土地利用对水体营养物影响的研究进展

日益严重的水质污染威胁到人类健康与生存,水体富营养化是其中一大治理难题。流域土地利用深刻影响水体中的营养物,定量刻画两者关系,可有效指导土地利用优化以改善水体质量。在国内外研究的基础上,本文梳理了样地实验、统计分析、经验模型和机理模型等4类研究土地利用和水体营养物关系的方法,并分析了不同方法应用的优缺点。以往研究多侧重土地利用数量结构,对强度和空间分布的量化及其与水体营养物关系的模型构建等研究尚显不足,多从单一或部分信息进行松散研究,导致不同研究中土地利用对水体营养物的解释能力差异显著。本文着重综述土地利用类型、强度差异和空间分布等3个方面对水体营养物影响的研究进展,并阐述关于两者定量关系尺度效应的争议和不确定性。目前主要存在问题包括现有研究土地利用和水体营养物的关系手段不足、土地利用多组分信息和水体营养物关系规律不清和尺度效应不确定性等3方面。因此,本文以水体污染物的产生、迁移、转化等的生态水文过程为线索,提出土地利用多信息空间综合表达和量化研究框架作为核心突破口。应用该框架,未来围绕融合过程机理与经验统计的模型开发、富营养化过程关联的土地利用多信息综合量化和多尺度结构的构建等3个方面开展研究,旨在为丰富土地利用对水体营养物影响研究提供一定的参考价值。

The decline process and major pathways of Microcystis bloom in Taihu Lake, China

Eutrophication has become a serious concern in many lakes, resulting in cyanobacterial blooms. However, the mechanism and pathways of cyanobacteria decline are less understood. To identify and define the growth and decline of Microcystis blooms in Taihu Lake of China, and to illuminate the destination of surface floating blooms, we investigated the biomass distribution and variations in colony size, morphology, and floating velocity from October 2008 to September 2009. The results showed that the Microcystis bloom declined in response to biomass decrease, colony disaggregation, buoyancy reduction, and increased phytoplankton biodiversity, and these indicative parameters could be applied for recognition of the development phases of the bloom. Three major decline pathways were proposed to describe the bloom decline process, colony disaggregation （Pathway I）, colony settlement （Pathway II）, and cell lysis in colonies （Pathway III）. We proposed a strategy to define the occurrence and decline of Microcystis blooms, to evaluate the survival state under different stress conditions, and to indicate the efficiency of controlling countermeasures against algal blooms.

Nutritive Equilibrium in Rice Plant Populations for High Yield

The effects of nitrogen, phosphorus and potassium application level, seed rate and transplanting density on the growth and development of rice plants were studied to find out nutrient status in high-yielding rice plants and to increase grain yield by adequate fertilization. There was an equilibrium relationship among nutrient elements for high-yielding rice plant populations. The equilibrium index of nutrient amount, content and distribution in high-yielding rice plants should be generally greater than-2 but less than 2. The optimum nutritive proportion of nitrogen: phosphorus: potassium assimilated by the plants was about 10: 2: 9 at the ripening stage. But the content and the proportion varied with the growth stages. Therefore, the nutrient in rice plant populations should be in a dynamic equilibrium, so as to achieve high yield.

Changes in the small-jellyfish community in recent decades in Jiaozhou Bay, China

