Occurrence of endocrine-disrupting chemicals in riverine sediments from the Pearl River Delta,China

The endocrine-disrupting chemicals (EDCs) was investigated in 28 riverine sediments from the Pearl River system, China and analyzed by an ultrasonication extraction and GC–MS method. The concentrations of 4-tert-octylphenol (OP), 4-nonylphenol (NP), and bisphenol A (BPA) in the sediments were in the ranges of <2.0–210, 107–16198 and <1.7–430 ng/g dw, respectively. The steroid estrogens estrone (E1) and 17β-estradiol (E2) in the sediments ranged from <1.3 to 10.9 ng/g dw and from <0.9 to 2.6 ng/g dw, respectively. The spatial distribution of these chemicals was related to the discharge of domestic and industrial wastewater along the rivers. The positive correlation between EDCs and total organic carbon indicates that sedimentary organic carbon is an important factor in controlling the distributions of EDCs. Compared with other previous studies, the ZR and DR rivers from the PRD were heavily contaminated by APs and BPA.     

Occurrence of endocrine-disrupting chemicals in riverine sediments from the Pearl River Delta, China

The endocrine-disrupting chemicals (EDCs) was investigated in 28 riverine sediments from the Pearl River system, China and analyzed by an ultrasonication extraction and GC-MS method. The concentrations of 4-tert-octylphenol (OP), 4-nonylphenol (NP), and bisphenol A (BPA) in the sediments were in the ranges of <2.0-210, 107-16198 and <1.7-430 ng/g dw, respectively. The steroid estrogens estrone (E1) and 17β-estradiol (E2) in the sediments ranged from <1.3 to 10.9 ng/gdw and from <0.9 to 2.6 ng/gdw, respectively. The spatial distribution of these chemicals was related to the discharge of domestic and industrial wastewater along the rivers. The positive correlation between EDCs and total organic carbon indicates that sedimentary organic carbon is an important factor in controlling the distributions of EDCs. Compared with other previous studies, the ZR and DR rivers from the PRD were heavily contaminated by APs and BPA.     

珠江三角洲地震活动的若干特点

分析了二十世纪末30年来珠江三角洲地区地震活动的特征，认为珠江三角洲地区与东南沿海地震带在地震序列分布上总体趋势是一致的。在1970～1997年间，珠江三角洲地区b值滑动时间曲线从1984年起至1986年的高值异常可能是东南沿海地震带1986年开始的活跃幕的中期前兆。地震活动指数A(b)值曲线1988年及1994年的两处低值异常，则可能是本区1989年及1997年两个地震能量释放高峰的中期前兆。从本区及东南沿海地震带地震发生的时间进程上来看，本区很可能是东南沿海地震带区域应力场的调整单元。     

Magnetic properties of sediments from the Pearl River Delta,South China: Paleoenvironmental implications

Magnetic parameters and their environmental implications of sediments in a core (PD) from the Pearl River Delta, South China, indicate that ferrimagnetic minerals with low coercivity, such as magnetite, dominate the magnetic properties although small amounts of Fe-sulphides occur. The fraction of Fe-sulphides increases and becomes the dominant minerals determining the magnetic characteristics in grey-black organic-rich clay horizons, indicating an anoxic, sulphate-reducing swamp environment resulting from a marine regression. In the "Huaban clay" , hard magnetic minerals, such as hematite and goethite, largely control the magnetic properties of the sediments and imply a long period of exposure and weathering. Where magnetite is the main magnetic mineral, its fraction and grain size determine properties such as magnetic susceptibility (κ ) and saturation isothermal remanent magnetization (SIRM). Ratios of SIRM/κ and χarm/SIRM reflect changes in sea level with high SIRM/κ and χarm/SIRM correlating with a smaller magnetic mineral grain size and rising sea level. Based on downcore variations of these environmental magnetic parameters along with sediment characteristics and microfauna, the sedimentary environment of the Pearl River Delta area can be divided into two main cycles of transgression and regression during the late Pleistocene and Holocene with more sub-cycles of sea level fluctuation during each transgression.     

