivel basal de los BDF situados en las zonas urbanizadas con actividad agrícola. En estos últimos se ha observado también que el aporte de nutrientes contribuye significativamente al deterioro de la calidad del agua. La conclusión es que un diagnóstico ambiental de estos BDF requiere un enfoque regional de los procesos hidrológicos para adoptar acciones adecuadas para su conservación.

Observaciones sobre algunas características ecológicas de las plantas que habitan los bañados de desborde fluvial afectados por la urbanización y las prácticas agrícolas

El objetivo de este trabajo fue exponer, a través de cuatro casos de estudio de bañados de desborde fluvial localizados en la llanura pampeana (NE de la Provincia de Buenos Aires), la composición y la cobertura relativa de los ensambles de la vegetación asociada a estos humedales. También, se explora las características vinculadas a la tolerancia de las plantas a la presencia de agua, como indicadoras de la variabilidad hidrológica, que definen a estos ambientes sometidos a diferentes usos del suelo. Se realizaron relevamientos florísticos mediante transectas transversales al curso del agua, estableciéndose en cada una, nueve unidades muestrales de 1 m2, en los bañados ubicados en los arroyos Chubichaminí, Cajaravillas, Del Gato y Carnaval, durante marzo de 2020. El análisis de los inventarios de los cuatro humedales permitió identificar 44 taxa. La cobertura relativa de las especies, clasificadas de acuerdo a la tolerancia de las plantas a la permanencia del agua en los bañados, posibilitó reconocer cómo los usos del suelo influyen en las características de los mismos. Los que se encuentran en las zonas rurales, mejor conservados y que mantienen la conectividad con el agua subterránea, se observó que la cobertura relativa de especies hidrófitas obligadas de humedales más las especies facultativas fue superior al 85 %, que las observadas en zonas periurbanas con actividad agrícola. En estos últimos, se halló la mayor cobertura de especies terrestres (18-30%). Reconocer las características de la vegetación que habita en estos humedales contribuirá a establecer estrategias de manejo para la conservación y rehabilitación, como así también delimitar estos humedales.

A wetland oasis at Wadi Gharandal spanning 125–70 ka on the human migration trail in southern Jordan

AbstractFormer lakes and wetlands can provide valuable insights to the late Pleistocene environments encountered by the first humans to enter the Levant from Africa. Fluvial incision along Wadi Gharandal in hyperarid southern Jordan has exposed remnants of a small riverine wetland that accumulated as a sedimentary sequence up to ~20 m thick. We conducted a chronometric and sedimentological study of this wetland, including 10 optically stimulated luminescence dates. The wetland sequence accumulated during the period ~125 to 70 ka in response to a positive water balance coupled with a (possibly coseismic) landslide that dammed the outlet. The valley fill was dissected when the dam was incised shortly after ~36 ± 3 ka. Comparison of our ages with regional palaeoclimate indicates that the Gharandal oasis developed during the relatively humid Marine Isotope Stage 5. A minimum age of 74 ± 7 ka for two Levallois flakes collected from stratified sediments suggests that the oasis was visited by humans during the critical 130–90 ka time window of human migration out of Africa. Gharandal joins a growing network of freshwater sites that enabled humans to cross areas of the Levant and Arabia along corridors of human dispersal.

Sediment and Nutrient Retention Capacity of Natural Riverine Wetlands in Southwest Ethiopia

Although wetlands in temperate regions have been studied for their pollutant remediation potential, the sediment and nutrient retention capacity of natural wetlands in tropical environments remains understudied. In this study, a mass balance approach was used to estimate the amount of sediment and nutrients retained at 40 different study sites located in four natural riverine wetlands in Southwest Ethiopia. Awetu and Boye wetlands retained a substantial amount of total suspended solids (TSS) and nutrients whereas Kofe and Kito wetlands had a net release. Overall, the amount of TSS retained by the four wetlands was estimated to be 6266.5 kg/ha/day. On the other hand, the net retention of Total Organic Nitrogen (TON) and Total Phosphorous (TP) was estimated to be 37.6 kg/ha/day and 40.9 kg/ha/day respectively. A stepwise multiple regression analysis revealed that anthropogenic activities such as farming, grazing, waste dumping and clay mining were the main variables that negatively affected the retention of TSS and nutrients. Farming alone explained 58% of the variation in TSS retention and cattle grazing explained 25% of the variation in TON retention. Therefore, watershed management interventions considering the mitigation of anthropogenic activities could be considered to reduce sediment and nutrient input and release.

