Temporal and spatial variation of nitrogen and phosphorus and eutrophication assessment for a typical arid river—Fuyang River in northern China

Based on water quality surveys over 2 years(July to December,in 2014 and 2015) in a typical arid river in northern China the Xingtai segment of the Fuyang River basin — the variation of nitrogen(N) and phosphorus(P) was analyzed.The extent of water eutrophication of this segment was also assessed using a universal index formula for eutrophic evaluation and a logarithmic power function.The results showed that the average concentration of total N(TN) was 27.2 mg/L(NH_3-N,63.5%),total P(TP) was 2.0 mg/L(solution reactive phosphorus,68.8%).Temporal and spatial variations of N and P in this segment were observed.Concentrations of N and P in the arid season were higher than those in the rainy season.Spatially,the N and P concentrations followed the same trend;i.e.,higher in the city segment than in the suburbs,and decreasing along the river.The water eutrophication in the studied segment reached extremely high levels at all times(eutrophication index ≥76.3).Spatially,its trend was clearly linked with N and P.Water shortage,pollution accumulation and a weak self-purification function are the main reasons for the prominent eutrophication in this segment.     

What drives the change of nitrogen and phosphorus loads in the Yellow River Basin during 2006-2017?

The Yellow River Basin (YRB) plays a very important role in China's economic and social development and ecological security. In particular, the ecosystem of the YRB is sensitive to climate change. However, the change of nutrient fluxes in this region during the past years and its main driving forces remain unclear. In this study, a hydrologic model R System for Spatially Referenced Regressions on Watershed Attributes (RSPARROW) was employed to simulate the spatio-temporal variations in the fluxes of total nitrogen (TN) and total phosphorus (TP) during the period of 2006-2017. The results suggested that the TN and TP loads increased by 138% and 38% during 2006-2014, respectively, and decreased by 66% and 71% from 2015 to 2017, respectively. During the period of 2006-2017, the annual mean fluxes of TN and TP in the YRB were in the range of 3.9 to 591.6 kg/km²/year and 1.7 to 12.0 kg/km²/year, respectively. TN flux was low in the upstream area of the Yellow River, and presented a high level in the middle and lower reaches. However, the flux of TP in Gansu and Ningxia section was slightly higher than that in the lower reaches of the Yellow River. Precipitation and point source are the key drivers for the inter-annual changes of TN loads in most regions of the YRB. While the inter-annual variations of TP loads in the whole basin are mainly driven by the point source. This study demonstrates the important impacts of climate change on nutrient loads in the YRB. Moreover, management measures should be taken to reduce pollution sources and thus provide solid basis for control of nitrogen and phosphorus in the YRB.     

Energy of forest systems in the Three Gorge Reservoir Area

１ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｆｏｒｅｓｔｒｙｈａｓｍａｄｅａｇｒｅａｔｐｒｏｄｕｃｔｉｖｉｔｙｉｎｔｈｅＴｈｒｅｅＧｏｒｇｅＲｅｓｅｒｖｏｉｒａｒｅａｉｎＣｈｉｎａ，ａｎｄｉｔｒｅａｃｈｅｄｍｕｃｈｄｅｓｉｒａｂｌｅｂｉ...     

Environmental threats to the Three Gorges Reservoir Region:Are mutagenic and genotoxic substances important?

<正>The Three Gorges Dam project(TGDP),with a total static investment of 95.46 billion RMB(US$10.97 billion)based on the 1993 price level,commenced in 1994 and was completed in 2012.The creation of the Three Gorges Reservoir following the completion of the TGDP had brought about significant changes to the Three Gorges Reservoir Region(TGRR),stretching from the town of Sandouping in Hubei Province to the Jiangjin District of Chongqing Municipality.The TGDP has led to progressive urbanization and industrialization of the TGRR,accompanied by increased shipping activities,greater     