Occurrence and distribution of phthalate esters in riverine sediments from the Pearl River Delta region,South China

Sixty-eight sediment samples collected from Dongjiang River, Xijiang River, Beijiang River and Zhujiang River in the Pearl River Delta (PRD) region, Southern China, were analyzed for 16 phthalate esters (PAEs). PAEs were detected in all riverine sediments analyzed, which indicate that PAEs are ubiquitous environmental contaminants. The Σ₁₆PAEs concentrations in riverine sediments in the PRD region ranged from 0.567 to 47.3 μg g⁻¹ dry weight (dw), with the mean and median concentrations of 5.34 μg g⁻¹ dw and 2.15 μg g⁻¹ dw, respectively. Elevated PAEs concentrations in riverine sediments in the PRD region were found in the highly urbanized and industrialized areas. Of the 16 PAEs, diisobutyl phthalate (DiBP), di-n-butyl phthalate (DnBP) and di(2-ethylhexyl) phthalate (DEHP) dominated the PAEs, with the mean and median concentrations of 1.12 μg g⁻¹ dw, 0.420 μg g⁻¹ dw and 3.72 μg g⁻¹ dw, and 0.429 μg g⁻¹ dw, 0.152 μg g⁻¹ dw and 1.55 μg g⁻¹ dw, respectively, and accounted for 94.2–99.7% of the Σ₁₆PAEs concentrations. Influenced by local sources and the properties of PAEs, a gradient trend of concentrations and a fractionation of composition from more to less industrialized and urbanized areas were discovered. As compared to the results from other studies, the riverine sediments in the PRD region were severely contaminated with PAEs. Information about PAEs contamination status and its effect on the aquatic organisms in the PRD region may deserve further attention.     

珠江三角洲未来几年地震危险性分析

在分析珠江三角洲地区历史、现今地震活动性和前兆观测资料后认为,今后几年该区将处于地震活动水平较低的平静时段,陆地区域发生MS5级以上地震的可能性很小.未来地震的可能性将主要来自陆地4级地震、周边地区和近海海域5级地震.     

Trends of precipitation in Beijiang River Basin,Guangdong Province,China

An analysis of spatial and temporal trends of precipitation in Beijiang River basin, Guangdong Province, China during 1959–2003 was performed using 17 time series (including monthly, annual, wet season, dry season, early flood period and late flood period totals) both on station based and sub‐basin based data sets. Two nonparametric methods (Mann–Kendall and Sen's T) were used for data analysis. The results showed that (1) downward trends of temporal distribution were mostly detected during the early flood period, especially in May, while upward trends were observed in July and the dry season; (2) downward trends of spatial distribution were mostly detected in the southern Beijiang River basin, while upward trends were observed north of this area. Our results indicated a delayed rainy season and a northward trend of the precipitation belt compared to recent years. Copyright © 2007 John Wiley & Sons, Ltd.     

Optimal allocation of water quantity and waste load in the Northwest Pearl River Delta,China

The Northwest Pearl River Delta is one of the most developed areas in China and has faced serious water problems because of its fast economic growth, urbanisation and other developments. It is widely believed that an integrated management of the socio-economic factors cross individual administrative cities is an effective way to solve the water problems. To serve this purpose, this paper aims to develop an integrated model for the optimal allocation of water quantity and waste load. In order to consider the interaction between water quantity and waste load allocation, the Saint-Venant equations were used to simulate dynamic water flow for the water quantity allocation, whereas the one dimensional advection–dispersion mass transport equation was used to simulate water quality for the waste load allocation. In addition to the maximisation of the economic benefits, which is often considered as an objective of optimal water resource allocation models, the minimisation of water shortages and maximisation of waste load were also introduced as objectives of the model. To solve the multi-objective allocation model, a second generation non-dominated sorting genetic algorithm was employed because of its computational efficiency and running time. The results indicate that it is a serious task to reduce the COD in the Northwest Pearl River Delta since the maximum waste load allocations under water quality targets is less than the present amount of waste discharged into rivers in the study area.     

The characteristics of nutrients and eutrophication in the Pearl River estuary,South China

In the spring of 1998, 24-h time series and synchronization of vertical profiles of NO(3)-N, NO(2)-N, NH(3)-N, PO(4)-P, chlorophyll a, suspended substance, salinity, temperature and other chemical parameters were taken at 10 stations in the Pearl River estuary in order to analyze the status and characteristics of nutrients and eutrophication. The results indicated that dissolved inorganic nitrogen (DIN) mainly came from the four river channels in the main estuary, and NO(3)-N was the main form of DIN in most area. The concentration of DIN was general above 0.30 mg l(-1) in the estuary, and more than 0.50 mgl(-1) in most part. Phosphate from four river channels was not the main sources, but land-based sources from the area near Shenzhen Bay or along the estuary were obvious, and other land-based sources outside the estuary brought by coastal current and flood tide current were also the main contributions. The concentration of phosphate was generally about 0.015 mg l(-1) except the area near Shenzhen Bay. The ratio of N:P was generally high, and it was higher in the north than in the south. The highest ratio was higher than 300, and the lowest one was over 30. The concentration of chlorophyll a was about 0.8-7.8 mg m(-3), and turbidity and phosphate may be the main two limiting factors for algal bloom in the estuary. The concentration of nutrients decreased slightly in the past decade, but still stayed at a high level. The nutrients mainly came from domestic sewage, industrial wastewater, agriculture fertilizer and marine culture in the Pearl River estuary.     