Factors controlling organic carbon distributions in a riverine wetland.

As a significant reservoir of organic carbon (OC), natural wetlands play an important role in mitigating greenhouse effects. To determine what factors might influence OC, we analyzed the distributions of dissolved organic carbon (DOC), light fraction organic carbon (LFOC), and heavy fraction organic carbon (HFOC) in sediments taken from the Yanghe River Wetland (YRW) and assessed the effects of several environmental variables on the distribution of the different carbon types. The microbial community abundances and compositions of the sampled sediments were analyzed by 16S rRNA amplicon sequencing. Redundancy analysis (RDA) was used to reveal the environmental factors that affect the distribution of OC. The DOC and LFOC contents varied significantly in the research area, while HFOC content showed no variation. The DOC content was significantly affected by sediment pH, vegetation height, and microbial abundances, and the LFOC content was significantly affected by water pH. We also proposed a novel indicator to study the microbial effect on the distribution of OC content in wetlands: weighted abundance of related microbes (WARM). This study identifies the environmental factors that could affect the distribution of OC in a riverine wetland and outlines the calculation of a novel indicator.

The influence of surrounding land cover on wetland habitat conditions: a case study of inland wetlands in South Korea.

Wetland ecosystems have been globally degraded and lost due to rapid urbanization and climate change. An assessment of national scale inventory, including wetland types and conditions, is urgently required to understand the big picture of endangered wetlands, such as where they are and how they look like. We analyzed the spatial patterns of each inland wetland type (brackish wetland was included) in South Korea and the relative importance of land cover categories on wetland conditions. The wetlands were grouped into four dominant types (riverine, lake, mountain, and human-made) according to their topography. Riverine wetlands constituted the largest area (71.3%). The relative ratio of wetlands in a well-conserved condition (i.e., “A” rank) was highest in riverine wetlands (23.8%), followed by mountain wetlands (22.1%). The higher proportion of grasslands was related to a better condition ranking, but the increasing bareland area had a negative impact on wetland conditions. We also found that wetlands located near wetland protected areas tend to be in a better condition compared to remote sites. Our results further support the importance of the condition of surrounding areas for wetland conservation.

Modified hydrogeomorphic approach for estimating quantitative change of riverine wetland functions

HydroGeoMorphic (HGM) approach could examine relatively more details for wetland functions. However, HGM cannot be utilized in assessing the functional improvement of wetlands because it is limited to evaluating the similarity between the reference and the target wetlands. Therefore, this study proposes the Modified HydroGeoMorphic (MHGM) approach for considering better functions of target wetlands. The values of Index of Function (FCI) and variables in HGM are in the range of 0.0 to 1.0 and so, in MHGM, we redefine the values of variables in 0.0 to 2.0 to find a better function for the target wetland. Based on the monitored variables, FCIs for the wetland functions were estimated and the functions of dynamic surface and subsurface water storage, spatial structure of habitat, and maintaining the distribution and abundance of vertebrates in Imjin riverine wetland as a target wetland showed better FCIs than those of Hwapo which is a reference. This means that MHGM reflects an actual change in FCI, leading to a more favorable evaluation of the target compared to the reference wetland. This indicates that MHGM considers actual functional progress of wetlands by improving HGM's limitations in assessing change.

Large weir construction causes the loss of seasonal habitat in riverine wetlands: a case study of the Four Large River Projects in South Korea

From 2009 to 2012, South Korea carried out national-wide construction projects in four rivers; sixteen large-weirs were constructed to control flood risk and to secure water resources. Environmental impact assessment of the weir construction evaluated conditional changes by comparing post-survey records with pre-construction periods. However, the ecological assessment for the weir construction in a long-term perspective has been still limited. In this study, we compared the long-term dynamics of riverine habitat in two construction sites (Nakdong River and Geum River), and one reference site (Seomjin River) in South Korea using 33-years database of satellite imagery. We classified 30 m-grid riverine habitats into three temporal types (i.e., permanent water, seasonal water, and non-flooded habitat) based on annual flooding frequency and its temporal trend was compared. After weirs construction, the area of permanent water was increased (Nakdong R.: +36.0%, Geum R.: +10.9%); seasonal habitat and non-flooded habitat were decreased (Nakdong R: −36.5% and −37.4%; Geum R: −22.9% and −28.2%, respectively). And annual flux of habitat transitions into different habitat types has been decreased only in weir construction sites. Among different habitat transition categories, habitat change into permanent water was the highest during the weir construction periods. Our long-term analysis of riverine habitat can be used to understand temporal changes and recovery after weir construction and channel dredging.