A three-dimensional model for the transportation of Fe and Mn in Arha Reservoir

ＩｎｔｒｏｄｕｃｔｉｏｎＡｒｈａＲｅｓｅｒｖｏｉｒｉｓｌｏｃａｔｅｄｉｎｔｈｅｐｌａｔｅａｕｒｅｇｉｏｎｏｆＳｏｕｔｈｗｅｓｔＣｈｉｎａ.Ｔｈｉｓｒｅｓｅｒｖｏｉｒ,ｗｉｔｈａｖｏｌｕｍｅｏｆ445ｍｉｌｌｉｏｎｍ3,ｗａｓｂｕｉｌｔｉｎ1960ａｎｄｉｓｔｈ?..     

Characteristics of phosphorus chemistry and its geographical distribution in the Haihe River valley,North China

ＣｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｐｈｏｓｐｈｏｒｕｓｃｈｅｍｉｓｔｒｙａｎｄｉｔｓｇｅｏｇｒａｐｈｉｃａｌｄｉｓｔｒｉｂｕｔｉｏｎｉｎｔｈｅＨａｉｈｅＲｉｖｅｒｖａｌｌｅｙ，ＮｏｒｔｈＣｈｉｎａＪｉａｎｇＧａｏｍｉｎｇ；ＨｕａｎｇＹｉｎｘｉａｏ；Ｌ...     

Dynamic response of chlorsulfuron herbicide to nitrogen mineralization and the ratio of microbial biomass nitrogen to nitrogen mineralization in the soil

ＩｎｔｒｏｄｕｃｔｉｏｎＨｅｒｂｉｃｉｄｅｓａｒｅｎｏｗｕｓｅｄｅｘｔｅｎｓｉｖｅｌｙｉｎｃｒｏｐｐｒｏｄｕｃｔｉｏｎ.Ｔｈｅｉｎｃｒｅａｓｉｎｇｕｓｅｏｆｈｅｒｂｉｃｉｄｅｓｗｉｔｈｎｉｔｒｏｇｅｎｆｅｒｔｉｌｉｚｅｒｓｈａｓｃｒｅａｔｅｄｓｅｒｉ?..     

River flood risk and adaptation in Europe—assessment of the present status

Flood disasters have had a devastating effect worldwide over the past century, both in terms of human suffering and material losses. The study of these events and development of more effective adaptation and mitigation policies has become a priority, both in Europe and other parts of the globe. This paper detects and presents the spatial distribution of river flood risks in Europe. The methodology we developed involves an assessment of three key risk components: exposure, vulnerability and hazard. A topography-based flood hazard map of Europe, identifying low-lying areas adjacent to rivers, is presented and used to identify risk, together with land-use data and damage-stage relationship for different land uses. The study covers river flood risk for the entire European continent. This methodology can be used to determine the level of future risk, using the estimations on Hazard, Exposure and Vulnerability from specific climate and economic development models. Annual average flood damage is estimated for European regions, in absolute monetary terms and in % of regional Gross Domestic Product (GDP). The results highlight regions where the threat to the economy from river flood hazard is of major concern.     

Nutrient cycling characteristics of Quercus acutisima and Pinus massoniana mixed forest in the Three Gorge Reservoir area, China

ＮｕｔｒｉｅｎｔｃｙｃｌｉｎｇｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆＱｕｅｒｃｕｓａｃｕｔｉｓｉｍａａｎｄＰｉｎｕｓｍａｓｏｎｉａｎａｍｉｘｅｄｆｏｒｅｓｔｉｎｔｈｅＴｈｒｅＧｏｒｇｅＲｅｓｅｒｖｏｉｒａｒｅａ，ＣｈｉｎａＷｕＧａｎｇＤｅｐａｒｔｍｅｎ...     