广东五华白石嶂钼矿区矿床地质特征

白石嶂钼矿区归属于环太平洋钼成矿带华南褶皱系钨-铜-钼成矿省,成矿于中生代燕山期。矿床赋存于燕山二期细粒二云母花岗岩株南东端西侧与上三叠-下侏罗统地层的接触带,白石嶂断裂（F19）与杨塘断裂的交汇部位。本文从区域地质背景入手,着重研究了地层、构造、岩浆岩与成矿的关系;并对矿床的成矿专属性作了初步探讨。文章对围岩及其蚀变特征与矿体/矿石赋存特征、矿体规模之间的关系作了较深入的分析;并在分析成矿物质来源、总结矿化富集规律的基础上,结合粤东地区钼矿成矿特征,总结出本区控矿地质条件与成矿规律,为粤东地区该类矿床的寻找提供理论上的参考。     

地下流体地震前兆多层次跟踪法短期预测在粤闽交界和珠江三角洲地区的应用

利用粤闽交界地区、珠江三角洲地区连续10年左右的地下流体资料，研究利用多层次跟踪法进行地震短期预测的效果，结果表明，该法的粤闽交界及近海地区的应用效果较好，但在珠江三角洲及近海地区暂不宜应用。     

Spatial assessment of hydrologic alteration across the Pearl River Delta,China, and possible underlying causes

The alterations of the water level across the Pearl River Delta (PRD) were investigated using a ‘range of variability approach’ (RVA) based on monthly water level datasets extracted from 17 gauging stations. A mapping method was used to illustrate the spatial patterns in the degrees of alteration of water levels. The results indicated that more stations showing moderate and high alterations in monthly mean maximum and minimum water levels when compared with monthly maximum and minimum water levels. River channels characterized by higher alterations of water levels were observed mainly in the regions north of 22° 30′N. Alterations of water levels across the PRD were a consequence of various influencing factors. However, changed hypsography due to extensive and intensive human activities, particularly the large‐scale dredging and excavation of the river sand, may be taken as one of the major causes for the substantial hydrologic alteration. This study indicated that the river channels characterized by altered water levels are mostly those characterized by highly and moderately intensive sand dredging. The changed ratio of the streamflow between Makou and Sanshui stations, the major upstream flow control stations, also influenced the water level alterations of the Pearl River delta. The results of this study will be of great significance in water resources management and better human mitigation of the natural hazards due to the altered water level under the changing environment. Copyright © 2009 John Wiley & Sons, Ltd.     

Human-induced regulations of river channels and implications for hydrological alterations in the Pearl River Delta, China

Sound understanding of hydrological alterations and the underlying causes means too much for the water resource management in the Pearl River Delta. Incision of river channels plays the key role in the hydrological alterations. As for the causes behind the river channel incision, sand dredging within the river network of the Pearl River Delta is usually assumed to play the overwhelming role in changes of geometric shapes of the river channels. Based on thorough analysis of well-collected data of channel geometry, streamflow, sediment load and water level, this study exposes new findings, investigating possible underlying causes behind the changes of the geometric shapes of the river channels at the Sanshui and Makou station. The results of this study indicate: (1) different changing properties of the geometric shapes are identified at the Sanshui and Makou stations. Larger magnitude of changes can be found in the river channel geometry of the cross section at the Sanshui station when compared to that at the Makou station. Lower water level due to fast riverbed downcutting at the Sanshui station than that at the Makou station is the major reason why the reallocation of streamflow occurred and hence the hydrological alterations over the Pearl River Delta; (2) depletion of sediment load as a result of construction of water reservoirs in the middle and upper Pearl River basin, sand dredging mainly in the Pearl River Delta and heavy floods all contribute much to the incision or deposition of the riverbed. Regulations of erosion and siltation process of the river channel often alleviate the incision of the river channels after a relatively long time span, and which makes it even harder to differentiate the factors causing the river channel incision; (3) the intensifying urbanization in the lower Pearl River basin greatly alters the underlying surface properties, which has the potential to shorten the recession of the flood event and may cause serious scouring processes and this role of flash floods in the incision of the river channels can not be ignored. This study is of great scientific and practical merits in improving human understanding of regulations of river channels and associated consequences with respect to hydrological alterations and water resource management, particularly in the economically booming region of China.     

