Purple Rock Research Articles

Characteristics and Risk Assessment of Heavy Metal Contamination in Arable Soils Developed from Different Parent Materials

This study analyzes the heavy metal pollution in cultivated soils developed from different parent materials in Yunnan Province and assesses their risk levels. The results show significant regional differences in soil heavy metal pollution, greatly influenced by the type of parent material. Cadmium (Cd) pollution is most severe in multiple parent material soil regions, particularly in areas with carbonate and purple rocks, exhibiting a high pollution risk. Other heavy metals such as zinc (Zn), copper (Cu), and lead (Pb) also show varying degrees of enrichment in different parent material zones, posing potential pollution risks. The soil pollution levels of heavy metals were classified using the geo-accumulation index method. It was found that soils developed from carbonate rocks and purple rocks have the most severe heavy metal pollution, while soils from quartzitic rocks, acidic crystalline rocks, and basalt exhibit relatively lower pollution levels. By analyzing the characteristics of heavy metal pollution in different parent materials, this study provides a scientific basis for regional soil pollution management and sustainable agricultural development.

Acidic condition accelerates cation release from purple rock in Southwestern China

In spite of the fact that rock weathering performs an essential task in the evolution of the Earth’s surface, the quantitative assessment between pH and rates of chemical weathering remain unclear. This study aims to characterize the chemical weathering rate of purple rocks and then develops a model to calculate the release rates of cations (K+, Na+, Ca2+ and Mg2+) under various pH conditions. Two types of purple rock were sampled from the Shaximiao Group (J2s) and Penglaizhen Group (J3p), and a series of laboratory experiments were performed by soaking the purple rocks in solutions with pHs from 2.5 to 7.0, over 24 treatment cycles. The results showed that the release rates of cations apparently increased as the pH decreased. The release of Ca2+ was the dominant process of chemical weathering in J3p under various pH treatments, while K+ and Na+ were remarkably high in J2s (with the exception of the pH 2.5 treatment). Quantitative analysis revealed that the rate of cation release was significantly related to the H+ concentration (p < 0.001) and the air temperature (p < 0.001). The relationship between cation release and acidity was found to be an exponential function. Our results suggested that solution acidity serves as an important driving force for cation release rates from purple rocks and that environmental acidification would enhance rock weathering.

A dataset for geochemical characteristics of purple rock and its weathering crust in the Sichuan Basin (before 1990)

A dataset for geochemical characteristics of purple rock and its weathering crust in the Sichuan Basin (before 1990)

Ghost Oceans

Ghost Oceans Elizabeth Lee (bio) I stand on a cliff in northern New Mexico, seeing my insides in the rocks. Fascia, red muscle, marbled fat, teeth perched on eroding banks of red and gray earth, dark, ancient blood soaked deep in the sandstone and hard volcanic ash. There's something I know I have to find here if only I could remember what it was. I slide my hands over my tender stomach and the question rises again. Why did the baby die? The white orb of the sun swallows into itself all color and sound and feeling, and my body goes limp. It's my fault. When I first came to New Mexico, I saw all kinds of interesting shapes in the red and purple rocks: Roast beef, ice cream, a camel's back. I felt desperate for a new life. I'd lived for too long in the same 73 degree weather, looking up at a perpetually cloudless sky; I had worked for years in television, anticipating what might look real and feel real, when everything about work and life felt hopelessly fake. I needed a portal to the divine like I needed my childhood wonder again; most importantly, I needed to know there were things in the world that would outlast my body and its memories. After we found out we were pregnant, my husband and I stared at the black computer screen in the doctor's office, studying the ghost lines that curved across each other like tiny white fossils, and waited for a heartbeat. The doctor finally pointed to a white blur. "There it is, and there's the chord." He took a deep breath. "But it's gone into the fallopian tube. I'm sorry, if we leave it there, your tube will rupture. You'll bleed to death." Two days later, he cut out the fallopian tube and the embryo still inside. The blood started immediately, turning my blue-tiled bathroom into a warm vault, thick with the scent of iron and sea salt. I hunched over my abdomen and frowned at all the translucent wires coming out of it. How could I be entirely sure that they hadn't switched out my body parts while I was unconscious and made me part alien? I wiped and saw clumps of dark jelly on the toilet paper. Are you my baby? I asked. Are you? Of course, it was madness, talking to my own blood like that. The baby was gone. My left fallopian tube was gone. But I had lost my mind that day, and it was all I could do not to throw myself out the window when I saw the red home inside my womb had started breaking apart. ________ The wind whips around me. It's like that in New Mexico, coming and going in sudden fits as if to remind the world to stay alert. The sun has made its descent down the sky and the horizon looks like it's on fire, the scorched land more like Mars than Earth. It seems the perfect metaphor for life as my parents talked about it, always describing it as hard and cruel. Survival was the only real true thing, so we'd better prepare. My mother was a quiet and somber woman, letting me twist her coarse hair and drape my leg over her waist while she slept as if she didn't exist at all. I reached for her body at all hours of the day to make [End Page 63] sure she hadn't left me behind. I wasn't sure why, but I always had the sense that she wanted to leave her life, and it frightened me. When her eyes turned to black glass, I knew she had gone deep inside but that she'd be back. I knew great things lived inside that very place because she'd eventually paint beautiful visions on stretched-out silk in her workroom: a woman's face, her collarbone, an ocean wave breaking on sand. She'd eventually hang them up against the tired white walls of our hallways. I don't remember much from that time, but I...