Seasonal variation and health risk assessment of atmospheric polycyclic aromatic hydrocarbons（PAHs） in the urban area of Xi＇an

利用大流量主动采样器于2008年8月至2009年7月采集了西安城区大气样品,研究了大气中多环芳烃（PAHs）的季节变化特征.结果表明,西安大气中16种美国EPA优控的PAHs（∑PAHs）气固两相总浓度为37～620ng·m-3（年平均为195ng·m-3）,具有明显的季节差异,依次为夏季（74ng·m-3）〈春季（106ng·m-3）〈秋季（213ng·m-3）〈冬季（360ng·m-3）.气态PAHs以3～4环为主,颗粒态PAHs以5～6环为主.分子组成表明西安大气PAHs主要来自于燃煤和机动车尾气及生物质燃烧的复合源.应用BaP毒性当量因子及健康风险评价模型对西安城区成人和儿童进行PAHs健康风险评价,结果显示成人和儿童的日均暴露剂量分别为24.3×10-6mg·kg-·1d-1和5.6×10-6mg·kg-·1d-1,终身致癌超额危险度分别为7.5×10-5和1.7×10-5,可能造成成人和儿童的预期寿命损失分别约为467.6min和107.5min.     

Agricultural non-point nitrogen pollution control function of different vegetation types in riparian wetlands： A case study in the Yellow River wetland in China

Riparian wetland is the major transition zone of matter, energy and information transfer between aquatic and terrestrial ecosystems and has important functions of water purification and non-point pollution control. Using the field experiment method and an isotope tracing technique, the agricultural non-point nitrogen pollution control function of di erent vegetation types in riparian wetland was studied in the Kouma Section of the Yellow River. The results showed that the retention of agricultural non-point nitrogen pollution by riparian wetland soil occurs mainly in top 0–10 cm layer. The amount of nitrogen retained by surface soils associated with three types of vegetation are 0.045 mg/g for Phragmites communis Trin Linn, 0.036 mg/g for Scirpus triqueter Linn, and 0.032 mg/g for Typha angustifolia Linn, which account for 59.21%, 56.25%, and 56.14% of the total nitrogen interception, respectively. Exogenous nitrogen in 0–10 cm soil layer changes more quickly than in other layers. One month after adding K15NO3 to the tested vegetation, nitrogen content was 77.78% for P. communis Trin, 68.75% for T. angustifolia, and 8.33% for S. triqueter in the surface soil. After three months, nitrogen content was 93.33% for P. communis Trin, 72.22% for S. triqueter, and 37.50% for T. Angustifolia. There are large di erences among vegetation communities respecting to purification of agricultural non-point nitrogen pollution. The nitrogen uptake amount decreases in the sequence: new shoots of P. communis Trin (9.731 mg/g) > old P. communis Trin (4.939 mg/g) > S. triqueter (0.620 mg/g) > T. angustifolia (0.186 mg/g). Observations indicated that the presence of riparian wetlands as bu ers on and adjacent to stream banks could be recommended to control agricultural non-point pollution.     

Long-term nitrogen and phosphorus removal,shifts of functional bacteria and fate of resistance genes in bioretention systems under sulfamethoxazole stress

To understand the long-term performance of bioretention systems under sulfamethoxazole (SMX) stress, an unplanted bioretention system (BRS) and two modified BRSs with coconut-shell activated carbon (CAC) and CAC/zero-valent-iron (Fe0) granules (CAC-BRS and Fe/CAC-BRS) were established. Both CAC-BRS and Fe/CAC-BRS significantly outperformed BRS in removing total nitrogen (TN)(CAC-BRS:82.48%; Fe/CAC-BRS:78.08%; BRS:47.51%), total phosphorous (TP)(CAC-BRS:79.36%; Fe/CAC-BRS:98.26%; BRS:41.99%),and...     