Water Purifying Capacity of Natural Riverine Wetlands in Relation to Their Ecological Quality

Wetlands are among the crucial nature based solutions for river water purification. The ecological integrity of this multi-purpose ecosystem could be disrupted due to overloading of nutrients and other pollutants. We investigated the water purifying effect and ecological integrity of three natural riverine wetlands (urban downstream in Boye and urban upstream in Fisho and Kitto). We sampled water, macroinvertebrates, and diatoms, to compare sites before joining the wetland, within the wetland and after passing through the wetland. The lower concentration of nutrients, and BOD in sites after joining the wetland showed the presence of pollution attenuation. Macroinvertebrate and diatom based bio-indices depicted higher biodiversity and lower relative abundance of tolerant taxa in sites after joining the wetland, which implicated the potential of studied wetlands to reduce pollutants and sustain biodiversity. The wetland fed by heavily polluted streams showed the most degraded ecological quality compared to the other two, fed by less polluted streams. An RDA model visualized this pollution gradient among sites. Generally, this study confirmed the potential of natural wetlands to attenuate nutrients and organic pollutants and sustain biodiversity. However, when the incoming water is heavily degraded, the retention of pollutants seriously affect the wetland’s ecological integrity.

The roles of environmental variation and spatial distance in explaining diversity and biogeography of soil denitrifying communities in remote Tibetan wetlands.

The relative importance of local environments and dispersal limitation in shaping denitrifier community structure remains elusive. Here, we collected soils from 36 riverine, lacustrine and palustrine wetland sites on the remote Tibetan Plateau and characterized the soil denitrifier communities using high-throughput amplicon sequencing of the nirS and nirK genes. Results showed that the richness of nirS-type denitrifiers in riverine wetlands was significantly higher than that in lacustrine wetlands but not significantly different from that in palustrine wetlands. There was no clear distinction in nir community composition among the three kinds of wetlands. Irrespective of wetland type, the soil denitrification rate was positively related to the abundance, but not the α-diversity, of denitrifying communities. Soil moisture, carbon availability and soil temperature were the main determinants of diversity [operational taxonomic unit (OTU) number] and abundance of thenirS-type denitrifier community, while water total organic carbon, soil NO3- and soil moisture were important in controlling nirK-type denitrifier diversity and abundance. The nirS community composition was influenced by water electrical conductivity, soil temperature and water depth, while the nirK community composition was affected by soil electrical conductivity. Spatial distance explained more variation in the nirS community composition than in the nirK community composition. Our findings highlight the importance of both environmental filtering and spatial distance in explaining diversity and biogeography of soil nir communities in remote and relatively undisturbed wetlands.

Valuing Fishing Activity of the Deepor Beel

The Deepor Beel is one of the large and important riverine wetlands in the Brahmaputra valley of Assam, India. The only Ramsar site of Assam, the Beel is one of the richest biodiversity grounds in the wetland eco-system of the state. The Deepor Beel is the hub of a wide range of organisms. It provides various goods and services directly or indirectly to the villages near to the beel for their livelihood. Despite its contribution to society and ecology as a whole, these goods and services of the Beel are undervalued in the policy provisions. The prime reason for this undervaluation is that most of the goods and services of the Beel are non-marketable and those goods which have direct use-values are never valued in an economic term. To fill the gap partially, this study tries to estimate the direct use values of the Deepor Beel. Among the goods the Deepor Beel provides, fishing can be considered one of the economically significant goods. Fishing provides livelihood directly to 825 households living near the Beel. Therefore, this research tries to estimate the direct use value of fishing in the Deepor Beel. A market price approach is applied to estimate the value of this wetland resource. Net Present Value (NPV) of fishing is also estimated. The total estimated value of fishing is INR 11,64,69,375 per annum. The estimated value of fishing per hectare is INR 29,015.78 per annum. The estimated Net Present Value (NPV) of fishing is INR 97,05,78,125. This valuation is important to draw the attention of the policymakers for resource investment in conserving the Beel for continued benefits.