Monitoring of rainfall infiltration to under surface using DC resistivity method

The use of non-agricultural land in Universitas Pendidikan Indonesia causes the land absorption to be smaller than the use of soil for agriculture so that it can lead to surface runoff. This study discusses how to monitor rainwater infiltration to subsurface using resistivity method with Wenner’s configuration and weather data. The data retrieval takes place twice with a span of two months and is in the same place. In the model is also seen when the layer of purple rocks have decreased in volume from the first data retrieval on the second data retrieval. While the rain water infiltration layer more evenly. Monthly weather reference data showed that temperature and evapotranspiration relationships over the months showed the results from September to December were relatively stable with average temperatures of four months being 22.38 ºC and evapotranspiration was 5.02 cm / month. Therefore, the evaporation caused by all water, soil, vegetation and the earth’s surface located at the site is 5.02 cm / month. Monitoring of rainfall infiltration within two months from the first measurement having rainfall infiltration of 3.9 mm / h indicates that infiltration rate is very fast and the magnitude of evapotranspiration is 5.02 cm / month.

Relationships between the lithology of purple rocks and the pedogenesis of purple soils in the Sichuan Basin, China

Classified as Regosols in the Food and Agriculture Organization (FAO) Taxonomy, purple soils formed from purple rocks and are mainly distributed in the Sichuan Basin of southwestern China. A number of studies have focused on the soil water, nutrients, texture and erosion of purple soils. This study was conducted to understand the lithological features of the related purple rocks and their effects on the pedogenesis of purple soils in the Sichuan Basin. The results showed the following: due to variability in the paleoenvironment, purple rocks mainly consist of sandstone and mudstone with various stratal thicknesses and various particle sizes. The lithology of the purple rocks leads the purple soils have an obvious inheritance from their parent rocks. An apparent purple color and numerous rock fragments derived from the purple parent rock are observed throughout the profile, with no clear soil stratification. The particle size contents of the purple soils are closely related to those of their parent rocks. The clay-sized fractions in the purple soils are generally dominated by illite, vermiculite, chlorite, and montmorillonite with little quartz and with or without kaolinite, which is generally the same as that in the parent purple rocks. In addition, the purple soils are characterized by obvious inherited mineralogy, chemical composition, pH value, OM content and nutrient content. Therefore, the diagenetic environment determined the lithology of the purple rock, and the lithology of the purple rock determined the pedogenic characteristics of the purple soil to some extent. Purple soils are characterized by rapid physical weathering and pedogenetic processes and slow chemical pedogenetic processes.