We used long term monitoring data to evaluate changes in abundance and species dominance of small-jellyfish (collected with zooplankton net whose bell diameter was less than 5 cm) between 1991 and 2009 in the Jiaozhou Bay, China. Zooplankton samples were vertically towed with conical plankton net from near-bottom to surface, identified microscopically, and mapped in time-space using Grapher 7.0 and Surfer 8.0. Results show that the abundance of small-jellyfish throughout the bay had been increasing during 2001-2009 on average of 15.2 ind./m 3 , almost 5 times higher than that between 1991 and 2000. The occurrence of peak abundance shifted from spring to summer after 2000, and two peaks appeared in spring and summer, respectively, after 2005. Both the abundance and the frequency of blooms of small-jellyfish increased after 2000 in the bay. In addition, the biodiversity of jellyfish has increased significantly in recent years with a change in dominant species. Several new dominant species appeared after 2000, including Rathkae octopunctata in winter, Phialidium hemisphaericum in spring, summer, and autumn, Phialucium carolinae in spring, and Pleurobrachia globosa in summer and autumn, while some previous dominant species throughout the 1990s (Eirene ceylonensis, Zanclea costata, Lovenella assimilis, and Muggiaea atlantica) were no longer dominant after 2000. The abundance of small-jellyfish was positively correlated with the density of dinoflagellates, and the abundance of zooplankton. We believe that the changes in smalljellyfish abundance and species composition were the result of eutrophication, aquaculture and coastal construction activities around the bay. Concurrently, seawater warming and salinity decrease in recent decades promoted the growth and reproduction of small-jellyfish in the bay.

Phosphorus Speciation in Wetland Sediments of Zhujiang (Pearl) River Estuary,China

Phosphorus fractions and adsorption-release characteristics of sediments in the Zhujiang （Pearl） River estuary wetland were investigated. Results showed that the total phosphorus （TP） content in surface sediments ranged from 648.9 mg/kg to 1064.0 mg/kg; inorganic phosphorus （IP） was the major fraction of TP and ranged from 422.5 mg/kg to 643.9 mg/kg. Among the inorganic phosphorus, the main fractions were phosphorus bound to A1 and Fe （Fe/A1-P）, and calcium-bound phosphorus （Ca-P）, accounting for 23%-42% and 21%-67% of IP, respectively. The vertical distribution of TP contents were significantly positive correlated with organic phosphorus （Org-P） and Fe/A1-P contents. The bio-available phosphorus contents in vertical sediments varied from 128.6 mg/kg to 442.9 mg/kg, mainly existed in Fe-AI/P fraction, and increased from the bottom to top sediments. The transport of phosphorus in sediment-water in- terface was controlled by the soil characteristics. The active Fe and A1 content was considered as the main factor that determines adsorp- tion capacity in vegetated marsh wetland. The P buffering capacity of the sediments in vegetated marsh wetland was greater than that in mudflat wetland. The potential risk of eutrophication in the study area is high. Reducing terrestrial phosphorus discharge and preventing the sediment Fe/A1-P release to the interstitial water are the possible solutions to reduce the risk of eutrophication in estuary wetlands, and planting vegetation in estuary wetland can also reduce the release of phosphorus in surface sediment.

Does salinity change determine zooplankton variability in the saline Qarun Lake(Egypt)?

Zooplankton and 14 abiotic variables were studied during August 2011 at 10 stations in Lake Qarun, Egypt. Stations with the lowest salinity and highest nutrient concentrations and turbidity were close to the discharge of waters from the El-Bats and E1-Wadi drainage systems. A total of 15 holozooplankton species were identified. The salinity in Lake Qarun increased and fluctuated since 1901：12 g/L in 1901; 8.5 g/L in 1905; 12.0 g/L in 1922; 30.0 g/L in 1985; 38.7 g/L in 1994; 35.3 g/L in 2006, and 33.4 g/L in 2011. The mean concentration of nutrients （nitrate, nitrite and orthophosphate） gradually increased from 35, 0.16 and 0.38 μg/L, respectively, in 1953-1955 to 113, 16.4, and 30.26 μg/L in 2011. From 1999-2003 some decrease of species diversity occurred. Average total zooplankton density was 30 000 ind./m^3 in 1974-1977; 356 125 ind./m^3 in 1989; 534 000 ind./m^3 in 1994-1995; from 965 000 to 1 452 000 ind./m^3 in 2006, and 595 000 ind./m^3 in 2011. A range of long-term summer salinity variability during the last decades was very similar to a range of salinity spatial variability in summer 2011. There is no significant correlation between zooplankton abundance and salinity in spatial and long-term changes. We conclude that salinity fluctuations since at least 1955 did not directly drive the changes of composition and abundance of zooplankton in the lake. A marine community had formed in the lake, and it continues to change. One of the main drivers of this change is a regular introduction and a pressure of alien species on the existent community. Eutrophication also plays an important role. The introduction ofMnemiopsis leidyi, first reported in 2014, may lead to a start of a new stage of the biotic changes in Lake Qarun, when eutrophication and the population dynamics of this ctenophore will be main drivers of the ecosystem change.

