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Due to the shortage of phosphate and the eutrophication caused by phosphorus pollution, it is urgent to recover phosphate from wastewater. Given their high adsorption capacity and convenient separation from water to which a magnetic field is applied, ferrite composites have received increasing attention for phosphate recovery. In this study, Spinel La@MgFe 2 O 4 was prepared using a one-step co-precipitation method. La 3+ loading on grain boundary defects of MgFe 2 O 4 , and phosphorus absorption capacity were examined using X-ray diffraction (XRD), Fourier-transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometry (VSM). The structure of La@MgFe 2 O 4 involved La 3+ loading on grain boundary defects of MgFe 2 O 4 in the form of La(OH) 3 . The addition of La changed the crystallinity and morphology of MgFe 2 O 4 , which greatly improved the capacity of MgFe 2 O 4 for phosphorus adsorption. Saturation magnetization remained at 14 emu·g -1 , which was easily separated from water using an external magnetic field. The maximum adsorption capacity was 143.156 mg·g -1 at pH 6 and 10℃, which was comparable to that achieved at 25℃. Kinetic observations showed that a low phosphorus concentration (10 mg·L -1 ) could result in extremely low phosphorus adsorption by La@MgFe 2 O 4 after 30 min. The adsorption mechanism shows that phosphorus is removed through ligand exchange and the formation of inner spherical complexes. La@MgFe 2 O 4 has highly selective adsorption with respect to phosphate, and the adsorbent can be reused many times after desorption. Based on addition of 1 g·L -1 of La@MgFe 2 O 4 in the treatment of low temperature municipal wastewater in Northern China, phosphate concentrations could be reduced to less than 0.5 mg·L -1 an hour, offering a promising means of phosphate adsorption even in cold regions.

Adsorption is an economical and effective method for recovering phosphate from wastewater. In order to improve the adsorption capacity of Fe 3 O 4 for phosphate and for easy separation from water under the action of an external magnetic field, CaO 2 was used in this study as an oxidant to partially oxidize Fe 2+ . A phosphorus recovery adsorbent, Ca doped Fe 3 O 4 (CMIO), was prepared and was characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF) and vibrating sample magnetometer (VSM) techniques. The results showed that CMIO had a Ca 2+ doped Fe 3 O 4 crystal structure with a saturation magnetization of 38.82 emu·g -1 , which was easily separated from water by using an external magnetic field. The phosphorus adsorption capacity of the CMIO decreased with an increase of pH value. When pH=2 and T =25℃, the maximum adsorption capacity was 24.10 mg·g -1 , which is almost five times the adsorption capacity of pure Fe 3 O 4 . The phosphorus adsorption of CMIO was in accord with the Langmuir isotherm adsorption model, and the adsorption process followed the pseudo-second order kinetic model. The complexation of phosphate occurred on the inner surface of the CMIO to form a ≡Fe-Ca-P ternary complex, which can adsorb phosphorus. Compared with other anions in the aqueous solution, CMIO had good adsorption selectivity to PO 4 3- , and the adsorbed PO 4 3- could be desorbed by NaOH solution.The quality loss of the CMIO was less than 4% once, and multiple recycling was possible.

28 typical wetlands were selected to monitor the contaminants in water monthly, that influenced by urbanization in different scales. On the other hand, the land use types such as impervious area and forest area in the catchments of urban wetlands were analyzed by GIS and landscape ecology. And then the effects of urbanization index (UEI) was employed to reveal the relationship between urbanization level and water quality in Xianlin New City of Nanjing. Results indicated that: (1) the seasonal variations of water quality showed that water quality in summer was worse than those in other seasons, and the water quality in winter was good. However there were no significant differences between the spring and the autumn. (2) the relationship was significant between urbanization level and water quality, and the water quality tended to be getting worse when the urbanization level was getting higher. The concentrations of TP, TN, NH(4+)-N, and Chla were 0.27, 1.07, 0.15 and 17.94 mg x L(-1) respectively in the high urbanization (HU) level wetland while the concentrations were 0.12, 0.56, 0.12 and 4.85 mg x L(-1) in the low urbanization (LW) level wetland. (3) there was a threshold between UEI and the water quality. On the whole, the water quality would get worse quickly when the value of UEI exceeded 2.2.

Exploring the quantitative relationship between landscape characteristics and surface water quality indicators can provide important information to urban landscape planning and water environment protection. Jiuxiang River watershed in Nanjing city, being as a typical case study area, its landscape classification maps was conducted in 2009 by remote sensing digital images interpretation. Based on the remote sensing images and real-time monitoring data from October 2009 to September 2010, geospatial analysis and statistical analysis were integrated to explore the relationship between landscape composition, landscape pattern (landscape-level and class-level) and river water quality at the subwatershed scale. Results showed that most of landscape compositions influenced river water quality. Percentage of built-up land and unused land was positively related to total nitrogen (TN), total phosphorus (TP), ammonia nitrogen (NH4(+) -N) and permanganate index, while percentage of forestland showed a negative relationship. At the landscape level, the water quality was good when the size of patch was big. But at class-level, the aggregated distribution of the built-up land, unused land and arable land might cause TN, TP, permanganate index and NH4(+) -N concentration increased. But the aggregated distribution of the forestland had the opposite effect on water quality indicators.

Water is the basis of wetland, the degree of water health directly determines the function of wetland ecosystem. The theory and method of water health were established in the study. Water health included both water status health and water process health. Water status health was reflected by hydrologic condition and water quality. Water process health was calculated by water elasticity, water stability and resilience. Xixi Wetland Park was taken as the case study. The results indicated that: 1) Seasonal variations of water health were apparent in Xixi Wetland. Water health index was the highest (46.36) and stayed under the sub-health condition in summer. In contrast, water health index was the lowest (37.35) and unhealth in winter; 2) the degrees of water health were obviously different between ponds and creeks. Water health index in ponds was 42.72, which was higher than that of creeks (37.99); 3) Water in Xixi Wetland Park was sub-health with 53.80 as its water health index. Based on the result of study, to enhance water health of creeks in winter is an effective measure to improve water health in Xixi Wetland Park.

As the first national wetland park and the representatively urban wetland, Xixi wetland must provide the services of tourism and recreation especially. Based on the data which had been collected monthly from March to August in 2009, the objectives of this paper were to describe the characteristics of water quality in temporally and spatially. The results indicated that: (1) the characteristics of water quality in spatially are significantly corrected with the function of wetland. Total nitrogen (TN) and total phosphorus (TP) average concentrations are 0.78 mg/L and 0.07 mg/L respectively in natural ponds, while the concentrations of TN and TP in ornamental ponds are 1.37 mg/L and 0.17 mg/L respectively. The concentrations of TN and TP are 2.91 mg/L and 0.18 mg/L in natural streams and 1.91 mg/L and 0.09 mg/L in sight-seeing streams; (2) the nutrition in Xixi wetland is different in temporally. The nutrition in Xixi is at the level of moderate eutrophication, while the nutrition is higher in summer than it in spring; (3) the level of eutrophication in pounds is lower than it in streams, of which the level of eutrophication in natural ponds is lower than it in ornamental ponds and the level of eutrophication in natural streams is higher than it in sight-seeing streams by contraries. In order to improve water quality in Xixi wetland, the valid measure is to strengthen the management of ornamental ponds and natural streams.