Using the sediment fingerprinting method to identify the sediment sources in small catchments with similar geological conditions

Traditional fingerprinting methods discriminate sediment sources based on differences in the source geological conditions or land use types. However, whether this method is effective if both the geological conditions and land use types are similar and the circumstances under which the method can be used remain unclear. To further understand the scope of applying the fingerprint identification method, this study selected the Wangjiagou catchment, which consists of subcatchments A and B, as the target. In this catchment, corn (Zea mays L.) was the species with the highest proportion in the dry land. Furthermore, the geological conditions in the catchment are consistent and, the soil is Eutric Regosol developed from the purple rock strata of the Jurassic system. A total of 85 source samples were collected in subcatchments A and B, and 11 sediment samples were collected at the outlets of the each of the subcatchments in the rainy season (from June to October). This research analyzed 48 geochemical elements as the potential fingerprint factors. In this case, the optimum composite fingerprint consisted of five individual properties (Zn, Ce, La, Li and Eu) in subcatchment, whereas four geochemical properties (Mn, La, Ni and Lu) passed the stepwise discriminant function analysis in subcatchment B. These properties exhibited discriminative powers of 100% in the respective subcatchments. The research results indicated the following: first, the multivariate mixing model can provide the contribution rates of each sediment source; second, the goodness of fit (GOF) of this model was greater than 95% in both subcatchments; and third, the sediment uncertainty of each source was within 5% in both subcatchment A and B. These findings indicate that the fingerprinting method can be used in areas with small differences in land use and geological conditions. The results show that great focus needs to paid to soil erosion on slope land in subcatchment A and mulberry fields in subcatchment B. In this area, high-impact human activities (i.e., extensive channel excavation and highly intense machine cultivation) have negated certain soil and water conservation measures. Therefore, in order to reduce soil erosion and ensure that the existing soil and water conservation measures are effective, farmers should implement rational channel management and no tillage or minimal tillage practices. Furthermore, to improve the fertilizer utilization rate of agro-ecosystems, deep fertilizer application and straw return technology should be promoted.

Impacts of simulated acid solution on the disintegration and cation release of purple rock (mudstone) in Southwest China

Rock disintegration and cation release not only impact on terrestrial geomorphology but also provide nutrients for plants. Further, fractal theory has been widely used to characterize the distribution of fragments in rocks for measuring the degree of disintegration. Yet the effects of an acidic environment on the trajectory of fractal dimensions of rock disintegration and cation release are not fully clear. Therefore, to investigate the impacts of a solution's pH on disintegration and cation release from the purple rock in southwest China, a series of laboratory experiments were performed by soaking the purple rocks in solutions with pHs from 2.5 to 7.0, over 24 treatment cycles. The results show that the lower the pH, the fewer cycles required to obtain a stable fractal dimension. The fractal dimension of purple rock under different pH values approached three after 24 treatment cycles, until decay ratios (the mass of decayed rock of <2 mm clastic particles to sampled rock mass) were >90%. Acidic treatment increased cation release, especially when the pH value of the solution was below 3.5. Compared with a deionised water soaking solution, the amounts of K+, Na+, Ca2+, and Mg2+ were increased by 4.92, 1.27, 1.12, and 1.08 times with pH values of 2.5, 3.5, 4.5 and 5.6 soaking solution, respectively, at the disintegration stage. In addition, the release of Ca2+ and Mg2+ were more sensitive to acid than that of K+ and Na+, and Ca2+ weathering occupied the dominant position in the cation weathering rates. Moreover, due to disintegration processes that transformed each rock sample into fragments, fresh surfaces were exposed from which cations were liberated, creating a significant (p < 0.05 to p < 0.01) positive correlation between 5 and 20 mm particles and cation release, while a negative relationship (p < 0.05 to p < 0.01) was found between <2 mm particles and cation release.

A quantitative determination of the effect of moisture on purple mudstone decay in Southwestern China

AimsThe moisture condition is well known to be a key factor that apparently influences rock decay, but little is known about the quantitative correlations between a rock's decay rate and its moisture content, which makes it difficult to quantitatively predict the rate of rock decay under varied moisture conditions. Thus, in this paper our aim is to observe the decay rates of various purple mudstones with different moisture contents and to develop an equation to calculate the decay rate. MethodsThree types of purple mudstones were sampled from the Tuodian group (J3t), Matoushan group (K2m), and Lufeng group (J1l), respectively, all located in the Chuxiong district of Yunnan province, southwestern China. All samples were manually cut into cubes of 50mm×50mm×50mm, divided into nine groups, wetted on a sieve with 2mm pores according to nine treatment levels, and then dried in an oven in the laboratory. Thirty-nine such wetting–drying cycles were carried out for each treatment. Decay rates were calculated by weighing the mass remaining on the sieve after each treatment cycle, and the average decay rates were estimated from the 39cycles. ResultsThe results showed that the average decay rate of the tested rocks rose with increasing rock moisture content and that the rank order of the decay rate was J3t>K2m>J1l. ConclusionsA significant exponential relationship between the average rock decay rate and rock moisture content for all three purple rocks was found to quantitatively predict the decay rate of purple rock under varied moisture conditions.