Non-alcoholic fatty liver disease and the metabolic syndrome:Effects of weight loss and a review of popular diets,Are low carbohydrate diets the answer?

Non-alcoholic fatty liver disease （NAFLD） encompasses a wide spectrum of fat-induced liver injury, ranging from relatively benign steatosis to cirrhosis and liver failure. The presence of obesity and insulin resistance is strongly associated with non-alcoholic fatty liver and confers on it a greater risk of histologically advanced disease. There is a growing concern in the medical profession as the prevalence of this disease continues to rise in parallel with the rise in obesity and the metabolic syndrome. Treatment options are limited and dietary weight loss is often advised. Low fat diets are difficult to adhere to and recent studies have shown the potential of low carbohydrate diets for weight loss and improving insulin resistance. Thus far, no study has evaluated the effect of low carbohydrate diets on NAFLD. Future studies will be required to address this question and others with regards to the nutritional adequacy and long-term side effects of these diets.

Relationship between environmental factors and plankton in the Bayuquan Port, Liaodong Bay,China：a five-year study

To understand the relationship between the plankton community and environmental factor and water quality in the Bayuquan Port of Liaodong Bay, China, and investigations were carried ou during six dif ferent periods(April 2009, April 2010, October 2011, April 2012, October 2012, and Apri 2013). This area was characterized by high levels of nutrient and suspended solids(SPS) during surve periods, and eutrophication led to the occurrence of red tides in April and October 2012 and April 2013 Our analyses revealed that the plankton communities of Bayuquan Port lacked stability and were af fecte seriously by external disturbance(e.g., oceanographic engineering and river runof f). Our data indicate tha oil, dissolved inorganic nitrogen(DIN), SPS, and chlorophyll a(Chl- a) were key factors that regulated th phytoplankton and zooplankton communities. The partial redundancy analysis(partial RDA) suggested tha oil and SPS were the most important environmental variables af fecting the phytoplankton community i April 2010 and 2012, whereas DIN concentration played a governing role in zooplankton dynamics. Oi and Chl-a concentrations af fected signifi cantly the zooplankton community in October 2012. Therefore, th plankton communities could refl ect both dynamic changes in coastal environmental factors and the ongoin eutrophication process caused by anthropogenic activities in this area.

Removal of eutrophication factors and heavy metal from a closed cultivation system using the macroalgae,Gracilaria sp.(Rhodophyta)

In this study, the ability of macroalgae Gracilaria sp. of removing eutrophication factors and toxic heavy metals A1, Cr, and Zn in a closed cultivation system is reported. The results show that the concentration of the three heavy metals decreased significantly during the experimental period in an algal biomass dependent manner. The biofiltration capacity of the alga for A1, Cr, and Zn is 10.1%-72.6%, 52.5%-83.4% and 36.5%,91.7%, respectively. Using more materials resulted in stronger heavy metal removal. Additionally, the concentration of chl-a, TN, TP and DIN of water samples fxom aquariums involving large, medium, and small algal biomass cultivation increased first and then decreased during the experiment. COD value of all three groups decreased with time and displayed algal biomass dependency： more algae resulting in a greater COD value than those of less biomass. Furthermore, changes in COD reflect an obvious organic particles deprivation process of algae. This is the first report on heavy metal removal effect by Gracilaria species. The results suggest that macroalgae can be used as a biofilter for the treatment of nutrient-enriched or heavy-metal polluted water, to which an appropriate time range should be carefully determined.