Soil properties alter plant and microbial communities to modulate denitrification rates in subtropical riparian wetlands

AbstractThe capacity of riparian wetlands to remove nitrogen from upland runoff through the denitrification process is mainly controlled by soil properties and biological communities. However, the pathways or mechanisms by which soil properties and biological communities may regulate riparian denitrification rates are still largely unknown. Here, we measured the potential and unamended denitrification rates in sediments from riverine wetlands along a nitrogen‐rich river in subtropical China. We also investigated the plant richness, vegetation cover, and abundance of denitrifying microorganisms in wetland soils. The results show that both potential and unamended denitrification rates presented strong seasonality, and were found to be significantly associated with nitrogen concentration in soils, implying that denitrification process in riparian wetlands is probably nitrogen limited. Moreover, potential and unamended denitrification rates were positively related to denitrifier abundance, plant richness, and vegetation cover. Using structural equation modeling, we found that moisture and nitrogen concentration could influence denitrification rates directly; the indirect effects of these factors on denitrification rates mediated through modulating the structure of plant and microbial communities. These findings suggest that denitrification rates and nitrogen removal capacities in riparian wetlands are jointly modulated by soil properties and biological communities.

Study to Develop a Co-Relationship between Water Quality and Land use Pattern as Index of Riverine Wetland with Statistical Approach

Abstract This investigation additionally recognizes partner cooperation issue and furthermore to moderate the real issue through subjective and quantitative appraisal of riverine wetland. Considering a floodplain wetland in rustic West Bengal, the concentration was extended to perceive the type of wetland capacities as per the idea of individuals’ contribution by group examination. Be that as it may, NDVI was connected to ponder the total weeds condition into the wetland to decide the connection between Water Quality Index (WQI) with Normalized Difference Vegatation Index (NDVI) and its impact on valuation. In ANOVA, which is computed by MINITAB programming, centrality level was lower than 0.05 for each case.

Howard T. Odum and wetland ecology

Howard Thomas Odum (1924-2003) was an important transitional figure in the development of wetland ecology in the United States. Although he was educated before wetland ecology became a recognized subdiscipline of ecology, his research during the first half of his academic career (ca. 1950 to 1975) was focused primarily on wetlands. By the early 1970s, he was self-identifying as a wetland ecologist, e.g., by establishing the Center for Wetlands at the University of Florida. Although Odum was interested in much more than wetlands, especially during the last half of his lengthy career, he contributed significantly to increasing the visibility of wetlands and to the development of wetland ecology in four principal ways: (1) his innovative and influential research on the trophic structure of Silver Springs, a riverine wetland; (2) his highly visible research on the use of Cypress Domes to treat waste water; (3) his establishment of a major academic, wetland research institute, the Center for Wetlands; and (4) his many graduate students who obtained influential jobs in academia, government agencies and private companies. When Odum started his academic career wetland ecology did not exist. Halfway through it, wetland ecology began to arise as a distinct discipline and Odum was one of the major reason why this happened.

Assemblage of dematiaceous and Ingoldian fungi associated with leaf litter of decomposing Typha latifolia L. (Typhaceae) in riverine wetlands of the Pampean plain (Argentina) exposed to different water quality

The purpose of this study was to analyze the rate of sporulation, richness, and spore diversity of dematiaceous and Ingoldian fungi colonizing Typha latifolia leaves during a 40-day period of decomposition, as well as the loss of mass in Typha latifolia, in four riverine wetlands of Pampean plain (Argentina) with different water quality. Higher sporulation rates, richness, and diversity of the fungi as well as loss of mass of the leaves that they colonized were associated with lower water quality. Anguilospora longissima, Arthrinium sp., Margaritispora aquatica, and Tricellula botryosa were dominant taxa. Redundancy analysis showed two fungal assemblages related to different environmental conditions. One assemblage was related to higher nutrient levels and higher temperature, characterized mainly by dematiaceous fungi. The other assemblage was related to higher levels of pH and dissolved oxygen, which was mainly represented by Ingoldian fungi. The results obtained in our study demonstrated the link between these fungal assemblages and changes in water quality, revealing their potential as indicators of environmental changes in rivers exposed to different types of land use.

