Fanlong Kong

Spatial variation of dissolved organic carbon in soils of riparian wetlands and responses to hydro-geomorphologic changes in Sanjiang Plain, China

Spatial variation of dissolved organic carbon (DOC) in soils of riparian wetlands and responses to hydro-geomorphologic changes in the Sanjiang Plain were analyzed through in situ collecting soil samples in the Naoli River and the Bielahong River. The results showed that the average contents of DOC for soil layer of 0–100 cm were 730.6 mg/kg, 250.9 mg/kg, 423.0 mg/kg and 333.1 mg/kg respectively from riverbed to river terrace along the transverse directions of the Naoli watershed. The content of the soil DOC was the highest in the riverbed, lower in the high floodplain and much lower in the river terrace, and it was the lowest in the low floodplain. The difference in the content and vertical distribution of DOC between the riverbed and the three riparian wetlands was significant, while it was not significant among the low floodplain, the high floodplain and the river terrace. The variability of soil DOC was related to the hydrological connectivity between different landscape position of the riparian wetlands and the adjacent stream. Extremely significant correlations were observed between DOC and total organic carbon (TOC), total iron (TFe), ferrous iron (Fe(II)) whose correlation coefficients were 0.819, −0.544 and −0.709 in riparian wetlands of the Naoli River. With the increase of wetland destruction, soil pH increased and soil DOC content changed. The correlation coefficients between soil DOC and TOC, TFe, Fe(II) also changed into 0.759, −0.686 and −0.575 respectively in the Bielahong River. Under the impact of drainage ditches, the correlations between soil DOC and TFe, Fe(II) were not obvious, while the soil pH was weakly alkaline and was negatively correlated with soil DOC in the previous high floodplain. It indicates that riparian hydro-geomorphology is the main factor that could well explain this spatial variability of soil DOC, and the agricultural environmental hydraulic works like ditching also must be considered.

Comparative bioavailability of ammonium, nitrate, nitrite and urea to typically harmful cyanobacterium Microcystis aeruginosa.

Phosphorus is generally considered as the prime limiting nutrient responsible for cyanobacterial blooms. However, recent research is drawing attention to the importance of bioavailable nitrogen (N) in freshwater eutrophication. This study investigated the bioavailability of NO3(-)-N, NO2(-)-N, NH4(+)-N and Urea-N under different concentrations of 1.2, 3.6 and 6.0mgL(-1) to Microcystis aeruginosa. Overall, Urea-N ranked the first in promoting M. aeruginosa growth, followed by NO3(-)-N and NO2(-)-N. However, the algal growth cultured in NH4(+)-N was depressed under test N levels. The bioavailability of N to M. aeruginosa was seriously influenced by both N forms and N concentrations (p<0.01). Total N concentrations in Urea-N treatment decreased the fastest, which were corresponding with the μ values of M. aeruginosa. The high enzymic activities of nitrate reductase, nitrite reductase and glutamine synthetase indicated that the decomposition process for urea is effective, which contributed in N assimilation and utilization in M. aeruginosa cells.

Effects of environmental conditions and aboveground biomass on CO2 budget in Phragmites australis wetland of Jiaozhou Bay, China

Estuarial saline wetlands have been recognized as a vital role in CO2 cycling. However, insufficient attention has been paid to estimating CO2 fluxes from estuarial saline wetlands. In this study, the static chamber-gas chromatography (GC) method was used to quantify CO2 budget of an estuarial saline reed (Phragmites australis) wetland in Jiaozhou Bay in Qingdao City of Shandong Province, China during the reed growing season (May to October) in 2014. The CO2 budget study involved net ecosystem CO2 exchange (NEE), ecosystem respiration (Reco) and gross primary production (GPP). Temporal variation in CO2 budget and the impact of air/soil temperature, illumination intensity and aboveground biomass exerted on CO2 budget were analyzed. Results indicated that the wetland was acting as a net sink of 1129.16 g/m2during the entire growing season. Moreover, the values of Reco and GPP were 1744.89 g/m2 and 2874.05 g/m2, respectively; the ratio of Reco and GPP was 0.61. Diurnal and monthly patterns of CO2 budget varied significantly during the study period. Reco showed exponential relationships with air temperature and soil temperature at 5 cm, 10 cm, 20 cm depths, and soil temperature at 5 cm depth was the most crucial influence factor among them. Meanwhile, temperature sensitivity (Q10) of Reco was negatively correlated with soil temperature. Light and temperature exerted strong controls over NEE and GPP. Aboveground biomass over the whole growing season showed non-linear relationships with CO2 budget, while those during the early and peak growing season showed significant linear relationships with CO2 budget. This research provides valuable reference for CO2 exchange in estuarial saline wetland ecosystem.