Removal of Nitrogen and Phosphorus from Animal and Municipal Wastewaters as Dittmarite

Phosphorus and nitrogen are known causes of eutrophication in rivers, lakes streams and estuaries. The sources of these nutrients are diverse and they include chemical fertilizers, CAFOs （Confmed Animal Feeding Operations）, land application of animal and municipal as well as industrial wastewaters. Application of manure slurries to crop land beyond allowable limits could result in high levels of phosphorus and nitrogen in runoff that negatively impact aquatic animals. Municipal wastewater treatment plants are setup to remove these nutrients from domestic and industrial wastewater through a network of treatment processes. Controlling the discharge of phosphorus and nitrogen in wastewater is a key factor in preventing eutrophication. This paper presents work done to enhance a chemical precipitation process that removes over 90% of dissolved phosphorus and nearly 20% of dissolved nitrogen from both synthetic and municipal wastewaters. The objective of the study is to remove nitrogen and phosphorus from wastewater as dittmarite, a value-added mineral fertilizer found in nature. A laboratory procedure was developed that generated significant quantities of dittmarite from various wastewaters. Pure dittrnarite contains nitrogen, phosphorus and magnesium in approximate molar ratios of 1：1.2：1.2 that can support plant growth. It is produced as a wet precipitate from chemical reactions that occur in the wastewater treatment process; it can be dried for proper handling and utilization. Municipal wastewater treatment plants, high volume fish producers, CAFOs and individual rural homeowners could all benefit from this technology for on-site removal of nitrogen and phosphorus from produced wastewaters.

Coastal Sea Water Quality of Nha Trang Bay, Khanh Hoa, Viet Nam

Nha Trang Bay is famous not only because of its beauty, but also of the biodiversity values, especially coral reefs. Thus, the sea water quality monitoring systems are necessary for effective and available managements to protect the ecosystems and for sustainable development. There have been several monitoring systems here but they have been done separately and unconnectedly. This research was done to take an overview and access the status and changes of water quality from 2007-2014. The data obtained rainy seasons over the years showed a quite good environment here. The environment changes were also monitored and there were some changes between seasons and over years, decreasing, increasing, or unobvious trends. However, the difference was not so much; and there was not the sign of environmental degradation in the bay from 2007 to 2014. Besides, the stoichiometric nutrients limitations were initially assessed. Since Si ratios here were always higher compared to N and P, there was not increased potential for non-diatom algal blooms. Together with the recorded nutrients concentration data, it can be said that there was no evidence of eutrophication in the bay. Although there was partial contamination of some parameters at few moments, the sea water quality of Nha Trang bay was still in a good condition （according to Vietnamese and ASEAN criteria）.

Assessment of Aquatic Physico-chemistry and Eutrophication Rate at the Lake Tondano

The purpose of this research was conducted to determine the physical factors, namely water temperature, total dissolved solids, total suspended solids, electrical conductivity and chemical water including pH, phosphate, BOD （biochemical oxygen demand）, COD （chemical oxygen demand）, DO （dissolved oxygen）. The factors of physics and chemistry can affect the rate of eutrophication. The data obtained through laboratory analysis of physical and chemical parameters of water samples. Water samples were taken from 8 observation stations. Highly variable results were obtained in each observation station. Data physical parameters were tested with statistical multiple linear regression to determine the effect on water quality, the results show that the physical properties do not affect the rate of eutrophication in Lake Tondano. That is, the amount of total dissolved solids content and total suspended solids, will not affect the rate of eutrophication in Lake Tondano. The results of multiple linear regression satistik test against chemical parameter data that is phosphate, BOD, COD and DO showed as a significant effect on the rate of eutrophication in lakes. The higher phosphate levels will be higher as the increase of the rate of eutrophication in Lake Tondano.