Speciation and distribution characteristics of heavy metals in the Changjiang River water

ＳｐｅｃｉａｔｉｏｎａｎｄｄｉｓｔｒｉｂｕｔｉｏｎｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｈｅａｖｙｍｅｔａｌｓｉｎｔｈｅＣｈａｎｇｊｉａｎｇＲｉｖｅｒｗａｔｅｒ￥ＣｈｅｎＸｉｂａｏ；ＺｈａｎｇＳｈｅｎ；ＤｏｎｇＷｅｎｊｉａｎｇ；ＺｈａｎｇＬｉｃｈｅｎｇ（...     

Streamwater phosphorus and nitrogen across a gradient in rural–agricultural land use intensity

This paper provides an overview of the impacts of rural land use on lowland streamwater phosphorus (P) and nitrogen (N) concentrations and P loads and sources in lowland streams. Based on weekly water quality monitoring, the impacts of agriculture on streamwater P and N hydrochemistry were examined along a gradient of rural–agricultural land use, by monitoring three sets of ‘paired’ (near-adjacent) rural headwater streams, draining catchments which are representative of the major geology, soil types and rural/agricultural land use types of large areas of lowland Britain. The magnitude and timing of P and N inputs were assessed and the load apportionment model (LAM) was applied to quantify ‘continuous’ (point) source and ‘flow-dependent’ (diffuse) source contributions of P to these headwater streams. The results show that intensive arable farming had only a comparatively small impact on streamwater total phosphorus (TP loads), with highly consistent stream diffuse-source TP yields of ca. 0.5 kg-P ha^?1 year^?1 for the predominantly arable catchments with both clay and loam soils, compared with 0.4 kg-P ha^?1 year^?1 for low agricultural intensity grassland/woodland on similar soil types. In contrast, intensive livestock farming on heavy clay soils resulted in dramatically higher stream diffuse-source TP yields of 2 kg-P ha^?1 year^?1. The streamwater hydrochemistry of the livestock-dominated catchment was characterised by high concentrations of organic P, C and N fractions, associated with manure and slurry sources. Across the study sites, the impacts of human settlement were clearly identifiable with effluent inputs from septic tanks and sewage treatment works resulting in large-scale increases in soluble reactive phosphorus (SRP) loads and concentrations. At sites heavily impacted by rural settlements, SRP concentrations under baseflow conditions reached several hundred μg-P L^?1. Load apportionment modelling demonstrated significant ‘point-source’ P inputs to the streams even where there were no sewage treatment works within the upstream catchment. This indicates that, even in sparsely populated rural headwater catchments, small settlements and even isolated groups of houses are sufficient to cause significant nutrient pollution and that septic tank systems serving these rural communities are actually operating as multiple point sources, rather than a diffuse input.     

Role of phosphorus on the biogeochemical behavior of cadmium in the contaminated soil under leaching and pot experiments

Phosphorus (P) is involved in various biochemical reactions in plant growth,so it is beneficial to plants growing in soils contaminated by metals,including cadmium (Cd).However,few studies have reported on the mechanistic roles of P in mitigating Cd toxicity to ryegrass root,and especially in alleviating the disruption of the mitochondrial function of living cells.In this study,the physiological and biochemical mechanisms associated with ryegrass growth under various Cd and P treatments were inv...     

Chlorobenzenes in waterweeds from the Xijiang River （Guangdong section） of the Pearl River

The Xijiang River is the major source of water for about 4.5 millions of urban population and 28.7 millions of rural population. The water quality is very important for the health of the rural population. The concentration and distribution of chlorobenzenes (CBs) in both water and waterweeds collected from 4 stations in the Xijiang River (Gangdong section) of the Pearl River in April and November were determined. The result showed that nearly every congener of CBs was detected. The total contents of CBs (∑CBs) in the river water ranged from 111.1 to 360.0 ng/L in April and from 151.9 to 481.7 ng/L in November, respectively. The pollution level of CBs in the water in April was higher than that in November. The contents of ∑ CBs in waterweeds ranged from 13.53×102 μg/g to 38.27×102μg/g dry weight (dw). There was no significant difference between April and November in waterweeds. The distribution of CBs in roots, caulis, and leaves of Vallisneria spiralis L. showed different patterns. The leaves mainly contained low-molecular-weight CBs(DCBs), whereas the roots accumulated more PCBs and HCBs. The average lgBCFlip (bioconcentration factor) of CBs ranged from 0.64 to 3.57 in the waterweeds. The spatial distribution character of CBs in the Xijiang River was: Fengkai County ＜ Yunan County ＜Yun'an County ＜ Gaoyao County according to the ∑CBs, and the pollution deteriorated from the upstream to the downstream of the Xijiang River. Further analysis demonstrated that the discharge of waste containing CBs may be the main source of CBs pollution in the Xijiang River.     