Water Quality Management Based on Division of Dry and Wet Seasons in Pearl River Delta,China

In the Pearl River Delta (PRD), river water quality deteriorates continually due to the population increase and ongoing industrialization and urbanization. In this study, a water quality management paradigm based on the seasonal variation is proposed. For better exploring the seasonal change of water quality, wavelet analysis was used to analyze the division of dry and wet seasons in the PRD during 1952–2009. Then water quality seasonal variation in 2008 and relevant impact factors were analyzed by multivariate statistic methods as a case to make some management measures. The results show that there are some differences of dry and wet seasons division among different years. Wet season mainly appear from April to September, which occupy the largest proportion among the 58 years (about 70%) and then followed by the wet season from May to October (about 13.8% of the total years). As to the water quality of 2008, significant differences exist between dry and wet seasons for 17 water quality parameters except TP, , Fe²⁺, and Zn²⁺. Levels of parameters pH, EC, COD_Mn, BOD₅, , , and Cl^? in dry season are much higher than those in wet season. In dry season the variations of river water quality are mainly influenced by domestic sewage, industrial effluents, and salt water intrusion. While in wet season, except the aforementioned pollution sources, drainages from cultivated land and livestock farm are also the main factors influencing water pollution. Thus, water quality management measures are proposed in dry and wet seasons, respectively. The results obtained from this study would further facilitate water quality protection and water resources management in the PRD.     

Distribution and source apportionments of polychlorinated biphenyls (PCBs) in mariculture sediments from the Pearl River Delta,South China

Surface and core sediments collected from six mariculture farms in the Pearl River Delta (PRD) were analyzed to evaluate contamination levels of polychlorinated biphenyls (PCBs). The ∑PCBs (37 congeners) concentrations ranged from 5.10 to 11.0 ng g⁻¹ (mean 7.96 ng g⁻¹) in surface and 3.19 to 22.1 ng g⁻¹ (mean 7.75 ng g⁻¹) in core sediments, respectively. The concentrations were significantly higher than that measured in the sediments of their corresponding reference sites, whereby the average enrichment percentages were 62.0% and 42.7% in surface and core sediments, respectively. Significant correlations (R² = 0.77, p < 0.05) of PCB homologue group proportions between fish feeds and surface mariculture sediments suggested that fish feed input was probably the main source for the enrichment of PCBs. Due to the fact that PCBs could be transferred along food chains, PCB contamination in fish feeds and mariculture sediments should not be overlooked.     

Risks posed by trace organic contaminants in coastal sediments in the Pearl River Delta, China

Local marine environments in China's Pearl River Delta (PRD), the most rapidly developing region in one of the world's fastest growing economies, have been experiencing significant environmental stress during the past decades. This investigation was conducted to determine the status and trends of persistence organic pollutants (POPs) such as polycyclic aromatic hydrocarbons (PAHs), petroleum hydrocarbons (PHCs), polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides and dioxin-related compounds in marine sediments collected from sixteen coastal stations in the Pearl River Delta (PRD) in March 2003. Elevated concentrations of PAHs (94-4300 ng/g), PCBs (6.0-290 ng/g), PHCs (14-150 microg/g), and DDTs (1.4-600 ng/g) were detected in sediment samples. In addition, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-like activities in the sediment samples were estimated to range from 0.3 to 440 pg TCDD-EQ/g. Sediments collected from Xiashan contained the greatest concentrations of trace organic contaminations amongst all the sampling stations in the present study. The degree of trace organic contamination was, in general, more severe at stations situated along the west shores of the PRD than their counterparts in the east. A preliminary assessment was performed to examine the probable risks to the marine ecosystem due to POPs. The results showed that OC pesticide contamination in the PRD was particularly serious and might pose a threat to the health of the marine inhabitants.     

Polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides in water columns from the Pearl River and the Macao harbor in the Pearl River Delta in South China

Polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) were measured in suspended particles and dissolved phase from the Baiertang water column and the Macao water column samples as collected from the Guangzhou channel of the Pearl River and the Macao harbor, where the sediments were heavily contaminated with organic pollutants. Total OCPs concentration varies from 23.4 to 61.7 ng/l in Baiertang water column and from 25.2 to 67.8 ng/l in Macao column, while total PAHs concentration varies from 987.1 to 2878.5 ng/l in the Baiertang water column and from 944.0 to 6654.6 ng/l in the Macao column. The vertical distribution profiles of pollutants and the partition of pollutants between particles and dissolved phases indicate that the sediments in Baiertang act as an important source of selected pollutants, and the pollutants in water of this region were mainly originated from the release and re-suspension of contaminants residing in the sediments. The sediments in Macao harbor act as a reservoir for organochlorine pesticides, such as DDTs mainly introduced by river inflow from Xijiang and PAHs input by brackish water from the Lingdingyang estuary. Combustion of fossil fuels and petroleum input are the main sources of PAHs in the Macao water column, while combustion of fossil fuels and coal is responsible for the PAHs in the Baiertang water column. The ratios of DDT/(DDD+DDE) for the Macao water column samples demonstrate that such chemicals were input into this region in recent times.     

Distribution and source apportionments of polychlorinated biphenyls (PCBs) in mariculture sediments from the Pearl River Delta, South China

Surface and core sediments collected from six mariculture farms in the Pearl River Delta (PRD) were analyzed to evaluate contamination levels of polychlorinated biphenyls (PCBs). The ∑PCBs (37 congeners) concentrations ranged from 5.10 to 11.0 ng g(-1) (mean 7.96 ng g(-1)) in surface and 3.19 to 22.1 ng g(-1) (mean 7.75 ng g(-1)) in core sediments, respectively. The concentrations were significantly higher than that measured in the sediments of their corresponding reference sites, whereby the average enrichment percentages were 62.0% and 42.7% in surface and core sediments, respectively. Significant correlations (R2=0.77, p<0.05) of PCB homologue group proportions between fish feeds and surface mariculture sediments suggested that fish feed input was probably the main source for the enrichment of PCBs. Due to the fact that PCBs could be transferred along food chains, PCB contamination in fish feeds and mariculture sediments should not be overlooked.     

Occurrence and phase distribution of polycyclic aromatic hydrocarbons in riverine runoff of the Pearl River Delta,China

The occurrence and phase distribution of polycyclic aromatic hydrocarbons (PAHs) in waters at the eight riverine outlets of the Pearl River Delta (China) were examined based on a monthly sampling program from March 2005 to February 2006. The total concentrations of PAHs in the aqueous phase and suspended particulate matter (SPM) combined ranged from 55.5 to 522 ng/L, at the mid level of the global values in rivers and estuaries. No clear temporal and spatial trends of PAH concentrations were found. However, the concentrations of PAHs associated with SPM coincided with the monthly precipitation of Guangzhou, indicating the importance of atmospheric deposition. The PAHs found in the region were likely derived from a combined pyrolytic and petrogenic origin, as suggested by the molecular indices of PAHs. Normalized partition coefficient (K_oc) between water and SPM was correlated with octanol–water partition coefficient (K_ow) to understand the environmental behavior of PAHs.     

Thallium Distribution in Sediments from the Pearl River Basin,China

Thallium (Tl) is a rare element of high toxicity. Sediments sampled in three representative locations near industries utilizing Tl‐containing raw materials from the Pearl River Basin, China were analyzed for their total Tl contents and the Tl contents in four sequentially extracted fractions (i.e., weak acid exchangeable, reducible, oxidizable, and residual fraction). The results reveal that the total Tl contents (1.25–19.1 µg/g) in the studied sediments were slightly high to quite high compared with those in the Chinese background sediments. This indicates the apparent Tl contamination of the investigated sediments. However, with respect to the chemical fractions, Tl is mainly associated with the residual fraction (>60%) of the sediments, especially of those from the mining area of Tl‐bearing pyrite minerals, indicating the relatively low mobility, and low bioavailability of Tl in these sediments. This obviously contrasts with the previous findings that Tl is mainly entrapped in the first three labile fractions of the contaminated samples. Possible reasons were given for the dominating association of Tl with the residual fraction (>95%) of the mining area sediments. The significant role of certain K‐containing silicates or minerals of these sediments on retaining Tl in the residual fraction, discovered by this study, provides a special field of research opportunity for the Tl‐containing wastewater treatment.