Nutrient and eutrophication characteristics of the Dongshan Bay, South China

We recorded NO3-N, NOz-N, NH4-N, PO4-P, SiO3-Si, salinity, and temperature data at 10 stations in the Dongshan Bay in May, June, July, August, October, and November 2008, analyzing nutrient and eutrophication characteristics. The mean concentration of dissolved inorganic nitrogen （DIN） was 0.304）.40 mg/dm3; generally, NO3-N was the main form in most areas. The mean concentrations of PO4-P and SiO3-Si were 0.0404）.060 mg/dm3 and 1.00-1.50 mg/dm3, respectively. We proved that the majority of the SiO3-Si in the Dongshan Bay came from the Zhangjiang River, with some coming from the Bachimen Strait. DIN originated from both the Zhangjiang River and the Bachimen Strait. Most PO4-P originated from the Bachimen Strait, and some came from the Zhangjiang River. We found that P was an overall limiting factor to the phytoplankton community in most of the Dongshan Bay, and that Si and N were in surplus. However, near the Bachimen Strait Si became a limiting factor, especially for diatoms, while P and N were in comparative surplus. We used a potential eutrophication assessment method to analyze eutrophication, and showed that the most serious eutrophication occurred near the Zhangjiang River estuary and near the Bachimen Strait. In 2008, DIN levels were four times higher than that in 1988; PO4-P levels were three- fold higher, while SiO3-Si was approximately double. Dissolved nutrients increased between 1988 and 2008. DIN increased at the greatest rate comparing to PO4-P and SiO3-Si, thus the N/P and N/Si mol ratios increased. Further studies on the effects of high DIN concentrations on the phytoplankton communities and marine ecosystems of the Dongshan Bay are needed.

Phosphorus Reduction from Urban Wastewater Treatment Plant with Trickling Filters

The purpose of this research is to investigate a biofilm system with trickling filter as a biological alternative process during low cost treatment connection with the possibility of reducing nutrients such as phosphorus. Given that nitrogen with phosphorus that are leading causes of algal bloom resulting in increased eutrophication or chemical nutrients are the basis of this document analysis. This increase in organisms results in less oxygen in water bodies and at times, slow decay leads many fresh water ponds, lakes and rivers. The process of eutrophication unfortunately tends to favor pollution and algae, which reduce the quality of the water. Kosovo has not a long tradition in the treatment of wastewater, especially in removing phosphorus, since the country has only a plant for wastewater treatment. The present plant is intended to protect the Klina river from eutrophication from wastewater discharged after treatment. This plant currently reduced phosphorus efficiently, but the goal of this paper is to increase the percentage of removal of phosphorus to 40% through trickling filters, presenting options for optimizing work on plant Skenderaj.

Changes in phytoplankton communities along nutrient gradients in Lake Taihu:evidence for nutrient reduction strategies

An annual investigation on phytoplankton communities was conducted to reveal the effects of nutrients on phytoplankton assemblages in Lake Taihu,East China. A total of 78 phytoplankton taxa were identified. Phytoplankton biomass was higher in the northern part of the lake than in the southern part. Cyanobacteria and Bacillariophyta alternated dominance in the northern area,where algal blooms often appear,and co-dominated in the southern area. In the northern part,the proportions of cyanobacteria and Bacillariophyta varied significantly in total biovolume,both along the phosphorus(P) gradient,and between total nitrogen levels(≤3 mg/L and >3 mg/L TN). The proportions of cyanobacteria and Bacillariophyta had no signif icant variations in total biovolume along P and N(nitrogen) gradients in the southern part. Correlation analysis and CCA results revealed that P was the key factor regulating phytoplankton community structure. Nitrogen was also important for the phytoplankton distribution pattern. It was concluded that nutrient structure was heterogeneous in space and shaped the distribution pattern of phytoplankton in the lake. Both exogenous P and internally sourced Prelease needs to be considered. N reduction should be considered simultaneously with P control to efficiently reduce eutrophication and algal blooms.