Effect of moisture and temperature conditions on the decay rate of a purple mudstone in southwestern China

Soil formation and geomorphology are primarily influenced by the rock decay, which in turn is strongly determined by moisture and temperature conditions. However, it remains unclear whether rock decay is dominated by thermal stresses or by hydration disintegration, and there is little information on mudstone decay rate in southwestern China. This study hypothesized that rock decay is dominated by hydration mechanism, and focused on the physical decay characteristics of typical purple mudstones using a combination of field and laboratory-based experiments. The bedrock of a Penglaizhen group (J3p) in Yanting County, Sichuan Province, southwestern China, was exposed and covered with nylon fabric in situ. Soil depths of 10, 20, 40 and 60cm were laid on this nylon fabric in 2003, and the decay rate (the quantity of clastic particles <2mm that were decayed from the bedrock, in tkm−2yr−1) under the nylon fabric was measured both in 2005 and 2009. In addition, fresh mudstones sampled from the Matoushan group (K2m), the Tuodian group (J3t) and the Lufeng group (J1l) in Yuanmou County, Shuangbai County, and Lufeng County of Yunnan Province, southwestern China, respectively, were subjected to alternating applications of moisture, temperature and their interaction (seven treatments) in the laboratory, and their decay ratios (the mass of decayed rock of <2mm clastic particles to sampled rock mass, in percent) were measured in 2010. In the field, the decay rate of the bedrock showed a significant (p<0.05) positive relationship with both the daily moisture and temperature variation at the interface between the soil and bedrock. In the laboratory, results showed that the effect of moisture variation, but not temperature alternation, on rock decay was apparent, suggesting that purple rock decay is dominated by hydration mechanism. Freezing–thawing in particular affects the sampled rocks, because it causes more spalling and fracturing. The J3t rock had the highest decay ratio because it had the highest clay mineral content and porosity of the three rock types. Hierarchical clustering analysis suggested that the variation of moisture content and H2O phase (solid or liquid) within rock plays a key role in rock decay processes. Both field and laboratory studies consistently showed that the alteration of wetting–drying and freezing–thawing, as well as moisture content, substantially influenced rock decay.

Major element geochemistry of purple soils/rocks in the red Sichuan Basin, China: implications of their diagenesis and pedogenesis

Major element compositions and chemical weathering features of the purple soils and their corresponding rocks in the Red Sichuan Basin, China were studied in this paper to infer the diagenetic features of the purple rocks and the pedogenetic features of the purple soils. The results showed that all of the rock and soil samples, except those from Yibin, have strongly similar major element compositions and the distribution patterns of their major element compositions are similar to those of the upper continental crust. Chemical index of alteration, chemical index of weathering and Na2O/K2O indicate that the purple soils and rocks have similar chemical weathering intensities, whereas the Al2O3–CaO* + Na2O–K2O (A–CN–K) relationship, suggests that chemical weathering was strong during diagenesis of the purple rocks, but weak during pedogenesis of the purple soils. Variations in major element compositions of the purplish rock samples, except that from Yibin, do not primarily reflect differences in compositions of the sediment source, sediment recycling and potassium metasomatism, and therefore the effects of chemical weathering on the major element compositions were mainly dependent on climate condition and the residence time of material exposed to chemical weathering. Chemical weathering of the purple rocks reached only moderate degrees under the general influence of warm and humid climate during Jurassic and Cretaceous. Warmer and more humid climate conditions partly resulted in stronger chemical weathering of rocks in the southern region of the basin than in the central and western region, whereas shorter residence time of material in upslope position partly resulted in weaker chemical weathering of rocks in the eastern region than in the central and western region. The same climate and stable tectonic setting led to comparable chemical weathering intensities of rocks in the Ziliujing and Jiaguan Formations. Gradually colder and dryer climate from Early Jurassic to Middle Jurassic then to Late Jurassic and shorter residence time in tectonically active setting of Middle Jurassic and late Late Jurassic resulted in the following order of chemical weathering intensity of the purple Jurassic rocks: Ziliujing Formation ≫ Shaximiao Formation ≈ Suining Formation > Penglaizhen Formation.