Mapping the maximum inundation extent of lowland intermittent riverine wetland depressions using LiDAR

Accurate high-resolution maps of maximum wetland inundation extents are valuable inventorial resources, but mapping such boundaries can be difficult, time consuming and involve a level of subjectivity from the surveyor. A novel, objective and efficient method is presented for delineating the maximum inundation extents of lowland intermittent riverine wetland depressions using a high resolution LiDAR-derived digital terrain model (DTM). The method was specifically developed for wetland depressions associated with the lower reaches of the Murrumbidgee River in the southern Murray Darling Basin, Australia, but is suitable for any similar intermittent wetland depressions where the natural inundation extent is otherwise unclear. The method is based on the premise that immediately after rising water reaches a threshold level, much larger volumes of water are required to inundate not just the discrete wetland depression but also its surrounding local area; that threshold level can be considered the wetland fill level. Using a series of water levels and a corresponding series of the volume between each water level and a DTM of a wetland area, the maximum rate of increasing acceleration in volume with respect to water level, i.e. the wetland fill level, can be identified. The fill levels of eight wetland areas, ranging in size from 44 to 384 ha, were produced by this method and subsequently used to map their maximum inundation extents. Corresponding maps of the inundation frequency gradient were independently determined from a time series of Landsat derived inundation maps. The level of separation in inundation frequency of map cells inside the maximum inundation extents compared to those outside, determined by the Kolmogorov Smirnov statistic, validated the technique, while identifying that a minimum level of variation in the elevation of the wetland area may be necessary for it to be successfully applied. The technique has potential to be applied more widely as an objective and relatively inexpensive procedure to identify the potential maximum inundation extent of intermittent floodplain wetlands when a good quality high resolution DTM, acquired during a dry phase, is available.

Rapid Assessment of Wetland Condition Reflects Amphibian Community Composition

Kentucky has lost over 80% of its wetlands, and because state-wide monitoring was historically minimal, this number is likely underestimated. The Kentucky Wetland Rapid Assessment Method (KY-WRAM) was developed to assess wetland condition. Our objective was to determine if the KY-WRAM reflects condition by comparing it to intensive assessment of amphibian communities, while simultaneously addressing which environmental variables explain the distribution and abundance of amphibian species in riverine wetlands. Wetlands (n = 44) were randomly selected and stratified by score for comparison of amphibian communities across a disturbance gradient. Factors including KY-WRAM score, nutrients, dissolved oxygen, landscape disturbance, predatory fish, and atrazine were included as model parameters to potentially explain species richness and abundance. KY-WRAM score explained the majority of variation in richness (R2 = 0.62), which was significantly greater at medium and high category sites compared to low. KY-WRAM was also an important predictor of abundance for seven amphibian species. Results indicate KY-WRAM is a good predictor of wetland condition and strongly relates to amphibian communities. Other variables that contributed to explaining abundance were landscape disturbance, wetland size, predatory fish, and river basin. Our study contributes to overall validation of the KY-WRAM. Future validation studies should focus on other basins, wetland types, and taxa.

Polycyclic Aromatic Hydrocarbons in Sediments/Soils of the Rapidly Urbanized Lower Reaches of the River Chaohu, China.

Polycyclic aromatic hydrocarbons (PAHs) are highly teratogenic, persistent carcinogens, and ubiquitous environmental pollutants. To determine the impact of rapid urbanization on sediment/soil PAHs, we collected 30 cm soil cores in ditch wetlands, riverine wetlands, and agricultural lands along the lower reaches of the Shiwuli River feeding Chaohu Lake, China. Ecological risk effects were evaluated by two models based upon Benzo[a]pyrene toxic equivalency (TEQ-BaP) and total toxic units (TUs). The presence of PAHs, such as BbF, BkF, InP, and BgP, that are known pollutants of concern, suggests certain ecological risks. The concentration of PAHs in the surface layer followed in the order of: ditch wetlands (617.2 ng/g average), riverine wetlands (282.1 ng/g average), agricultural lands (103.7 ng/g average). PAHs in ditch sediments were vertically distributed evenly, and PAHs in agricultural soils were concentrated in the surface soil. In riverine wetland sediments, the 2-, 3-, and 4-ring PAHs had a uniform distribution, whereas the 5- and 6-ring PAHs were concentrated in the surface soil. Redundancy analysis (RDA) explored the correlation between the environmental properties and the occurrence of PAHs. Total organic carbon (p = 0.010), percent clay (p = 0.020), and distance (p = 0.020) were the primary factors in ditch wetlands. Depth (p = 0.010) and distance (p = 0.006) were the main factors in agricultural lands. There were no significant correlations in riverine wetlands. The correlation between the distance from the built-up urban areas and pollutant concentration showed that the closer the distance, the greater the concentration of PAHs.