Temporal-spatial variation of DOC concentration, UV absorbance and the flux estimation in the Lower Dagu River, China

Dissolved organic carbon (DOC) is an important component for both carbon cycle and energy balance. The concentration, UV absorbance, and export flux of DOC in the natural environment dominate many important transport processes. To better understand the temporal and spatial variation of DOC, 7 sites along the Lower Dagu River were chosen to conduct a comprehensive measurement from March 2013 to February 2014. Specifically, water samples were collected from the Lower Dagu River between the 26th and 29th of every month during the experimental period. The DOC concentration (CDOC) and UV absorbance were analyzed using a total organic carbon analyzer and the ultraviolet-visible absorption spectrum, and the DOC export flux was estimated with a simple empirical model. The results showed that the CDOC of the Lower Dagu River varied from 1.32 to 12.56 mg/L, consistent with global rivers. The CDOC and UV absorbance showed significant spatial variation in the Dagu River during the experiential period because of the upstream natural processes and human activities in the watershed. The spatial variation is mainly due to dam or reservoir constructions, riverside ecological environment changes, and non-point source or wastewater discharge. The seasonal variation of CDOC was mainly related to the source of water DOC, river runoff, and temperature, and the UV absorbance and humification degree of DOC had no obvious differences among months (P<0.05). UV absorbance was applied to test the CDOC in Lower Dagu River using wave lengths of 254 and 280 nm. The results revealed that the annual DOC export flux varied from 1.6 to 3.76 × 105 g C/km2/yr in a complete hydrological year, significantly lower than the global average. It is worth mentioning that the DOC export flux was mainly concentrated in summer (∼90% of all-year flux in July and August), since the runoff in the Dagu River took place frequently in summer. These observations implied environment change could bring the temporal-spatial variation of DOC and the exports, which would further affect the land-ocean interactions in the Lower Dagu River and the global carbon cycle.

Research on Wetland Protection and Restoration of Luyang Lake in Weinan City, Shaanxi Province

Luyang Lake is a unique wetland area which includes a large wetland complex in Guan Hong Plain and also a representative site of this wetland type in China. It has high value for preservation and scientific research. However, the wetlands in this lake have been severely degraded by the long history of human activities such as excavation of salt and sodium sulfate ponds and agriculture. Based on the analysis of hydrological and water quality conditions of the existing wetlands, an overall consideration of the wetland types, resource status, distribution of target species, and the water source, the study suggests a series of engineering measures to restore wetland ecosystem and improve ecological environmental quality in Luyang Lake. The engineering projects mainly include the following aspects: i) connect water system through cutting of drainages and, retreat farmlands to lakes or wetlands, ii) construct artificial wetland to purify polluted waters, iii)improve the habitat so as to provide excellent staging, breeding, and wintering habitats for wetland birds.

Study on the Test of Desalinating Brackish Water in Qingdao City

The water resources of coastal area in Qingdao City are seriously lacking, and most of water is brackish water under the influence of the seawater intrusion. This article used a novel and innovative technology CGH (Carrier Gas Humidiflcation) to desalt the water in order to solve the drinkable water in the coastal area in Qingdao City. The result indicated that the CGH is a simple, low energy, and reliable system for brackish water reclamation and could remove NaCl, MgCh and other dissolved solids in the brackish water effectively.

Study on the Test of Arsenic Removal for Drinking Water in the Rural Areas

Arsenic is a kind of substance with high toxicity. Arsenic pollution exists in the drinking water of rural areas, which would be harmful for human health. Based on adsorption methods, this article designed a water treatment system to remove arsenic from drinking water in the rural areas. The water treatment system uses a stabilized waste material as the adsorption material to meet the need for dispersed drink water and promote environmental stewardship. The result indicated that the adsorption-based system with desirable properties is a simple, easily maintained and energy efficient system for the removal of arsenic from drinking water in rural areas.