Comparison of Surface Electrochemical Properties between Purple Rocks and their Derived Soils as Related to Pedogenesis

Soil surface electrochemical properties may have an important effect on soil fertility and genesis. Few researches are available on the changes of surface electrochemical properties of purple soils during the pedogenesis. In present work, four purple rocks and their derived soils under arable, orchard, forest and grass were collected to determine surface electrochemical properties including surface specific area, surface charge quantity, surface charge density, electric field strength, and surface potential using the kinetic method. The results indicated that soil surface specific area and surface charge quantity of soils were both significantly higher than their parent rocks. There were similar trends in surface potential, surface charge density and electric field strength of soils and parent rocks, soils derived from Shaximiao Formation (J2s) and Suining Formation (J3s) were higher than those of parent rocks, whereas the reverse trends existed in Feixianguan Formation (T1f) and Penglaizhen Formation (J3p). At the same time, surface potential of soil samples collected from four sites with different land utilization, i.e., Arable, Orchard, Forest and Grass, were determined to illustrate the various trends of soil electrochemical properties change. Under different land use patterns, the descending orders of soil surface potential in Shaximiao Formation (J2s) and Suining Formation (J3s) were both as follows: orchard &gt; forest &gt; arable &gt; grass; the order in Feixianguan Formation (T1f) and Penglaizhen Formation (J3p) were as: orchard &gt; forest &gt; grass &gt; arable. On the other hand, the value of soil surface charge quantity was increased with clay content and soil acidity because of the intensive physical weathering and slight chemical weathering. Therefore, the surface electrochemical properties may have some agreements with the weathering extent of the purple soils. Soil surface potential, surface charge quantity, surface charge density, electric field strength, and surface specific area could be employed as reference criteria for pedogenesis of purple soils.

Tillage pedogenesis of purple soils in southwestern China

Land cultivation and tillage process, and their consequent impacts on soil erosion, have been criticized as the main cause of degradation of land or soil quality. However, purple soils, classified as Regosols in FAO Taxonomy or Entisols in USDA Taxonomy, are formed from purple rocks of the Trias-Cretaceous system, have been developed or at least accelerated the development due to continual tillage operation, especially digging and ridging. The present study took micromorphological investigation on the sedimentary rocks and the soils under different operations of tillage. Results show that the purple rock of Feixiangguan Formation of the Trias system (T1f) is the easiest to physical weathering and the most fertile soil material enriched in nutrients, and it has been, therefore, mostly cultivated and intensively tilled around the year. It has the fastest soil formation rate. Soil formation rate in the cropland with conventional tillage is higher than that in the forestland and the grassland. It implies that the artificial brokenness and tillage disturbance play a great role in physical weathering and initiating soil formation processes.

Anthropic pedogenesis of purple rock fragments in Sichuan Basin, China

Considerable amounts of rock fragments are found in many “Purple soils” developed from purple rocks in the Sichuan basin of southwestern China. We describe the effects of anthropic pedogenetic processes on purple rock fragments associated with soil amelioration by determining changes in rock fragment size distribution, transformation of P and K of purple rocks into soils, and the complexing of purple rock particles (soil mineral particles) with organic matter during anthropic pedogenesis of “Purple soils” in Sichuan basin of southwestern China. The pedogenetic capacity of rock fragments can be expressed by the content of < 2.0 mm particles as weathered products of rock fragment disintegration. The pedogenetic capacity of the purple rocks studied ranges from 0.3% to 6.2% under natural conditions. The rates of P and K transformed from purple rocks are closely associated with the pedogenetic capacity of rock fragments( r = 0.891 ⁎⁎; 0.961 ⁎⁎, n = 16). Digging (simulated by sieving) and crop planting facilitate pedogenesis of purple rock fragments and their mineral nutrient transformations. The soil mineral particles preserve 18%–36% of the organic carbon added as corn straw. The organic carbon is complexed after corn straw is mixed with < 1.0 mm soil mineral particles for 1 year. The improvement of newly reclaimed purple soils is enhanced by the complexing effect of organic substances with purple rock particles. The pedogenesis of purple rock in Sichaun basin can be accelerated by anthropic activity, such as tillage, crop planting, fertilization, and land reclamation.