Nutrient cycling characteristics of Quercus acutissima and Pinus massoniana mixed forest in the Three Gorge Reservoir area, China

The cycling characteristics of nitrogen(N), phosphorus(P) and potassium(K) of the Quercus acutissima and Pinus massonianamixed forest which is the most common forest type in the Three Gorge Reservoir areas in China, were systematically analyzed. The results showed that N, P and K accumulated in the plant pool and in the litter pool, while total N, P, and K were deficient in the soil pool and in the forest systems. Contents of N in the soil of depth 20—40 cm were the key factor limiting growth of trees. The biological outside cycling coefficients were 8.78, 72.5 and 11.7 times of inside cycling coefficients of N, P and K, respectively. 33.92, 10.26 and 15.88 kg of N, P and K return to the litter pool from branches, leaves and throughfall per year, but, 14.31, 1.32 and 10.48 kg of N, P and K return to the soil from litter pool per year respectively. It is clear that 58% of N, 87% of P, and 34% of K are lost by surface runoff per year. 5.49%, 1.30%, and 8.34% of N, P and K withdraw from leaves to branches, 4.99%, 1.99% and 7.30% of N, P and K withdraw from branches to trunks per year, respectively.     

Vertical and temporal distribution of nitrogen and phosphorus and relationship with their influencing factors in aquatic-terrestrial ecotone： a case study in Taihu Lake, China

Vertical and temporal distributions of N and P in soil solution in aquatic-terrestrial ecotone （ATE） of Taihu Lake were investigated, and the relations among N, P, ORP （oxidation reduction potential）, TOC, root system biomass and microorganism were studied. As a whole, significant declines in TN, NO3^--N, DON （dissolved organic nitrogen） and TP concentration in soil solution have occurred with increase of the depth, and reached their minima at 60 cm depth, except for NH4^＋-N, which increased with depth. The concentration of TP increased gradually from spring to winter in the topsoil, the maximum 0.08 mg/L presented in the winter while the minimum 0.03 mg/L in spring. In the deeper layer, the concentration value of TP fluctuated little. As for the NO3^--N, its seasonal variation was significant at 20 cm depth, its concentration increased gradually from spring to autumn, and decreased markedly in winter. Vertical and temporal distribution of DON is contrary to that of NO3^--N. The results also show that the variation of N and P in the percolate between adjacent layers is obviously different. The vertical variation ofTN, TP, NO3^--N, NH4^＋-N and DON is significant, of which the variation coefficient of NO3^--N along the depth reaches 100.23%, the highest; while the variation coefficient of DON is 41.14%, the smallest. The results of correlation analysis show that the concentration of nitrogen and phosphorus correlate significantly with TOC, ORP, root biomass and counts of nitrifying bacteria. Most nutrients altered much from 20 to 40 cm along the depth. However, DON changed more between 60 and 80 cm. Results show that soil of 0-60 cm depth is active rhizoplane, with strong capability to remove the nitrogen and phosphorus in ATE. It may suggest that there exists the optimum ecological efficiency in the depth of above 60 cm in reed wetland. This will be very significant for ecological restoration and reestablishment.     

Sequential fractionation of reactive phosphorus in the sediment of a shallow eutrophic lake——Donghu Lake, China

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