Spacial Distribution Characteristics, Activity and Degradation Capability of the Biofilm in Integrated Vertical-flow Constructed Wetland

The spacial distribution characteristics, activity and degradation capability of the biofilm in integrated vertical-flow constructed wetland were investigated. Results showed that the biofilm widely distributed in the substrate of integrated vertical-flow constructed wetland and mainly in the 0-10 cm top layer where the activity ofdehydrogenase of the biofilm was also higher than that of other layers. The water quality could also affect the activity of the biofilm, for the TF（1,3,5-Triphenylformazan） amount reduced by the biofim incubated in water of the higher eutrophication was larger, too. The PCP （pentachlorophenol） removal rate by the substrate with biofilm was 1.5 times that without biofilm. In total, the biofilm of the down-flow chamber appeared larger biomass, higher dehydrogenase activity and stronger degradation capability of organic contamination than that in up-flow chamber and it was the major place for removal of the organic matters in waste water.

Impact of REE La and its EDTA complexes on eutrophic water body

The different concentrations （0.10, 0.25, 0.50, 1.00 mg/L） of La^3＋ and the different concentrations （0.10, 0.25, 0.50, 1.00 mg/L） of La-EDTA were added into the simulant water body separately and the contents of DO, COD, N, P in the water body were determined regularly, The results prove that, when REE concentration is 0.25 mg/L or 0.50 mg/L, the growth of algae and eutrophication can be promoted. The promotive effect of latter is obvious. The condition that REE concentration is 0.10 mg/L or 1.00 mg/L can inhibit the growth of algae and eutrophication. Not only the promotive effect but also the inhibitive effect of La^3 ＋ is stronger than La-EDTA.

Managing Water Quality in Huntsman Lake （Virginia, USA）reDevelopment and Implementation of Restoration Strategies

Huntsman Lake is located within the Middle Run of the Pohick Creek watershed, which is itself located within the much larger Chesapeake Bay watershed. Data collected from both the water column and the lake＇s sediments indicate that phosphorus-rich bottom sediments are an important internal loading source, and these internal phosphorus loads would continue to adversely impact water quality until and unless sediments are removed or inactivated. The implementation of artificial circulation was anticipated to be able to increase the sequestration of phosphorus within better oxygenated bottom sediments, and was the first lake management strategy deployed in Huntsman Lake. In the first two years after the installation of a whole-lake circulation system, the lake＇s waters are no longer stratified, and the bottom waters are no longer hypoxic and/or anoxic. While there is no evidence of a subsequent reduction in concentrations of nitrogen or chlorophyll-a, average phosphorus concentrations have decreased. However, high variability in the phosphorus data decreases our confidence that this is a sustained improvement. These results are consistent with prior findings, including those from downstream systems, that the reversal of the symptoms of eutrophication can involve lag-periods up to several years, if they are successful at all.

Bioaccumulation of Mercury in Fish Species from Different Trophic Level

Mercury （Hg） is an environmental pollutant, and can bioaccumulate and biomagnify in the food web. Twenty four fish samples of different tropic level i.e., Herbivore, Omnivore and Carnivore were collected from two contaminated rivers, the Megna and the Buriganga which surround the Dhaka division for the assessment of toxic Hg. Fourteen samples were found to contain Hg in the range of 0.01-0.09 mg/kg. The highest Hg （0.09 mg/kg） was found in the Carnivore, Bele （Glossogobius giuris）. However, all fish species had lower amount of Hg than the maximum Hg limit （0.5 mg/kg for fish） set by World Health Organization （WHO）. Among all the fish species, the order of bioaccumulation was carnivore 〉 omnivore 〉 herbivore. Kajoli （Ailia coila）, Shing （Heteropnuestes fossilis）, Rui （Labeo rohita）, Chewa （Tryauchen vagine）, Rita （Rita rita）, Hilsha （Tenualosa ilisha）, Small Puti （Puntius sophore）, Bacha （Eutropiichthys vacha） and Chingri （smallprawn） were not found to contain any Hg which indicated that fish species from these rivers are safe for human consumption.