(339) Preemergence Weed Control in Container-grown Herbaceous Perennials

During the 2004 season, preemergence herbicide was applied to 12 container-grown herbaceous perennials and woody plants and evaluated for weed control, phytotoxicity, and effect on plant growth. The herbicide and rates were: pendimethalin (Pendulum 2G) 908 g (label rate), 1816 g, and 3632 g/acre a.i. Herbicides were applied to lady's mantle (Alchemilla mollis), purple rock cress (Aubretia species), blue wild indigo (Baptisia australis), pink pussytoes (Antennaria dioica var. rosea), common sneezeweed (Helenium autumnale), redhot poker (Kniphofia uvaria), showy goldenrod (Solidago speciosa), heartleaf foamflower (Tiarella cordifolia), lavender (Lavendula angustifolia), blue flax (Linum perenne), catmint (Nepeta ×faassenii), and hen and chicks (Sempervivum tectorum). At 32 and 117 days after application, plants were evaluated for phytotoxicity. No phytotoxicity symptoms were apparent on any of the plants tested. Weed control was good in most cases with this herbicide but it did not control all weeds. Increasing the rates from 1× (label rate) did not significantly improve weed control.

Factors influencing the onset and duration of receptivity of female purple rock crabs, Hemigrapsus sexdentatus (H. Milne Edwards, 1837) (Brachyura: Grapsidae)

The effects of males, field, and laboratory conditions on the receptivity of females were tested in the New Zealand purple rock crab Hemigrapsus sexdentatus. Onset and duration of female receptivity is of interest because it influences the time available for mating and therefore the operational sex ratio (OSR), male–male competition, and the extent of sperm competition. Females were receptive once a year for a short time prior to oviposition. The breeding season was highly synchronised and lasted for about 3 weeks (from the end of March to mid-April; southern autumn), after which, almost all females carried eggs. We found few receptive females in the field (0% to 4.9%) during the breeding season despite a large number of crabs examined (935 in 1999 and 555 in 2000), suggesting that females are receptive for less than a day. The onset of the breeding season was the same for the wild crabs and those held in field cages, but the duration of receptivity increased to several days for caged females. The onset of the breeding season of females in the laboratory was earlier compared to females in the field and had, overall, a longer breeding season. Females isolated from males stayed receptive significantly longer (5.5 days) than females caged with males (3.3 days), suggesting that the duration of female receptivity is adjusted according to the presence or absence of males. Our results suggest that females have some control over their receptivity in relation to male presence, and this could influence the outcome of sexual selection.

Habitat preferences of waders (Charadrii) on the coast of the Orkney Islands

Capsule Twelve species of wader were surveyed on 494 coastal sections, revealing features in addition to substratum type that are important in habitat selection. Aims To determine which habitat characteristics affect the probability of waders occurring on coastal sections of Orkney in winter, and to measure the strength of these habitat preferences. Methods A total of 494 sections of shoreline in the Orkney Islands were surveyed for 12 species of wader in winters 1982/3 and 1983/4. A series of environmental variables (exposure, substratum type within the inter-tidal zone, shore width and steepness) were noted in the field and taken from maps. Logistic regression models were used to examine the probability of a given species occurring on a section, with given physical characteristics. Results Ringed Plover Charadrius hiaticula, Sanderling Calidris alba and Bar-tailed Godwit Limosa lap-ponica preferred sand shores; Lapwing Vanellus vanellus, Snipe Gallinago gallinago, Redshank Tringa totanus, Curlew Numenius arquata and Dunlin Calidris alpina preferred mud; Oystercatcher Haematopus ostralegus, Golden Plover Pluvialis apricaria and Purple Sandpiper Calidris maritima preferred rock; and Turnstone Arenaria interpres preferred gravel and rock shores. The strength of a preference for substratum type was greatest in Sanderling, Bar-tailed Godwit, Lapwing and Purple Sandpiper, and least in Oystercatcher, Curlew, Golden Plover and Turnstone. Some species displayed additional preferences for exposed shores (Purple Sandpiper, Ringed Plover and Bar-tailed Godwit), sheltered shores (Curlew and Redshank) and wide shores (Sanderling, Purple Sandpiper, Dunlin, Bar-tailed Godwit and Turnstone). No species preferred steep shores or cliffs. Conclusions Simple habitat descriptions coupled with map-derived variables, can provide an initial insight into the habitat preferences of waders. Further work relating wader distribution to invertebrate food supplies is required.

The Utilization Prospect of Terrace Slope Land in Purple Rock Area of Middle Sichuan Basin

Terrace-slope land, referring to the side slope of terraces and the ridge of paddyfields is one of the land resources in the Sichuan Basin, China, with favorable sunlight and heat, but a limited amount of water and soil. We investigated the amount and distribution of terrace slopes in the purple rock area of the central part of the Sichuan Basin, and examined the effects of different approaches to ameliorate the soil and water conditions of terrace slopes. The results showed that the total area of terrace slopes accounted for 15% of the basin land, and that for different treatments, decrease in runoff and soil loss was in order: straw mulch > contour ridge > rye grass strip > CK and micro basin gathering.

Nectonema zealandica n. sp. (Nematomorpha: Nectonematoidea) parasitising the purple rock crab Hemigrapsus edwardsi (Brachyura: Decapoda) in New Zealand, with notes on the prevalence of infection and host defence reactions.

A new species of marine hairworm, Nectonema zealandica (Nematomorpha: Nectonematoidea), is described from the purple rock crab Hemigrapsus edwardsi Hilgendorf from the South Island, New Zealand. This is the first record of Nectonema in the South Pacific Ocean and the southernmost locality for the genus. The description is based on juveniles and pre-adults taken from crabs. The new species is characterised by its stomal structure, presence of four cephalic papillae, mesenchyme arranged in eight lobes in pre-adults, insertion of muscle layer increasing body diameter at the septum and translucent anterior chamber. Data on the prevalence of infection over a three-year period, rates of parasitism in relation to host sex and size, and host defence reactions are presented. A list of all reported hosts of nectonematids is included.

Recovery from exhausting exercise in a bimodally breathing crab, Leptograpsus variegatus (Decapoda: Grapsidae)

The acid-base status of the postbranchial haemolymph of adult purple rock crabs Leptograpsus variegatus Fabricius, 1793, was examined at 15°C after running in air on a motorized treadmill at 8.2 cm·s −1 (≈0.5 body lengths·s −1) for a mean time of 4.8 min. Serial haemolymph samples were taken from resting crabs maintained under conditions which allowed a free choice between air and seawater, in the same animals immediately after exercising to exhaustion and after 1, 4, and 24 h of recovery in either air or completely submerged in seawater. Activity produced a marked haemolymph acidosis (0.4 pH units) which had both respiratory and metabolic components. Haemolymph [lactate −] increased by ≈8 mmol·1 −1 immediately post-exercise and had risen slightly more after 1 h's recovery in water and in air. Excess lactate was cleared with a half-time of ≈6.5 h. Despite the slow lactate clearance, restoration of pH commenced within 1 h in both groups and was nearly completed at this time in the water-recovery group. After 24 h recovery in air, the acid-base status of the haemolymph was essentially similar to the pre-exercise state with respect to pH, [lactate −], total CO 2, P co 2 (calc), [Ca 2+],and osmolarity. However, after 24 h recovery in seawater, total CO 2 and P co 2 (calc) were lower than pre-exercise values and a small respiratory alkalosis appeared. This indicates that, when given a choice of media, adults of this crab adopt an essentially aerial respiratory and acid-base status. Compared with Cyclograpsus lavauxi, another New Zealand high-shore grapsid, L. variegatus appears better able to deal with disturbances of acid-base state associated with aerial activity and can restore haemolymph pH without return to water.